Formation of lacustrine plains in west-central Alaska as a result of permafrost degradation and aggradation

NASA Astrophysics Data System (ADS)

Kanevskiy, M. Z.; Jorgenson, M. T.; Shur, Y.; O'Donnell, J.; Harden, J. W.; Fortier, D.

2012-12-01

Perennially frozen lacustrine sediments containing a large amount of ground ice comprise a significant part of the upper permafrost of the lowlands of west-central Alaska, including Koyukuk Flats and Innoko Flats. Study sites are located in the discontinuous permafrost zone, where permafrost was encountered mainly within uplifted peat plateaus. The upper part of studied sections is formed by frozen peat up to 3 m thick underlain by lacustrine silt, which is mostly ice-rich. Cryogenic structure of lacustrine sediments at different sites has common features: (1) prevalence of layered, braided, and reticulate cryostructures; (2) high variability in the ice content of sediments; (3) high density and low water content of soil aggregates separated by ice lenses. Volume of visible ice in silt reaches at places 40% and more. The thickness of ice lenses generally varies from 1 to 5 cm and occasionally reaches 10 cm. Remnants of peat plateaus are surrounded by unfrozen bogs and fens, formed as a result of thawing and settling of ice-rich lacustrine silt. Modern thermokarst scars initially form at places where ice-rich silt is not protected by a thick layer of organic material. Further development of thermokarst bogs includes lateral enlargement of thaw bulbs and collapsing of the margins of peat plateaus. Lacustrine silt within taliks is covered by woody peat accumulated under forests during the stage of permafrost plateau formation and then by aquatic sphagnum peat accumulated in taliks after collapse. We relate the formation of ice-rich lacustrine sediments to development of lake thermokarst, which affected ice-rich silty yedoma deposits during the transition from Pleistocene to Holocene. Terrain development in lacustrine lowlands of west-central Alaska includes five stages related to permafrost aggradation and degradation from the late Pleistocene to the present time: 1) formation of the ice-rich syngenetic permafrost (yedoma) during the late Pleistocene; 2) yedoma degradation in the yearly Holocene and formation of thaw lakes; 3) complete yedoma degradation under thaw lakes and refreezing of thawed sediments at elevated areas; 4) peat accumulation and freezing of sediments in thaw lake basins; and 5) new cycle of thermokarst and formation of taliks under thaw lakes, bogs and fens. Stages of terrain development of lacustrine lowlands since the Late Pleistocene

Mediterranean Outflow and surface water variability off southern Portugal during the early Pleistocene: A snapshot at Marine Isotope Stages 29 to 34 (1020-1135 ka)

NASA Astrophysics Data System (ADS)

Voelker, Antje H. L.; Salgueiro, Emilia; Rodrigues, Teresa; Jimenez-Espejo, Francisco J.; Bahr, André; Alberto, Ana; Loureiro, Isabel; Padilha, Maria; Rebotim, Andreia; Röhl, Ursula

2015-10-01

Centennial-to-millennial scale records from IODP Site U1387, drilled during IODP Expedition 339 into the Faro Drift at 558 m water depth, now allow evaluating the climatic history of the upper core of the Mediterranean Outflow (MOW) and of the surface waters in the northern Gulf of Cadiz during the early Pleistocene. This study focuses on the period from Marine Isotope Stages (MIS) 29 to 34, i.e. the interval surrounding extreme interglacial MIS 31. Conditions in the upper MOW reflect obliquity, precession and millennial-scale variations. The benthic δ18O signal follows obliquity with the exception of an additional, smaller δ18O peak that marks the MIS 32/31 transition. Insolation maxima (precession minima) led to poor ventilation and a sluggish upper MOW core, whereas insolation minima were associated with enhanced ventilation and often also increased bottom current velocity. Millennial-scale periods of colder sea-surface temperatures (SST) were associated with short-term maxima in flow velocity and better ventilation, reminiscent of conditions known from MIS 3. A prominent contourite layer, coinciding with insolation cycle 100, was formed during MIS 31 and represents one of the few contourites developing within an interglacial period. MIS 31 surface water conditions were characterized by an extended period (1065-1091 ka) of warm SST, but SST were not much warmer than during MIS 33. Interglacial to glacial transitions experienced 2 to 3 stadial/interstadial cycles, just like their mid-to-late Pleistocene counterparts. Glacial MIS 30 and 32 recorded periods of extremely cold (< 12 °C) SST that in their climatic impact were comparable with the Heinrich events of the mid and late Pleistocene. Glacial MIS 34, on the other hand, was a relative warm glacial period off southern Portugal. Overall, surface water and MOW conditions at Site U1387 show a strong congruence with Mediterranean climate, whereas millennial-scale variations are closely linked to North Atlantic circulation changes.

Sedimentary evolution of the Pliocene and Pleistocene Ebro margin, northeastern Spain

USGS Publications Warehouse

Alonso, B.; Field, M.E.; Gardner, J.V.; Maldonado, A.

1990-01-01

The Pliocene and Pleistocene deposits of the Spanish Ebro margin overlie a regional unconformity and contain a major disconformity. These unconformities, named Reflector M and Reflector G, mark the bases of two seismic sequences. Except for close to the upper boundary where a few small channel deposits are recognized, the lower sequence lacks channels. The upper sequence contains nine channel-levee complexes as well as base-of-slope aprons that represent the proximal part of the Valencia turbidite system. Diverse geometries and variations in seismic units distinguish shelf, slope, base-of-slope and basin-floor facies. Four events characterize the late Miocene to Pleistocene evolution of the Ebro margin: (a) formation of a paleodrainage system and an extensive erosion-to-depositional surface during the latest Miocene (Messinian), (b) deposition of hemipelagic units during the early Pliocene, (c) development of canyons during the late Pliocene to early Pleistocene, and (d) deposition of slope wedges, channel-levee complexes, and base-of-slope aprons alternating with hemipelagic deposition during the Pleistocene. Sea-level fluctuations influenced the evolution of the sedimentary sequences of the Ebro margin, but the major control was the sediment supply from the Ebro River. ?? 1990.

Surficial geologic map of the Red Rock Lakes area, southwest Montana

USGS Publications Warehouse

Pierce, Kenneth L.; Chesley-Preston, Tara L.; Sojda, Richard L.

2014-01-01

The Centennial Valley and Centennial Range continue to be formed by ongoing displacement on the Centennial fault. The dominant fault movement is downward, creating space in the valley for lakes and the deposition of sediment. The Centennial Valley originally drained to the northeast through a canyon now represented by a chain of lakes starting with Elk Lake. Subsequently, large landslides blocked and dammed the drainage, which created Lake Centennial, in the Centennial Valley. Sediments deposited in this late Pleistocene lake underlie much of the valley floor and rest on permeable sand and gravel deposited when the valley drained to the northeast. Cold Pleistocene climates enhanced colluvial supply of gravelly sediment to mountain streams and high peak flows carried gravelly sediment into the valley. There, the lower gradient of the streams resulted in deposition of alluvial fans peripheral to Lake Centennial as the lake lowered through time to the level of the two present lakes. Pleistocene glaciers formed in the high Centennial Range, built glacial moraines, and also supplied glacial outwash to the alluvial fans. Winds from the west and south blew sand to the northeast side of the valley building up high dunes. The central part of the map area is flat, sloping to the west by only 0.6 meters in 13 kilometers (2 feet in 8 miles) to form a watery lowland. This lowland contains Upper and Lower Red Rock Lakes, many ponds, and peat lands inside the “water plane,” above which are somewhat steeper slopes. The permeable sands and gravels beneath Lake Centennial sediments provide a path for groundwater recharged from the adjacent uplands. This groundwater leaks upward through Lake Centennial sediments and sustains wetland vegetation into late summer. Upper and Lower Red Rock Lakes are formed by alluvial-fan dams. Alluvial fans converge from both the south and the north to form outlet thresholds that dam the two shallow lakes upstream. The surficial geology aids in understanding how the landscapes in and around the Red Rock Lakes Wildlife Refuge were formed and how they transmit water. This report uses metric units except for altitudes that are also given in feet because contours on the base map are in feet and the reader would have to convert from metric units to feet to understand the map relationships.

The Phosphates of Pleistocene-Holocene Sediments of the Eastern Gallery of Denisova Cave

NASA Astrophysics Data System (ADS)

Shunkov, M. V.; Kulik, N. A.; Kozlikin, M. B.; Sokol, E. V.; Miroshnichenko, L. V.; Ulianov, V. A.

2018-01-01

Authigenic phosphate mineralization was first studied on the territory of Russia on the basis of the Holocene and Pleistocene deposits of Denisova Cave. The formation of phosphates in the eastern gallery is related to biodegradation of the horizons of guano of insectivorous bats, which inhabited the cave in the absence man. The results confirmed the archaeological record of the Holocene and the upper part of Pleistocene sequences of the eastern gallery.

Historic Settlement in the Upper Tombigbee Valley.

DTIC Science & Technology

1981-02-28

dI~bibiitioni IS UnA ted. SECURITY CLASSIFICATION OF THIS AGE (When De i En ered) REPORT DOCUMENTATION PAGE READ ISTRUCTIONS BEFOR E COMPLETING FORM...V ag TE1.1ESS E, T0 11B I BEE VATE--4A FIG 1 TH RUT OFTH TENES- TNBGE WAE-AY 5"~~’C~/ J cultural geographers. Although the specific problems which...of sand, sandstone, clay, and clay stone. The superficial deposits of Pleistocene and Holocene ages consist of clay, sand, and gravel deposited by

Geologic map of the Weldona 7.5' quadrangle, Morgan County, Colorado

USGS Publications Warehouse

Berry, Margaret E.; Taylor, Emily M.; Slate, Janet L.; Paces, James B.; Hanson, Paul R.; Brandt, Theodore R.

2018-03-21

The Weldona 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The South Platte River, originating high in the Colorado Rocky Mountains, has played a major role in shaping surficial geology in the map area, which is several tens of kilometers downstream from where headwater tributaries join the river. Recurrent glaciation (and deglaciation) of basin headwaters has affected river discharge and sediment supply far downstream, influencing deposition of alluvium and river incision in the Weldona quadrangle. During the Pleistocene the course of the river within the map area shifted progressively southward as it incised, and by late middle Pleistocene the river was south of its present position, cutting and filling deep paleochannels now covered by younger alluvium. The river shifted back to the north during the late Pleistocene. Kiowa and Bijou Creeks are unglaciated tributaries originating in the Colorado Piedmont east of the Front Range that also have played a major role in shaping surficial geology of the map area. Periodically during the late Pleistocene, major flood events on these tributaries deposited large volumes of sediment at their confluences, forming a broad, low-gradient fan of sidestream alluvium that could have occasionally dammed the river for short periods of time. Eolian sand deposits of the Sterling (north of river) and Fort Morgan (south of river) dune fields cover much of the quadrangle and record past episodes of sand mobilization during times of prolonged drought. With the onset of irrigation and damming during historical times, the South Platte River has changed from a broad, shallow, and sandy braided river with highly variable seasonal discharge to a much narrower, deeper river with braided-meandering transition morphology and more uniform discharge.

The survival environment of Mammuthus-Coelodonta Fauna in Qinggang, Heilongjiang Province, NE China

NASA Astrophysics Data System (ADS)

Zhao, K.

2017-12-01

The disappearance of world's megafaunal mammal taxa during the late Upper Pleistocene is the subject of considerable scientific interest. Until now, there are still controversy about the environmental background and influence mechanism of the extinction. Northeast of China possesses abundant Mammuthus-Coelodonta Fauna fossil in the Upper Pleistocene sediment, which is an ideal region for the exploration of survival background and disappearance process of megafauna. Qinggang County, Heilongjiang Province is famous for unearthing of Mammuthus primigenius. In this study, we use the pollen records from Yingxiancun section, Qingggang County to reconstruct the survival environment of Mammuthus-Coelodonta Fauna in the area. Our study shows that mammal fossils are found in the lacustrine sediment which belongs to the Gunxiangtun formation in NE China. The vegetation types in the environment are mainly Artemisia, Compositae, Gramineae, Cyperaceae accompanied by few Picea. The pollen assemblages indicate the area was covered by meadow with few conifer forests. As a whole, the vegetation types in Qinggang belong to the Mammoth steppe during Upper Pleistocene in the Eurasian.

Inner tooth morphology of Homo erectus from Zhoukoudian. New evidence from an old collection housed at Uppsala University, Sweden.

PubMed

Zanolli, Clément; Pan, Lei; Dumoncel, Jean; Kullmer, Ottmar; Kundrát, Martin; Liu, Wu; Macchiarelli, Roberto; Mancini, Lucia; Schrenk, Friedemann; Tuniz, Claudio

2018-03-01

Locality 1, in the Lower Cave of the Zhoukoudian cave complex, China, is one of the most important Middle Pleistocene paleoanthropological and archaeological sites worldwide, with the remains of c. 45 Homo erectus individuals, 98 mammalian taxa, and thousands of lithic tools recovered. Most of the material collected before World War II was lost. However, besides two postcranial elements rediscovered in China in 1951, four human permanent teeth from the 'Dragon Bone Hill,' collected by O. Zdansky between 1921 and 1923, were at the time brought to the Paleontological Institute of Uppsala University, Sweden, where they are still stored. This small sample consists of an upper canine (PMU 25719), an upper third molar (PMU M3550), a lower third premolar crown (PMU M3549), and a lower fourth premolar (PMU M3887). Some researchers have noted the existence of morpho-dimensional differences between the Zhoukoudian and the H. erectus dental assemblage from Sangiran, Java. However, compared to its chrono-geographical distribution, the Early to Middle Pleistocene dental material currently forming the Chinese-Indonesian H. erectus hypodigm is quantitatively meager and still poorly characterized for the extent of its endostructural variation. We used micro-focus X-ray tomography techniques of virtual imaging coupled with geometric morphometrics for comparatively investigating the endostructural conformation (tissue proportions, enamel thickness distribution, enamel-dentine junction morphology, pulp cavity shape) of the four specimens stored in Uppsala, all previously reported for their outer features. The results suggest the existence of time-related differences between continental and insular Southeast Asian dental assemblages, the Middle Pleistocene Chinese teeth apparently retaining an inner signature closer to the likely primitive condition represented by the Early Pleistocene remains from Java, while the Indonesian stock evolved toward tooth structural simplification. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fault-sourced alluvial fans and their interaction with axial fluvial drainage: An example from the Plio-Pleistocene Upper Valdarno Basin (Tuscany, Italy)

NASA Astrophysics Data System (ADS)

Fidolini, Francesco; Ghinassi, Massimiliano; Aldinucci, Mauro; Billi, Paolo; Boaga, Jacopo; Deiana, Rita; Brivio, Lara

2013-05-01

The present study deals with the fault-sourced, alluvial-fan deposits of the Plio-Pleistocene Upper Valdarno Basin (Northern Apennines, Italy). Different phases of alluvial fan aggradation, progradation and backstep are discussed as possible effects of the interaction among fault-generated accommodation space, sediment supply and discharge variations affecting the axial fluvial drainage. The Upper Valdarno Basin, located about 35 km SE of Florence, is filled with 550 m palustrine, lacustrine and alluvial deposits forming four main unconformity-bounded units (i.e. synthems). The study alluvial-fan deposits belong to the two uppermost synthems (Montevarchi and Torrente Ciuffenna synthems) and are Early to Middle Pleistocene in age. These deposits are sourced from the fault-bounded, NE margin of the basin and interfinger with axial fluvial deposits. Alluvial fan deposits of the Montevarchi Synthem consist of three main intervals: i) a lower interval, which lacks any evidence of a depositional trend and testify balance between the subsidence rate (i.e. fault activity) and the amount of sediment provided from the margin; ii) a coarsening-upward middle interval, pointing to a decrease in subsidence rate associated with an augment in sediment supply; iii) a fining-upward, upper interval (locally preserved), documenting a phase of tectonic quiescence associated with a progressive re-equilibration of the tectonically-induced morphological profile. The basin-scale unconformity, which separates the Montevarchi and Torrente Ciuffenna synthems was due to the entrance of the Arno River into the basin as consequence of a piracy. This event caused a dramatic increase in water discharge of the axial fluvial system, and its consequent embanking. Such an erosional surface started to develop in the axial areas, and propagated along the main tributaries, triggering erosion of the alluvial fan deposits. Alluvial-fan deposits of the Torrente Ciuffenna Synthem accumulated above the unconformity during a phase of tectonic quiescence, and show a fining-upward depositional trend. This trend was generated by a progressive decrease in sediment supply stemming out from upstream migration of the knickpoints developed during the embanking of the axial system.

Early Pleistocene Climate in Western Arid Central Asia Inferred from Loess-Palaeosol Sequences in North Iran

NASA Astrophysics Data System (ADS)

Wang, X.; Wei, H.; Khormali, F.; Taheri, M.; Danukalova, G.; Chen, F.

2016-12-01

Arid central Asia (ACA) is one of the most arid regions in the mid-latitudes and one of the main potential dust sources for the northern hemisphere. The relatively weak study of Pleistocene loess/dust records from in situ ACA hinders our comprehensive understanding of the spatio-temporal record of aeolian loess accumulation and long term climatic changes in Asia as a whole. The northern Iran is located in the westernmost part of ACA. The precipitation here is mainly influenced by the zonal Westerlies, while the dust is mainly transported by regional westerly and northwest-northeasterly winds. Previous loess study in northern Iran demonstrate that most of the loess deposits in this region accumulated during the middle to late Pleistocene, and that the palaeosol and loess layers formed during interglacial and glacial periods, respectively. However, the Early Pleistocene loess and paleoclimate history in this key region remains porely constraints. In this work we focus on the chronology, sedimentology, and paleoclimatic records of the early Pleistocene loess-paleosol sequence in north Iran. Multi-sedimentological evidence suggests the widely distributed red-coloured silt-dominated sediments, unconformably underlying the upper Pleistocene loess successions, in north Iran are aeolian in origin. The dominance of the coarse dust component in the loess samples suggests the main body of the Iranian loess was transported predominantly by the local low-level winds from proximal source regions. Magnetostratigraphy with biostratigraphic age constraints indiciate the red-colored loess accumulated between 2.4 and 1.81 Ma, an equivalent of the Wucheng formation on the Chinese Loess Plateau. Paleoclimatic proxy incies and micromorphological evidence reveals that the climate during the early Pleistocene in the western ACA was semi-arid, but wetter, warmer, and less windy than during the late Pleistocene and present interglacial. Comparison of loess records between north Iran and the Chinese loess Plateau suggest that the orbital-scale palaeoclimatic changes in ACA are in-phase with those of monsoonal Asia, a relationship which was probably related to the growth and decay of northern hemisphere ice sheets.

Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): new archaeological and taphonomic research at BK, Upper Bed II.

PubMed

Domínguez-Rodrigo, M; Mabulla, A; Bunn, H T; Barba, R; Diez-Martín, F; Egeland, C P; Espílez, E; Egeland, A; Yravedra, J; Sánchez, P

2009-09-01

New archaeological excavations and research at BK, Upper Bed II (Olduvai Gorge, Tanzania) have yielded a rich and unbiased collection of fossil bones. These new excavations show that BK is a stratified deposit formed in a riverine setting close to an alluvial plain. The present taphonomic study reveals the second-largest collection of hominin-modified bones from Olduvai, with abundant cut marks found on most of the anatomical areas preserved. Meat and marrow exploitation is reconstructed using the taphonomic signatures left on the bones by hominins. Highly cut-marked long limb shafts, especially those of upper limb bones, suggest that hominins at BK were actively engaged in acquiring small and middle-sized animals using strategies other than passive scavenging. The exploitation of large-sized game (Pelorovis) by Lower Pleistocene hominins, as suggested by previous researchers, is supported by the present study.

Reconstructing Mid-Pleistocene paleovegetation and paleoclimate in the Golan Heights using the δ(13)C values of modern vegetation and soil organic carbon of paleosols.

PubMed

Hartman, Gideon

2011-04-01

The Golan Heights borders the Upper Jordan Valley on its eastern side and likely served as a prime foraging area for hominin groups that inhabited the Upper Jordan Valley during the Mid-Pleistocene. This study tests the hypothesis that Mid-Pleistocene climate in the Golan region was similar to that of the present day. Carbon isotope composition of present day plant communities and soil organic carbon from the Golan were compared to those of paleosols from Nahal Orvim to reconstruct Mid-Pleistocene paleoclimatic conditions. After correcting the paleosol values for recent changes in atmospheric carbon isotope values and potential biodegradation, the isotopic results show a strong similarity to those of present day local plants and soils. These results indicate that during the Mid-Pleistocene, the Golan was dominated by C(3) vegetation, shared similar climatic conditions with the present day, and displayed long-term environmental stability. The span of time of paleosol formation is unknown and might cover multiple climatic episodes; thus, although short climatic fluctuations may have occurred, their impact was not substantial enough to be detected in the Nahal Orvim paleosols. This study concludes that the Golan slopes provided hominins and large grazers with a reliable and highly nutritious foraging area that complemented the Jordan Valley riparian ecosystem. Copyright © 2010 Elsevier Ltd. All rights reserved.

A geometric morphometric analysis of hominin upper second and third molars, with particular emphasis on European Pleistocene populations.

PubMed

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2012-09-01

The study of dental morphology by means of geometric morphometric methods allows for a detailed and quantitative comparison of hominin species that is useful for taxonomic assignment and phylogenetic reconstruction. Upper second and third molars have been studied in a comprehensive sample of Plio- and Pleistocene hominins from African, Asian and European sites in order to complete our analysis of the upper postcanine dentition. Intraspecific variation in these two molars is high, but some interspecific trends can be identified. Both molars exhibit a strong reduction of the distal cusps in recent hominin species, namely European Homo heidelbergensis, Homo neanderthalensis and Homo sapiens, but this reduction shows specific patterns and proportions in the three groups. Second molars tend to show four well developed cusps in earlier hominin species and their morphology is only marginally affected by allometric effects. Third molars can be incipiently reduced in earlier species and they evince a significant allometric component, identified both inter- and intraspecifically. European Middle Pleistocene fossils from Sima de los Huesos (SH) show a very strong reduction of these two molars, even more marked than the reduction observed in Neanderthals and in modern human populations. The highly derived shape of SH molars points to an early acquisition of typical Neanderthal dental traits by pre-Neanderthal populations and to a deviation of this population from mean morphologies of other European Middle Pleistocene groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

Environmental, depositional and cultural changes in the upper Pleistocene and early Holocene; the Cinglera del Capello Sequence (Capellades, Spain)

USGS Publications Warehouse

Vaquero, Manuel; Allué, Ethel; Bischoff, James L.; Burjachs, Francesc; Vallverdú, Josep

2013-01-01

The correlation between environmental and cultural changes is one of the primary archeological and paleoanthropological research topics. Analysis of ice and marine cores has yielded a high-resolution record of millennial-scale changes during the Late Pleistocene and Holocene eras. However, cultural changes are documented in low-resolution continental deposits; thus, their correlation with the millennial-scale climatic sequence is often difficult. In this paper, we present a rare occurrence in which a thick archeological sequence is associated with a high-resolution environmental record. The Cinglera del Capello is a tufa-draped cliff located in the northeastern Iberian Peninsula, 50 km west of Barcelona. This cliff harbors several rock-shelters with Late Pleistocene and Early Holocene deposits. Together, the deposits of four rock-shelters span from 7000 to 70,000 years ago and provide a high-resolution record of the environmental and human dynamics during this timespan. This record allows the correlation of the cultural and environmental changes. The multiproxy approach to the Cinglera evidence indicates that the main cultural stages of the Late Pleistocene and Early Holocene (Middle Paleolithic, Upper Paleolithic and Mesolithic) are associated with significant changes in the environmental and depositional contexts.

Malacological and palynological evidence of the Lower Pleistocene cold phase at the Carpathian Foothills (Southern Poland)

NASA Astrophysics Data System (ADS)

Stworzewicz, Ewa; Granoszewski, Wojciech; Wójcik, Antoni

2012-05-01

Early Pleistocene sediments bearing gastropod shells and pollen flora were found during coring at Jawornik (South Poland) at a depth interval of 54.30-39.00 m, beneath the oldest till of the Carpathians. Thirteen land-snail taxa identified in 55 samples of the core formed two molluscan assemblages. In the bottom part, typical cold-loving snails were found (e.g. Vallonia tenuilabris, Pupilla loessica, Vertigo genesii, Columella columella), whereas in the upper part only Semilimax kotulae was present. The succession of molluscan assemblages may suggest that at the site of deposition, after a phase of tundra, steppe-tundra or forest-steppe landscape with patches of wet habitats in cold climate, the climate became slightly milder but still cool, favourable to the spreading of boreal (coniferous) woodlands. Pollen analysis was performed only for the upper part of the profile. The pollen spectra, besides the Tertiary (Miocene) elements, contained sporomorphs common to the Tertiary and Quaternary floras. Among them, the highest percentages were noted for Pinus haploxylon t., P. diploxylon t., Picea, Quercus, Ericaceae, Betula, and Ulmus. The fact that the sediments with organic remains underlie the oldest Scandinavian till suggests that they are older than the oldest glacial unit of the South-Polish Complex (Narevian = Menapian, ~ 1.2 Ma).

Geomorphic response to sea level and climate changes during Late Quaternary in a humid tropical coastline: Terrain evolution model from Southwest India.

PubMed

K, Maya; S, Vishnu Mohan; Limaye, Ruta B; Padmalal, Damodaran; Kumaran, Navnith K P

2017-01-01

The coastal lands of southern Kerala, SW India in the vicinity of Achankovil and Thenmala Shear Zones reveal a unique set of geomorphic features like beach ridges, runnels, chain of wetlands, lakes, estuaries, etc. The chain of wetlands and water bodies that are seen in the eastern periphery of the coastal lands indicates the remnants of the upper drainage channels of the previously existed coastal plain rivers of Late Pleistocene age that are later broadened due to coastal erosion under the transgressive phase. The terrain evolutionary model developed from the results of the study shows that the Late Pleistocene transgressive events might have carved out a major portion of the land areas drained by the coastal plain rivers and as a result the coastal cliff has been retreated several kilometers landwards. The NNE-SSW trending beach ridges located close to the inland wetlands indicate the extent of shoreline shift towards eastwards during Late Pleistocene period. The present beach parallel ridges in the younger coastal plain indicate the limit of the Mid Holocene shoreline as the transgression was not so severe compared to Late Pleistocene event. The zone of convergence of the two sets of beach ridges coincides with the areas of economically viable heavy mineral placers that resulted from the size and density based sorting under the repeated transgressive events to which the coast had subjected to. The chain of wetlands in the eastern side of the study area has been evolved from a mega lagoon existed during Late Pleistocene. The Pallikkal River that links discrete eastern wetland bodies has been evolved into its present form during Early Holocene.

Geomorphic response to sea level and climate changes during Late Quaternary in a humid tropical coastline: Terrain evolution model from Southwest India

PubMed Central

K., Maya; S., Vishnu Mohan; Limaye, Ruta B.; Padmalal, Damodaran

2017-01-01

The coastal lands of southern Kerala, SW India in the vicinity of Achankovil and Thenmala Shear Zones reveal a unique set of geomorphic features like beach ridges, runnels, chain of wetlands, lakes, estuaries, etc. The chain of wetlands and water bodies that are seen in the eastern periphery of the coastal lands indicates the remnants of the upper drainage channels of the previously existed coastal plain rivers of Late Pleistocene age that are later broadened due to coastal erosion under the transgressive phase. The terrain evolutionary model developed from the results of the study shows that the Late Pleistocene transgressive events might have carved out a major portion of the land areas drained by the coastal plain rivers and as a result the coastal cliff has been retreated several kilometers landwards. The NNE—SSW trending beach ridges located close to the inland wetlands indicate the extent of shoreline shift towards eastwards during Late Pleistocene period. The present beach parallel ridges in the younger coastal plain indicate the limit of the Mid Holocene shoreline as the transgression was not so severe compared to Late Pleistocene event. The zone of convergence of the two sets of beach ridges coincides with the areas of economically viable heavy mineral placers that resulted from the size and density based sorting under the repeated transgressive events to which the coast had subjected to. The chain of wetlands in the eastern side of the study area has been evolved from a mega lagoon existed during Late Pleistocene. The Pallikkal River that links discrete eastern wetland bodies has been evolved into its present form during Early Holocene. PMID:28467465

Stratigraphy and hydrologic conditions at the Brookhaven National Laboratory and vicinity, Suffolk County, New York, 1994-97

USGS Publications Warehouse

Scorca, Michael P.; Dorsch, William R.; Paquette, Douglas E.

1999-01-01

Brookhaven National Laboratory (BNL) has installed many test borings as part of an effort to delineate the extent of ground-water contamination at the site. In 1994, the U.S. Geological Survey began a study in cooperation with BNL to define the stratigraphy in the 28-square-mile area encompassing BNL, and to monitor ground-water levels in the 300 squaremile area of central Suffolk County that surrounds BNL. The uppermost geologic units at BNL are of Pleistocene age. These sediments are underlain unconformably by the Matawan Group-Magothy Formation, undifferentiated (referred to as the Magothy Formation), of Cretaceous age, which typically consists of light- to dark-gray, variably sorted sand interbedded with light- to dark-gray clay layers; it also contains beds of grayish-brown to brownish-gray sand. Bed thicknesses differ substantially within each boring and tend to be laterally discontinuous as a result of their terrestrial deltaic depositional environment, although a prominent clay unit, referred to as the ?grayish-brown clay? in this report, was encountered at many borings. Pollen-sample analyses confirm that this unit is of Cretaceous age and is the uppermost unit of Cretaceous sediments in several parts of the study area. The upper surface of the Cretaceous deposits is irregular within the 28-square-mile study area and has relief of about 120 feet. Several prominent channels and ridges in the surface are aligned generally northwest-southeast. The Cretaceous surface beneath BNL is characterized more by local erosional features than by the regional cuesta shape that was suggested by previous authors. The overlying Pleistocene-aged units include (1) a sand layer overlain by the Gardiners Clay, (2) the Gardiners Clay, and (3) upper Pleistocene deposits, which include the Upton unit, glacial outwash, glaciolacustrine deposits, and terminal moraine deposits. The sand unit below the Gardiners Clay was the first Pleistocene unit to be deposited atop the irregular surface of the Cretaceous deposits in this area. The Gardiners Clay was deposited during a major rise in sea level as the sea encroached into parts of the present-day BNL study area. The shallow part of the upper Pleistocene deposits generally consists of light-brown sand and gravel but overlies green to grayish-green, variably sorted sand, silt, and clay at altitudes of 50 to 70 feet below sea level in some parts of the study area. This lower part of the upper Pleistocene deposits in the study area was referred to by previous investigators as the unidentified unit and has been designated as the Upton unit in this report. The discharge of ground water to the Peconic and Carmans Rivers locally affects the water-table configuration. The main ground-water divide on Long Island is about 0.5 miles north of the site; a secondary divide originates near the start of flow of the Peconic River and extends east-southeastward toward the South Fork. The water-table configuration on the BNL site is affected by pumping from supply wells and remediation wells, by infiltration of the water through recharge basins, by discharge from the sewage-treatment plant, and by local near-surface clay units. The horizontal hydraulic gradient at BNL typically is 0.001 foot per foot but can steepen near recharge basins and pumping wells. Vertical flow gradients within the upper Pleistocene deposits (upper glacial aquifer) were as large as 0.007 foot per foot (downward) in the northern part of BNL and were negligible in the southern part. Downward vertical gradients between the lower part of the upper glacial aquifer and the upper part of the Magothy Formation (Magothy aquifer) were about 0.018 foot per foot throughout the site.

Paleobotanical analysis of materials from fossil gopher burrows and upper pleistocene host deposits, the Kolyma River lower reaches

NASA Astrophysics Data System (ADS)

Lopatina, D. A.; Zanina, O. G.

2006-10-01

The comparative analysis of palynomorphs and plant megafossils (fruits, seeds, twigs, leaves) in the Upper Pleistocene host sediments and materials filling in fossil burrows of gophers, their coprolites included, at the Duvannyi Yar, Stanchikovskii Yar and Zelenyi Mys sites of the Kolyma Lowland is carried out. Genera Salix, Lychnis, Silene, Draba, Potentilla, Larix, and families Poaceae, Polygonaceae, Cyperaceae, Compositae, and Leguminosae are determined among palynological remains and megafossils. Factors responsible for qualitative and quantitative differences in taxonomic compositions of palynological and megafossil assemblages are biological peculiarities of plants, different character of fossilization of palynomorphs and large plant remains, geographic conditions, different genesis of assemblages (allochthonous for microfossils and autochthonous for megafossils), and inadequately known morphology of certain spore and pollen taxa. The comprehensive paleobotanical analysis leads to the conclusion that the study region was occupied in the Late Pleistocene by plant communities of humid to somewhat dryer tundra with separate areas of pioneering and steppe vegetation.

Evidences of Pleistocene tectonic deformations along the SE border of the Upper Rhine Graben (Freiburg area, Germany)

NASA Astrophysics Data System (ADS)

Brüstle, A.; Nivière, B.; Bertrand, G.; Gourry, J. C.; Carretier, S.; Fracassi, U.; Winter, T.

2003-04-01

The Upper Rhine Graben (URG) is a NNE-trending continental rift that was mostly active from Upper Eocene to Lower Miocene. However, the relatively well-preserved topography of its shoulders, at the scale of the whole basin, suggests a Pleistocene reactivation of its borders. We evaluate here such a possibility along its SE border, in the vincinity of Freiburg (Germany). Despite a continuous but diffuse seismic activity, evidences of near-surface deformations are not yet described. We coupled at the regional and local scales a multi-disciplinary approach, including morphological and geological analyses, to identify the markers of an assumed Pleistocene deformation. The imagery analysis reveals that the Oligocene structural pattern is yet well-marked in the topography by continuous escarpments, few tenth of kilometers long and from 20--30 to 300--500 m high. The correlation of boreholes allowed us to build isohypse and isopach maps of the Quaternary deposits and to propose a river system evolution scenario for the Quaternary. More interesting are the local depocenters located above the hanging wall of the faults and suggesting a Pleistocene tectonic reactivation. Thus, a minimum Pleistocene vertical offset of about 30 m can be illustrated above the main border fault. We then focused on the western Rhine river fault where very young deposits are suspected to have recorded a wechselian deformation. The morphological aspect of the scarp (location above the structural fault, linearity and continuity of the scarp, topographic tilting and presence of hanging valleys...), borehole data and electric tomography survey realized across the scarplet, located at toe of the main scarp, testify of a possible deformation. In particular, a ˜15 m vertical offset of the Wechselian deposits is illustrated in two localities, along the fault, where trenching will be performed in a near future to validate the ages of deformed deposits and obtain information on the strain scenario.

Cover beds older than the mid-pleistocene revolution and the provenance of their eolian components, La Sal Mountains, Utah, USA

NASA Astrophysics Data System (ADS)

Krautz, Jana; Gärtner, Andreas; Hofmann, Mandy; Linnemann, Ulf; Kleber, Arno

2018-04-01

We used uranium-lead (U-Pb) dating of zircons from a tephra layer deposited in the La Sal Mountains to assign an age of more than c. 1.3 Ma to underlying loess-mixed slope deposits (cover beds) and paleosols developed therein. For the first time, we show that properties of cover beds and soils before the Mid-Pleistocene Revolution were similar to those formed after the revolution. However, the deepest exposed carbonate-enriched horizon is much farther developed than younger ones, indicating that there was a period of enrichment by far exceeding intensities of younger calcic horizons some time before the revolution, possibly in Neogene times. Remarkable differences between age distributions of detrital zircons (DZ) within the cover beds allow reconstructing the regional provenance of mixed eolian matter with high accuracy: we were able to trace particular cover beds back to areas with outcropping Permian and Upper Cretaceous rocks.

Nimrod Lake, An Archeological Survey of a Reservoir Drawdown.

DTIC Science & Technology

1978-01-01

nomadic bands hunted late Pleistocene megafauna (e.g., mammoths, mastodons, bison and smaller game) and also gathered wild plant foods. The most...primary exploitation of Pleistocene megafauna , in particular the bison, to subsistence strategies exercising more variation in faunal and floral...a- the upper end of the reservoir where the reservoir is confined to the river channel and the gradient is much steeper, other factors in addition to

External auditory exostoses in the Xuchang and Xujiayao human remains: Patterns and implications among eastern Eurasian Middle and Late Pleistocene crania

PubMed Central

2017-01-01

In the context of Middle and Late Pleistocene eastern Eurasian human crania, the external auditory exostoses (EAE) of the late archaic Xuchang 1 and 2 and the Xujiayao 15 early Late Pleistocene human temporal bones are described. Xujiayao 15 has small EAE (Grade 1), Xuchang 1 presents bilateral medium EAE (Grade 2), and Xuchang 2 exhibits bilaterally large EAE (Grade 3), especially on the right side. These cranial remains join the other eastern Eurasian later Pleistocene humans in providing frequencies of 61% (N = 18) and 58% (N = 12) respectively for archaic and early modern human samples. These values are near the upper limits of recent human frequencies, and they imply frequent aquatic exposure among these Pleistocene humans. In addition, the medial extents of the Xuchang 1 and 2 EAE would have impinged on their tympanic membranes, and the large EAE of Xuchang 2 would have resulted in cerumen impaction. Both effects would have produced conductive hearing loss, a serious impairment in a Pleistocene foraging context. PMID:29232394

External auditory exostoses in the Xuchang and Xujiayao human remains: Patterns and implications among eastern Eurasian Middle and Late Pleistocene crania.

PubMed

Trinkaus, Erik; Wu, Xiu-Jie

2017-01-01

In the context of Middle and Late Pleistocene eastern Eurasian human crania, the external auditory exostoses (EAE) of the late archaic Xuchang 1 and 2 and the Xujiayao 15 early Late Pleistocene human temporal bones are described. Xujiayao 15 has small EAE (Grade 1), Xuchang 1 presents bilateral medium EAE (Grade 2), and Xuchang 2 exhibits bilaterally large EAE (Grade 3), especially on the right side. These cranial remains join the other eastern Eurasian later Pleistocene humans in providing frequencies of 61% (N = 18) and 58% (N = 12) respectively for archaic and early modern human samples. These values are near the upper limits of recent human frequencies, and they imply frequent aquatic exposure among these Pleistocene humans. In addition, the medial extents of the Xuchang 1 and 2 EAE would have impinged on their tympanic membranes, and the large EAE of Xuchang 2 would have resulted in cerumen impaction. Both effects would have produced conductive hearing loss, a serious impairment in a Pleistocene foraging context.

Integrated sequence stratigraphy of the postimpact sediments from the Eyreville core holes, Chesapeake Bay impact structure inner basin

USGS Publications Warehouse

Browning, J.V.; Miller, K.G.; McLaughlin, P.P.; Edwards, L.E.; Kulpecz, A.A.; Powars, D.S.; Wade, B.S.; Feigenson, M.D.; Wright, J.D.

2009-01-01

The Eyreville core holes provide the first continuously cored record of postimpact sequences from within the deepest part of the central Chesapeake Bay impact crater. We analyzed the upper Eocene to Pliocene postimpact sediments from the Eyreville A and C core holes for lithology (semiquantitative measurements of grain size and composition), sequence stratigraphy, and chronostratigraphy. Age is based primarily on Sr isotope stratigraphy supplemented by biostratigraphy (dinocysts, nannofossils, and planktonic foraminifers); age resolution is approximately ??0.5 Ma for early Miocene sequences and approximately ??1.0 Ma for younger and older sequences. Eocene-lower Miocene sequences are subtle, upper middle to lower upper Miocene sequences are more clearly distinguished, and upper Miocene- Pliocene sequences display a distinct facies pattern within sequences. We recognize two upper Eocene, two Oligocene, nine Miocene, three Pliocene, and one Pleistocene sequence and correlate them with those in New Jersey and Delaware. The upper Eocene through Pleistocene strata at Eyreville record changes from: (1) rapidly deposited, extremely fi ne-grained Eocene strata that probably represent two sequences deposited in a deep (>200 m) basin; to (2) highly dissected Oligocene (two very thin sequences) to lower Miocene (three thin sequences) with a long hiatus; to (3) a thick, rapidly deposited (43-73 m/Ma), very fi ne-grained, biosiliceous middle Miocene (16.5-14 Ma) section divided into three sequences (V5-V3) deposited in middle neritic paleoenvironments; to (4) a 4.5-Ma-long hiatus (12.8-8.3 Ma); to (5) sandy, shelly upper Miocene to Pliocene strata (8.3-2.0 Ma) divided into six sequences deposited in shelf and shoreface environments; and, last, to (6) a sandy middle Pleistocene paralic sequence (~400 ka). The Eyreville cores thus record the fi lling of a deep impact-generated basin where the timing of sequence boundaries is heavily infl uenced by eustasy. ?? 2009 The Geological Society of America.

Investigating the effects of Pleistocene events on genetic divergence within Richardsonius balteatus, a widely distributed western North American minnow

PubMed Central

2014-01-01

Background Biogeographers seek to understand the influences of global climate shifts and geologic changes to the landscape on the ecology and evolution of organisms. Across both longer and shorter timeframes, the western North American landscape has experienced dynamic transformations related to various geologic processes and climatic oscillations, including events as recently as the Last Glacial Maximum (LGM; ~20 Ka) that have impacted the evolution of the North American biota. Redside shiner is a cyprinid species that is widely distributed throughout western North America. The species’ native range includes several well-documented Pleistocene refugia. Here we use mitochondrial DNA sequence data to assess phylogeography, and to test two biogeographic hypotheses regarding post-glacial colonization by redside shiner: 1) Redside shiner entered the Bonneville Basin at the time of the Bonneville Flood (Late Pleistocene; 14.5 Ka), and 2) redside shiner colonized British Columbia post-glacially from a single refugium in the Upper Columbia River drainage. Results Genetic diversification in redside shiner began in the mid to late Pleistocene, but was not associated with LGM. Different clades of redside shiner were distributed in multiple glacial age refugia, and each clade retains a signature of population expansion, with clades having secondary contact in some areas. Conclusions Divergence times between redside shiner populations in the Bonneville Basin and the Upper Snake/Columbia River drainage precedes the Bonneville Flood, thus it is unlikely that redside shiner invaded the Bonneville Basin during this flooding event. All but one British Columbia population of redside shiner are associated with the Upper Columbia River drainage with the lone exception being a population near the coast, suggesting that the province as a whole was colonized from multiple refugia, but the inland British Columbia redside shiner populations are affiliated with a refugium in the Upper Columbia River drainage. PMID:24885371

Timing and origin for sand dunes in the Green River Lowland of Illinois, upper Mississippi River Valley, USA

USGS Publications Warehouse

Miao, X.; Hanson, P.R.; Wang, Hongfang; Young, A.R.

2010-01-01

The recent increase in dune studies in North America has been heavily focused in the Great Plains, while less attention has historically been given to the dune fields east of the Mississippi River. Here we report ages and suggest a potential sediment source for sand dunes in the Green River Lowland, Illinois, which may provide a better understanding of the dynamic interactions between eolian, glacial, lacustrine and fluvial processes that shaped the landscapes of the upper Midwest. Seven coherent optically stimulated luminescence ages (OSL, or optical ages) obtained from four sites suggest that major dune construction in the Green River Lowland occurred within a narrow time window around 17,500 ago. This implies either an enhanced aridity or an episodic increase of sediment supply at 17,500 years ago, or combination of the both. Contrary to previous assertions that dune sand was sourced from the deflation of the underlying outwash sand deposited when the Lake Michigan Lobe retreated from the area, we propose that Green River Lowland dunes sand originated from the Green Bay Lobe through the Rock River. Specifically, sediment supply increased in the Rock River valley during drainage of Glacial Lake Scuppernong, which formed between ???18,000 and 17,000 years ago, when the Green Bay Lobe retreated from its terminal moraine. The lake drained catastrophically through the Rock River valley, providing glacial sediment and water to erode the preexisting sandy sediments. Throughout the remainder of the late Pleistocene, the Laurentide Ice Sheet drained into larger more northerly glacial lakes that in turn drained through other river valleys. Therefore, the dunes in the Green River Lowland formed only during the catastrophic drainage of Glacial Lake Scuppernong, but were stabilized through the remainder of the Pleistocene. This scenario explains the abrupt dune construction around 17,500 years ago, and explains the lack of later dune activity up to the Pleistocene-Holocene transition. OSL and radiocarbon ages also indicate that dunes were reactivated during the early, middle and late Holocene. Some eolian activation occurred within well-defined dry intervals in the upper Midwest, suggesting that increased aridity may have been the primary driver in mobilizing sand. However, many ages do not correspond to drier periods. In contrast to the relative coherency of the Pleistocene OSL ages from multiple study sites, the Holocene OSL ages do not overlap from one site to another, suggesting that increased aridity alone cannot explain the multiple phases of dune reactivation in the Holocene. Therefore, we conclude that the combined effect of localized disturbances and greater aridity acted in concert to increase eolian sand activity in the Holocene. The multiple periods of eolian activity during the Holocene suggest a high potential for future sand activation in the region, and these results are informative for environmental prediction and potential future mitigation.

Hydrologic framework of Long Island, New York

USGS Publications Warehouse

Smolensky, Douglas A.; Buxton, Herbert T.; Shernoff, Peter K.

1990-01-01

Long Island, N.Y., is underlain by a mass of unconsolidated geologic deposits of clay, silt, sand, and gravel that overlie southward-sloping consolidated bedrock. These deposits are thinnest in northern Queens County (northwestern Long Island), where bedrock crops out, and increase to a maximum thickness of 2,000 ft in southeastern Long Island. This sequence of unconsolidated deposits consists of several distinct geologic units ranging in age from late Cretaceous through Pleistocene, with some recent deposits near shores and streams. These units are differentiated by age, depositional environment, and lithology in table 1. Investigations of ground-water availability and flow patterns may require information on the internal geometry of the hydrologic system that geologic correlations and interpretation alone cannot provide; hydrologic interpretations in which deposits are differentiated on the basis of water-transmitting properties are generally needed also. This set of maps and vertical sections depicts the hydrogeologic framework of the unconsolidated deposits that form Long Island's ground-water system. These deposits can be classified into eight major hydrogeologic units (table 1). The hydrogeologic interpretations presented herein are not everywhere consistent with strict geologic interpretation owing to facies changes and local variations in the water-transmitting properties within geologic units. These maps depict the upper-surface altitude of seven of the eight hydrogeologic units, which, in ascending order, are: consolidated bedrock, Lloyd aquifer, Raritan confining unit, Magothy aquifer, Monmouth greensand, Jameco aquifer, and Gardiners Clay. The upper glacial aquifer—the uppermost unit—is at land surface over most of Long Island and is, therefore, not included. The nine north-south hydrogeologic sections shown below depict the entire sequence of unconsolidated deposits and, together with the maps, provide a detailed three-dimensional interpretation of Long Island's hydrogeologic framework. The structure-contour map that shows the upper-surface altitude of the Cretaceous deposits is included to illustrate the erosional unconformity between the Cretaceous and overlying Pleistocene deposits. Pleistocene erosion played a major role in determining the shape and extent of the Lloyd aquifer, the Raritan confining unit, and the Magothy aquifer, and thus partly determined their hydrogeologic relation with subsequent (post-Cretaceous) deposits.

Geologic model of a small, intraslope basin: Garden Banks 72 field, offshore Louisiana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolb, R.A.; Tuller, J.N.; Link, M.H.

1989-03-01

Garden Banks 72 field is 115 mi off the Louisiana coast and lies near the shelf-slope break in water depths ranging from 450 to 800 ft. During the middle Pleistocene, the area was the site of a small, restricted basin on the upper slope, into which turbidite sandstones were deposited. These sandstones have been slumped, uplifted, and faulted, forming oil and gas traps in the field. Mobil and partners AGIP and Kerr-McGee leased block 72 in 1984. Three wells and two sidetracks have been drilled, discovering oil and gas in middle Pleistocene sandstones. A total of 650 ft of coremore » was cut in two wells. Geologic data in the block have been supplemented by 2-D and 3-D seismic surveys. Trapping mechanisms in the field are both structural and stratigraphic. The structural high is on the southwest flank of a northwest-southeast-trending shale/salt ridge. The middle Pleistocene reservoir sandstones trend northeast, and their seismic signature consists of discontinuous, hummocky reflections; the presence of hydrocarbons in these sandstones causes anomalous seismic responses. Amplitude terminations often cross structural contours, implying stratigraphic pinch-outs. Data from electric logs, seismic, and cores demonstrate that the middle Pleistocene reservoir sandstones are the result of deposition by turbidites into a small, restricted basin. Associated facies identified include channels, levees, and possible sheet (lobe) sandstones. Postdepositional activity has included slumping and reworking by bottom currents (contour currents ). The resulting depositional model for this field can be applied to many of the recent discoveries in the Flexure trend.« less

Rangewide glaciation in the Sierra Nevada, California

USGS Publications Warehouse

Moore, James G.; Moring, Barry C.

2013-01-01

The 600-km-long Sierra Nevada underwent extensive Pleistocene glaciation except for its southernmost 100 km. Presently, ∼1700 small glaciers and ice masses near the crest of the range occur above 3250 m in elevation; these covered an area of ∼50 km2 in 1972. Fourteen of the largest glaciers decreased by about one half in area during the period from 1900 to 2004.Rock glaciers, generally glacial ice covered by 1–10 m of rockfall debris, occur in about the same span of the range as ice and permanent snowfields. They are, on average, lower by 200–300 m, apparently because of the insulating layer of rocky rubble that protects their internal ice from the sun’s heat and from wind.The principal Pleistocene glacial stages are the Sherwin (ca. 820 ka), Tahoe (170–130 and ca. 70 ka), Tioga (14–28 ka), and Recess Peak (13 ka). Some 7040 glacial lakes, produced primarily by quarrying from bedrock, were mostly exposed after recession of the Tioga glacial stage. The lakes largely mark the area of primary snow accumulation. Below the lower limit of the lakes, ice flowed downward into river-cut canyons, forming major trunk glaciers within the zone of ablation.The range is in general a westward-tilted block upfaulted on its east side. Therefore, the main late Pleistocene trunk glaciers (Tahoe/Tioga) west of the crest extend 25–60 km, whereas those east of the crest extend only 5–20 km. Because of higher precipitation northward, glacial features such as the toes of existing glaciers and rock glaciers, as well as the late season present-day snowline, all decrease in elevation northward. Likewise, the elevation of the lower limit of glacial lakes, an indication of the zone of snow accumulation during the late Pleistocene, decreases about the same degree. This similarity suggests that the overall climate patterns of the late Pleistocene, though cooler, were similar to those of today. The east slope glaciers show a similar northward depression, but they are ∼500–1000 m higher.The upper part of the glacial system was erosive over a broad highland area as the evenly distributed ice in the accumulation zone moved to lower elevation. The abundant lake basins record this erosive action. The lower part of the glacier system was largely confined to major preexisting river canyons in which melting dominated. The average of rangewide estimates of the equilibrium line altitude (ELA)—the boundary between the upper snow and ice accumulation zone and the lower ablation zone—of many late Pleistocene glaciers parallels, and is only 200–300 m above, the altitude of the lower limit of the lakes. Hence, the lake zone provides a means of estimating the ELA.

Earthquake-induced soft-sediment deformation structures in Late Pleistocene lacustrine deposits of Issyk-Kul lake (Kyrgyzstan)

NASA Astrophysics Data System (ADS)

Gladkov, A. S.; Lobova, E. U.; Deev, E. V.; Korzhenkov, A. M.; Mazeika, J. V.; Abdieva, S. V.; Rogozhin, E. A.; Rodkin, M. V.; Fortuna, A. B.; Charimov, T. A.; Yudakhin, A. S.

2016-10-01

This paper discusses the composition and distribution of soft-sediment deformation structures induced by liquefaction in Late Pleistocene lacustrine terrace deposits on the southern shore of Issyk-Kul Lake in the northern Tien Shan mountains of Kyrgyzstan. The section contains seven deformed beds grouped in two intervals. Five deformed beds in the upper interval contain load structures (load casts and flame structures), convolute lamination, ball-and-pillow structures, folds and slumps. Deformation patterns indicate that a seismic trigger generated a multiple slump on a gentle slope. The dating of overlying subaerial deposits suggests correlation between the deformation features and strong earthquakes in the Late Pleistocene.

Geomorphology and Sediment Stability of a Segment of the U.S. Continental Slope off New Jersey.

PubMed

Robb, J M; Hampson, J C; Twichell, D C

1981-02-27

The morphology of complex deposits of Pleistocene sediments covering the upper continental slope between Lindenkohl Canyon and South Toms Canyon results from both depositional and erosional processes. Small slump or slide features were detected primarily on the flanks of canyons or valleys and were observed to occur only within Pleistocene-aged sediments. Eocene to Miocene sediments are exposed over much of the mid- and lower slope in this area.

Evidence for Pliocene and Quaternary landscape development on open sections of the Langenlois brick-yard (Lower Austria)

NASA Astrophysics Data System (ADS)

Jaburova, I.; Hofer, I.; Terhorst, B.; Fladerer, F. A.; Ottner, F.; Roetzel, R.

2009-04-01

The study area is located in the abandoned brick-yard of Langenlois, 8 km NE to the city of Krems in Lower Austria where thick fluvial sediments from the Pliocene and Pleistocene loess and loess-like deposits on top of the Upper Pliocene or Early Pleistocene gravel are present. J. Fink (1976) investigated the older S exposed sections of the brick-yard and described several fluvial layers at the base of the exposure, followed by two brownish paleosols, a reddish and well-developed paleosol complex which in the upper part is overlain by loess. In the upper south-eastern part of the section described by Fink (1976) an intense erosional phase represented by a fluvial channel refilled with reddish sands is visible. This study presents the results from the W exposed section of the brick-yard, where five upper Pliocene and Pleistocene sedimentary units could be documented. The sequences show a thickness of 5 m in average and extend about a distance of 100 m. Within these sequences a gradual shift from fluvial to terrestrial-aeolian influence characterises the sedimentary structure. Field survey, sedimentary and mineralogical analyses combined with palaeontological data allow to reconstruct the Pliocene and Quaternary landscape evolution and to evaluate the Langenlois sequences with respect to regional stratigraphy data in the loess-covered area of the Kremsfeld. FINK, J. (Ed.) (1976): Exkursion durch den österreichischen Teil des nördlichen Alpenvorlandes und den Donauraum zwischen Krems und Wiener Pforte. Mittteilungen der Kommission für Quartärforschung der Österreichischen Akademie der Wissenschaften, Bd 1.

The geochemistry of loess: Asian and North American deposits compared

USGS Publications Warehouse

Muhs, Daniel R.

2018-01-01

Loess is widely distributed over Asia and North America and constitutes one of the most important surficial deposits that serve as terrestrial records of the Quaternary. The oldest Pleistocene loess in China is likely ∼2.6 Ma, thus spanning much or all of the Pleistocene. In North America, most loess is no older than the penultimate glacial period, with the exception of Alaska, where the record may go back to ∼3.0 Ma. On both continents, loess deposits date primarily to glacial periods, and interglacial or interstadial periods are represented by paleosols. Both glacial and non-glacial sources of silts that comprise the bulk of loess deposits are found on both continents. Although loess has been considered to be representative of the average upper continental crust, there are regionally distinctive compositions of loess in both Asia and North America. Loess deposits in Asia from Yakutia, Tajikistan, and China have compositionally distinct major element compositions, due to varying abundances of silicate minerals, carbonate minerals, and clay minerals. In North America, loess in the Mississippi River valley, the Great Plains, and Alaska are also distinguishable with regard to major element composition that reflects highly diverse source sediments. Trace element geochemistry (Sc-Th-Zr and the rare earth elements) also shows regional diversity of loess bodies, in both Asia and North America. On both continents, most loess bodies show significant contributions from later-cycle, altered sedimentary rocks, as opposed to direct derivation from igneous rocks. Further, some loess bodies have detectable contributions from mafic igneous rocks as well as major contributions from average, upper-crustal, felsic rocks. Intercalated paleosols in loess sections show geochemical compositions that differ significantly from the underlying loess parent materials. Ratios of soluble-to-insoluble elements show depletions in paleosols due to chemical weathering losses of calcite, dolomite, plagioclase, mica, apatite, and smectite. In Asia and North America, the last interglacial paleosol is more weathered than equivalent modern soils, which could be due either to a climate that was warmer and more humid, a longer period of pedogenesis, or both. In Asia, early Pleistocene loess and paleosols are both more weathered than those from the middle and late Pleistocene, forming prior to a mid-Pleistocene aridification of Asia from uplift of the Tibetan Plateau. Understanding the geochemistry of loess and paleosols can tell us much about past atmospheric circulation, past temperature and moisture regimes, and even tectonic processes.

The geochemistry of loess: Asian and North American deposits compared

NASA Astrophysics Data System (ADS)

Muhs, Daniel R.

2018-04-01

Loess is widely distributed over Asia and North America and constitutes one of the most important surficial deposits that serve as terrestrial records of the Quaternary. The oldest Pleistocene loess in China is likely ∼2.6 Ma, thus spanning much or all of the Pleistocene. In North America, most loess is no older than the penultimate glacial period, with the exception of Alaska, where the record may go back to ∼3.0 Ma. On both continents, loess deposits date primarily to glacial periods, and interglacial or interstadial periods are represented by paleosols. Both glacial and non-glacial sources of silts that comprise the bulk of loess deposits are found on both continents. Although loess has been considered to be representative of the average upper continental crust, there are regionally distinctive compositions of loess in both Asia and North America. Loess deposits in Asia from Yakutia, Tajikistan, and China have compositionally distinct major element compositions, due to varying abundances of silicate minerals, carbonate minerals, and clay minerals. In North America, loess in the Mississippi River valley, the Great Plains, and Alaska are also distinguishable with regard to major element composition that reflects highly diverse source sediments. Trace element geochemistry (Sc-Th-Zr and the rare earth elements) also shows regional diversity of loess bodies, in both Asia and North America. On both continents, most loess bodies show significant contributions from later-cycle, altered sedimentary rocks, as opposed to direct derivation from igneous rocks. Further, some loess bodies have detectable contributions from mafic igneous rocks as well as major contributions from average, upper-crustal, felsic rocks. Intercalated paleosols in loess sections show geochemical compositions that differ significantly from the underlying loess parent materials. Ratios of soluble-to-insoluble elements show depletions in paleosols due to chemical weathering losses of calcite, dolomite, plagioclase, mica, apatite, and smectite. In Asia and North America, the last interglacial paleosol is more weathered than equivalent modern soils, which could be due either to a climate that was warmer and more humid, a longer period of pedogenesis, or both. In Asia, early Pleistocene loess and paleosols are both more weathered than those from the middle and late Pleistocene, forming prior to a mid-Pleistocene aridification of Asia from uplift of the Tibetan Plateau. Understanding the geochemistry of loess and paleosols can tell us much about past atmospheric circulation, past temperature and moisture regimes, and even tectonic processes.

Sulphur and oxygen isotopic characters of dissolved sulphate in groundwater from the Pleistocene aquifer in the southern Jordan Valley (Jericho area, Palestine).

PubMed

Khayat, Saed; Hötzl, Heinz; Geyer, Stefan; Ali, Wasim; Knöller, Kay; Strauch, Gerhard

2006-09-01

Sulphate and chloride concentrations in the shallow Pleistocene aquifer systems in the lower Jordan valley area indicate a general trend of increasing salinity eastward and southward. This study was conducted in one of the important sub-basins feeding the Pleo-Pleistocene aquifer in the Jericho area in the southern part of the valley using S and O isotopes of dissolved sulphate. The results show that sulphate has mainly two contributions to the groundwater. One is the surface seepage, which is present as a salty leachate form with the positive delta34Ssulphate values of primary gypsum in Lisan and Samara formations, and the second is the upwelling saline water which was in contact with a deep secondary gypsum, aragonites and salty rocks and rose up under heavy abstraction with depleted 34S in sulphate and relatively high sulphate and chloride content. The latest was clearly shown in the Arab Project wells to the east that is undergoing a continuous heavy abstraction. The isotopic signatures of S and O in these wells to the east show that this depleted 34S and highly concentrated sulphate might also indicate a dissolved sulphate originating from pyrite oxidation that results from the interaction with a pyrite-rich aquifer, which can well up with salty water under heavy abstraction and is oxidised in the upper aerobic shallow aquifer.

Sediment storage and transport in Pancho Rico Valley during and after the Pleistocene-Holocene transition, Coast Ranges of central California (Monterey County)

USGS Publications Warehouse

Garcia, A.F.; Mahan, S.A.

2009-01-01

Factors influencing sediment transport and storage within the 156??6 km2 drainage basin of Pancho Rico Creek (PRC), and sediment transport from the PRC drainage basin to its c. 11000 km2 mainstem drainage (Salinas River) are investigated. Numeric age estimates are determined by optically stimulated luminescence (OSL) dating on quartz grains from three sediment samples collected from a 'quaternary terrace a (Qta)' PRC terrace/PRC-tributary fan sequence, which consists dominantly of debris flow deposits overlying fluvial sediments. OSL dating results, morphometric analyses of topography, and field results indicate that the stormy climate of the Pleistocene-Holocene transition caused intense debris-flow erosion of PRC- tributary valleys. However, during that time, the PRC channel was backfilled by Qta sediment, which indicates that there was insufficient discharge in PRC to transport the sediment load produced by tributary-valley denudation. Locally, Salinas Valley alluvial stratigraphy lacks any record of hillslope erosion occurring during the Pleistocene-Holocene transition, in that the alluvial fan formed where PRC enters the Salinas Valley lacks lobes correlative to Qta. This indicates that sediment stripped from PRC tributaries was mostly trapped in Pancho Rico Valley despite the relatively moist climate of the Pleistocene-Holocene transition. Incision into Qta did not occur until PRC enlarged its drainage basin by c. 50% through capture of the upper part of San Lorenzo Creek, which occurred some time after the Pleistocene-Holocene transition. During the relatively dry Holocene, PRC incision through Qta and into bedrock, as well as delivery of sediment to the San Ardo Fan, were facilitated by the discharge increase associated with stream-capture. The influence of multiple mechanisms on sediment storage and transport in the Pancho Rico Valley-Salinas Valley system exemplifies the complexity that (in some instances) must be recognized in order to correctly interpret terrestrial sedimentary sequences in tectonically active areas. ?? 2009 John Wiley & Sons, Ltd.

Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon village, Porcupine river, east-central Alaska

USGS Publications Warehouse

Fouch, T.D.; Carter, L.D.; Kunk, Michael J.; Smith, C.A.S.; White, J.M.

1994-01-01

Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins. ?? 1994.

Multidisciplinary approach for fault detection: Integration of PS-InSAR, geomorphological, stratigraphic and structural data in the Venafro intermontane basin (Central-Southern Apennines, Italy)

NASA Astrophysics Data System (ADS)

Amato, Vincenzo; Aucelli, Pietro P. C.; Bellucci Sessa, Eliana; Cesarano, Massimo; Incontri, Pietro; Pappone, Gerardo; Valente, Ettore; Vilardo, Giuseppe

2017-04-01

A multidisciplinary methodology, integrating stratigraphic, geomorphological and structural data, combined with GIS-aided analysis and PS-InSAR interferometric data, was applied to characterize the relationships between ground deformations and the stratigraphic and the morphostructural setting of the Venafro intermontane basin. This basin is a morphostructural depression related to NW-SE and NE-SW oriented high angle normal faults bordering and crossing it. In particular, a well-known active fault crossing the plain is the Aquae Juliae Fault, whose recent activity is evidenced by archeoseismological data. The approach applied here reveals new evidence of possible faulting, acting during the Lower to Upper Pleistocene, which has driven the morphotectonic and the environmental evolution of the basin. In particular, the tectonic setting emerging from this study highlights the influence of the NW-SE oriented extensional phase during the late Lower Pleistocene - early Middle Pleistocene, in the generation of NE-SW trending, SE dipping, high-angle faults and NW-SE trending, high-angle transtensive faults. This phase has been followed by a NE-SW extensional one, responsible for the formation of NW-SE trending, both NW and SE dipping, high-angle normal faults, and the reactivation of the oldest NE-SW oriented structures. These NW-SE trending normal faults include the Aquae Juliae Fault and a new one, unknown until now, crossing the plain between the Venafro village and the Colle Cupone Mt. (hereinafter named the Venafro-Colle Cupone Fault, VCCF). This fault has controlled deposition of the youngest sedimentary units (late Middle Pleistocene to late Upper Pleistocene) suggesting its recent activity and it is well constrained by PS-InSAR data, as testified by the increase of the subsidence rate in the hanging wall block.

The temporal bones from Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain). A phylogenetic approach.

PubMed

Martínez, I; Arsuaga, J L

1997-01-01

Three well-preserved crania and 22 temporal bones were recovered from the Sima de los Huesos Middle Pleistocene site up to and including the 1994 field season. This is the largest sample of hominid temporal bones known from a single Middle Pleistocene site and it offers the chance to characterize the temporal bone morphology of an European Middle Pleistocene population and to study the phylogenetic relationships of the SH sample with other Upper and Middle Pleistocene hominids. We have carried out a cladistic analysis based on nine traits commonly used in phylogenetic analysis of Middle and Late Pleistocene hominids: shape of the temporal squama superior border, articular eminence morphology, contribution of the sphenoid bone to the median glenoid wall, postglenoid process projection, tympanic plate orientation, presence of the styloid process, mastoid process projection, digastric groove morphology and anterior mastoid tubercle. We have found two autapomorphies on the Home erectus temporal bone: strong reduction of the postglenoid process and absence of the styloid process. Modern humans, Neandertals and the Middle Pleistocene fossils from Europe and Africa constitute a clade characterized by a convex superior border of the temporal squama. The European Middle Pleistocene fossils from Sima de los Huesos, Petralona, Steinheim, Bilzingsleben and Castel di Guido share a Neandertal apomorphy: a relatively flat articular eminence. The fossils from Ehringsdorf, La Chaise Suardi and Biache-Saint-Vaast also display another Neandertal derived trait: an anteriorly obliterated digastric groove. Modern humans and the African Middle Pleistocene fossils share a synapomorphy: a sagittally orientated tympanic plate.

A new otter from the Early Pleistocene of Pantalla (Italy), with remarks on the evolutionary history of Mediterranean Quaternary Lutrinae (Carnivora, Mustelidae)

NASA Astrophysics Data System (ADS)

Cherin, Marco; Iurino, Dawid Adam; Willemsen, Gerard; Carnevale, Giorgio

2016-03-01

Here we describe a well-preserved sub-complete lutrine cranium from the late Villafranchian (Early Pleistocene) of Pantalla (Italy) and we assign it to the new taxon Lutraeximia umbra, gen. et sp. nov. The new genus Lutraeximia is characterized by a relatively short and large cranium, with a peculiar shape of the postorbital area and a short and vertical muzzle in lateral view. We refer to the same genus the partially complete skeleton of Lutra trinacriae from the Middle-Late Pleistocene of Sicily. Lutraeximia umbra was a medium-large otter (predicted body mass larger than 13.5 kg) with a unique combination of characters in the upper dentition. A phylogenetic analysis based on craniodental characters places Lutraeximia umbra in a monophyletic clade including the living Lutrogale perspicillata plus the extinct Lutrogale cretensis and three Pleistocene otters from Italy: Sardolutra ichnusae and the sister taxa Lutraeximia trinacriae and Lutraeximia umbra. The recognition of this clade evidences the broad diversity of peri-Mediterranean Lutrinae during the Pleistocene.

Revising the archaeological record of the Upper Pleistocene Arctic Siberia: Human dispersal and adaptations in MIS 3 and 2

NASA Astrophysics Data System (ADS)

Pitulko, Vladimir; Pavlova, Elena; Nikolskiy, Pavel

2017-06-01

As the main external driver, environmental changes largely predetermine human population distribution, especially in the Arctic, where environmental conditions were often too extreme for human survival. Not that long ago the only evidence of human presence here was the Berelekh site in the lower reaches of the Indighirka River. This landmark dates to 13,000-12,000 years ago but it was widely accepted as documentation of the earliest stage of human dispersal in the Arctic. New research discussed here, shows that humans began colonizing the Siberian Arctic at least by the end of the early stage of MIS 3 at around 45,000 years ago. For now, this earliest known stage of human occupation in the arctic regions is documented by the evidence of human hunting. The archaeological record of continued human occupation is fragmentary; nevertheless, evidence exists for each significant phase including the Last Glacial Maximum (LGM). Siberian Arctic human populations were likely supported by the local mammoth population, which provided humans with food and raw material in the form of mammoth tusks. Processing of mammoth ivory is recognized widely as one of the most important peculiarities of the material culture of ancient humans. In fact, ivory tool manufacturing is one of the most important innovations of the Upper Palaeolithic in northern Eurasia. Technology that allowed manufacturing of long ivory shafts - long points and full-size spears - was critical in the tree-less open landscapes of Eurasian mammoth steppe belt. These technological skills reach their greatest extent and development shortly before the Last Glacial Maximum but are recognizable until the Pleistocene-Holocene boundary across Northern Eurasia in all areas populated by mammoths and humans. Loss of this stable source of raw material due to the late Pleistocene mammoth extinction may have provoked a shift in post-LGM Siberia to the Beringian microblade tradition. This paper reviews the most important archaeological findings made in arctic Siberia over the last twenty years.

Disappearance of the last lions and hyenas of Europe in the Late Quaternary - a chain reaction of large mammal prey migration, extinction and human antagonism

NASA Astrophysics Data System (ADS)

Diedrich, Cajus G.

2010-05-01

In the Eemian to Early/Middle Weichselian (Late Pleistocene), when the Scandinavian and Alpine Glaciers were still small, and northern Germany under mammoth steppe to taiga palaoenvironment conditions, Late Quaternary steppe lions were well distributed in northern to central Germany, whereas generally all over Central Europe bones and rarely articulated skeletons were found less at open air but mainly at cave sites (Diedrich 2007a, 2008a-b, 2009a-b, 2010a-c, k, in review a-b; Diedrich and Rathgeber in review). A similar distribution, but more dense, is reported for the Late Quaternary Ice Age spotted hyenas (Diedrich 2005, 2006, 2007b-c, 2008a, c, 2010f-j, in review c-d, Diedrich and Žák 2006). The last lions of northern Europe were thought to have reached into the final Magdalénan (cf. Musil 1980). This can be not concluded with a restudy of the bone material from the Late Magdalenian (V-VI) Teufelsbrücke stone arch site near Saalfeld (Thuringia, Central Germany) and many other Magdalenian stations (open air and caves) in northern to central Germany (Münsterland Bay, Sauerland Karst, Harz Mountain Karst, Thuringian Karst). None of those sites yield remains of final Upper Pleistocene spotted hyenas or steppe lion bones anymore, nor in the few preserved Late Magdalenian mobile art can those be recognized in those regions. The last lion remains seem to reach into the Aurignacian or possibly into the Early Gravettian (early Late Weichselian) documented especially at the cave bear den, hyena den and overlapping Neandertalian to Modern human camp site Balve Cave (Sauerland Karst, cf. archaeology in Günther 1964) where still a mammoth fauna is documented for that time (Diedrich 2010a). The last and by archaeological layers dated hyena remains were also found in the Balve Cave and are from the Late Middle Palaeolithic cave site reaching a maximum Aurignacian age documenting an overlapping of hyena den and human camp site use (Diedrich 2010a, b). In northern Germany there are no records of indirectly dated hyena and lion remains being younger then even Aurignacian/Early Gravettian (35.000-28.000 BP). Those largest Late Quaternary predators must have got extinct in northern Germany with the Late Weichselian/Wuermian extending Skandinavian Glacier, which reached northern Europe between Hamburg and Berlin its maximum extension about 24.000 BP (Skupin et al. 1993). The two largest predators of the Late Quaternary of Europe seem to have been well represented in the Gravettian and up to Magdalénian Late Palaeolithic of southern Europe, in which mainly lions, but only rarely hyenas are well documented within the cave and mobile art (e.g Breuil 1952, Begouen and Clottes 1987, Chauvet et al. 1995, Diedrich and Rathgeber in review, Diedrich 2005). Hyenas and lions must have been represented in the Gravettian, Early and Middle and possibly even ?Late Magdalenian in southern Europe, which must have resulted from a southern migration of those predators during the Late Weichselian/Wuermian together with the megafauna and humans. The disappearance of hyenas and lions also correlate with the extinction of mammoth and woolly rhinoceros in northern Germany. The large mammals such as elephants and rhinoceroses were highly important for hyenas and lions during the Late Quaternary. Hyenas had a systematic scavenging strategy on both large prey which was even "transferred" until today compared to modern spotted hyenas and lions of Africa (Diedrich 2010d, e, in prep). Where those Late Quaternary giant mammals such as woolly mammoth and woolly rhinoceros were absent in middle mountainous regions (e.g. Sauerland Karst, Harz Mountain Karst, Bohemian Karst, Thuringian Karst) those had to kill other medium sized animals such as horse or steppe bison and those in larger amounts (Diedrich 2008, 2010c). Woolly rhinoceros and woolly mammoth seem to be not known in northern Germany after Aurignacian/?Early Gravettian times (Sauerland Karst and Münsterland Bay, Harz Mountain Karst) such as humans (archaeology cf. Günther 1988) but there are also lacking radiocarbon dating series or new excavations. Humans must have been in antagonism to the large predators about their prey and also their Late Palaeolithic sanctuaries - the large caves especially in southern Europe, in which they left thousands of animal figurations mainly during the Gravettian to Late Magdalenian periods (e.g. Breuil 1952, Begouen and Clottes 1987, Chauvet et al. 1995). Therefore the extinction reason of the largest predators of the Late Quaternary seems to be a complex combination of climate change with resulting maximum glacier extension which finally caused a southern directed megafaunal migration and reduction of the available caves and habitat areas in general. Finally in those southern European regions a higher competition about larger caves as cave bear hibernation places, hyena den sites and human settlement/sanctuary sites must have happened. Therefore an active hunt onto lions and hyenas can not be excluded nor be proven well yet, even if there are finds of necklesses in Europe from Late Palaeolithic ages made of mainly carnivore teeth including rare lion and hyena teeth, which might have been only collected. The resettlement of the northern European region by humans and a reduced "reindeer fauna" and its main and largest predators such as wolves and wolverines after the maximum glacier extension in the middle Late Weichselian started not before the Late Magdalenian (Magdalénian V: e.g. Perick Caves, Martins Cave - Sauerland Karst; Rübeland Caves - Harz Mountain Karst, Teufelsbrücke stone arch - Thuringian Karst). Humans occupied at that post-maximum glaciation time many caves in the Sauerland Karst region and even at open air sites in the Münsterland Bay or central Germany (cf. Bosinski 1987, Günther 1988). Within this Late Magdalénian V-VI times in the record of ten thousands of bones from more then 100 sites no hyena or lion remains are recorded anymore in northern and central Germany, such as cave bears. References Begouen R. and Clottes J. 1987. Les Trois Frères after Breuil. Antiquity, 61: 180-187. Bosinski, G. 1987. Die große Zeit der Eiszeitjäger. Europa zwischen 40.000 und 10.000 v.Chr. Jahrbuch des Römisch-Germanischen Zentralmuseums, 34: 13-139. Breuil, H. 1952. Four Hundred Centuries of Cave Art. Montignac, Dordogne, 414 pp. Chauvet, J.-M., Deschamps B.E, and Hillaire C. 1995. Grotte Chauvet. Altsteinzeitliche Höhlenkunst im Tal der Ardèche. Thorbecke Speläo 1, Sigmaringen, 120 pp. Diedrich, C. 2005. Eine oberpleistozäne Population von Crocuta crocuta spelaea (GOLDFUSS 1823) aus dem eiszeitlichen Fleckenhyänenhorst Perick-Höhlen von Hemer (Sauerland, NW Deutschland) und ihr Kannibalismus. Philippia, 12 (2): 93-115, Kassel. Diedrich, C. 2006. The Crocuta crocuta spelaea (Goldfuss 1823) population from the early Upper Pleistocene hyena open air prey deposit site Biedensteg near Bad Wildungen (Hess, NW Germany) and the contribution to their phylogenetic position, coprolites and prey. Cranium, 23 (2): 39-53, Amsterdam. Diedrich, C. 2007a. Upper Pleistocene Panthera leo spelaea (Goldfuss 1810) skeleton remains from Praha-Podbaba and the contribution to other lion finds from loess and river terrace sites in Central Bohemia (Czech Republic). Bulletin of Geosciences, 82 (2), 99-117, Prague. Diedrich, C. 2007b. Crocuta crocuta spelaea (GOLDFUSS 1823) remains from the Upper Pleistocene hyaena Teufelskammer Cave den site near Hochdahl in the Neander valley (NRW, NW Germany). Cranium, 24 (2): 39-44, Amsterdam. Diedrich, C. 2007c. The Upper Pleistocene Crocuta crocuta spelaea (GOLDFUSS 1823) population and its prey from the gypsum karst den site Westeregeln near Magdeburg (Middle Germany). Abhandlungen und Berichte für Naturkunde, 30: 57-83, Magdeburg. Diedrich, C. 2008a. Late Pleistocene Hystrix (Acanthion) brachyura LINNAEUS 1758 from the Fuchsluken cave at the Rote Berg near Saalfeld (Thuringia, Germany) - a porcupine and hyena den and contribution to their palaeobiogeography. - The Open Palaeontological Journal, 2008 (1): 33-41. Diedrich, C. 2008b. The rediscovered holotypes of the Upper Pleistocene spotted hyena Crocuta crocuta spelaea (Goldfuss 1823) and the steppe lion Panthera leo spelaea (Goldfuss, 1810) and taphonomic discussion to the Zoolithen Cave hyena den at Geilenreuth (Bavaria, South-Germany). Zoological Journal of the Linnaean Society London, 154, 822-831. Diedrich, C. 2008c. Late Pleistocene hyenas Crocuta crocuta spelaea (GOLDFUSS 1823) from Upper Rhine valley open air sites and the contribution to skull shape variability. Cranium, 25-2: (in press), Amsterdam. Diedrich, C. 2009a. Upper Pleistocene Panthera leo spelaea (GOLDFUSS 1810) remains from the Bilstein Caves (Sauerland Karst) and contribution to the steppe lion taphonomy, palaeobiology and sexual dimorphism. Annales de Paléontologie, 95 (2009) 117-138, Amsterdam. Diedrich, C. 2009b. Steppe lion remains imported by Ice Age spotted hyenas into the Late Pleistocene Perick Caves hyena den in Northern Germany. Quaternary Research 71 (3): 361-374, Amsterdam. Diedrich, C. 2010a. Pleistocene Panthera leo spelaea (Goldfuss, 1810) remains from the Balve Cave (NW Germany) - a hyena den and Middle Palaeolithic human site. - International Journal of Osteoarchaeology (acepted). Diedrich, C. 2010b. Ein Skelett einer kranken Löwin Panthera leo spelaea (Goldfuss 1810) und andere männliche Löwenreste aus Neumark-Nord. - Archäologie in Sachsen-Anhalt, Sonderbad (accepted). Diedrich, C. 2010c. Late Pleistocene lion Panthera leo spelaea (GOLDFUSS 1810) remains from the Keppler Cave (Sauerland Karst, NW Germany). Cranium 26, Amsterdam (in press). Diedrich, C. 2010c. Specialized horse killers in Europe - foetal horse remains in the Late Pleistocene Srbsko Chlum-Komín Cave hyena den in the Bohemian Karst (Czech Republic) and actualistic comparisons to modern African spotted hyenas as zebra hunters. - Quaternary International. Diedrich, C. 2010d. Mammuthus primigenius (Blumenbach, 1799) carcass destructors, bone collectors, crackers and gnawers of the Late Pleistocene in Central Europe - the Ice Age spotted hyenas and their feeding strategies on their largest prey - the mammoth. Abstract Vth International Conference on Mammoths and their relatives, Le Puy-en-Velay, France. Diedrich, C. 2010e. Späteiszeiliche Fleckenhyänen-Fressstrategien und Steppenlöwen an ihrer größte Beute - dem Waldelefanten Palaeoloxodon antiquus Falconer & Cautley 1845 in Neumark-Nord. Archäologie in Sachsen-Anhalt, Sonderband (accepted). Diedrich, C. 2010f. Die späteiszeitlichen Fleckenhyänen und deren Exkremente aus Neumark-Nord. Archäologie in Sachsen-Anhalt, Sonderband (accepted). Diedrich, C. 2010g. Rare Upper Pleistocene Crocuta crocuta spelaea (GOLDFUSS 1823) remains from northern Czech Republic open air loess sites along the Elbe River. Cranium, (accepted). Diedrich, C. 2010h. Europe's first Upper Pleistocene Crocuta crocuta spelaea (GOLDFUSS 1823) skeleton from a small cannibalistic hyena population found in the main dome of the Koněprusy Caves - a hyena cave prey depot site in the Bohemian Karst (Czech Republic). Acta Palaeontologica Polonica (in review). Diedrich, C. 2010i. Periodical use of the Balve Cave (NW Germany) as a Late Pleistocene Crocuta crocuta spelaea (GOLDFUSS 1823) den - hyena occupations and bone accumulations versa human Middle Palaeolithic activity. Quaternary International. Diedrich, C. 2010j. The Crocuta crocuta spelaea (GOLDFUSS 1823) population from the Late Pleistocene Rösenbeck Cave den in NW Germany and contribution to the sexual dimorphism and palaeobiogeography of the last hyenas of Europe. Annales de Paléontologie. Diedrich, C. 2010k. Upper Pleistocene Panthera leo spelaea (Goldfuss 1810) remains from an open air loess bone accumulation site in Freyburg a. U. (Central Germany). Jahresschrift für mitteldeutsche Vorgeschichte (accepted). Diedrich, C. in prep. Coelodonta antiquitatis (Blumenbach 1799) hunters and scavengers - the Late Pleistocene spotted hyena Crocuta crocuta spelaea (Goldfuss 1823) and its feeding strategy on its most important prey in Europe. Diedrich, C. in review a. A diseased Panthera leo spelaea (Goldfuss, 1810) lioness from a forest elephant graveyard in the Late Pleistocene (Eemian) interglacial lake at Neumark-Nord, Central Germany. Quaternary International. Diedrich, C. in review b. Late Pleistocene steppe lion Panthera leo spelaea (Goldfuss, 1810) remains from the open air hyena den Emscher River terrace site Bottrop and other sites of northern Germany - new proves for hyena-lion antagonism. Palaeogeography, Palaeoclimatology, Palaeoecology. DIEDRICH, C. in review c. The Crocuta crocuta spelaea (GOLDFUSS 1823) population and its prey from the Upper Pleistocene Teufelskammer Cave hyena den site in the Neandertal (NRW, NW Germany). Annales de Paléontologie. Diedrich, C. in review d. The Late Pleistocene Crocuta crocuta spelaea (Goldfuss, 1823) population from the Late Pleistocene hyena open air Emscher River terrace den near Bottrop (NWGermany) and other sites in the Westphalian Bay and its mammoth and woolly rhinoceros prey. Quaternary International. Diedrich, C. and Rathgeber, T. in review. Late Pleistocene steppe lion Panthera leo spelaea (Goldfuss, 1810) skeleton remains of the Upper Rhine valley (SW Germany) and contribution to their palaeobiogeography, sexual dimorphism and palaeoecology. Palaeogeography Palaeoclimatology Palaeoecology. Diedrich, C. AND Žák, K. 2006. Prey deposits and den sites of the Upper Pleistocene hyena Crocuta crocuta spelaea (Goldfuss, 1823) in horizontal and vertical caves of the Bohemian Karst (Czech Republic). Bulletin of Geosciences, 81 (4), 237-276. Günther, K. 1964. Die altsteinzeitlichen Funde der Balve Höhle. Bodenaltertümer Westfalens, 8, 1-165. Günther, K. 1988. Alt- und Mittelsteinzeitliche Fundplätze in Westfalen. Teil 2. Einführung in die Vor- und Frühgeschichte Westfalens 6, 1-183. Musil, R. 1980. Die Großsäoger und Vögel der Teufelsbrücke. In: Feustel, R. Magdalénienstation Teufelsbrücke. II: Paläontologischer Teil. Weimarer Monographien zur Ur- und Frühgeschichte 3, 1-71. Skupin, K., Speetzen, E. and Zandstra, J.G. 1993. Die Eiszeit in Nordwestdeutschland. GLA Nordrhein-Westfalen, Krefeld, 143 pp.

Geology, hydrology, and water quality of the Tracy-Dos Palos area, San Joaquin Valley, California

USGS Publications Warehouse

Hotchkiss, W.R.; Balding, G.O.

1971-01-01

The Tracy-Dos Palos area includes about 1,800 square miles on the northwest side of the San Joaquin Valley. The Tulare Formation of Pliocene and Pleistocene age, terrace deposits of Pleistocene age, and alluvium and flood-basin deposits of Pleistocene and Holocene age constitute the fresh ground-water reservoir Pre-Tertiary and Tertiary sedimentary and crystalline rocks, undifferentiated, underlie the valley and yield saline water. Hydrologically most important, the Tulare Formation is divided into a lower water-bearing zone confined by the Corcoran Clay Member and an upper zone that is confined, semiconfined, and unconfined in different parts of the area. Alluvium and flood-basin deposits are included in the upper zone. Surficial alluvium and flood-basin deposits contain a shallow water-bearing zone. Lower zone wells were flowing in 1908, but subsequent irrigation development caused head declines and land subsidence. Overdraft in both zones ended in 1951 with import of surface water. Bicarbonate water flows into the area from the Sierra Nevada and Diablo Range. Diablo Range water is higher in sulfate, chloride, and dissolved solids. Upper zone water averages between 400 and 1,200 mg/l (milligrams per liter) dissolved solids and water hardness generally exceeds 180 mg/l as calcium carbonate. Nitrate, fluoride, iron, and boron occur in excessive concentrations in water from some wells. Dissolved constituents in lower zone water generally are sodium chloride and sodium sulfate with higher dissolved solids concentration than water from the upper zone. The foothills of the Diablo Range provide favorable conditions for artificial recharge, but shallow water problems plague about 50 percent of the area and artificial recharge is undesirable at this time.

Making different things, but eating the same food? Correlation between cultural and subsistence changes during the Pleistocene-Holocene boundary in the northeastern Iberian Peninsula

NASA Astrophysics Data System (ADS)

Rufà, Anna; Vaquero, Manuel

2018-03-01

The end of the Pleistocene is characterized by a succession of climatic oscillations from the onset of MIS 2. These oscillations were associated with important environmental transformations that culminated in the Pleistocene to the Holocene transition, with latter climate amelioration. However, the changes during this period are not only restricted to the environment, as important cultural transformations took place. The cultural traditions characteristics from the end of the Upper Paleolithic disappear with the emergence of the traits characteristic of the Mesolithic culture. This is clearly attested in the well-known lithic record, but also in other domains of material culture, like bone industry and art. Nevertheless, the extent to which these cultural and environmental transformations were associated with changes in subsistence strategies remains unclear, at least at the Mediterranean basin of the Iberian Peninsula. Apparently, the exploitation of faunal resources during the Mesolithic does not seem to change so much with respect to the end of the Upper Paleolithic, especially concerning the consumption of small prey. The main goal of this paper is (1) to analyze how environmental transformations could or could not intervene on the modes of life of Prehistoric populations during these transitional periods, and (2) to discuss the apparent dichotomy between cultural changes and subsistence strategies at the end of the Upper Paleolithic and the Mesolithic in northeastern Iberia. In that sense, we will include the case of the Molí del Salt site (Catalonia, Spain) as an example to explain these trends. This site has an archaeological sequence from the Upper Magdalenian to the Mesolithic, which makes it a reference place to comprehend the dynamics of human populations during this period.

Late Pleistocene-Holocene alluvial stratigraphy of southern Baja California, Mexico

NASA Astrophysics Data System (ADS)

Antinao, José Luis; McDonald, Eric; Rhodes, Edward J.; Brown, Nathan; Barrera, Wendy; Gosse, John C.; Zimmermann, Susan

2016-08-01

A late Pleistocene to Holocene alluvial stratigraphy has been established for the basins of La Paz and San José del Cabo, in the southern tip of the Baja California peninsula, Mexico. Six discrete alluvial units (Qt1 through Qt6) were differentiated across the region using a combination of geomorphologic mapping, sedimentological analysis, and soil development. These criteria were supported using radiocarbon, optically stimulated luminescence and cosmogenic depth-profile geochronology. Major aggradation started shortly after ∼70 ka (Qt2), and buildup of the main depositional units ended at ∼10 ka (Qt4). After deposition of Qt4, increasing regional incision of older units and the progressive development of a channelized alluvial landscape coincide with deposition of Qt5 and Qt6 units in a second, incisional phase. All units consist of multiple 1-3 m thick alluvial packages deposited as upper-flow stage beds that represent individual storms. Main aggradational units (Qt2-Qt4) occurred across broad (>2 km) channels in the form of sheetflood deposition while incisional stage deposits are confined to channels of ∼0.5-2 km width. Continuous deposition inside the thicker (>10 m) pre-Qt5 units is demonstrated by closely spaced dates in vertical profiles. In a few places, disconformities between these major units are nevertheless evident and indicated by partly eroded buried soils. The described units feature sedimentological traits similar to historical deposits formed by large tropical cyclone events, but also include characteristics of upper-regime flow sedimentation not shown by historical sediments, like long (>10 m) wavelength antidunes and transverse ribs. We interpret the whole sequence as indicating discrete periods during the late Pleistocene and Holocene when climatic conditions allowed larger and more frequent tropical cyclone events than those observed historically. These discrete periods are associated with times when insolation at the tropics was higher than the present-day conditions, determined by precessional cycles, and modulated by the presence of El Niño-like conditions along the tropical and northeastern Pacific. The southern Baja California alluvial record is the first to document a precession-driven alluvial chronology for the region, and it constitutes a strong benchmark for discrimination of direct tropical influence on any other alluvial record in southwestern North America.

New Tertiary stratigraphy for the Florida Keys and southern peninsula of Florida

USGS Publications Warehouse

Cunningham, K.J.; McNeill, D.F.; Guertin, L.A.; Ciesielski, P.F.; Scott, T.M.; De Verteuil, L.

1998-01-01

Seven lithologic formations, ranging in age from Oligocene to Pleistocene, were recently penetrated by core holes in southernmost Florida. From bottom to top, they are the early Oligocene Suwannee Limestone; late-early Oligocene-to-Miocene Arcadia Formation, basal Hawthorn Group; late Miocene Peace River Formation, upper Hawthorn Group; newly proposed late Miocene-to-Pliocene Long Key and Stock Island Formations; and Pleistocene Key Largo and Miami Limestones. The rocks of the Suwannee Limestone form a third-order sequence. Although the entire thickness was not penetrated, 96 m of Suwannee core from one well contains at least 50 vertically stacked, exposure-capped limestone cycles, presumably related to rapid eustatic fluctuations while experiencing tropical to subtropical conditions. The Arcadia Formation is a composite sequence containing four high-frequency sequences composed of multiple vertically stacked carbonate cycles. Most cycles do not show evidence of subaerial exposure and were deposited under more temperate conditions, relative to the Suwannee Limestone. The Arcadia Formation in southernmost Florida is bounded by regional unconformities representing third-order sequence boundaries. Post-Arcadia transgression produced a major backstepping of sediment accumulation above the upper sequence boundary of the Arcadia Formation. The Peace River Formation, composed of diatomaceous mudstones, has been identified only beneath the Florida peninsula and is not present beneath the Florida Keys. Deposition occurred during marine transgressive to high-stand conditions and a local phosphatization event (recorded in northeast Florida). The transgression is possibly related to a global rise in sea level, which resulted in upwelling of relatively cooler, relatively nutrient-rich water masses onto the Florida Platform. It is proposed that the absence of Peace River sediments beneath the Keys is due to sediment bypass of the upper surface of the Arcadia, a result of sediment sweeping by an ancestral Florida current. During late Miocene to Pliocene time in the Florida Keys, siliciclastics of the Long Key Formation and fine-grained carbonates of the Stock Island Formation prograded toward the southern edge of the Florida Platform and downlapped onto the regional unconformity at the top of the Arcadia. Shallow-marine Pleistocene limestones (Key Largo and Miami Limestones), deposited during tropical to subtropical conditions, drape over accretionary successions of the Long Key and Stock Island Formations.

Extreme mobility in the Late Pleistocene? Comparing limb biomechanics among fossil Homo, varsity athletes and Holocene foragers.

PubMed

Shaw, Colin N; Stock, Jay T

2013-04-01

Descriptions of Pleistocene activity patterns often derive from comparisons of long bone diaphyseal robusticity across contemporaneous fossilized hominins. The purpose of this study is to augment existing understanding of Pleistocene hominin mobility patterns by interpreting fossil variation through comparisons with a) living human athletes with known activity patterns, and b) Holocene foragers where descriptions of group-level activity patterns are available. Relative tibial rigidity (midshaft tibial rigidity (J)/midshaft humeral rigidity (J)) was compared amongst Levantine and European Neandertals, Levantine and Upper Palaeolithic Homo sapiens, Holocene foragers and living human athletes and controls. Cross-country runners exhibit significantly (p<0.05) greater relative tibial rigidity compared with swimmers, and higher values compared with controls. In contrast, swimmers displayed significantly (p<0.05) lower relative tibial rigidity than both runners and controls. While variation exists among all Holocene H. sapiens, highly terrestrially mobile Later Stone Age (LSA) southern Africans and cross-country runners display the highest relative tibial rigidity, while maritime Andaman Islanders and swimmers display the lowest, with controls falling between. All fossil hominins displayed relative tibial rigidity that exceeded, or was similar to, the highly terrestrially mobile Later Stone Age southern Africans and modern human cross-country runners. The more extreme skeletal structure of most Neandertals and Levantine H. sapiens, as well as the odd Upper Palaeolithic individual, appears to reflect adaptation to intense and/or highly repetitive lower limb (relative to upper limb) loading. This loading may have been associated with bipedal travel, and appears to have been more strenuous than that encountered by even university varsity runners, and Holocene foragers with hunting grounds 2000-3000 square miles in size. Skeletal variation among the athletes and foraging groups is consistent with known or inferred activity profiles, which support the position that the Pleistocene remains reflect adaptation to extremely active and mobile lives. Copyright © 2013 Elsevier Ltd. All rights reserved.

Homo erectus and Middle Pleistocene hominins: brain size, skull form, and species recognition.

PubMed

Rightmire, G Philip

2013-09-01

Hominins that differ from Homo erectus, the Neanderthals, and recent humans are known from Middle Pleistocene localities across the Old World. The taxonomic status of these populations has been clouded by controversy. Perhaps the most critical problem has been an incomplete understanding of variation in skull form. Here, both H. erectus and later mid-Pleistocene hominins are the focus of an investigation aimed at clarifying the relationships among brain volume, basicranial dimensions, neurocranial shape, and certain facial characters. Brain size in H. erectus averages about 950 cm(3), while in a series of Middle Pleistocene crania from Africa and Europe, volume is about 1230 cm(3). If encephalization is the primary mechanism operating in the mid-Pleistocene, then diverse aspects of cranial form cannot all be treated as independent variables. Correlation is utilized to examine the associations among measurements for more than 30 H. erectus crania that are reasonably well preserved. A similar approach is used with the Middle Pleistocene sample. Patterns of covariation are compared in order to assess integration. Next, factor analysis is applied to the H. erectus specimens in an attempt to identify modules, tightly integrated traits that can evolve independently. Studies of the variation within H. erectus are followed by direct comparisons with the Middle Pleistocene population. Discriminant functions facilitate the description of intergroup differences. Traits that vary independently from brain volume include anterior frontal broadening, lateral expansion of the parietal vault, elevation of the lambda-inion chord, and rounding of the sagittal contour of the occipital. This finding helps to resolve the problem of species recognition. Neurocranial proportions as well as characters from the cranial base and face can be incorporated into a differential diagnosis for the mid-Pleistocene sample. Evidence presented here supports arguments for speciation in the Middle Pleistocene. Copyright © 2013 Elsevier Ltd. All rights reserved.

Extent of Pleistocene lakes in the western Great Basin

USGS Publications Warehouse

Reheis, Marith C.

1999-01-01

During the Pliocene to middle Pleistocene, pluvial lakes in the western Great Basin repeatedly rose to levels much higher than those of the well-documented late Pleistocene pluvial lakes, and some presently isolated basins were connected. Sedimentologic, geomorphic, and chronologic evidence at sites shown on the map indicates that Lakes Lahontan and Columbus-Rennie were as much as 70 m higher in the early-middle Pleistocene than during their late Pleistocene high stands. Lake Lahontan at its 1400-m shoreline level would submerge present-day Reno, Carson City, and Battle Mountain, and would flood other now-dry basins. To the east, Lakes Jonathan (new name), Diamond, Newark, and Hubbs also reached high stands during the early-middle(?) Pleistocene that were 25-40 m above their late Pleistocene shorelines; at these very high levels, the lakes became temporarily or permanently tributary to the Humboldt River and hence to Lake Lahontan. Such a temporary connection could have permitted fish to migrate from the Humboldt River southward into the presently isolated Newark Valley and from Lake Lahontan into Fairview Valley. The timing of drainage integration also provides suggested maximum ages for fish to populate the basins of Lake Diamond and Lake Jonathan. Reconstructing and dating these lake levels also has important implications for paleoclimate, tectonics, and drainage evolution in the western Great Basin. For example, shorelines in several basins form a stair-step sequence downward with time from the highest levels, thought to have formed at about 650 ka, to the lowest, formed during the late Pleistocene. This descending sequence indicates progressive drying of pluvial periods, possibly caused by uplift of the Sierra Nevada and other western ranges relative to the western Great Basin. However, these effects cannot account for the extremely high lake levels during the early middle Pleistocene; rather, these high levels were probably due to a combination of increased effective moisture and changes in the size of the Lahontan drainage basin.

Middle-Late Pleistocene marine terraces and fault activity in the Sant'Agata di Militello coastal area (north-eastern Sicily)

NASA Astrophysics Data System (ADS)

Giunta, Giuseppe; Gueli, Anna M.; Monaco, Carmelo; Orioli, Silvia; Ristuccia, Gloria M.; Stella, Giuseppe; Troja, Sebastiano O.

2012-04-01

The coastal sector of Sant'Agata di Militello (north-eastern Sicily) is characterized by a flight of raised Middle-Upper Pleistocene marine terraces occurring at different heights with respect to present sea level. In particular, the geomorphological survey and the analysis of stereo-pairs of aerial photographs allowed to recognize at least five main orders of well preserved Quaternary surfaces and relative deposits mostly located at the hanging wall and at the footwall of the Pleistocene northwest-dipping Capo d'Orlando normal fault, which controlled the geomorphological evolution of the coastal area. The marine terraces show an overall good morphological continuity and are formed by marine platforms overlain by littoral deposits made up of yellow littoral sand and gravels in a sandy matrix. The continental sedimentary cover of the 3rd order terrace contains mammal-bearing deposits that were previously dated 200 ± 40 ka BP by isoleucine epimerization method, allowing to relate them to MIS 7.1 high-stand. In order to better define the whole terrace chronology, deposit samples were analyzed by Optically Stimulated Luminescence (OSL) methodology, a conventional SAR protocol used with sand-sized quartz. New datings, together with the detailed morphostructural analysis, allow to relate the 2nd and 4th order terraces to MIS 5.5 and 8.5, respectively, and to reconstruct the tectonic evolution of this coastal area, constraining the activity of the Capo d'Orlando fault.

Periglacial process and Pleistocene environment in northern China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo Xudong; Liu Dongsheng; Yan Fuhua

1991-03-01

In the present time, five kinds of periglacial phenomena have been defined: ice wedges, periglacial involutions, congelifolds, congeliturbations, and loess dunes. From the stratigraphical and geochronological data, the periglacial process is divided into six stages. (1) Guanting periglacial stage, characterized by the congeliturbative deposits that have developed in early Pleistocene Guanting loess-like formation. Paleomagnetic dating gives 2.43 Ma B.P. (2) Yanchi periglacial stage, characterized by the congelifold that has developed in middle Pleistocene Yanchi Lishi loess formation. Paleomagnetic dating gives 0.50 Ma B.P. (3) Zhaitang periglacial stage (II), characterized by the periglacial involutions that have developed in lower middle Pleistocenemore » Lishi loess formation. Paleomagnetic dating gives 0.30 Ma B.P. (4) Zhaitang periglacial state (I), characterized by the ice (soil) wedge that has developed in upper-middle Pleistocene Lishi loess formation. Paleomagnetic dating gives 0.20 Ma B.P. (5) Qiansangyu periglacial stage (II), characterized by the ice (sand) wedges that has developed in late Pleistocene Malan loess formation. Paleomagnetic dating gives 0.13 Ma B.P. (6) Qiansangyu periglacial stage (I), characterized by the ice (soil) wedge that has developed in late Pleistocene Malan loess-like formation. Thermoluminescent dating gives 0.018 Ma B.P. Spore-pollen composition analysis shows that the savannah steppe environment prevailed in northern China during Pleistocene periglacial periods. These fossilized periglacial phenomena indicate a rather arid and windy periglacial environment with a mean annual temperature estimated some 12-15C colder than that in the present.« less

Geologic map of the upper Arkansas River valley region, north-central Colorado

USGS Publications Warehouse

Kellogg, Karl S.; Shroba, Ralph R.; Ruleman, Chester A.; Bohannon, Robert G.; McIntosh, William C.; Premo, Wayne R.; Cosca, Michael A.; Moscati, Richard J.; Brandt, Theodore R.

2017-11-17

This 1:50,000-scale U.S. Geological Survey geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This report also incorporates new detailed geologic mapping of previously poorly understood areas within the map area and reinterprets previously studied areas. The mapped region extends into the Proterozoic metamorphic and intrusive rocks in the Sawatch Range west of the valley and the Mosquito Range to the east. Paleozoic rocks are preserved along the crest of the Mosquito Range, but most of them have been eroded from the Sawatch Range. Numerous new isotopic ages better constrain the timing of both Proterozoic intrusive events, Late Cretaceous to early Tertiary intrusive events, and Eocene and Miocene volcanic episodes, including widespread ignimbrite eruptions. The uranium-lead ages document extensive about 1,440-million years (Ma) granitic plutonism mostly north of Buena Vista that produced batholiths that intruded an older suite of about 1,760-Ma metamorphic rocks and about 1,700-Ma plutonic rocks. As a result of extension during the Neogene and possibly latest Paleogene, the graben underlying the valley is filled with thick basin-fill deposits (Dry Union Formation and older sediments), which occupy two sub-basins separated by a bedrock high near the town of Granite. The Dry Union Formation has undergone deep erosion since the late Miocene or early Pliocene. During the Pleistocene, ongoing steam incision by the Arkansas River and its major tributaries has been interrupted by periodic aggradation. From Leadville south to Salida as many as seven mapped alluvial depositional units, which range in age from early to late Pleistocene, record periodic aggradational events along these streams that are commonly associated with deposition of glacial outwash or bouldery glacial-flood deposits. Many previously unrecognized Neogene and Quaternary faults, some of the latter with possible Holocene displacement, have been identified on lidar (light detection and ranging) imagery which covers 59 percent of the map area. This imagery has also permitted more accurate remapping of glacial, fluvial, and mass-movement deposits and aided in the determination of their relative ages. Recently published 10beryllium cosmogenic surface-exposure ages, coupled with our new geologic mapping, have revealed the timing and rates of late Pleistocene deglaciation. Glacial dams that impounded the Arkansas River at Clear Creek and possibly at Pine Creek failed at least three times during the middle and late Pleistocene, resulting in catastrophic floods and deposition of enormous boulders and bouldery alluvium downstream; at least two failures occurred during the late Pleistocene during the Pinedale glaciation.

Map Showing Quaternary Geology and Geomorphology of the Granite Park Area, Grand Canyon, Arizona

USGS Publications Warehouse

Hereford, Richard; Burke, Kelly J.; Thompson, Kathryn S.

2000-01-01

View to west-northwest showing map area and setting of Granite Park; Grand Canyon, Arizona. The Colorado River flows from right to left. Granite Park Wash is the light-colored area in foreground of photograph. The debris fan of 209 Mile Canyon is at left center. Pleistocene gravel is exposed in the steep, light-colored bank above 209 Mile Rapids at left edge of photograph. The black-colored ledge that forms the dark cliff at upper right of photograph is the basalt flow of Hamblin (1994). Sand dunes, debris fans, and terraces of the Colorado River cover the lower half of this area shown in this photograph.

Postimpact deformation associated with the late Eocene Chesapeake Bay impact structure in southeastern Virginia

USGS Publications Warehouse

Johnson, G.H.; Kruse, S.E.; Vaughn, A.W.; Lucey, J.K.; Hobbs, C. H.; Powars, D.S.

1998-01-01

Upper Cenozoic strata covering the Chesapeake Bay impact structure in southeastern Virginia record intermittent differential movement around its buried rim. Miocene strata in a graben detected by seismic surveys on the York River exhibit variable thickness and are deformed above the creater rim. Fan-like interformational and intraformational angular unconformities within Pliocene-Pleistocene strata, which strike parallel to the crater rim and dip 2-3?? away from the crater center, indicate that deformation and deposition were synchronous. Concentric, large-scale crossbedded, bioclastics and bodies of Pliocene age within ~20km of the buried crater rim formed on offshore shoals, presumably as subsiding listric slump blocks rotated near the crater rim.

Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments

PubMed Central

Rofes, Juan; Garcia-Ibaibarriaga, Naroa; Aguirre, Mikel; Martínez-García, Blanca; Ortega, Luis; Zuluaga, María Cruz; Bailon, Salvador; Alonso-Olazabal, Ainhoa; Castaños, Jone; Murelaga, Xabier

2015-01-01

Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ13C and δ15N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ18O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña’s sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere. PMID:26391668

Dental maturational sequence and dental tissue proportions in the early Upper Paleolithic child from Abrigo do Lagar Velho, Portugal

PubMed Central

Bayle, Priscilla; Macchiarelli, Roberto; Trinkaus, Erik; Duarte, Cidália; Mazurier, Arnaud; Zilhão, João

2010-01-01

Neandertals differ from recent and terminal Pleistocene human populations in their patterns of dental development, endostructural (internal structure) organization, and relative tissue proportions. Although significant changes in craniofacial and postcranial morphology have been found between the Middle Paleolithic and earlier Upper Paleolithic modern humans of western Eurasia and the terminal Pleistocene and Holocene inhabitants of the same region, most studies of dental maturation and structural morphology have compared Neandertals only to later Holocene humans. To assess whether earlier modern humans contrasted with later modern populations and possibly approached the Neandertal pattern, we used high-resolution microtomography to analyze the remarkably complete mixed dentition of the early Upper Paleolithic (Gravettian) child from Abrigo do Lagar Velho, Portugal, and compared it to a Neandertal sample, the late Upper Paleolithic (Magdalenian) child of La Madeleine, and a worldwide extant human sample. Some aspects of the dental maturational pattern and tooth endostructural organization of Lagar Velho 1 are absent from extant populations and the Magdalenian specimen and are currently documented only among Neandertals. Therefore, a simple Neandertal versus modern human dichotomy is inadequate to accommodate the morphostructural and developmental variation represented by Middle Paleolithic and earlier Upper Paleolithic populations. These data reinforce the complex nature of Neandertal-modern human similarities and differences, and document ongoing human evolution after the global establishment of modern human morphology. PMID:20080622

Geochemical evidence for enhanced preservation of organic matter in the oxygen minimum zone of the continental margin of northern California during the Late Pleistocene

USGS Publications Warehouse

Dean, Walter E.; Gardner, James V.; Anderson, Roger Y.

1994-01-01

The present upper water mass of the northeastern Pacific Ocean off California has a well-developed oxygen minimum zone between 600 and 1200 m wherein concentrations of dissolved oxygen are less than 0.5 mL/L. Even at such low concentrations of dissolved oxygen, benthic burrowing organisms are abundant enough to thoroughly bioturbate the surface and near-surface sediments. These macro organisms, together with micro organisms, also consume large quantities of organic carbon produced by large seasonal stocks of plankton in the overlying surface waters, which are supported by high concentrations of nutrients within the California Current upwelling system. In contrast to modern conditions of bioturbation, laminated sediments are preserved in upper Pleistocene sections of cores collected on the continental slope at water depths within the present oxygen minimum zone from at least as far north as the California-Oregon border and as far south as Point Conception. Comparison of sediment components in the laminae with those delivered to sediment traps as pelagic marine “snow” demonstrates that the dark-light lamination couplets are indeed annual (varves). These upper Pleistocene varved sediments contain more abundant lipid-rich “sapropelic” (type II) organic matter than the overlying bioturbated, oxidized Holocene sediments. The baseline of stable carbon isotopic composition of the organic matter in these slope cores does not change with time, indicating that the higher concentrations of type II organic matter in the varved sediments represent better preservation of organic matter rather than any change in the source of organic matter.

The Republic of the Philippines coalbed methane assessment: based on seventeen high pressure methane adsorption isotherms

USGS Publications Warehouse

Flores, Romeo M.; Stricker, Gary D.; Papasin, Ramon F.; Pendon, Ronaldo R.; del Rosario, Rogelio A.; Malapitan, Ruel T.; Pastor, Michael S.; Altomea, Elmer A.; Cuaresma, Federico; Malapitan, Armando S.; Mortos, Benjamin R.; Tilos, Elizabeth N.

2006-01-01

Introduction: The Republic of the Philippines has some 19 coal districts that contain coal deposits ranging from Eocene to Pleistocene in age. These coal districts include: (1) Catanduanes (Eocene); (2) Cebu, Zamboanga Sibuguey, Bukidnon, Maguindanao, Sarangani, and Surigao (Oligocene to Miocene); (3) Batan Island, Masbate, Semirara (including Mindoro), and Quezon-Polilio (lower-upper Miocene); (4) Davao, Negros, and Sorsogon (middle-upper Miocene); (5) Cotabato (lower Miocene-lower Pliocene), Cagayan-Isabella, and Quirino (upper Miocene-Pliocene); (6) Sultan Kudarat (upper Miocene-Pleistocene); and (7) Samar-Leyte (lower Pliocene-Pleistocene). In general, coal rank is directly related to the age of the deposits - for example, the Eocene coal is semi-anthracite and the Pliocene-Pleistocene coal is lignite. Total coal resources in these 19 coal districts, which are compiled by the Geothermal and Coal Resources Development Division (GCRDD) of the Department of Energy of the Philippines, are estimated at a minimum of 2,268.4 million metric tonnes (MMT) (approximately 2.3 billion metric tones). The largest resource (550 MMT) is the subbituminous coal in the Semirara (including Mindoro) coal district, and the smallest (0.7 MMT) is the lignite-subbituminous coal in the Quirino coal district. The combined lignite and subbituminous coal resources, using the classification by GCRDD and including Semirara and Surigao coal districts, are about 1,899.2 MMT, which make up about 84 percent of the total coal resources of the Philippines. The remaining resources are composed of bituminous and semi-anthracite coal. The subbituminous coal of Semirara Island in the Mindoro- Semirara coal district (fig. 2) is known to contain coalbed methane (CBM), with the coal being comparable in gas content and adsorption isotherms to the coal of the Paleocene Fort Union Formation in the Powder River Basin in Wyoming, USA (Flores and others, 2005). As a consequence, the presence of CBM in the Semirara coal led to the present study of determining the adsorption isotherms, or gas (CBM) holding or storage capacity, of coal beds of various ages from selected coal districts in the Philippines. Samples for the study were collected from the Batan Island, Catanduanes, Cagayan-Isabella, Cebu, Negros, Samar, Semirara, Cotabato, Surigao, and Malangas coalfield of the Zamboanga Sibuguey coal districts by five field geology teams from the GCRDD.

Morphological description and comparison of the dental remains from Atapuerca-Sima de los Huesos site (Spain).

PubMed

Martinón-Torres, María; Bermúdez de Castro, José María; Gómez-Robles, Aida; Prado-Simón, Leyre; Arsuaga, Juan Luis

2012-01-01

The systematic excavation of the Sima de los Huesos (SH) site in Sierra de Atapuerca (Burgos, Spain) has yielded the largest hominin collection worldwide for the Middle Pleistocene. The dental sample now consists of more than 500 teeth that provide exceptional opportunities to define the dental morphological pattern of a Middle Pleistocene population as well as develop hypotheses about the origins of the Neanderthals. The dental collection has now increased to over 533 specimens (525 permanent and 8 deciduous teeth), necessitating new morphological assessments. Thus, we present a detailed morphological description of the SH permanent dentition recovered up to 2007, accomplishing comparisons with European Middle Pleistocene hominins, Neanderthals, and early and contemporary Homo sapiens. We find that SH dentitions present all the morphological traits that, either in their degree of expression, frequency, or particular combination, are usually considered as typical of Homo neanderthalensis. This study ratifies the deep roots of the Neanderthal lineage in the Middle Pleistocene of Europe. In addition, SH teeth are morphologically "more Neanderthal" than other penecontemporaneous Middle Pleistocene samples such as Mauer or Arago, and even more derived than some classic Neanderthal samples. Thus, our study would not sustain the linearity of the accretion process hypothesized for the origins of the Neanderthals, and we suggest that other evolutionary models and scenarios should be explored for the Middle and Upper Pleistocene of Europe. We propose that more than one hominin lineage may have coexisted during the Middle Pleistocene in Europe. Copyright © 2011 Elsevier Ltd. All rights reserved.

A new Lower Pleistocene archeological site in Europe (Vallparadís, Barcelona, Spain)

PubMed Central

Martínez, Kenneth; Garcia, Joan; Carbonell, Eudald; Agustí, Jordi; Bahain, Jean-Jaques; Blain, Hugues-Alexandre; Burjachs, Francesc; Cáceres, Isabel; Duval, Mathieu; Falguères, Christophe; Gómez, Manuel; Huguet, Rosa

2010-01-01

Here we report the discovery of a new late Lower Pleistocene site named Vallparadís (Barcelona, Spain) that produced a rich archeological and paleontological sequence dated from the upper boundary of the Jaramillo subchron to the early Middle Pleistocene. This deposit contained a main archeological layer with numerous artifacts and a rich macromammalian assemblage, some of which bore cut marks, that could indicate that hominins had access to carcasses. Paleomagnetic analysis, electron spin resonance-uranium series (ESR-US), and the biostratigraphic chronological position of the macro- and micromammal and lithic assemblages of this layer reinforce the proposal that hominins inhabited Europe during the Lower Pleistocene. The archeological sequence provides key information on the successful adaptation of European hominins that preceded the well-known fossil population from Atapuerca and succeeded the finds from Orce basin. Hence, this discovery enables us to close a major chronological gap in the early prehistory of Iberia. According to the information in this paper and the available data from these other sites, we propose that Mediterranean Western Europe was repeatedly and perhaps continuously occupied during the late Matuyama chron. PMID:20231433

Late Middle Pleistocene hominin teeth from Panxian Dadong, South China.

PubMed

Liu, Wu; Schepartz, Lynne A; Xing, Song; Miller-Antonio, Sari; Wu, Xiujie; Trinkaus, Erik; Martinón-Torres, María

2013-05-01

The hominin teeth and evidence of hominin activities recovered from 1991 to 2005 at the Panxian Dadong site in South China are dated to the late Middle Pleistocene (MIS 8-6 or ca. 130-300 ka), a period for which very little is known about the morphology of Asian populations. The present study provides the first detailed morphometric description and comparisons of four hominin teeth (I(1), C1, P(3) and P3) from this site. Our study shows that the Panxian Dadong teeth combine archaic and derived features that align them with Middle and Upper Pleistocene fossils from East and West Asia and Europe. These teeth do not display any typical Neanderthal features and they are generally more derived than other contemporaneous populations from Asia and Africa. However, the derived traits are not diagnostic enough to specifically link the Panxian Dadong teeth to Homo sapiens, a common problem when analyzing the Middle Pleistocene dental record from Africa and Asia. These findings are contextualized in the discussion of the evolutionary course of Asian Middle Pleistocene hominins, and they highlight the necessity of incorporating the Asian fossil record in the still open debate about the origin of H. sapiens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Plio-Pleistocene synsedimentary fault compartments, foundation for the eastern Olduvai Basin paleoenvironmental mosaic, Tanzania.

PubMed

Stollhofen, Harald; Stanistreet, Ian G

2012-08-01

Normal faults displacing Upper Bed I and Lower Bed II strata of the Plio-Pleistocene Lake Olduvai were studied on the basis of facies and thickness changes as well as diversion of transport directions across them in order to establish criteria for their synsedimentary activity. Decompacted differential thicknesses across faults were then used to calculate average fault slip rates of 0.05-0.47 mm/yr for the Tuff IE/IF interval (Upper Bed I) and 0.01-0.13 mm/yr for the Tuff IF/IIA section (Lower Bed II). Considering fault recurrence intervals of ~1000 years, fault scarp heights potentially achieved average values of 0.05-0.47 m and a maximum value of 5.4 m during Upper Bed I, which dropped to average values of 0.01-0.13 m and a localized maximum of 0.72 m during Lower Bed II deposition. Synsedimentary faults were of importance to the form and paleoecology of landscapes utilized by early hominins, most traceably and provably Homo habilis as illustrated by the recurrent density and compositional pattern of Oldowan stone artifact assemblage variation across them. Two potential relationship factors are: (1) fault scarp topographies controlled sediment distribution, surface, and subsurface hydrology, and thus vegetation, so that a resulting mosaic of microenvironments and paleoecologies provided a variety of opportunities for omnivorous hominins; and (2) they ensured that the most voluminous and violent pyroclastic flows from the Mt. Olmoti volcano were dammed and conduited away from the Olduvai Basin depocenter, when otherwise a single or set of ignimbrite flows might have filled and devastated the topography that contained the central lake body. In addition, hydraulically active faults may have conduited groundwater, supporting freshwater springs and wetlands and favoring growth of trees. Copyright © 2011 Elsevier Ltd. All rights reserved.

2 - 4 million years of sedimentary processes in the Labrador Sea: implication for North Atlantic stratigraphy

NASA Astrophysics Data System (ADS)

Mosher, D. C.; Saint-Ange, F.; Campbell, C.; Piper, D. J.

2012-12-01

Marine sedimentary records from the western North Atlantic show that a significant portion of sediment deposited since the Pliocene originated from the Canadian Shield. In the Labrador Sea, previous studies have shown that bottom currents .strongly influenced sedimentation during the Pliocene, while during the Quaternary, intensification of turbidity current flows related to meltwater events were a dominant factor in supplying sediment to the basin and in the development of the North Atlantic Mid-Ocean Channel (NAMOC). Despite understanding this general pattern of sediment flux, details regarding the transfer of sediment from the Labrador Shelf to deep water and from the Labrador Sea to the North Atlantic remain poorly understood. Our study focuses on sedimentary processes occurring along the Labrador margin since the Pliocene and their consequences on the margin architecture, connection to the NAMOC, and role in sediment flux from the Labrador basin to the Sohm Abyssal Plain. Piston core and high resolution seismic data reveal that during the Pliocene to mid Pleistocene, widespread slope failures led to mass transport deposition along the entire Labrador continental slope. After the mid Pleistocene, sedimentation along the margin was dominated by the combined effects of glaciation and active bottom currents. On the shelf, prograded sedimentary wedges filled troughs and agraded till sheets form intervening banks. On the slope, stacked glaciogenic fans developed seaward of transverse troughs between 400 and 2800 mbsl. On the lower slope, seismic data show thick sediment drifts capped by glacio-marine mud. This unit is draped by well stratified sediment and marks a switch from a contourite dominated regime to a turbidite dominated regime. This shift occurred around 0.5 - 0.8 ka and correlates to the intensification of glaciations. Late Pleistocene sediments on the upper slope consist of stratified sediments related to proglacial plume fall-out. Coarse grained sediments, other than ice rafted detritus, by-passed the upper and middle slope and were transported to the lower slope and deep ocean. Seismic profiles and multibeam data along the Labrador Slope show a complex network of channels, with wide flat-bottomed channels off Saglek Bank to narrow channels off Cartwright Bank. The channels merge around 3000 mbsl to form single wide (~20 km) channels that eventually intersect, or flow parallel to the NAMOC. Rapid development of the NAMOC from the mid to late Pleistocene affected depositional patterns for sediment sourced from the Labrador margin. Downslope-transported sediment from the Labrador margin mostly tends to fill the basin or feed into NAMOC through tributary systems, whereas sediments derived from Hudson Strait feed the NAMOC and eventually the Sohm Abyssal plain. Sediment transported southward by the Western Boundary Undercurrent and Labrador Current likely reflect input along the margin, from Hudson Strait to Orphan Basin. Turbidite spill-over deposits are observed onlapping the continental margin of Labrador and Newfoundland as far south as Newfoundland Ridge.

Upper Mississippi embayment shallow seismic velocities measured in situ

USGS Publications Warehouse

Liu, Huaibao P.; Hu, Y.; Dorman, J.; Chang, T.-S.; Chiu, J.-M.

1997-01-01

Vertical seismic compressional- and shear-wave (P- and S-wave) profiles were collected from three shallow boreholes in sediment of the upper Mississippi embayment. The site of the 60-m hole at Shelby Forest, Tennessee, is on bluffs forming the eastern edge of the Mississippi alluvial plain. The bluffs are composed of Pleistocene loess, Pliocene-Pleistocene alluvial clay and sand deposits, and Tertiary deltaic-marine sediment. The 36-m hole at Marked Tree, Arkansas, and the 27-m hole at Risco, Missouri, are in Holocene Mississippi river floodplain sand, silt, and gravel deposits. At each site, impulsive P- and S-waves were generated by man-made sources at the surface while a three-component geophone was locked downhole at 0.91-m intervals. Consistent with their very similar geology, the two floodplain locations have nearly identical S-wave velocity (VS) profiles. The lowest VS values are about 130 m s-1, and the highest values are about 300 m s-1 at these sites. The shear-wave velocity profile at Shelby Forest is very similar within the Pleistocene loess (12m thick); in deeper, older material, VS exceeds 400 m s-1. At Marked Tree, and at Risco, the compressional-wave velocity (VP) values above the water table are as low as about 230 m s-1, and rise to about 1.9 km s-1 below the water table. At Shelby Forest, VP values in the unsaturated loess are as low as 302 m s-1. VP values below the water table are about 1.8 km s-1. For the two floodplain sites, the VP/VS ratio increases rapidly across the water table depth. For the Shelby Forest site, the largest increase in the VP/VS ratio occurs at ???20-m depth, the boundary between the Pliocene-Pleistocene clay and sand deposits and the Eocene shallow-marine clay and silt deposits. Until recently, seismic velocity data for the embayment basin came from earthquake studies, crustal-scale seismic refraction and reflection profiles, sonic logs, and from analysis of dispersed earthquake surface waves. Since 1991, seismic data for shallow sediment obtained from reflection, refraction, crosshole and downhole techniques have been obtained for sites at the northern end of the embayment basin. The present borehole data, however, are measured from sites representative of large areas in the Mississippi embayment. Therefore, they fill a gap in information needed for modeling the response of the embayment to destructive seismic shaking.

Large mammals from the Upper Neopleistocene reference sections in the Tunka rift valley, southwestern Baikal Region

NASA Astrophysics Data System (ADS)

Shchetnikov, A. A.; Klementiev, A. M.; Filinov, I. A.; Semeney, E. Yu.

2015-03-01

This work presents the data on new finds of fossil macrotheriofauna in the reference sections of the Upper Neopleistocene sediments in the Tunka rift valley (southwestern Baikal Region). The osteological material of a number of Late Neopleistocene mammals including extinct species rare for the Baikal region such as Crocuta spelaea, Panthera spelaea, and Spirocerus kiakhtensis (?) was directly dated with a radiocarbon (AMS) method. The obtained 14C data (18000-35000 years) allow one to rejuvenate significantly the upper limit of the common age interval of habitat of these animals in southern part of Eastern Siberia. Cave hyena and spiral-horned antelope lived in the Tunka rift valley in the Baikal region in Late Kargino time (37-24 ka), and cave lion survived the maximum in the Sartan cryochron in the region (21-20 ka). The study of collected paleontological collections provides a basis for selection of independent Kargino (MIS 3) faunal assemblages to use them for regional biostratigraphic analysis of Pleistocene deposits. Radiocarbon age dating of samples allows one to attribute confidently all paleofaunal remains available to the second half of the Late Pleistocene.

A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

PubMed

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2015-05-01

Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pleistocene to Holocene contrasts in organic matter production and preservation on the California continental margin

USGS Publications Warehouse

Dean, W.E.; Gardner, J.V.

1998-01-01

Organic matter in sediments from cores collected from the upper continental slope (200-2700 m) off California and southern Oregon shows marked differences in concentration and marine character between the last glacial interval (ca. 24-10 ka) and either Holocene time or last interstadial (oxygen isotope stage 3, ca. 60-24 ka). In general, sediments deposited during Holocene time and stage 3 contain higher amounts of marine organic matter than those deposited during the last glacial interval, and this contrast is greatest in cores collected off southern California. The most profound differences in stage 3 sediments are between predominantly bioturbated sediments and occasional interbeds of laminated sediments. The sediments are from cores collected within the present oxygen minimum zone on the upper continental slope from as far north as the Oregon-California border to as far south as Point Conception. These upper Pleistocene laminated sediments contain more abundant hydrogen-rich (type II) marine algal organic matter than even surface sediments that have large amounts of nonrefractory organic matter. The stable carbon-isotopic composition of the organic matter does not change with time between bioturbated and laminated sediments, indicating that the greater abundance of type II organic matter in the laminated sediments is not due to a change in source but rather represents a greater degree of production and preservation of marine organic matter. The presence of abundant, well-preserved organic matter supports the theory that the oxygen minimum zone in the northeastern Pacific Ocean was more intense, and possibly anoxic, during late Pleistocene time as a result of increased coastal upwelling that enhanced algal productivity.

Expression of seasonal and ENSO forcing in climatic variability at lower than ENSO frequencies: evidence from Pleistocene marine varves off California

USGS Publications Warehouse

Anderson, R.Y.; Linsley, B.K.; Gardner, J.V.

1990-01-01

Upper Pleistocene marine sediments along the upper continental slope off northern and central California contain alternations of varved and bioturbated sediments and associated changes in biota and sediment composition. These alternations can be related to conditions that accompany El Nin??o and anti-El Nin??o (ENSO) circulation. Anti-El Nin??o conditions are characterized by increased upwelling and productivity and by low concentrations of dissolved oxygen in the oxygen minimum zone that resulted in varve preservation. El Nin??o conditions are characterized by little or no upwelling, low productivity, and higher concentrations of dissolved oxygen that resulted in zones of bioturbation. Alternations of varves and zones of bioturbation, that range from decades to millennia, occur through the upper Pleistocene section. The inferred long-term alternations in El Nin??o and anti-El Nin??o conditions appear to be a re-expression of ENSO's primary 3-7 year cycle. Decadal to millennial cycles of productivity associated with El Nin??o and anti-El Nin??o conditions may have served as a "carbon pump" and transferred atmospheric CO2 to the marine reservoir. Changes in sediment composition and organisms associated with El Nin??o or anti-El Nin??o conditions can be related to both seasonal and ENSO phenomena. Expression of these changes at lower-than-ENSO frequencies may be partly explained by adding the effects of seasonal variability to effects produced by a self-oscillating ENSO system. However, deterministic mechanisms, including solar modulation of ENSO, may also contribute to long-term alternations of El Nin??o and anti-El Nin??o conditions. ?? 1990.

Geologic map of the Fort Morgan 7.5' quadrangle, Morgan County, Colorado

USGS Publications Warehouse

Berry, Margaret E.; Taylor, Emily M.; Slate, Janet L.; Paces, James B.; Hanson, Paul R.; Brandt, Theodore R.

2018-06-08

The Fort Morgan 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the late Pliocene to the present. The South Platte River, originating high in the Colorado Rocky Mountains, has played a major role in shaping surficial geology in the map area, which is several tens of kilometers downstream from where headwater tributaries join the river. Recurrent glaciation (and deglaciation) of basin headwaters has affected river discharge and sediment supply far downstream, influencing deposition of alluvium and river incision in the Fort Morgan quadrangle. Distribution and characteristics of the alluvial deposits indicate that during the Pleistocene the course of the river within the map area shifted progressively southward as it incised, and by late middle Pleistocene the river was south of its present position, cutting and filling a deep paleochannel near the south edge of the quadrangle. The river shifted back to the north during the late Pleistocene. Kiowa and Bijou Creeks are unglaciated tributaries originating in the Colorado Piedmont east of the Front Range that also have played a major role in shaping surficial geology of the map area. Periodically during the late Pleistocene, major flood events on these tributaries deposited large volumes of sediment at and near their confluences, forming a broad, low-gradient fan composed of sidestream alluvium that could have occasionally dammed the river for short periods of time. Wildcat Creek, also originating on the Colorado Piedmont, and the small drainage of Cris Lee Draw dissect the map area north of the river. Eolian sand deposits of the Sterling (north of river) and Fort Morgan (south of river) dune fields cover much of the quadrangle and record past episodes of sand mobilization during times of prolonged drought. With the onset of irrigation and damming during historical times, the South Platte River has changed from a broad, shallow, and sandy braided river with highly variable seasonal discharge to a much narrower, deeper river with braided-meandering transition morphology and more uniform discharge.

Human footprints in Central Mexico older than 40,000 years

NASA Astrophysics Data System (ADS)

González, Silvia; Huddart, David; Bennett, Matthew R.; González-Huesca, Alberto

2006-02-01

The timing, route and origin of the first colonization to the Americas remains one of the most contentious topics in human evolution. A number of migration routes have been suggested and there are different views as to the antiquity of the earliest human occupation. Some believe that settlement happened as early as 30 ka BP, but most of the currently accepted early sites in North America date to the latest Pleistocene, related to the expansion of the Clovis culture, while the oldest directly radiocarbon dated human remains are 11.5 ka BP. In this context new evidence is presented in this paper, in the form of human footprints preserved in indurated volcanic ash, to suggest that Central Mexico was inhabited as early as over 40 ka BP. Human and animal footprints have been found within the upper bedding surfaces of the Xalnene volcanic ash layer that outcrops in the Valsequillo Basin, south of Puebla, Mexico. This ash layer was produced by a subaqueous monogenetic volcano erupting within a palaeo-lake, dammed by lava within the Valsequillo Basin during the Pleistocene. The footprints were formed during low stands in lake level along the former shorelines and indicate the presence of humans, deer, canids, big felids, and probably camels and bovids. The footprints were buried by ash and lake sediments as lake levels rose and transgressed across the site. The ash has been dated to at least 40 ka BP by OSL dating of incorporated, baked lake sediments.

Geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado

USGS Publications Warehouse

Shroba, Ralph R.; Kellogg, Karl S.; Brandt, Theodore R.

2014-01-01

The geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado, portrays the geology in the upper Arkansas valley and along the lower flanks of the Sawatch Range and Mosquito Range near the town of Granite. The oldest rocks, exposed in the southern and eastern parts of the quadrangle, include gneiss and plutonic rocks of Paleoproterozoic age. These rocks are intruded by younger plutonic rocks of Mesoproterozoic age. Felsic hypabyssal dikes, plugs, and plutons, ranging in age from Late Cretaceous or Paleocene to late Oligocene, locally intruded Proterozoic rocks. A small andesite lava flow of upper Oligocene age overlies Paleoproterozoic rock, just south of the Twin Lakes Reservoir. Gravelly fluvial and fan deposits of the Miocene and lower Pliocene(?) Dry Union Formation are preserved in the post-30 Ma upper Arkansas valley graben, a northern extension of the Rio Grande rift. Mostly north-northwest-trending faults displace deposits of the Dry Union Formation and older rock units. Light detection and ranging (lidar) imagery suggests that two short faults, near the Arkansas River, may displace surficial deposits as young as middle Pleistocene. Surficial deposits of middle Pleistocene to Holocene age are widespread in the Granite quadrangle, particularly in the major valleys and on slopes underlain by the Dry Union Formation. The main deposits are glacial outwash and post-glacial alluvium; mass-movement deposits transported by creep, debris flow, landsliding, and rockfall; till deposited during the Pinedale, Bull Lake, and pre-Bull Lake glaciations; rock-glacier deposits; and placer-tailings deposits formed by hydraulic mining and other mining methods used to concentrate native gold. Hydrologic and geologic processes locally affect use of the land and locally may be of concern regarding the stability of buildings and infrastructure, chiefly in low-lying areas along and near stream channels and locally in areas of moderate to steep slopes. Low-lying areas along major and minor streams are subject to periodic stream flooding. Mass-movement deposits and deposits of the Dry Union Formation that underlie moderate to steep slopes are locally subject to creep, debris-flow deposition, and landsliding. Proterozoic rocks that underlie steep slopes are locally subject to rockfall. Sand and gravel resources for construction and other uses in and near the Granite quadrangle are present in outwash-terrace deposits of middle and late Pleistocene age along the Arkansas River and along tributary streams in glaciated valleys.

Insights on the first peopling of Europe from magnetostratigraphy of the Pleistocene lithic tool-bearing Kozarnika cave sediments, Bulgaria

NASA Astrophysics Data System (ADS)

Monesi, E.; Muttoni, G.; Sirakov, N.; Kent, D. V.; Guadelli, J. L.; Scardia, G.; Zerboni, A.; Ferrara, E.

2017-12-01

We present a new sedimentological profile and a magnetostratigraphy of the tool-bearing Kozarnika cave sediments from Bulgaria. Modal analysis of cave infilling sedimentary texture indicates that most of the layers are produced by reworked wind-blown sediment (loess). We found evidence for a relatively thick and well defined normal magnetic polarity in the upper-middle part of the section interpreted as a record of the Brunhes Chron, followed downsection by reverse polarity directions. The Brunhes-Matuyama boundary (0.78 Ma) is placed in the upper part of Layer 13 Lower. The lowermost levels with Lower Paleolithic tools are close to - or possibly straddling the - Brunhes-Matuyama boundary. Our results are in substantial agreement with the age of onset of loess deposition in the Danube valley, which occurred shortly before the Brunhes-Matuyama boundary. Moreover, our data fit well with the hypothesis that hominins first entered Europe across a Danube-Po migration conduit during the late Early Pleistocene.

Late Quaternary refugia of Mediterranean taxa in the Portuguese Estremadura: charcoal based palaeovegetation and climatic reconstruction

NASA Astrophysics Data System (ADS)

Figueiral, I.; Terral, J.-F.

2002-02-01

The study of archaeological charcoal preserved in the sediments of Buraca Grande (Estremadura, Portugal) are used to aid the reconstruction of vegetation available to prehistoric settlements from the Upper Palaeolithic to the Neolithic. Results indicate the possible existence of three different phases. The first is mostly characterized by the presence of Pinus type sylvestris and of Buxus sempervirens. During the second phase, these taxa are replaced by more thermophilous elements dominated by Olea europaea. The decrease of Olea europaea in the last archaeological layer appears to represent the beginning of a third phase. The eco-anatomical analyses of charcoal fragments identified as Olea europaea allowed us to evaluate the palaeoclimatic conditions during this period. Two main phases are recognized; the first (Upper Pleistocene) is drier and cooler than present, while the Holocene sequence is comparable to present-day conditions. Results from both analyses are complementary and appear to show that this region was a refuge area for thermophilous taxa during the colder periods of the Pleistocene.

Navy Fan, California Borderland: Growth pattern and depositional processes

USGS Publications Warehouse

Normark, W.R.; Piper, D.J.W.

1984-01-01

Navy Fan is a Late Pleistocene sand-rich fan prograding into an irregularly shaped basin in the southern California Borderland. The middle fan, characterized by one active and two abandoned 'distributary' channels and associated lobe deposits, at present onlaps part of the basin slope directly opposite from the upper-fan valley, thus dividing the lower-fan/basin-plain regions into two separate parts of different depths. Fine-scale mesotopographic relief on the fan surface and correlation of individual turbidite beds through nearly 40 cores on the middle and lower fan provide data for evaluating the Late Pleistocene and Holocene depositional processes. ?? 1984 Springer-Verlag New York Inc.

Normal faulting and mass movement during ridge subduction inferred from porosity transition and zeolitization in the Costa Rica subduction zone

NASA Astrophysics Data System (ADS)

Hamahashi, Mari; Screaton, Elizabeth; Tanikawa, Wataru; Hashimoto, Yoshitaka; Martin, Kylara; Saito, Saneatsu; Kimura, Gaku

2017-07-01

Subduction of the buoyant Cocos Ridge offshore the Osa Peninsula, Costa Rica substantially affects the upper plate structure through a variety of processes, including outer forearc uplift, erosion, and focused fluid flow. To investigate the nature of a major seismic reflector (MSR) developed between slope sediments (late Pliocene-late Pleistocene silty clay) and underlying higher velocity upper plate materials (late Pliocene-early Pleistocene clayey siltstone), we infer possible mechanisms of sediment removal by examining the consolidation state, microstructure, and zeolite assemblages of sediments recovered from Integrated Ocean Drilling Program Expedition 344 Site U1380. Formation of Ca-type zeolites, laumontite and heulandite, inferred to form in the presence of Ca-rich fluids, has caused porosity reduction. We adjust measured porosity values for these pore-filling zeolites and evaluated the new porosity profile to estimate how much material was removed at the MSR. Based on the composite porosity-depth curve, we infer the past burial depth of the sediments directly below the MSR. The corrected and uncorrected porosity-depth curves yield values of 800 ± 70 m and 900 ± 70 m, respectively. We argue that deposition and removal of this entire estimated thickness in 0.49 Ma would require unrealistically large sedimentation rates and suggest that normal faulting at the MSR must contribute. The porosity offset could be explained with maximum 250 ± 70 m of normal fault throw, or 350 ± 70 m if the porosity were not corrected. The porosity correction significantly reduces the amount of sediment removal needed for the combination of mass movement and normal faulting that characterize the slope in this margin.

The high Andes, gene flow and a stable hybrid zone shape the genetic structure of a wide-ranging South American parrot

PubMed Central

2011-01-01

Background While the gene flow in some organisms is strongly affected by physical barriers and geographical distance, other highly mobile species are able to overcome such constraints. In southern South America, the Andes (here up to 6,900 m) may constitute a formidable barrier to dispersal. In addition, this region was affected by cycles of intercalating arid/moist periods during the Upper/Late Pleistocene and Holocene. These factors may have been crucial in driving the phylogeographic structure of the vertebrate fauna of the region. Here we test these hypotheses in the burrowing parrot Cyanoliseus patagonus (Aves, Psittaciformes) across its wide distributional range in Chile and Argentina. Results Our data show a Chilean origin for this species, with a single migration event across the Andes during the Upper/Late Pleistocene, which gave rise to all extant Argentinean mitochondrial lineages. Analyses suggest a complex population structure for burrowing parrots in Argentina, which includes a hybrid zone that has remained stable for several thousand years. Within this zone, introgression by expanding haplotypes has resulted in the evolution of an intermediate phenotype. Multivariate regressions show that present day climatic variables have a strong influence on the distribution of genetic heterogeneity, accounting for almost half of the variation in the data. Conclusions Here we show how huge barriers like the Andes and the regional environmental conditions imposed constraints on the ability of a parrot species to colonise new habitats, affecting the way in which populations diverged and thus, genetic structure. When contact between divergent populations was re-established, a stable hybrid zone was formed, functioning as a channel for genetic exchange between populations. PMID:21672266

Teleseismic traveltime tomography of Jeju Island, South Korea

NASA Astrophysics Data System (ADS)

Song, J.; Rhie, J.; Kim, S.; Lee, S. H.

2017-12-01

Jeju Island is the largest volcanic island in South Korea, which lies off the south coast of the Korean Peninsula. It is well known that the volcanism started in the Early Pleistocene (c. 1.7 Ma) and subsequent eruptions during Late Pleistocene to Holocene formed the bulk of the island with a number of small cones. However, the origin of magma and detailed mechanism of eruptions have not been fully understood yet. To address these issues, we applied teleseismic travel time tomography to image the underlying crust and upper mantle of the island. We carefully analyzed 185 teleseismic earthquakes (5.5 < Mw < 7.9) that occurred between Oct. 2013 and Nov. 2015. Broadband waveforms recorded by 23 seismic stations covering the whole island were used to measure travel time residuals of P and S waves using semi-automated adaptive stacking technique. The residuals are mapped as three-dimensional perturbations of velocity using iterative non-linear tomographic process with a subspace inversion technique and the fast marching method for grid based eikonal solver. We used AK135 global reference model as a starting velocity model for tomography inversion. The resulting P wave tomographic images exhibit relatively low velocity anomaly in the upper mantle, which extends to depths of nearly 60 km under the summit of the island, Mt. Halla. The anomaly is likely related to a relatively high-temperature magmatic body, which might be associated to the volcanism lasted until late Cenozoic. To better constrain possible compositions of the anomalies and the existence of melt fractions, we will continue to examine perturbation of Vp/Vs ratios and discuss the evolution of the volcanic island.

The Sima de los Huesos crania (Sierra de Atapuerca, Spain). A comparative study.

PubMed

Arsuaga, J L; Martínez, I; Gracia, A; Lorenzo, C

1997-01-01

The Sima de los Huesos (Sierra de Atapuerca) cranial remains found up to and including the 1995 field season are described and compared with other fossils in order to assess their evolutionary relationships. The phenetic affinities of the Sima de los Huesos crania and a large sample of Homo fossils are investigated through principal component analyses. Metrical comparisons of the Sima de los Huesos and other European and African Middle Pleistocene fossils with Neandertals are performed using Z-scores relative to the Neandertal sample statistics. The most relevant cranial traits are metrically and morphologically analyzed and cladistically evaluated. The Sima de los Huesos crania exhibit a number of primitive traits lost in Upper Pleistocene Neandertals (especially in the braincase, but also in the facial skeleton), as well as other traits that are transitional to the Neandertal morphology (particularly in the occipital bone), and features close to what is found in Neandertals (as the supraorbital morphology and midfacial prognathism). Different combinations of primitive and derived traits (shared with Neandertals) are also displayed by the other European Middle Pleistocene fossils. In conclusion, the Sima de los Huesos sample is evolutionarily related to Neandertals as well as to the other European Middle Pleistocene fossils. In our opinion, all the European Middle Pleistocene fossils belong to the Neandertal lineage, and none can be included in an Afroeuropean common ancestor of Neandertals and modern humans.

Homo erectus in Salkhit, Mongolia?

PubMed

Lee, Sang-Hee

2015-08-01

In 2006, a skullcap was discovered in Salkhit, Mongolia. The Salkhit skullcap has a mostly complete frontal, two partially complete parietals, and nasals. No chronometric dating has been published yet, and suggested dates range from early Middle Pleistocene to terminal Late Pleistocene. While no chronometric date has been published, the presence of archaic features has led to a potential affiliation with archaic hominin species. If it is indeed Homo erectus or archaic Homo sapiens, Salkhit implies a much earlier spread of hominins farther north and inland Asia than previously thought. In this paper, the nature of the archaic features in Salkhit is investigated. The Salkhit skullcap morphology and metrics were compared with Middle and Late Pleistocene hominin fossils from northeast Asia: Zhoukoudian Locality 1, Dali, and Zhoukoudian Upper Cave. Results show an interesting pattern: on one hand, the archaic features that Salkhit shares with the Zhoukoudian Locality 1 sample also are shared with other later hominins; on the other hand, Salkhit is different from the Middle Pleistocene materials in the same way later hominins differ from the Middle Pleistocene sample, in having a broader frontal and thinner supraorbital region. This may reflect encephalization and gracilization, a modernization trend found in many places. It is concluded that the archaic features observed in Salkhit are regionally predominant features rather than diagnostic features of an archaic species. Copyright © 2015 Elsevier GmbH. All rights reserved.

Pumice in the interglacial Whidbey Formation at Blowers Bluff, central Whidbey Island, WA, USA

USGS Publications Warehouse

Dethier, D.P.; Dragovich, J.D.; Sarna-Wojcicki, A. M.; Fleck, R.J.

2008-01-01

A new 40Ar/39Ar age of 128??9 ka and chemical analyses of pumice layers from interglacial alluvium at Blowers Bluff, Whidbey Island, WA, show that the deposits are part of the Whidbey Formation, a widespread, mainly subsurface unit. Glass chemistry of the dated dacitic pumice does not match any analyzed northern Cascade source, but upper Pleistocene dacites from Glacier Peak and early Pleistocene silicic rocks from the Kulshan caldera are chemically similar. The chemistry of pumiceous dacite in younger units, including the latest Pleistocene Partridge Gravel, is similar to that of the dated material. The deep troughs of the modern northern Puget lowland must have been filled during deposition of the Whidbey Formation, allowing volcanic-rich sediment to reach what is now Whidbey Island. Topographic analysis of LIDAR images demonstrates that extensive erosion occurred during latest Pleistocene ice retreat. The Partridge Gravel likely records subglacial fluvial erosion along an ice tunnel and ice-marginal deposition into adjacent marine waters. Pumice in the Partridge Gravel probably was reworked from stratigraphically and topographically lower deposits, including those at Blowers Bluff. ?? 2007 Elsevier Ltd and INQUA.

Paleopedological research of the dynamics alteration in environment of the Lover Volga region in the last macrocycle

NASA Astrophysics Data System (ADS)

Bagrova, Svetlana; Makeev, Alexander; Rusakov, Alexey; Yanina, Tatiana; Kurbanov, Redzhep

2017-04-01

Caspian Sea reflects in its development global climate changes, glacial-interglacial rhythms in Russian plains and mountain areas. It is stratigraphic region for drawing up a single stratigraphic and paleogeographic plan of the Upper Pleistocene of Northern Eurasia. To date, accumulated a considerable amount of material on the Quaternary history of Ponto-Caspian, based on stratigraphic, paleogeographic and geomorphological studies. However, paleopedological work in the region have been starting for the first time. Studying paleopedology in soil-sediment thickness have paramount importance, as they can reliably break down the steps of the surface on which stabilization was carried out paedogenesis with further sedimentation, and allow us to trace the stages of evolution of the environment of the region. The site (Srednyaya Akhtuba) located on the left bank of the Akhtuba River, 20 km from the Volzhsky city, the upper part of Lower Volga region. This marine terrace represented by 6 paedogenetic levels, including 7 soils (MIS1-MIS5) (Yanina, 2014) separated by sediments (precipitation) of different structure and genesis. The upper part of the section (0-150 cm) presented by a typical for the dry steppe area soil Kastanzem (WRB, 2014) (MIS1). Parent rock material is a great pack (>1m) of the Caspian marine sediments, represented by a series of layers of chocolate clays (MIS2) with interbedding of sands. Lower, is a pack (520-670 cm), formed during Atelian regression of the Caspian Sea (MIS3-MIS4), presented by one well-developed soil with truncated humus horizon and two loessic layers with signs of soil formation (rhizolithes, manganese nodule, cryogenesis structure and etc) MIS3 stage. The lower part of Atel-Ahtuba strata (910-1530 cm) is presented by carbonate loess without noticeable pedogenetic transformation. From a depth of 1530 cm begins thick layer of loess-soil series, presented by MIS5a-e Mezin pedocomplex, dedicated to the Late Khazar-Girkan transgression, with three well-preserved soils. The upper soil, Gleyic Phaeozem, has accretionary humus horizon (about 1 m), many krotovinas, and network of frost wedges 40-50 cm. Wedges start in the overlying Atel-Akhtuba loess layer indicating the beginning of the last glacial cycle (MIS4). The middle soil, Gleyic Chernozem, has first 5 cm humus horizon intermixed with Bg horizon of the upper soil (welded paleosol). Until the middle of the profile (1740 cm) are the end of the loess permafrost wedges. Gleyic features are due to seasonal overflooding. The lower soil of Mezin pedocomplex (MIS5e), Mollic Calcic Gleysol, formed in loess sediments accumulated during penultimate glaciation (MIS6) and has reworked upper boundary (10-13 cm), well-defined humus horizon with gley process. Three soils of Mezin pedocomplex have common features: semi terrestrial genesis with gleyic features due to long-term seasonal overflooding; well developed humus horizons and complex assemblage of carbonate neoformations, formed under steppe environment. Pedogenetic horizons serve as good stratigraphic markers that will help to correlate late Pleistocene soil-sedimentary sequences of the whole Caspian-Azov-Black sea region, East European Plain and link it with global stratigraphic schemes. Detailed analytical and further field studies are required to reveal further pedogenetic response to environmental changes in the area. Research was supported by Russian Science Foundation, project 14-17-00705

Middle Pleistocene Climate Change Recorded in Fossil Mammal Teeth from Tarija, Bolivia, and Upper Limit of the Ensenadan Land-Mammal Age

NASA Astrophysics Data System (ADS)

MacFadden, Bruce J.

2000-07-01

Fossiliferous middle Pleistocene sediments of the Tarija basin of southern Bolivia contain a classic Ensenadan land-mammal fauna. New carbon isotopic data reported here for 50 specimens of the grazing mammals Equus (horse) and Cuvieronius (mastodon), documented from eight stratigraphic levels at Tarija, vary significantly in the δ13C values of their teeth. The pattern of variation appears to reflect the proportion of C3 and C4 grasses eaten during colder (more C3) and warmer (more C4) times. Within age limits set by associated magnetostratigraphy, the cold periods can be correlated with particular even-numbered stages in the marine oxygen-isotope record, and the warm periods can be correlated with odd-numbered stages. The oldest fossil teeth analyzed from the Tarija section can thereby be assigned to stage 29, and the youngest to stages 17 or 15, that is; the teeth range in age from about 1.1 myr to as young as 0.7 myr. Based on correlation of the upper part of the Tarija beds to the isotopic stages, the upper limit of the Ensenadan land-mammal age is between 0.7 and 0.6 myr, which is younger than stated in most previous studies.

[The effect of reproduction biotopes on the genetic differentiation of populations of sockeye salmon Oncorhynchus nerka].

PubMed

Brykov, V A; Poliakova, N E; Podlesnykh, A V; Golub', E V; Golub', A P; Zhdanova, O L

2005-05-01

Variation of mitochondrial DNA (mtDNA) was examined in nine populations from three lake-river systems of Chukotka and Kamchatka. Significant differences were found between most of the sockeye salmon samples studied. The genetic differences among populations were not high and often did not correlate with the geographical distances between them. The low population divergence is explained by a short time of existence of most of them, having been formed after the recession of the upper Pleistocene glacier. When the populations were grouped according to their spawning biotopes (river or lake), they in general appeared more genetically similar than upon their grouping by geographical location (the lake-river systems). The differences between the river and lake populations in the lake--river systems increased from north to south.

Water chemistry at Snowshoe Mountain, Colorado: mixed processes in a common bedrock

USGS Publications Warehouse

Hoch, A.R.; Reddy, M.M.

2001-01-01

At Snowshoe Mountain the primary bedrock is quite homogeneous, but weathering processes vary as waters moves through the soils, vadose zone and phreatic zone of the subsurface. In the thin soil, physical degradation of tuff facilitates preferential dissolution of potassium ion from glass within the rock matrix, while other silicate minerals remain unaltered. In the vadose zone, in the upper few meters of fractured bedrock, dilute water infiltrates during spring snowmelt and summer storms, leading to preferential dissolution of augite exposed on fracture surfaces. Deeper yet, in the phreatic zone of the fractured bedrock, Pleistocene calcite fracture fillings dissolve, and dioctahedral and trioctahedral clays form as penetrative weathering alters feldspar and pyroxene. Alkalinity is generated and silica concentrations are buffered by mineral alteration reactions.

An Early Pleistocene hominin mandible from Atapuerca-TD6, Spain

PubMed Central

Carbonell, E.; Bermúdez de Castro, J. M.; Arsuaga, J. L.; Allue, E.; Bastir, M.; Benito, A.; Cáceres, I.; Canals, T.; Díez, J. C.; van der Made, J.; Mosquera, M.; Ollé, A.; Pérez-González, A.; Rodríguez, J.; Rodríguez, X. P.; Rosas, A.; Rosell, J.; Sala, R.; Vallverdú, J.; Vergés, J. M.

2005-01-01

We present a mandible recovered in 2003 from the Aurora Stratum of the TD6 level of the Gran Dolina site (Sierra de Atapuerca, northern Spain). The specimen, catalogued as ATD6-96, adds to the hominin sample recovered from this site in 1994–1996, and assigned to Homo antecessor. ATD6-96 is the left half of a gracile mandible belonging to a probably female adult individual with premolars and molars in place. This mandible shows a primitive structural pattern shared with all African and Asian Homo species. However, it is small and exhibits a remarkable gracility, a trait shared only with the Early and Middle Pleistocene Chinese hominins. Furthermore, none of the mandibular features considered apomorphic in the European Middle and Early Upper Pleistocene hominin lineage are present in ATD6-96. This evidence reinforces the taxonomic identity of H. antecessor and is consistent with the hypothesis of a close relationship between this species and Homo sapiens. PMID:15824320

Geologic aspects of the surficial aquifer in the upper East Coast planning area, Southeast Florida

USGS Publications Warehouse

Miller, Wesley L.

1980-01-01

The Upper East Coast Planning Area, as designated by the South Florida Water Management District, consists of St. Lucie County, Martin County, and eastern Okeechobee County. The surficial aquifer is the main source of freshwater for agricultural and urban uses in the area. The geologic framework of the aquifer is displayed by contour mapping and lithologic cross sections to provide water managers with a better understanding of the natural restraints that may be imposed on future development. The surficial aquifer is primarily sand, limestone, shell, silt, and clay deposited during the Pleistocene and Pliocene Epochs. The aquifer is unconfined and under water-table conditions in most of the area, but locally, artesian conditions exits where discontinuous clay layers act as confining units. Impermeable and semipermeable clays and marls of the Tamiami (lower Pliocene) and Hawthorn Formations (Miocene) unconformably underlie the surficial aquifer and form its base. Contour lines showing the altitude of the base of the aquifer indicate extensive erosion of the Miocene sediments prior to deposition of the aquifer materials. (USGS)

A reassessment of the early archaeological record at Leang Burung 2, a Late Pleistocene rock-shelter site on the Indonesian island of Sulawesi.

PubMed

Brumm, Adam; Hakim, Budianto; Ramli, Muhammad; Aubert, Maxime; van den Bergh, Gerrit D; Li, Bo; Burhan, Basran; Saiful, Andi Muhammad; Siagian, Linda; Sardi, Ratno; Jusdi, Andi; Abdullah; Mubarak, Andi Pampang; Moore, Mark W; Roberts, Richard G; Zhao, Jian-Xin; McGahan, David; Jones, Brian G; Perston, Yinika; Szabó, Katherine; Mahmud, M Irfan; Westaway, Kira; Jatmiko; Saptomo, E Wahyu; van der Kaars, Sander; Grün, Rainer; Wood, Rachel; Dodson, John; Morwood, Michael J

2018-01-01

This paper presents a reassessment of the archaeological record at Leang Burung 2, a key early human occupation site in the Late Pleistocene of Southeast Asia. Excavated originally by Ian Glover in 1975, this limestone rock-shelter in the Maros karsts of Sulawesi, Indonesia, has long held significance in our understanding of early human dispersals into 'Wallacea', the vast zone of oceanic islands between continental Asia and Australia. We present new stratigraphic information and dating evidence from Leang Burung 2 collected during the course of our excavations at this site in 2007 and 2011-13. Our findings suggest that the classic Late Pleistocene modern human occupation sequence identified previously at Leang Burung 2, and proposed to span around 31,000 to 19,000 conventional 14C years BP (~35-24 ka cal BP), may actually represent an amalgam of reworked archaeological materials. Sources for cultural materials of mixed ages comprise breccias from the rear wall of the rock-shelter-remnants of older, eroded deposits dated to 35-23 ka cal BP-and cultural remains of early Holocene antiquity. Below the upper levels affected by the mass loss of Late Pleistocene deposits, our deep-trench excavations uncovered evidence for an earlier hominin presence at the site. These findings include fossils of now-extinct proboscideans and other 'megafauna' in stratified context, as well as a cobble-based stone artifact technology comparable to that produced by late Middle Pleistocene hominins elsewhere on Sulawesi.

Abrupt shift in δ18O values at Medicine Lake volcano (California, USA)

USGS Publications Warehouse

Donnelly-Nolan, J. M.

1998-01-01

 Oxygen-isotope analyses of lavas from Medicine Lake volcano (MLV), in the southern Cascade Range, indicate a significant change in δ18O in Holocene time. In the Pleistocene, basaltic lavas with <52% SiO2 averaged +5.9‰, intermediate lavas averaged +5.7‰, and silicic lavas (≥63.0%SiO2) averaged +5.6‰. No analyzed Pleistocene rhyolites or dacites have values greater than +6.3‰. In post-glacial time, basalts were similar at +5.7‰ to those erupted in the Pleistocene, but intermediate lavas average +6.8‰ and silicic lavas +7.4‰ with some values as high as +8.5‰. The results indicate a change in the magmatic system supplying the volcano. During the Pleistocene, silicic lavas resulted either from melting of low-18O crust or from fractionation combined with assimilation of very-low-18O crustal material such as hydrothermally altered rocks similar to those found in drill holes under the center of the volcano. By contrast, Holocene silicic lavas were produced by assimilation and/or wholesale melting of high-18O crustal material such as that represented by inclusions of granite in lavas on the upper flanks of MLV. This sudden shift in assimilant indicates a fundamental change in the magmatic system. Magmas are apparently ponding in the crust at a very different level than in Pleistocene time.

Geology of Isla de Mona, Puerto Rico

USGS Publications Warehouse

Frank, E.F.; Wicks, Carol M.; Mylroie, J.; Troester, J.; Alexander, E.C.; Carew, J.L.

1998-01-01

Isla de Mona is a carbonate island located in the Mona Passage 68 km west of Puerto Rico. The tectonically uplifted island is 12 km by 5 km, with an area of 55 km2, and forms a raised flat-topped platform or meseta. The meseta tilts gently to the south and is bounded by near vertical cliffs on all sides. These cliffs rise from 80 m above sea level on the north to 20 m above the sea on the southern coast. Along the southwestern and western side of the island a three- to six-meter-high Pleistocene fossil reef abuts the base of the cliff to form a narrow coastal plain. The meseta itself consists of two Mio-Pliocene carbonate units, the lower Isla de Mona Dolomite and the upper Lirio Limestone. Numerous karst features, including a series of flank margin caves primarily developed at the Lirio Limestone/Isla de Mona Dolomite contact, literally ring the periphery of the island.

Middle Palaeolithic occupation in the Thar Desert during the Upper Pleistocene: the signature of a modern human exit out of Africa?

NASA Astrophysics Data System (ADS)

Blinkhorn, James; Achyuthan, Hema; Petraglia, Michael; Ditchfield, Peter

2013-10-01

The Thar Desert marks the transition from the Saharo-Arabian deserts to the Oriental biogeographical zone and is therefore an important location in understanding hominin occupation and dispersal during the Upper Pleistocene. Here, we report the discovery of stratified Middle Palaeolithic assemblages at Katoati in the north-eastern Thar Desert, dating to Marine Isotope Stages (MIS) 5 and the MIS 4-3 boundary, during periods of enhanced humidity. Hominins procured cobbles from gravels at the site as evidenced by early stages of stone tool reduction, with a component of more formalised point production. The MIS 5c assemblages at Katoati represent the earliest securely dated Middle Palaeolithic occupation of South Asia. Distinctive artefacts identified in both MIS 5 and MIS 4-3 boundary horizons match technological entities observed in Middle Palaeolithic assemblages in South Asia, Arabia and Middle Stone Age sites in the Sahara. The evidence from Katoati is consistent with arguments for the dispersal of Homo sapiens populations from Africa across southern Asia using Middle Palaeolithic technologies.

First Early Hominin from Central Africa (Ishango, Democratic Republic of Congo)

PubMed Central

Crevecoeur, Isabelle; Skinner, Matthew M.; Bailey, Shara E.; Gunz, Philipp; Bortoluzzi, Silvia; Brooks, Alison S.; Burlet, Christian; Cornelissen, Els; De Clerck, Nora; Maureille, Bruno; Semal, Patrick; Vanbrabant, Yves; Wood, Bernard

2014-01-01

Despite uncontested evidence for fossils belonging to the early hominin genus Australopithecus in East Africa from at least 4.2 million years ago (Ma), and from Chad by 3.5 Ma, thus far there has been no convincing evidence of Australopithecus, Paranthropus or early Homo from the western (Albertine) branch of the Rift Valley. Here we report the discovery of an isolated upper molar (#Ish25) from the Western Rift Valley site of Ishango in Central Africa in a derived context, overlying beds dated to between ca. 2.6 to 2.0 Ma. We used µCT imaging to compare its external and internal macro-morphology to upper molars of australopiths, and fossil and recent Homo. We show that the size and shape of the enamel-dentine junction (EDJ) surface discriminate between Plio-Pleistocene and post-Lower Pleistocene hominins, and that the Ishango molar clusters with australopiths and early Homo from East and southern Africa. A reassessment of the archaeological context of the specimen is consistent with the morphological evidence and suggest that early hominins were occupying this region by at least 2 Ma. PMID:24427292

Middle Pleistocene Hominin Teeth from Longtan Cave, Hexian, China

PubMed Central

Xing, Song; Martinón-Torres, María; Bermúdez de Castro, José María; Zhang, Yingqi; Fan, Xiaoxiao; Zheng, Longting; Huang, Wanbo; Liu, Wu

2014-01-01

Excavations at the Longtan Cave, Hexian, Anhui Province of Eastern China, have yielded several hominin fossils including crania, mandibular fragments, and teeth currently dated to 412±25 ka. While previous studies have focused on the cranial remains, there are no detailed analyses of the dental evidence. In this study, we provide metric and morphological descriptions and comparisons of ten teeth recovered from Hexian, including microcomputed tomography analyses. Our results indicate that the Hexian teeth are metrically and morphologically primitive and overlap with H. ergaster and East Asian Early and mid-Middle Pleistocene hominins in their large dimensions and occlusal complexities. However, the Hexian teeth differ from H. ergaster in features such as conspicuous vertical grooves on the labial/buccal surfaces of the central incisor and the upper premolar, the crown outline shapes of upper and lower molars and the numbers, shapes, and divergences of the roots. Despite their close geological ages, the Hexian teeth are also more primitive than Zhoukoudian specimens, and resemble Sangiran Early Pleistocene teeth. In addition, no typical Neanderthal features have been identified in the Hexian sample. Our study highlights the metrical and morphological primitive status of the Hexian sample in comparison to contemporaneous or even earlier populations of Asia. Based on this finding, we suggest that the primitive-derived gradients of the Asian hominins cannot be satisfactorily fitted along a chronological sequence, suggesting complex evolutionary scenarios with the coexistence and/or survival of different lineages in Eurasia. Hexian could represent the persistence in time of a H. erectus group that would have retained primitive features that were lost in other Asian populations such as Zhoukoudian or Panxian Dadong. Our study expands the metrical and morphological variations known for the East Asian hominins before the mid-Middle Pleistocene and warns about the possibility that the Asian hominin variability may have been taxonomically oversimplified. PMID:25551383

Plio Quaternary tectonic evolution and structure of the Catania foredeep, the northern Hyblean Plateau and the Ionian shelf (SE Sicily)

NASA Astrophysics Data System (ADS)

Torelli, Luigi; Grasso, Mario; Mazzoldi, Glauco; Peis, Davide

1998-11-01

Available multi- and single-channel seismic reflection profiles, calibrated by onshore borehole data, have been used for defining the structural styles in the shelf and slope of the Ionian Sea between Catania and Augusta (SE Sicily). The geological and geophysical data suggest that this area represents a segment of the foredeep-foreland system which collapsed after Late Pliocene times. The foundering was controlled by normal faults trending NE-SW, which flank the southern margin of the Catania foredeep. Onland, in outcrop, these faults appear largely to be post-dated by Lower Pleistocene sediments, nearshore carbonates passing laterally into basinal clays, which lie unconformably upon older substrata. Offshore, close to the southern edge of the foredeep, seismic lines allow recognition of two distinct units: a syn-rift wedge (Upper Pliocene submarine tholeiites and sediments), and a post-rift sequence which can be correlated with Lower Pleistocene carbonates, sands and clays recognisable on land, both in outcrop and by borehole data. The true frontal part of the thrust belt, as detected by the seismic lines, occupies the inner part of the area investigated and is buried by Upper Pliocene and Lower Pleistocene sediments. However, the compressive deformation seems to propagate toward the south-southeast by means of growing detachment levels developing at depth within Pleistocene marine clays, for a length of about 10 km, ahead of the present-day thrust front. Offshore, the faults trending NE-SW are dissected towards the east by faults trending NNW-SSE, subparallel to the Malta Escarpment, which flank the edge of the submerged Messina Rise. These faults, originating in a steep scarp which drops eastwards to the deep Ionian basin, have triggered submarine slides and affected the present-day seafloor sediments. As shown by seismic lines and as stressed by the modern seismicity of the area, some of the faults along the Malta Escarpment could be still active.

Climatic implications of correlated upper Pleistocene glacial and fluvial deposits on the Cinca and Gallego rivers, NE Spain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Claudia J; Mcdonald, Eric; Sancho, Carlos

We correlate Upper Pleistocene glacial and fluvial deposits of the Cinca and Gallego River valleys (south central Pyrenees and Ebro basin, Spain) using geomorphic position, luminescence dates, and time-related trends in soil development. The ages obtained from glacial deposits indicate glacial periods at 85 {+-} 5 ka, 64 {+-} 11 ka, and 36 {+-} 3 ka (from glacial till) and 20 {+-} 3 ka (from loess). The fluvial drainage system, fed by glaciers in the headwaters, developed extensive terrace systems in the Cinca River valley at 178 {+-} 21 ka, 97 {+-} 16 ka, 61 {+-} 4 ka, 47 {+-}more » 4 ka, and 11 {+-} 1 ka, and in the Gallego River valley at 151 {+-} 11 ka, 68 {+-} 7 ka, and 45 {+-} 3 ka. The times of maximum geomorphic activity related to cold phases coincide with Late Pleistocene marine isotope stages and heinrich events. The maximum extent of glaciers during the last glacial occurred at 64 {+-} 11 ka, and the terraces correlated with this glacial phase are the most extensive in both the Cinca (61 {+-} 4 ka) and Gallego (68 {+-} 7 ka) valleys, indicating a strong increase in fluvial discharge and availability of sediments related to the transition to deglaciation. The global Last Glacial Maximum is scarcely represented in the south central Pyrenees owing to dominantly dry conditions at that time. Precipitation must be controlled by the position of the Iberian Peninsula with respect to the North Atlantic atmospheric circulation system. The glacial systems and the associated fluvial dynamic seem sensitive to (1) global climate changes controlled by insolation, (2) North Atlantic thermohaline circulation influenced by freshwater pulses into the North Atlantic, and (3) anomalies in atmospheric circulation in the North Atlantic controlling precipitation on the Iberian peninsula. The model of glacial and fluvial evolution during the Late Pleistocene in northern Spain could be extrapolated to other glaciated mountainous areas in southern Europe.« less

Late Pleistocene age and archaeological context for the hominin calvaria from GvJm-22 (Lukenya Hill, Kenya)

PubMed Central

Tryon, Christian A.; Crevecoeur, Isabelle; Faith, J. Tyler; Ekshtain, Ravid; Nivens, Joelle; Patterson, David; Mbua, Emma N.; Spoor, Fred

2015-01-01

Kenya National Museums Lukenya Hill Hominid 1 (KNM-LH 1) is a Homo sapiens partial calvaria from site GvJm-22 at Lukenya Hill, Kenya, associated with Later Stone Age (LSA) archaeological deposits. KNM-LH 1 is securely dated to the Late Pleistocene, and samples a time and region important for understanding the origins of modern human diversity. A revised chronology based on 26 accelerator mass spectrometry radiocarbon dates on ostrich eggshells indicates an age range of 23,576–22,887 y B.P. for KNM-LH 1, confirming prior attribution to the Last Glacial Maximum. Additional dates extend the maximum age for archaeological deposits at GvJm-22 to >46,000 y B.P. (>46 kya). These dates are consistent with new analyses identifying both Middle Stone Age and LSA lithic technologies at the site, making GvJm-22 a rare eastern African record of major human behavioral shifts during the Late Pleistocene. Comparative morphometric analyses of the KNM-LH 1 cranium document the temporal and spatial complexity of early modern human morphological variability. Features of cranial shape distinguish KNM-LH 1 and other Middle and Late Pleistocene African fossils from crania of recent Africans and samples from Holocene LSA and European Upper Paleolithic sites. PMID:25730861

Late Pleistocene dune activity in the central Great Plains, USA

USGS Publications Warehouse

Mason, J.A.; Swinehart, J.B.; Hanson, P.R.; Loope, D.B.; Goble, R.J.; Miao, X.; Schmeisser, R.L.

2011-01-01

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of cold, short growing seasons with relatively low precipitation and low atmospheric CO2 that increased plant moisture stress, limiting the ability of vegetation to stabilize active dune sand. The apparent coexistence of large mobile dunes with boreal forest taxa suggests a Late Pleistocene environment with few modern analogs. ?? 2011 Elsevier Ltd.

Quaternary fluvial history of the Delaware River, New Jersey and Pennsylvania, USA: The effects of glaciation, glacioisostasy, and eustasy on a proglacial river system

NASA Astrophysics Data System (ADS)

Stanford, Scott D.; Witte, Ron W.; Braun, Duane D.; Ridge, John C.

2016-07-01

Fluvial, glacial, and estuarine deposits in the Delaware Valley record the response of the Delaware River to glaciation, sea-level change, and glacioisostasy during the Quaternary. Incision following an early Pleistocene glaciation created the present valley, which is inset into a Pliocene strath and fluvial plain. Middle and upper Pleistocene and Holocene deposits were laid down in this inset valley. Estuarine terraces in the lower valley and bayshore at + 20 m (probably Marine Isotope Stage [MIS] 11), + 8 m (MIS 5e), and + 3 m (MIS 5a or c), and a fluvial deposit that correlates to offshore MIS 3 marine deposits at - 20 m are at elevations consistent with glacioisostatic models. Successive incisions during lowstands in the middle and late Pleistocene lengthened, deepened, and narrowed the channel in the lower valley and shifted the channel westward in Delaware Bay. During MIS 2 glaciation, from 25 to 18 ka, the Delaware was diverted to the Hudson Shelf Valley by glacioisostatic tilting. Most glacial sediment was trapped in fluvial-lacustrine valley fills north of the terminal moraine. Incision of the valley fill was accomplished during the early stage of rebound, between 17 and 12 ka. Drainage to the Delaware shelf was restored between 15 and 13 ka as the forebulge collapsed. During incision, multiple postglacial terraces formed where the valley was perpendicular to rebound contours and so was steepened and elevated northward; and a single terrace formed where the valley paralleled the contours, and there was no differential elevation or steepening. About 65% of the original volume of MIS 2 glacial sediment remains in the main valley, and most of the eroded volume is in the channel in the lower valley beneath Holocene estuarine fill. Little glacial sediment reached the Delaware or Hudson shelf. Overbank deposition on the lower postglacial terrace and modern floodplain spans the Holocene. The volume of Holocene sediment in the estuary and bay yields a basinwide denudation rate of about 20 m/my.

Periglacial fires and trees in a continental setting of Central Canada, Upper Pleistocene.

PubMed

Bélanger, N; Carcaillet, C; Padbury, G A; Harvey-Schafer, A N; Van Rees, K J C

2014-03-01

Fire is a key factor controlling global vegetation patterns and carbon cycling. It mostly occurs under warm periods during which fuel builds up with sufficient moisture, whereas such conditions stimulate fire ignition and spread. Biomass burning increased globally with warming periods since the last glacial era. Data confirming periglacial fires during glacial periods are very sparse because such climates are likely too cold to favour fires. Here, tree occurrence and fires during the Upper Pleistocene glacial periods in Central Canada are inferred from botanical identification and calibrated radiocarbon dates of charcoal fragments. Charcoal fragments were archived in sandy dunes of central Saskatchewan and were dated >50000-26600 cal BP. Fragments were mostly gymnosperms. Parallels between radiocarbon dates and GISP2-δ¹⁸O records deciphered relationships between fire and climate. Fires occurred either hundreds to thousands of years after Dansgaard-Oeschger (DO) interstadial warming events (i.e., the time needed to build enough fuel for fire ignition and spread) or at the onset of the DO event. The chronological uncertainties result from the dated material not precisely matching the fires and from the low residual ¹⁴C associated with old sample material. Dominance of high-pressure systems and low effective moisture during post-DO coolings likely triggered flammable periglacial ecosystems, while lower moisture and the relative abundance of fuel overshadowed lower temperatures for fire spread. Laurentide ice sheet (LIS) limits during DO events are difficult to assess in Central Canada due to sparse radiocarbon dates. Our radiocarbon data set constrains the extent of LIS. Central Saskatchewan was not covered by LIS throughout the Upper Pleistocene and was not a continental desert. Instead, our results suggest long-lasting periods where fluctuations of the northern tree limits and fires after interstadials occurred persistently. © 2014 John Wiley & Sons Ltd.

Pleistocene permafrost features in soils in the South-western Italian Alps

NASA Astrophysics Data System (ADS)

D'Amico, Michele; Catoni, Marcella; Bonifacio, Eleonora; Zanini, Ermanno

2015-04-01

Because of extensive Pleistocenic glaciations which erased most of the previously existing soils, slope steepness and climatic conditions favoring soil erosion, most soils observed on the Alps (and in other mid-latitude mountain ranges) developed only during the Holocene. However, in few sites, particularly in the outermost sections of the Alpine range, Pleistocene glaciers covered only small and scattered surfaces because of the low altitude reached in the basins, and ancient soils could be preserved for long periods of time on particularly stable surfaces. In some cases, these soils retain good memories of past periglacial activity. We described and sampled soils on stable surfaces in the Upper Tanaro valley, Ligurian Alps (Southwestern Piemonte, Italy). The sampling sites were between 600 to 1600 m of altitude, under present day lower montane Castanea sativa/Ostrya carpinifolia forests, montane Fagus sylvatica and Pinus uncinata forests or montane heath/grazed grassland, on different quartzitic substrata. The surface morphology often showed strongly developed, fossil periglacial patterned ground forms, such as coarse stone circles on flat surfaces, or stone stripes on steeper slopes. The stone circles could be up to 5 m wide, while the sorted stripes could be as wide as 12-15 m. A strong lateral cryogenic textural sorting characterized the fine fraction too, with sand dominating close to the stone rims of the patterned ground features and silt and clay the central parts. The surface 60-120 cm of the soils were podzolized during the Holocene; as a result of the textural lateral sorting, the thickness of the podzolic E and Bs horizons varied widely across the patterns. The lower boundary of the Holocene Podzols was abrupt, and corresponded with dense layers with thick coarse laminar structure and illuvial silt accumulation (Cjj horizons). Dense Cjj diapiric inclusions were sometimes preserved in the central parts of the patterns. Where cover beds were developed, more superimposed podzol cycles were observed: the deeper podzols, included in the dense layer, were strongly cryoturbated and showed convoluted horizons and buried organic horizons. The presence of the dense Cjj horizons also influenced surface soil hydrology, which in turn influenced the expression of E and Bs horizons, in addition to textural lateral variability. In conclusion, surface morphology and soil properties evidence the presence of permafrost during cold Pleistocene phases, with an active layer 60-120 cm thick, associated with a particularly strong cryoturbation. However, all the permafrost features were not necessarily formed during the same periods, and dating of different materials would be necessary in order to obtain precise paleoenvironmental reconstructions of cold Quaternary phases in the Alps.

X-ray fluorescence results from IODP Expedition 355 sediments in Laxmi Basin, eastern Arabian Sea: Insights into late Miocene and Pleistocene carbonate production and burial and possible variations in monsoon intensit

NASA Astrophysics Data System (ADS)

Bowen, M. G.; Kulhanek, D. K.; Lyle, M. W.; Hahn, A.

2017-12-01

Variations in CaCO3 accumulation on the seafloor depend on a number of factors, including productivity of carbonate-producing organisms in the overlying water column, input of siliciclastic material from nearby continents, and changes in ocean chemistry. These factors are affected by variations in tectonics and climate. Here we use X-ray fluorescence (XRF) core scanning data to develop high-resolution chemical profiles calibrated with discrete samples to examine changes in carbonate production and burial in the eastern Arabian Sea. International Ocean Discovery Program (IODP) Expedition 355 cored two sites in the Indus Fan in Laxmi Basin. We scanned the Pleistocene composite sections from both sites at 2 cm resolution ( 150-300 year sampling resolution) using the Avaatech XRF core scanner at the IODP Gulf Coast Repository. In addition, we scanned a hemipelagic interval dated to the late Miocene ( 8 to 6 Ma) that spans the late Miocene climate transition to drier conditions globally, as documented by an expansion in C4 plants. The 2 cm scanning resolution represents 500 years between samples for the upper Miocene section. We used carbonate measurements on discrete samples to calibrate the XRF data, supplemented by analysis using a quantitative benchtop XRF at the University of Bremen. We find large variability in carbonate content in the Pleistocene and upper Miocene, varying from 15-80 wt%, with higher carbonate content correlating with lighter colored sediment. The aluminosilicate composition varies in part because of carbonate dilution but also because of changes in the source of clays and turbidites through the section. We also explore the use of chemical ratios to better understand the variations through the section. Changes in Ca/Fe (biogenic/terrestrial component) and Rb/Zr (fine/coarse grained) match well with visual observation of sediment composition in the cores. We can combine these with the oxygen isotope-derived age model for the Pleistocene section to examine orbital-scale variations in carbonate production and terrigenous input at the sites. We also explore proxies for precipitation (Ti/Ca) and weathering (Fe/K and Al/K) to elucidate changes in monsoon strength during the Pleistocene, although these results are preliminary.

Global deep-sea extinctions during the Pleistocene ice ages

NASA Astrophysics Data System (ADS)

Hayward, Bruce W.

2001-07-01

The dark, near-freezing environment of the deep oceans is regarded as one of the most stable habitats on Earth, and this stability is generally reflected in the slow turnover rates (extinctions and appearances) of the organisms that live there. By far the best fossil record of deep-sea organisms is provided by the shells of benthic foraminifera (Protista). A little-known global extinction of deep-sea benthic foraminifera occurred during the Pleistocene ice ages. In the southwest Pacific, it caused the disappearance of at least two families, 15 genera, and 48 species (˜15% 25% of the fauna) of dominantly uniserial, elongate foraminifera with distinctive apertural modifications. These forms progressively died back and became extinct during glacial periods in the late Pliocene to middle Pleistocene (ca. 2.5 0.6 Ma); most extinctions occurred between 1.0 and 0.6 Ma, at the time of the middle Pleistocene climatic revolution. This first high-resolution study of this extinction event indicates that it was far more significant for deep-sea diversity loss than previously reported (10 species). The middle Pleistocene extinction was the most dramatic last phase of a worldwide decline in the abundance of these elongate forms, a phase that began during cooling near the Eocene-Oligocene boundary and continued during the middle Miocene. Clearly these taxa declined when the world cooled, but the reason is yet to be resolved.

Geologic map of the Bodie Hills, California and Nevada

USGS Publications Warehouse

John, David A.; du Bray, Edward A.; Box, Stephen E.; Vikre, Peter G.; Rytuba, James J.; Fleck, Robert J.; Moring, Barry C.

2015-01-01

The Bodie Hills covers about 1,200 km2 straddling the California-Nevada state boundary just north of Mono Lake in the western part of the Basin and Range Province, about 20 km east of the central Sierra Nevada. The area is mostly underlain by the partly overlapping, middle to late Miocene Bodie Hills volcanic field and Pliocene to late Pleistocene Aurora volcanic field (John and others, 2012). Upper Miocene to Pliocene sedimentary deposits, mostly basin-filling sediments, gravel deposits, and fanglomerates, lap onto the west, north, and east sides of the Bodie Hills, where they cover older Miocene volcanic rocks. Quaternary surficial deposits, including extensive colluvial, fluvial, glacial, and lacustrine deposits, locally cover all older rocks. Miocene and younger rocks are tilted ≤30° in variable directions. These rocks are cut by several sets of high-angle faults that exhibit a temporal change from conjugate northeast-striking left-lateral and north-striking right-lateral oblique-slip faults in rocks older than about 9 Ma to north- and northwest-striking dip-slip faults in late Miocene rocks. The youngest faults are north-striking normal and northeast-striking left-lateral oblique-slip faults that cut Pliocene-Pleistocene rocks. Numerous hydrothermal systems were active during Miocene magmatism and formed extensive zones of hydrothermally altered rocks and several large mineral deposits, including gold- and silver-rich veins in the Bodie and Aurora mining districts (Vikre and others, in press).

Geomorphological control of gold distribution and gold particle evolution in glacial and fluvioglacial placers of the Ancocala-Ananea basin - Southeastern Andes of Peru

NASA Astrophysics Data System (ADS)

Hérail, Gérard; Fornari, Michel; Rouhier, Michel

1989-10-01

Gold placers are formed as a result of surficial processes but glacial and fluvioglacial systems are generally considered to be unfavourable for placer genesis. Nevertheless, some important glacial and fluvioglacial placers have been discovered and are currently being exploited in the Andes of Peru and Bolivia. In the Plio-Pleistocene Ananea-Ancocala basin (4300-4900 m above sea-level), the gold content of the various formations indicates that only glacial and fluvioglacial sediments related to the Ancocala and Chaquiminas Glaciations (middle and upper Pleistocene) contain gold in any notable quantity. Local concentrations of economic interest occur only where a glacier has cut through a primary mineralized zone. Glacial erosion of dispersed primary mineralizations does not produce high-content placers of the kind found in fluviatile environments. Gold distribution in tills is more irregular than in fluviatile sediments and no marked enrichment at bedrock occurs. The transition from a glacial to a fluvioglacial environment is characterized by an increase in gold content due to a relative concentration of the biggest gold flakes and by the appearance of a gold distribution pattern similar to that found in a fluviatile environment. During their transport by glacial and fluvioglacial processes, gold particles acquire specific features; the size and morphology of a gold flake population are determined by the sedimentological and geomorphological environment in which the flakes are carried.

Cordão Formation: loess deposits in the southern coastal plain of the state of Rio Grande do Sul, Brazil.

PubMed

Lopes, Renato P; Dillenburg, Sergio R; Schultz, Cesar L

2016-01-01

Loess consists of silt-dominated sediments that cover ~10% of the Earth's surface. In southern South America it occurs in Argentina, Bolivia, Paraguay and Uruguay, and its presence in southern Brazil was never studied in detail. Here is proposed a new lithostratigraphic unit, Cordão Formation, consisting of loess deposits in the southern Brazilian coastal plain. It consists of fine-very fine silt with subordinate sand and clay, found mostly in lowland areas between Pleistocene coastal barriers. These sediments are pale-colored (10YR hue) and forms ~1,5-2,0 meter-thick stable vertical walls. The clay minerals include illite, smectite, interstratified illite/smectite and kaolinite, the coarser fraction is mostly quartz and plagioclase. Caliche and iron-manganese nodules are also present. The only fossils found so far are rodent teeth and a tooth of a camelid (Hemiauchenia paradoxa). Luminescence ages indicate that this loess was deposited in the latest Pleistocene, between ~30 and 10 kyrs ago, and its upper portion was modified by erosion and accumulation of clay and organic matter in the Holocene. The estimated accumulation rate was ~630 g/m2/year. The probable source of this loess is the Pampean Aeolian System of Argentina and it would have been deposited by the increased aeolian processes of the last glacial.

A reassessment of the early archaeological record at Leang Burung 2, a Late Pleistocene rock-shelter site on the Indonesian island of Sulawesi

PubMed Central

Hakim, Budianto; Ramli, Muhammad; Aubert, Maxime; van den Bergh, Gerrit D.; Li, Bo; Burhan, Basran; Saiful, Andi Muhammad; Siagian, Linda; Sardi, Ratno; Jusdi, Andi; Abdullah; Mubarak, Andi Pampang; Moore, Mark W.; Roberts, Richard G.; Zhao, Jian-xin; McGahan, David; Jones, Brian G.; Perston, Yinika; Szabó, Katherine; Mahmud, M. Irfan; Westaway, Kira; Jatmiko; Saptomo, E. Wahyu; van der Kaars, Sander; Grün, Rainer; Wood, Rachel; Dodson, John

2018-01-01

This paper presents a reassessment of the archaeological record at Leang Burung 2, a key early human occupation site in the Late Pleistocene of Southeast Asia. Excavated originally by Ian Glover in 1975, this limestone rock-shelter in the Maros karsts of Sulawesi, Indonesia, has long held significance in our understanding of early human dispersals into ‘Wallacea’, the vast zone of oceanic islands between continental Asia and Australia. We present new stratigraphic information and dating evidence from Leang Burung 2 collected during the course of our excavations at this site in 2007 and 2011–13. Our findings suggest that the classic Late Pleistocene modern human occupation sequence identified previously at Leang Burung 2, and proposed to span around 31,000 to 19,000 conventional 14C years BP (~35–24 ka cal BP), may actually represent an amalgam of reworked archaeological materials. Sources for cultural materials of mixed ages comprise breccias from the rear wall of the rock-shelter–remnants of older, eroded deposits dated to 35–23 ka cal BP–and cultural remains of early Holocene antiquity. Below the upper levels affected by the mass loss of Late Pleistocene deposits, our deep-trench excavations uncovered evidence for an earlier hominin presence at the site. These findings include fossils of now-extinct proboscideans and other ‘megafauna’ in stratified context, as well as a cobble-based stone artifact technology comparable to that produced by late Middle Pleistocene hominins elsewhere on Sulawesi. PMID:29641524

Fossil woods of Detarioideae subfamily (Fabaceae) from El Palmar Formation (Late Pleistocene) in South America

NASA Astrophysics Data System (ADS)

Ramos, R. Soledad; Brea, Mariana; Kröhling, Daniela M.

2017-11-01

The main aim of the present paper is to describe the first Detarioideae fossil woods from El Palmar Formation (Late Pleistocene) in the Uruguay River Basin (Entre Ríos, Argentina). This study is based on five silicified wood specimens preserved in fluvial deposits, which were transported from their growth site. Two new genera and species are described: Paraoxystigma concordiensis gen. nov and sp. nov. has medium-sized vessels, paratracheal axial parenchyma, heterocellular and multiseriate rays, and diffuse axial canals similar in size and shape to vessels, and Gossweilerodendroxylon palmariensis gen. nov and sp. nov. has medium-sized vessels, alternate intervessel pits, paratracheal and apotracheal axial parenchyma, homocellular and uni to-multiseriate rays, and small diffuse axial canals. These Detarioideae fossil records in south-eastern South America support the existence of a very old relationship with the extant West African forests. Eco-anatomical features observed in these fossil woods, along with the climatic information available from the Nearest Living Relatives (NLRs) comparison, suggest warm and humid climatic conditions for the upper-middle basin of the Uruguay River during some periods of the Late Pleistocene.

Extensive deposits on the Pacific plate from Late Pleistocene North American glacial lake outbursts

USGS Publications Warehouse

Normark, W.R.; Reid, J.A.

2003-01-01

One of the major unresolved issues of the Late Pleistocene catastrophic-flood events in the northwestern United States (e.g., from glacial Lake Missoula) has been what happened when the flood discharge reached the ocean. This study compiles available 3.5-kHz high-resolution and airgun seismic reflection data, long-range sidescan sonar images, and sediment core data to define the distribution of flood sediment in deepwater areas of the Pacific Ocean. Upon reaching the ocean at the mouth of the Columbia River near the present-day upper continental slope, sediment from the catastrophic floods continued flowing downslope as hyperpycnally generated turbidity currents. The turbidity currents resulting from the Lake Missoula and other latest Pleistocene floods followed the Cascadia Channel into and through the Blanco Fracture Zone and then flowed west to the Tufts Abyssal Plain. A small part of the flood sediment, which was stripped off the main flow at a bend in the Cascadia Channel at its exit point from the Blanco Fracture Zone, continued flowing more than 400 km to the south and reached the Escanaba Trough, a rift valley of the southern Gorda Ridge. Understanding the development of the pathway for the Late Pleistocene flood sediment reaching Escanaba Trough provides insight for understanding the extent of catastrophic flood deposits on the Pacific plate.

Cross-sectional properties of the lower limb long bones in the Middle Pleistocene Sima de los Huesos sample (Sierra de Atapuerca, Spain).

PubMed

Rodríguez, Laura; Carretero, José Miguel; García-González, Rebeca; Arsuaga, Juan Luis

2018-04-01

The recovery to date of three complete and five partial femora, seven complete tibiae, and four complete fibulae from the Atapuerca Sima de los Huesos site provides an opportunity to analyze the biomechanical cross-sectional properties in this Middle Pleistocene population and to compare them with those of other fossil hominins and recent modern humans. We have performed direct comparisons of the cross-sectional geometric parameters and reduced major axis (RMA) regression lines among different samples. We have determined that Atapuerca Sima de los Huesos (SH) fossils have significantly thicker cortices than those of recent modern humans for the three leg bones at all diaphyseal levels, except that of the femur at 35% of biomechanical length. The SH bones are similar to those of Neandertals and Middle Pleistocene humans and different from Homo sapiens in their diaphyseal cross-sectional shape and strength parameters. When standardized by estimated body size, both the SH and Neandertal leg bones have in general greater strength than those of H. sapiens from the early modern (EMH), Upper Paleolithic (UP), and recent populations (RH). The Sima de los Huesos human leg bones have, in general terms, an ancestral pattern similar to that of Pleistocene humans and differing from H. sapiens. Copyright © 2017 Elsevier Ltd. All rights reserved.

Demographic expansion of two Tamarix species along the Yellow River caused by geological events and climate change in the Pleistocene.

PubMed

Liang, Hong-Yan; Feng, Zhi-Pei; Pei, Bing; Li, Yong; Yang, Xi-Tian

2018-01-08

The geological events and climatic fluctuations during the Pleistocene played important roles in shaping patterns of species distribution. However, few studies have evaluated the patterns of species distribution that were influenced by the Yellow River. The present work analyzed the demography of two endemic tree species that are widely distributed along the Yellow River, Tamarix austromongolica and Tamarix chinensis, to understand the role of the Yellow River and Pleistocene climate in shaping their distribution patterns. The most common chlorotype, chlorotype 1, was found in all populations, and its divergence time could be dated back to 0.19 million years ago (Ma). This dating coincides well with the formation of the modern Yellow River and the timing of Marine Isotope Stages 5e-6 (MIS 5e-6). Bayesian reconstructions along with models of paleodistribution revealed that these two species experienced a demographic expansion in population size during the Quaternary period. Approximate Bayesian computation analyses supported a scenario of expansion approximately from the upper to lower reaches of the Yellow River. Our results provide support for the roles of the Yellow River and the Pleistocene climate in driving demographic expansion of the populations of T. austromongolica and T. chinensis. These findings are useful for understanding the effects of geological events and past climatic fluctuations on species distribution patterns.

Influence of the post-Miocene tectonic activity on the geomorphology between Andes and Pampa Deprimida in the area of Provincia de La Pampa, Argentina

NASA Astrophysics Data System (ADS)

Vogt, Henri; Vogt, Thea; Calmels, Augusto P.

2010-09-01

The genesis of the relief between the Andes and the Pampa Deprimida plain between 36° and 39°S has never been considered. The region is intermediate between two contrasting geomorphic styles, the meridian-oriented highs and depressions of the Sierras Pampeanas to the north and the eastwards sloping northern Patagonian mesetas to the south. From geophysical data, it coincides with an intermediate zone between a flat-slab subduction zone to the north and a normal subduction zone to the south. From west to east (68° to 64°W), four units follow each other: the easternmost portion of the Sub-Andean piedmont, the depression of the Río Chadileuvú, a Plateau, and a high scarp separating it from the Pampa Deprimida lowland. The Plateau is the southernmost portion of the Brazilian shield. Geomorphological and sedimentological analyses led us to the following conclusions: 1. the Andes uplift created a large piedmont reaching the Pampa Deprimida and including the Plateau which between the Pliocene and the Middle Pleistocene was shaped in a series of stepped levels covered by Andean fluvial sediments; 2. the meridian-oriented Rio Chadileuvú depression is of tectonic origin, younger than the Middle Pleistocene, and breaks the continuity between the piedmont and the Plateau: this depression could be an incipient foreland basin; 3. the eastern scarp is a fault scarp, probably Upper Pleistocene in age, due to a faster activity of the fault zone between the craton and the Macachín Trough. This young morphotectonic activity coincides with the change from a west-east Patagonian pattern to a north-south orientation of the relief typical of the Sierras Pampeanas, but younger than them. The river network was affected by this evolution. During the Upper Miocene, a palaeo-Río Negro flowed to the north-east, then shifted southwards. The Río Colorado entered the Pampa region during the Upper Pliocene creating a set of stepped fluvial accumulation terraces, while the piedmont was drained by eastward streams. Following the formation of the Chadileuvú depression, a north-south drainage, largely endoreic, replaced the Sub-Andean flows. A capture of the Río Chadileuvú by the Río Colorado is going on due to the incision of the Río Colorado in the south. The regional landscape is therefore directly related to Late Pleistocene tectonic activity, whereas climate changes explain the different sedimentary characteristics of the surficial deposits.

The Impact of Mass Movement and Fluid Flow during Ridge Subduction inferred from Physical Properties and Zeolite Assemblage in the Upper Plate Slope of the Costa Rica Subduction Zone

NASA Astrophysics Data System (ADS)

Hamahashi, M.; Screaton, E.; Tanikawa, W.; Hashimoto, Y.; Martin, K. M.; Saito, S.; Kimura, G.

2015-12-01

The Costa Rica subduction zone offshore Osa Peninsula is known as an erosive margin with active seismicity and the subduction of the Cocos Ridge. One of the major unknowns in this margin is the nature of the unconformity at the base of the slope sediments in the upper plate and the high velocity materials below. To investigate the geologic processes across the unconformity, we examined the consolidation state and mineral assemblages of the sediments at the mid-slope Site 1380 drilled during IODP Expedition 344 by conducting microstructural observation, particle size analysis, X-ray fluorescence/diffraction analysis and resistivity measurement. The general compaction trend is controlled primarily by grain-size sorting and the physical property transition is likely caused by massive sediment removal under normal fault regime, thickness of which range between ~600-850 m determined from the composite porosity-depth curve. Across the unconformity between the late Pliocene~late Pleistocene silty clay (Unit 1) and late Pliocene~early Pleistocene clayey siltstone (Unit 2), the mineral/element components of the sediments is marked by the transitions in zeolite compositions; Unit 1 consists of laumontite and heulandite, whereas below the unconformity, Unit 2 sediments contain analcime, laumontite, and heulandite, but laumontite become less abundant at lower depth. The experienced temperature of the sediments in Unit 2 is estimated to have reached between ~86 and 122℃ as inferred from analcime burial diagenesis. This may correspond with the greater depth range prior to mass movement and normal faulting. The initial analcime burial diagenetic zone was likely cut off by the sediment removal across the unconformity, and later overprinted by high temperature fluid along the boundary forming laumontite and heulandite in the vicinity. These results illustrate that ridge subduction has substantial potential to cause mass movement, an extensional stress regime, and fluid flow from depth.

Chronology for the Cueva Victoria fossil site (SE Spain): Evidence for Early Pleistocene Afro-Iberian dispersals.

PubMed

Gibert, Luis; Scott, Gary R; Scholz, Denis; Budsky, Alexander; Ferràndez, Carles; Ribot, Francesc; Martin, Robert A; Lería, María

2016-01-01

Cueva Victoria has provided remains of more than 90 species of fossil vertebrates, including a hominin phalanx, and the only specimens of the African cercopithecid Theropithecus oswaldi in Europe. To constrain the age of the vertebrate remains we used paleomagnetism, vertebrate biostratigraphy and (230)Th/U dating. Normal polarity was identified in the non-fossiliferous lowest and highest stratigraphic units (red clay and capping flowstones) while reverse polarity was found in the intermediate stratigraphic unit (fossiliferous breccia). A lower polarity change occurred during the deposition of the decalcification clay, when the cave was closed and karstification was active. A second polarity change occurred during the capping flowstone formation, when the upper galleries were filled with breccia. The mammal association indicates a post-Jaramillo age, which allows us to correlate this upper reversal with the Brunhes-Matuyama boundary (0.78 Ma). Consequently, the lower reversal (N-R) is interpreted as the end of the Jaramillo magnetochron (0.99 Ma). These ages bracket the age of the fossiliferous breccia between 0.99 and 0.78 Ma, suggesting that the capping flowstone was formed during the wet Marine Isotopic Stage 19, which includes the Brunhes-Matuyama boundary. Fossil remains of Theropithecus have been only found in situ ∼1 m below the B/M boundary, which allows us to place the arrival of Theropithecus to Cueva Victoria at ∼0.9-0.85 Ma. The fauna of Cueva Victoria lived during a period of important climatic change, known as the Early-Middle Pleistocene Climatic Transition. The occurrence of the oldest European Acheulean tools at the contemporaneous nearby site of Cueva Negra suggest an African dispersal into SE Iberia through the Strait of Gibraltar during MIS 22, when sea-level was ∼100 m below its present position, allowing the passage into Europe of, at least, Theropithecus and Homo bearing Acheulean technology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pleistocene and Holocene geomorphological development in the Algarve, southern Portugal

NASA Astrophysics Data System (ADS)

Chester, David K.

2012-06-01

A detailed chronological framework for Pleistocene and Holocene geomorphology and landscape evolution in the Algarve is proposed. With regards to the Pleistocene, attention has focused on the origin, dating and stratigraphy of the Ludo Formation. Subsuming the classifications of earlier writers, it is now proposed that during the Pliocene a marine transgression occurred across a tectonically controlled basin that was constrained by the mountains of the Algarve interior to the north. Fluvial sands were then deposited in a regressive phase during the late Pliocene/early Pleistocene, while braided streams operating under semi-arid conditions subsequently laid down sands and gravels in the middle and upper Pleistocene. Lying unconformably over the Ludo Formation is an alluvial deposit (Odiáxere gravels and Loulé sands) of late Pleistocene/early Holocene date that is found within the river valleys of the Algarve. In the early-Holocene (ca.10, 000-ca.7000 BP) and early late-Holocene (ca.5000-ca.3000 BP), the situation in the Algarve was one of climatic amelioration (i.e., warmer and wetter conditions), rising sea levels, vegetation colonization, soil development and towards the end of this period trenching of the Odiáxere gravels and Loulé sands. From ca.3000 BP evidence is abundant that humans became important geomorphological agents either acting on their own or in combination with climatic factors. From around 5000 BP, conditions became dryer and, between ca.3000 BP and ca.700 BP, clearance of land by pre-Roman, Roman, and especially Islamic agricultural settlers caused widespread erosion and the deposition of extensive spreads of topsoil dominated sediment within river valleys (i.e., the Holocene terrace) and in coastal estuaries. A period followed up to 1900 CE when agricultural practices were less damaging to the soil, erosion was reduced and the Holocene terrace - together with coastal and estuarine deposits - was incised. In the past century and under increased human pressure, renewed erosion is in evidence in the interior valleys and at the coast.

Thin-skinned tectonics of upper Ojai Valley and Sulfur Mountain vicinity, Ventura basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huftile, G.J.

1988-03-01

The Upper Ojai Valley is a tectonic depression between opposing reverse faults. The active, north-dipping San Cayetano fault forms its northern border and has 5.8 km of dip-slip displacement at the Silverthread oil field and 2.6 km of displacement west of Sisar Creek. The fault dies out farther west in Ojai Valley. The southern border is formed by the late Quaternary Sisar-Big-Canyon-Lion fault set, which dips south and merges into a decollement within the south-dipping, ductile Rincon Formation. Folds with north-dipping fold axes, including the Lion Mountain anticline and Reeves syncline, are probably Pliocene. During the late Quaternary, the Sulfurmore » Mountain anticlinorium began forming as a fault-propagation fold, followed closely by the ramping of the south-dipping faults to the surface. One, the Lion fault, cuts the Pleistocene Saugus Formation. To the east, the San Cayetano fault overrides and folds the south-dipping faults. Cross-section balancing shows that the Miocene and younger rocks above the decollement are shortened 6.1 km more than the more competent rocks below. A solution to this bed-length problem is that the decollement becomes a ramp and merges at depth with the steeply south-dipping Oak Ridge fault. This implies that the Sisar, Big Canyon, and Lion faults are frontal thrusts to the Oak Ridge fault. Oil is produced primarily from Mohnian sands and shales north of the Big Canyon fault and from fractured Mohnian shale beneath the Sisar fault.« less

Stratigraphy of a proposed wind farm site southeast of Block Island: Utilization of borehole samples, downhole logging, and seismic profiles

NASA Astrophysics Data System (ADS)

Sheldon, Dane P. H.

Seismic stratigraphy, sedimentology, lithostratigraphy, downhole geophysical logging, mineralogy, and palynology were used to study and interpret the upper 70 meters of the inner continental shelf sediments within a proposed wind farm site located approximately two to three nautical miles to the southeast of Block Island, Rhode Island. Core samples and downhole logging collected from borings drilled for geotechnical purposes at proposed wind turbine sites along with seismic surveys in the surrounding area provide the data for this study. Cretaceous coastal plain sediments that consist of non-marine to marine sand, silt, and clay are found overlying bedrock at a contact depth beyond the sampling depth of this study. The upper Cretaceous sediments sampled in borings are correlated with the Magothy/Matawan formations described regionally from New Jersey to Nantucket. An unconformity formed through sub-aerial, fluvial, marine, and glacial erosion marks the upper strata of the Cretaceous sediments separating them from the overlying deposits. The majority of Quaternary deposits overlying the unconformity represent the advance, pulsing, and retreat of the Laurentide ice sheet that reached its southern terminus in the area of Block Island approximately 25,000 to 21,000 years before present. The sequence consists of a basal glacial till overlain by sediments deposited by meltwater environments ranging from deltaic to proglacial lakefloor. A late Pleistocene to early Holocene unconformity marks the top of the glacial sequence and was formed after glacial retreat through fluvial and subaerial erosion/deposition. Overlying the glacial sequence are sediments deposited during the late Pleistocene and Holocene consisting of interbedded gravel, sand, silt, and clay. Sampling of these sediments was limited and surficial reflectors in seismic profiles were masked due to a hard bottom return. However, two depositional periods are interpreted as representing fluvial and estuarine/marine environments respectively. One sample recovered at five meters contained shell fragments within a gray fine to coarse sand possibly representing a shallow estuarine to marine environment. A coarse near surface deposit described but not recovered in all borings may represent a transgressive unconformity and resulting lag deposit however due to lack of sampling and seismic resolution in the upper 5 meters, the nature of this deposit is merely speculation. In areas where depth to the glacial surface increased, sediments ranging from sand to fine-grained silt and clay were encountered in borings. In summary, the upper 70 meters of the inner continental shelf section within the study site consists of unconsolidated sediments spanning three major depositional periods. Sediments derived from glacial activity represent the bulk of samples collected. The glacial sequences represent various depositional environments, although most samples are interpreted to be the product of glacial meltwater deposition with distribution determined by source as well as highs and lows present in the antecedent topography. Finely laminated (varved) sediment to the south of Block Island indicates the presence of proglacial lakes in the area during the time of glacial retreat. Overlying sediments represent environments ranging from fluvial to marine.

Middle to Late Pleistocene coastal deposits of Eivissa (Western Mediterranean): Chronology and evolution.

NASA Astrophysics Data System (ADS)

Del Valle, Laura; Pomar, Francisco; Fornós, Joan J.; Gómez-Pujol, Lluís; Anechitei-Deacu, Valentina; Timar-Gabor, Alida

2016-04-01

This study deals with the sedimentary and stratigraphical description of Pleistocene deposits from seven coastal areas of Eivissa (Balearic Islands). Twenty two sedimentary facies have been described involving the succession of eolian, colluvial and edaphic environments. Carbonate sandstones, breccias and silty deposits are the main component of these sequences. Despite the extensive eolian systems outcropping along the coast of Eivissa, there are very few studies performed to chronological framework of these deposits. Luminescence measurements were carried out using an automated RisØ TL/OSL-DA-20 reader in the Luminescence Dating Laboratory of Babes-Bolyai University (Cluj-Napoca, Romania) under low intensity red light. OSL dating of nineteen eolian levels indicate that their deposition took place between the Middle and Late Pleistocene, establishing a paleoclimatic evolution of Eivissa Island since 755 ka to 70 Ka. Eolian activity in the Eivissa Island can be correlated with regression episodes which took place during cold periods associated with different isotopic stages, concretely the MIS 18, 16, 12, 10, 8, 6 and 4. Similar results have been obtained from many sites along the western Mediterranean Sea such as Mallorca (Pomar i Cuerda, 1979; Nielsen et al, 2004; Fornós et al, 2009), Sardinia (Andreucci et al, 2009; Pascucci et al, 2014), Liguria (Pappalardo et al., 2013). Keywords: Eolian dunes, Pleistocene, Climatic evolution, Eivissa. References - Andreucci, S.; Pascucci, V.; Murray, A. S.; Clemmensen, L. B. 2009. Late Pleistocene coastal evolution of San Giovanni di Sinis, west Sardinia (Western Mediterranean). Sedimentary Geology, 216: 104- 116 - Fornós, J.J.; Clemmensen, L.B.; Gómez-Pujol, L.; Murray, A. 2009. Late Pleistocene carbonate aeolianites on Mallorca, Western Mediterranean: a luminescence chronology. Quaternary Science reviews 28: 2697-2709. -Nielsen, K.A.; Clemmensen, L.B.; Fornós, J.J. 2004. Middle Pleistocene magnetostratigraphy and susceptibility stratigraphy: data from a carbonate aeolian system, Mallorca, Western Mediterranean. Quaternary Science Reviews, 23: 1733-1756 -Pappalardo, M.; Chelli, A.; Ciampalini, A.; Rellini, I.; Biagioni, F.; Brückner, H.; Fülling, A.; Firpo, M. 2013. Evolution of an Upper Pleistocene aeolianite in the northern Mediterranean (Liguria, NW Italy). Ital. j. Geosci. Vol. 132, 2: 290-303 -Pascucci, V.; Sechi, D.; Andreucci, S. 2014. Middle Pleistocene to Holocene coastal evolution of NW Sardinia (Mediterranean Sea, Italy). Quaternary International, 328-329: 3-20 -Pomar, L.; Cuerda, J. 1979. Los depósitos marinos pleistocénicos en Mallorca Acta Geológica Hispánica. Homenatge a Lluís Soler i Sarabaris. Vol. 14: 505-513

Geochronology of Middle and Upper Pleistocene Loess Sections in Hungary

NASA Astrophysics Data System (ADS)

Frechen, Manfred; Horváth, Erzsébet; Gábris, Gyula

1997-11-01

The application of both thermoluminescence and infrared stimulated luminescence dating to the extensively studied "classical" Hungarian loess/paleosol sequences from Basaharc, Mende, and Paks provides a reliable chronological framework and climatostratigraphic reconstruction for the last interglacial/glacial cycle. Based on this combined luminescence dating study a new chronology is proposed for the "Young Loess" in Hungary. Luminescence dating suggests that the loess below the MF2 horizon formed during the penultimate glaciation. The MF1 horizon probably formed during an interstade within oxygen isotope stage 3. For the youngest loess, overlying MF1, a very high accumulation rate was determined. Large time gaps occur above MF2 and MF1, indicating that most of the record of the last glaciation is missing in the standard sections at Basaharc, Mende, and Paks. Either large discontinuities or a very low accumulation rate occurred in all three type sections during the soil-forming periods. High-resolution studies of climatic proxies using this combined luminescence dating approach provide a reliable chronological framework for loess and loess derivatives of the last glacial cycle in Hungary, although a precise and complete chronostratigraphic reconstruction cannot be achieved from the incomplete records found at these sites.

Impact of structural and autocyclic basin-floor topography on the depositional evolution of the deep-water Valparaiso forearc basin, central Chile

USGS Publications Warehouse

Laursen, J.; Normark, W.R.

2003-01-01

The Valparaiso Basin constitutes a unique and prominent deep-water forearc basin underlying a 40-km by 60-km mid-slope terrace at 2.5-km water depth on the central Chile margin. Seismic-reflection data, collected as part of the CONDOR investigation, image a 3-3.5-km thick sediment succession that fills a smoothly sagged, margin-parallel, elongated trough at the base of the upper slope. In response to underthrusting of the Juan Ferna??ndez Ridge on the Nazca plate, the basin fill is increasingly deformed in the seaward direction above seaward-vergent outer forearc compressional highs. Syn-depositional growth of a large, margin-parallel monoclinal high in conjunction with sagging of the inner trough of the basin created stratal geometries similar to those observed in forearc basins bordered by large accretionary prisms. Margin-parallel compressional ridges diverted turbidity currents along the basin axis and exerted a direct control on sediment depositional processes. As structural depressions became buried, transverse input from point sources on the adjacent upper slope formed complex fan systems with sediment waves characterising the overbank environment, common on many Pleistocene turbidite systems. Mass failure as a result of local topographic inversion formed a prominent mass-flow deposit, and ultimately resulted in canyon formation and hence a new focused point source feeding the basin. The Valparaiso Basin is presently filled to the spill point of the outer forearc highs, causing headward erosion of incipient canyons into the basin fill and allowing bypass of sediment to the Chile Trench. Age estimates that are constrained by subduction-related syn-depositional deformation of the upper 700-800m of the basin fill suggest that glacio-eustatic sea-level lowstands, in conjunction with accelerated denudation rates, within the past 350 ka may have contributed to the increase in simultaneously active point sources along the upper slope as well as an increased complexity of proximal depositional facies.

A consistent magnetic polarity stratigraphy of Plio-Pleistocene fluvial sediments from the Heidelberg Basin (Germany)

NASA Astrophysics Data System (ADS)

Scheidt, Stephanie; Hambach, Ulrich; Rolf, Christian

2014-05-01

Deep drillings in the Heidelberg Basins provide access to one of the thickest and most complete successions of Quaternary and Upper Pliocene continental sediments in Central-Europe [1]. In absence of any comprehensive chronostratigraphic model, these sediments are so far classified by lithological and hydrogeological criteria. Therefore the age of this sequence is still controversially discussed ([1], [2]). In spite of the fact that fluvial sediments are a fundamental challenge for the application of magnetic polarity stratigraphy we performed a thorough study on four drilling cores (from Heidelberg, Ludwigshafen and nearby Viernheim). Here, we present the results from the analyses of these cores, which yield to a consistent chronostratigraphic framework. The components of natural remanent magnetisation (NRM) were separated by alternating field and thermal demagnetisation techniques and the characteristic remanent magnetisations (ChRM) were isolated by principle component analysis [3]. Due to the coring technique solely inclination data of the ChRM is used for the determination of the magnetic polarity stratigraphy. Rock magnetic proxies were applied to identify the carriers of the remanent magnetisation. The investigations prove the NRM as a stable, largely primary magnetisation acquired shortly after deposition (PDRM). The Matuyama-Gauss boundary is clearly defined by a polarity change in each core, as suggested in previous work [4]. These findings are in good agreement with the biostratigraphic definition of the base of the Quaternary ([5], [6], [7]). The Brunhes-Matuyama boundary could be identified in core Heidelberg UniNord 1 and 2 only. Consequently, the position of the Jaramillo and Olduvai subchron can be inferred from the lithostratigraphy and the development of fluvial facies architecture in the Rhine system. The continuation of the magnetic polarity stratigraphy into the Gilbert chron (Upper Pliocene) allows alternative correlation schemes for the cores Viernheim and Heidelberg. All things considered, the application of magnetic polarity stratigraphy on Pliocene and Pleistocene fluvial sediments from the Heidelberg Basin provides a consistent and independent chronology and opens the perspective for global correlations where other approaches hardly come to results. [1] GABRIEL, G., ELLWANGER, D., HOSELMANN, C. & WEIDENFELLER, M. 2008. Preface: The HeidelbergBasin Drilling Project. E & G (Quaternary Science Journal), 57, 253-260. [2] ELLWANGER, D. & WIELAND-SCHUSTER, U. 2012. Fotodokumentation und Schichtenverzeichnis der Forschungsbohrungen Heidelberg UniNord I und II. LGRB-Informationen, 26, 25-86. [3] KIRSCHVINK, J. L. 1980. The least-squares line and plane and the analysis of palaeomagnetic data. Geophysical Journal, Royal Astronomical Society, 62, 699-718. [4] ROLF, C., HAMBACH, U. & WEIDENFELLER, M. 2008. Rock and palaeomagnetic evidence for the Plio-/Pleistocene palaeoclimatic change recorded in Upper Rhine Graben sediments (Core Ludwigshafen-Parkinsel), Neth. J. Geosci., 87 (1), 41-50. [5] KNIPPING, M. 2008. Early and Middle Pleistocene pollen assemblages of deep core drillings in the northern Upper Rhine Graben, Germany, Neth. J. Geosci., 87(1), 51-65. [6] HEUMANN, G., pers. Comm. [7] HAHNE, J., pers. Comm.

Cheek tooth morphology and ancient mitochondrial DNA of late Pleistocene horses from the western interior of North America: Implications for the taxonomy of North American Late Pleistocene Equus

PubMed Central

Rodrigues, Antonia T.; Theodor, Jessica M.; Kooyman, Brian P.; Yang, Dongya Y.; Speller, Camilla F.

2017-01-01

Horses were a dominant component of North American Pleistocene land mammal communities and their remains are well represented in the fossil record. Despite the abundant material available for study, there is still considerable disagreement over the number of species of Equus that inhabited the different regions of the continent and on their taxonomic nomenclature. In this study, we investigated cheek tooth morphology and ancient mtDNA of late Pleistocene Equus specimens from the Western Interior of North America, with the objective of clarifying the species that lived in this region prior to the end-Pleistocene extinction. Based on the morphological and molecular data analyzed, a caballine (Equus ferus) and a non-caballine (E. conversidens) species were identified from different localities across most of the Western Interior. A second non-caballine species (E. cedralensis) was recognized from southern localities based exclusively on the morphological analyses of the cheek teeth. Notably the separation into caballine and non-caballine species was observed in the Bayesian phylogenetic analysis of ancient mtDNA as well as in the geometric morphometric analyses of the upper and lower premolars. Teeth morphologically identified as E. conversidens that yielded ancient mtDNA fall within the New World stilt-legged clade recognized in previous studies and this is the name we apply to this group. Geographic variation in morphology in the caballine species is indicated by statistically different occlusal enamel patterns in the specimens from Bluefish Caves, Yukon Territory, relative to the specimens from the other geographic regions. Whether this represents ecomorphological variation and/or a certain degree of geographic and genetic isolation of these Arctic populations requires further study. PMID:28817644

Cheek tooth morphology and ancient mitochondrial DNA of late Pleistocene horses from the western interior of North America: Implications for the taxonomy of North American Late Pleistocene Equus.

PubMed

Barrón-Ortiz, Christina I; Rodrigues, Antonia T; Theodor, Jessica M; Kooyman, Brian P; Yang, Dongya Y; Speller, Camilla F

2017-01-01

Horses were a dominant component of North American Pleistocene land mammal communities and their remains are well represented in the fossil record. Despite the abundant material available for study, there is still considerable disagreement over the number of species of Equus that inhabited the different regions of the continent and on their taxonomic nomenclature. In this study, we investigated cheek tooth morphology and ancient mtDNA of late Pleistocene Equus specimens from the Western Interior of North America, with the objective of clarifying the species that lived in this region prior to the end-Pleistocene extinction. Based on the morphological and molecular data analyzed, a caballine (Equus ferus) and a non-caballine (E. conversidens) species were identified from different localities across most of the Western Interior. A second non-caballine species (E. cedralensis) was recognized from southern localities based exclusively on the morphological analyses of the cheek teeth. Notably the separation into caballine and non-caballine species was observed in the Bayesian phylogenetic analysis of ancient mtDNA as well as in the geometric morphometric analyses of the upper and lower premolars. Teeth morphologically identified as E. conversidens that yielded ancient mtDNA fall within the New World stilt-legged clade recognized in previous studies and this is the name we apply to this group. Geographic variation in morphology in the caballine species is indicated by statistically different occlusal enamel patterns in the specimens from Bluefish Caves, Yukon Territory, relative to the specimens from the other geographic regions. Whether this represents ecomorphological variation and/or a certain degree of geographic and genetic isolation of these Arctic populations requires further study.

Alluvium-Buttressed Landslides: Conceptual Model and Examples from California

NASA Astrophysics Data System (ADS)

Johnson, P. L.; Cotton, W. R., Sr.; Shires, P. O.

2016-12-01

Large, deep-seated landslides typically occur in hillside settings without any natural buttressing, and many of these landslides have relatively low factors of safety (FS), the ratio of driving to resisting forces. However, where deep-seated landslides failed millennia ago into valleys that subsequently experienced alluvial aggradation, a natural buttress of alluvium may be deposited over the landslide toe, increasing the FS of these landslides. The eustatic model for alluvial buttressing of Quaternary landslides involves failure of slopes during sea level low stand at or near the late Pleistocene last glacial maximum (LGM, approximately 20 ka). Following LGM, mean sea level rose by over 120m to its present elevation. This rise in base level resulted in deposition of alluvial sediment in coastal valleys that had been v-shaped and downcutting prior to and during LGM. These valleys now have broad, low gradient floors formed by alluvial sediment, and the thick alluvial strata filling these valleys cover the toes of late Pleistocene landslides. In this study, three examples of large, deep-seated Pleistocene landslides that are buttressed by alluvium are presented. The McCracken Hill Landslide in Orange County and the Potrero Canyon Landslide Complex in Monterey County are located approximately 1.5 and 6 km, respectively, from the modern Pacific shore and closely fit the eustatic model of alluvial buttressing. At Knights Valley, in the upper Russian River watershed of eastern Sonoma County, a deep-seated alluvium-buttressed landslide is located approximately 65 km from the modern shore (measured along the Russian River and its tributary stream). The alluvium in Knights Valley may have ponded due to late Quaternary tectonic uplift of hills west of the valley. Streams that cross these hills are incised into bedrock downstream from Knights Valley and approaching the Russian River. Thus, the Knights Valley example (of an alluvium-buttressed landslide) demonstrates a rare exception to the broadly applicable eustatic model.

Geologic Map of the San Luis Quadrangle, Costilla County, Colorado

USGS Publications Warehouse

Machette, Michael N.; Thompson, Ren A.; Drenth, Benjamin J.

2008-01-01

The map area includes San Luis and the primarily rural surrounding area. San Luis, the county seat of Costilla County, is the oldest surviving settlement in Colorado (1851). West of the town are San Pedro and San Luis mesas (basalt-covered tablelands), which are horsts with the San Luis fault zone to the east and the southern Sangre de Cristo fault zone to the west. The map also includes the Sanchez graben (part of the larger Culebra graben), a deep structural basin that lies between the San Luis fault zone (on the west) and the central Sangre de Cristo fault zone (on the east). The oldest rocks exposed in the map area are the Pliocene to upper Oligocene basin-fill sediments of the Santa Fe Group, and Pliocene Servilleta Basalt, a regional series of 3.7?4.8 Ma old flood basalts. Landslide deposits and colluvium that rest on sediments of the Santa Fe Group cover the steep margins of the mesas. Rare exposures of the sediment are comprised of siltstones, sandstones, and minor fluvial conglomerates. Most of the low ground surrounding the mesas and in the graben is covered by surficial deposits of Quaternary age. The alluvial deposits are subdivided into three Pleistocene-age units and three Holocene-age units. The oldest Pleistocene gravel (unit Qao) forms extensive coalesced alluvial fan and piedmont surfaces, the largest of which is known as the Costilla Plain. This surface extends west from San Pedro Mesa to the Rio Grande. The primary geologic hazards in the map area are from earthquakes, landslides, and localized flooding. There are three major fault zones in the area (as discussed above), and they all show evidence for late Pleistocene to possible Holocene movement. The landslides may have seismogenic origins; that is, they may be stimulated by strong ground shaking during large earthquakes. Machette and Thompson based this geologic map entirely on new mapping, whereas Drenth supplied geophysical data and interpretations.

Geologic map of the Rio Puerco quadrangle, Bernalillo and Valencia Counties, New Mexico

USGS Publications Warehouse

Maldonado, Florian

2003-01-01

The Rio Puerco quadrangle is located southwest of Albuquerque in central New Mexico and covers part of the western part of the Isleta Reservation. The U.S. Geological Survey, the New Mexico Bureau of Geology and Mineral Resources, and the University of New Mexico have conducted geologic mapping on the Isleta Reservation and vicinity as part of the Middle Rio Grande Basin Project. The map area contains surficial deposits, calcic soils, fluvial deposits of the Rio Puerco, deposits of the Santa Fe Group, and three volcanic fields. The area is characterized by predominantly north-trending normal faults with generally down-to-the-east movement. Post-Santa Fe Group deposits are composed of surficial deposits (Pleistocene-Holocene) and fluvial deposits of the Rio Puerco (Pleistocene-Holocene). The surficial deposits are divided into eolian, alluvial, colluvial, and landslide deposits. The fluvial deposits of the Rio Puerco consist of four terrace and present channel deposits. The Santa Fe Group is divided into lower and upper parts. The lower part of the Santa Fe Group is exposed near the southwestern corner of the study area where deposits consist of reddish-brown mudstone and sandstone correlated to the Popotosa Formation (Unit 1) of Lozinsky and Tedford (1991). They interpreted deposition of the unit in a basin-floor playa setting. The Popotosa Formation is in fault contact to the east with deposits of the upper Santa Fe Group. The upper Santa Fe Group is derived from major tributary fluvial systems (ancestral Rio Puerco Puerco and possibly the Rio San Jose drainages) draining the adjacent Colorado Plateau and Sierra Nacimiento and correlated to parts of Kelley's (1977) Ceja Formation of the Santa Fe Group and equivalent to Machette's (1978) Sierra Ladrones Formation, Connell's Arroyo Ojito Formation (Connell and others, 1999, and Maldonado's lithofacies of the Isleta Reservation (Maldonado and Atencio,1998a, b). The group also locally includes a fine- grained unit (lower Pleistocene) referred to here as the sand, silt, and clay of Chavez Grant (Qsc). The Ceja Formation of the Santa Fe Group as defined here is divided into the following units in descending stratigraphic order: (1) upper sand and gravel unit (upper Pliocene), (2) middle silt, sand, and clay unit (upper Pliocene), and (3) lower sand and gravel unit (Pliocene). The three volcanic fields in the map area are: (1) basalt of Cat Hills, dated at 98-110 ka and composed of seven lava flows and four cinder cones; the flows overlie calcic soils that overlie the upper sand and gravel unit of the Ceja Formation; (2) lava flow of Cat Mesa, dated at about 3 Ma and interfingers with the upper part of the Ceja Formation; (3) diabase of Mohinas Mountain, dated at 8.3 Ma (Baldridge and others, 1987) and intrudes the Popotosa Formation. Numerous high-angle faults cut the area but are mostly buried. The faults generally trend north but deviate to the northwest and northeast. The major normal faults are the Cat Mesa and Mohinas Mountain faults.

First records of Canis dirus and Smilodon fatalis from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada

PubMed Central

Springer, Kathleen B.

2016-01-01

Late Pleistocene groundwater discharge deposits (paleowetlands) in the upper Las Vegas Wash north of Las Vegas, Nevada, have yielded an abundant and diverse vertebrate fossil assemblage, the Tule Springs local fauna (TSLF). The TSLF is the largest open-site vertebrate fossil assemblage dating to the Rancholabrean North American Land Mammal Age in the southern Great Basin and Mojave Desert. Over 600 discrete body fossil localities have been recorded from the wash, including an area that now encompasses Tule Springs Fossil Beds National Monument (TUSK). Paleowetland sediments exposed in TUSK named the Las Vegas Formation span the last 250 ka, with fossiliferous sediments spanning ∼100–13 ka. The recovered fauna is dominated by remains of Camelopsand Mammuthus, and also includes relatively common remains of extinct Equusand Bisonas well as abundant vertebrate microfaunal fossils. Large carnivorans are rare, with only Puma concolor and Panthera atrox documented previously. Postcranial remains assigned to the species Canis dirus (dire wolf) and Smilodon fatalis (sabre-toothed cat) represent the first confirmed records of these species from the TSLF, as well as the first documentation of Canis dirus in Nevada and the only known occurrence of Smilodonin southern Nevada. The size of the recovered canid fossil precludes assignment to other Pleistocene species of Canis. The morphology of the felid elements differentiates them from other large predators such as Panthera, Homotherium, and Xenosmilus, and the size of the fossils prevents assignment to other species of Smilodon. The confirmed presence of S. fatalis in the TSLF is of particular interest, indicating that this species inhabited open habitats. In turn, this suggests that the presumed preference of S. fatalis for closed-habitat environments hunting requires further elucidation. PMID:27366649

Climate-driven sediment aggradation and incision since the late Pleistocene in the NW Himalaya, India

NASA Astrophysics Data System (ADS)

Dey, Saptarshi; Thiede, Rasmus C.; Schildgen, Taylor F.; Wittmann, Hella; Bookhagen, Bodo; Scherler, Dirk; Jain, Vikrant; Strecker, Manfred R.

2016-09-01

Deciphering the response of sediment routing systems to climatic forcing is fundamental for understanding the impacts of climate change on landscape evolution. In the Kangra Basin (northwest Sub-Himalaya, India), upper Pleistocene to Holocene alluvial fills and fluvial terraces record periodic fluctuations of sediment supply and transport capacity on timescales of 103 to 105 yr. To evaluate the potential influence of climate change on these fluctuations, we compare the timing of aggradation and incision phases recorded within remnant alluvial fans and terraces with climate archives. New surface-exposure dating of six terrace levels with in-situ cosmogenic 10Be indicates the onset of incision phases. Two terrace surfaces from the highest level (T1) sculpted into the oldest preserved alluvial fan (AF1) date back to 53.4 ± 3.2 ka and 43.0 ± 2.7 ka (1σ). T2 surfaces sculpted into the remnants of AF1 have exposure ages of 18.6 ± 1.2 ka and 15.3 ± 0.9 ka, while terraces sculpted into the upper Pleistocene-Holocene fan (AF2) provide ages of 9.3 ± 0.4 ka (T3), 7.1 ± 0.4 ka (T4), 5.2 ± 0.4 ka (T5) and 3.6 ± 0.2 ka (T6). Together with previously published OSL ages yielding the timing of aggradation, we find a correlation between variations in sediment transport with oxygen-isotope records from regions affected by the Indian Summer Monsoon. During periods of increased monsoon intensity and post-Last Glacial Maximum glacial retreat, aggradation occurred in the Kangra Basin, likely due to high sediment flux, whereas periods of weakened monsoon intensity or lower sediment supply coincide with incision.

First records of Canis dirus and Smilodon fatalis from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada

USGS Publications Warehouse

Scott, Eric; Springer, Kathleen

2016-01-01

Late Pleistocene groundwater discharge deposits (paleowetlands) in the upper Las Vegas Wash north of Las Vegas, Nevada, have yielded an abundant and diverse vertebrate fossil assemblage, the Tule Springs local fauna (TSLF). The TSLF is the largest open-site vertebrate fossil assemblage dating to the Rancholabrean North American Land Mammal Age in the southern Great Basin and Mojave Desert. Over 600 discrete body fossil localities have been recorded from the wash, including an area that now encompasses Tule Springs Fossil Beds National Monument (TUSK). Paleowetland sediments exposed in TUSK named the Las Vegas Formation span the last 250 ka, with fossiliferous sediments spanning ∼100–13 ka. The recovered fauna is dominated by remains of Camelopsand Mammuthus, and also includes relatively common remains of extinct Equusand Bisonas well as abundant vertebrate microfaunal fossils. Large carnivorans are rare, with only Puma concolor and Panthera atrox documented previously. Postcranial remains assigned to the species Canis dirus (dire wolf) and Smilodon fatalis(sabre-toothed cat) represent the first confirmed records of these species from the TSLF, as well as the first documentation of Canis dirus in Nevada and the only known occurrence of Smilodonin southern Nevada. The size of the recovered canid fossil precludes assignment to other Pleistocene species of Canis. The morphology of the felid elements differentiates them from other large predators such as Panthera, Homotherium, and Xenosmilus, and the size of the fossils prevents assignment to other species of Smilodon. The confirmed presence of S. fatalis in the TSLF is of particular interest, indicating that this species inhabited open habitats. In turn, this suggests that the presumed preference of S. fatalis for closed-habitat environments hunting requires further elucidation.

Morphology and structure of Homo erectus humeri from Zhoukoudian, Locality 1

PubMed Central

Wei, Pianpian; He, Jianing; Liu, Wu

2018-01-01

Background Regional diversity in the morphology of the H. erectus postcranium is not broadly documented, in part, because of the paucity of Asian sites preserving postcranial fossils. Yet, such an understanding of the initial hominin taxon to spread throughout multiple regions of the world is fundamental to documenting the adaptive responses to selective forces operating during this period of human evolution. Methods The current study reports the first humeral rigidity and strength properties of East Asian H. erectus and places its diaphyseal robusticity into broader regional and temporal contexts. We estimate true cross-sectional properties of Zhoukoudian Humerus II and quantify new diaphyseal properties of Humerus III using high resolution computed tomography. Comparative data for African H. erectus and Eurasian Late Pleistocene H. sapiens were assembled, and new data were generated from two modern Chinese populations. Results Differences between East Asian and African H. erectus were inconsistently expressed in humeral cortical thickness. In contrast, East Asian H. erectus appears to exhibit greater humeral robusticity compared to African H. erectus when standardizing diaphyseal properties by the product of estimated body mass and humeral length. East Asian H. erectus humeri typically differed less in standardized properties from those of side-matched Late Pleistocene hominins (e.g., Neanderthals and more recent Upper Paleolithic modern humans) than did African H. erectus, and often fell in the lower range of Late Pleistocene humeral rigidity or strength properties. Discussion Quantitative comparisons indicate that regional variability in humeral midshaft robusticity may characterize H. erectus to a greater extent than presently recognized. This may suggest a temporal difference within H. erectus, or possibly different ecogeographical trends and/or upper limb loading patterns across the taxon. Both discovery and analysis of more adult H. erectus humeri are critical to further evaluating and potentially distinguishing between these possibilities. PMID:29372121

Long Term Water Level and Chemistry Evolution in Groundwater of the Mississippi Embayment, Arkansas, USA: Preliminary Results

NASA Astrophysics Data System (ADS)

Neumann, K.; Dowling, C. B.; Moraru, C.; Hannigan, R. E.

2008-12-01

The Mississippi Embayment, located in the southeastern U.S., is a syncline formed by the northward excursion of the Gulf of Coastal Plain. Structurally, the Mississippi Embayment is a hydrogeological basin consisting of six regional aquifers. These productive aquifers yield good-quality waters. The Mississippi Embayment Regional Ground Water Study group located at Arkansas State University compiled and organized the available water chemistry and groundwater level data from the USGS groundwater monitoring database. The uppermost unconfined horizon forms the Mississippi River Valley Alluvial Aquifer (ALVM), one of the largest unconfined aquifers in the world. The Holocene and Pleistocene ALVM is formed from sand, gravel, and loess. The majority of the groundwater wells (approximately 80%) are drilled in the ALVM. As the groundwater levels have fallen in the unconfined ALVM, more groundwater wells are drilled in the deeper aquifers-the Upper, Middle, and Lower Claiborne Aquifers. The Ecocene Upper Claiborne Aquifer protolith is sand, silt, and clay while the Eocene Middle Claiborne and Lower Claiborne aquifers are sand and minor clay. We focused our investigation of the spatial and temporal evolution of groundwater in the Arkansas section of the Mississippi Embayment by using wells with long term monitoring records (1928 - 2005). Overall, the groundwater levels of the unconfined aquifer (ALVM) have decreased; we have not yet evaluated the lower aquifer water level changes. Attention was paid to rock-water interactions along flowpaths in the ALVM and Upper Claiborne aquifers, and to temporal changes at specific sampling sites. The study is utilizing groundwater pH, cation, anion, and nutrient data in the programs AquaChem and PHREEQE to describe mineral and CO2 saturations in groundwater. First results indicate that the modeling allows the identification of different processes (CO2 pressure, calcite saturation) that control distinct geochemical provinces, e.g. urban regions and regions dominated by river water recharge.

Recent and relict topography of Boo Bee patch reef, Belize

USGS Publications Warehouse

Halley, R.B.; Shinn, E.A.; Hudson, J.H.; Lidz, B.; Taylor, D.L.

1977-01-01

Five core borings were taken on and around Boo Bee Patch Reef to better understand the origin of such shelf lagoon reefs. The cores reveal 4 stages of development: (1) subaerial exposure of a Pleistocene "high" having about 8 meters of relief, possibly a Pleistocene patch reef; (2) deposition of peat and impermeable terrigenous clay 3 meters thick around the high; (3) initiation of carbonate sediment production by corals and algae on the remaining 5 meters of hard Pleistocene topography and carbonate mud on the surrounding terrigenous clay; and (4) accelerated organic accumulation on the patch reef. Estimates of patch reef sedimentation rates (1.6 m/1000 years) are 3 to 4 times greater than off-reef sedimentation rates (0.4-0.5 m/1000 years). During periods of Pleistocene sedimentation on the Belize shelf, lagoon patch reefs may have grown above one another, stacking up to form reef accumulation of considerable thickness.

Neotectonic Activity from Karewa Sediments, Kashmir Himalaya, India

NASA Astrophysics Data System (ADS)

Agarwal, K. K.; Shah, R. A.; Achyuthan, H.; Singh, D. S.; Srivastava, S.; Khan, I.

2018-01-01

Intermontane basin sedimentation occurred during Pliocene-Pleistocene in the Karewa Basin which formed after the continent-continent collision resulting in the formation of Himalayan orogenic belt around Eocene. These are elongated, narrow, thrust bounded basins which have formed during the late stages of orogeny. Situated at a height of 1700-1800 m above sea level, the Karewa basin received sediments because of ponding of a pre-existing river system and the tectonic movements along the Great Himalayan Ranges in the north and the Pir-Panjal ranges in the south along active faults. About 1300 m thick sediments of largely fluvio-lacustrine, glacio-fluvio-lacustrine and eolian origin are exposed having evidences of neotectonically formed structural features such as folds and faults. Folds are more prominent in the Lower Karewa formation (Hirpur Formation) while faults (mostly normal faults) are abundant in the Upper Karewas (Nagum Formation). Drainage in the area varies from dendritic to anastomosing to parallel. Anastomosing drainage suggests sudden decrease in gradient while presence of linear features such as faults and ridges is evident by parallel drainage. Study of morphometric parameters such as stream length (Lsm) and stream length ratios (RL), bifurcation ratio (Rb), drainage density (D), form factor (Rf), circularity ratio (Rc), and elongation ratio (Re) also indicate intense tectonic activity in the recent past.

The influence of paleo currents upon the Santaren Channel and the adjacent carbonate platforms, Bahamas.

NASA Astrophysics Data System (ADS)

Paulat, Marco; Lüdmann, Thomas; Betzler, Christian; Eberli, Gregor; Lindhorst, Sebastian

2015-04-01

The closure of the Central American Seaway and the reorganization of the ocean currents had a global impact on earth's climate. The sedimentation of the Great Bahama Bank (GBB) and the smaller Cay Sal Bank (CSB) are influenced by the Atlantic North Equatorial Current and the Florida Current. New high-resolution multichannel seismic data sets tied to the IODP leg 166 wells document that the shape of Bahama Banks and the sedimentation processes in the Santaren Channel (SC) between GBB and CSB are strongly related to changes in the strength of these currents. Since the Upper Miocene, the SC is filled up by a huge package of drift sediments, namely the Santaren Drift (SD). The buildup of the SD causes a local high in the recent bathymetry perpendicular to the surrounding steep platform slopes. The SD shows a typical mounded morphology and progrades northwards in direction of the Florida Channel. The SD was established during the late Miocene. Seismic facies and internal configuration indicate an environment of a stable north flowing current with a major depocenter related to the center of the SC. Additionally, a second depocenter at the central eastern flank of CSB established and preserved till early Pleistocene when the slope sedimentation starts to dominate. This depocenter points to a strengthened countercurrent component in the eastern SC. From the lower Pliocene to the upper Pleistocene the volume of the SD expanded, associated with an intensification of the current in the SC along its eastern flank, indicated by deep erosional channels parallel to the margin of GBB in the northern part of the survey area. This trend probably was initiated as a consequence of current reorganization due to the final closure of the Central American Seaway. Lower slope sediments from GBB are eroded or only minor parts are preserved from lower Pliocene to upper Pleistocene. With late Pliocene falling sea-level, gravitational slope sedimentation from GBB into the SC increased with concurrent decrease in sedimentation rate of the SD. The drift depocenter shifted toward the margin of the GBB, approaching the modern situation.

The Long Pleistocene Paleoclimate Record from Stoneman Lake, Arizona: an Update

NASA Astrophysics Data System (ADS)

Werne, J. P.; Anderson, R. S.; Fawcett, P. J.; Brown, E. T.; Jimenez-Moreno, G.; Toney, J. L.; Dunbar, N. W.; Stockhecke, M.; Garrett, H.; Garcia, D.

2016-12-01

Long continuous lake sediment core records of Pleistocene paleoenvironmental and paleoclimatic change are rare in the American Southwest. Such records have the potential to provide long-term perspective on, for instance, the occurrence and duration of past megadroughts, vegetation change during glacial-interglacial transitions, and changes in precipitation sources, among many other aspects of environmental change. One site with the potential to study ancient megadroughts and long-term environmental change is Stoneman Lake, central Arizona, whose basin is a circular depression formed by a collapse in late Tertiary volcanics. The lake is presently spring fed, and has alternated between a marsh and a lake over the last 25 years, fluctuating by > 3 meters. This sensitivity is due to its small closed drainage basin (ca. 2.5 km2) with one small intermittant inflowing stream. We have been analyzing two parallel lacustrine sediment cores (70 m and 30 m deep), which were recovered in October of 2014. Our preliminary chronology is based on 8 AMS dates in the upper 7 m and two distinct tephras at 30.8 m and 36.3 m depth. The Holocene-Pleistocene boundary occurs at 2.8 m ( 11,000 cal yr B.P.) while the lowest finite AMS age at 4.2 m is 45,500 cal yr B.P. The most likely source of the tephra at 30.8 m is from Sugarloaf, San Francisco Volcanic Field, having a preliminary age of 700k. Based on this age, we estimate that the 70-m deep hole will provide a climate record back to 1.3 million years ago. Of particular interest are the interglacials that serve as good analogs for future climate including MIS 11 and MIS 19. In addition to our Geo-Tek analyses (MS, bulk density and high-resolution images) pollen data outlines glacial-interglacial changes since the mid-Pleistocene. Carbon isotopes from glacial-age sediments are more negative, suggesting a dominance of C3 plants, while less negative values during interglacials suggest a greater C4 component. ITRAX Scanning XRF and calculation of selected elemental ratios shows calcium is higher during interglacial periods (Holocene, MIS 5), consistent with great evaporation and lower lake levels. The K:Ti ratio may represent a dust input signal into the lake.

Neogene-Quaternary slow coastal uplift of Western Europe through the perspective of sequences of strandlines from the Cotentin Peninsula (Normandy, France)

NASA Astrophysics Data System (ADS)

Pedoja, K.; Jara-Muñoz, J.; De Gelder, G.; Robertson, J.; Meschis, M.; Fernandez-Blanco, D.; Nexer, M.; Poprawski, Y.; Dugué, O.; Delcaillau, B.; Bessin, P.; Benabdelouahed, M.; Authemayou, C.; Husson, L.; Regard, V.; Menier, D.; Pinel, B.

2018-02-01

The Cotentin Peninsula (Normandy, France) displays sequences of marine terraces and rasas, the latter being wide Late Cenozoic coastal erosion surfaces, that are typical of Western European coasts in Portugal, Spain, France and southern England. Remote sensing imagery and field mapping enabled reappraisal of the Cotentin coastal sequences. From bottom to top, the N Cotentin sequence includes four previously recognized Pleistocene marine terraces (T1 to T4) at elevations < 40 m as well as four higher and older rasas (R1 to R4) reaching 200 ± 5 m in elevation. Low-standing marine terraces are not observed in the central part of the Peninsula and a limited number of terraces are described to the south. The high-standing rasas are widespread all over the peninsula. Such strandline distributions reveal major changes during the Late Cenozoic. Progressive uplift of an irregular sea-floor led to subaerial exposure of bathymetric highs that were carved into rocky platforms, rasas and marine terraces. Eventually, five main islands coalesced and connected to the mainland to the south to form the Cotentin Peninsula. On the basis of previous dating of the last interglacial maximum terrace (i.e. Marine Isotopic Stage, MIS 5e), sequential morphostratigraphy and modelling, we have reappraised uplift rates and derived: (i) mean Upper Pleistocene (i.e. since MIS 5e 122 +/- 6 ka, i.e. kilo annum) apparent uplift rates of 0.04 ± 0.01 mm/yr, (ii) mean Middle Pleistocene eustasy-corrected uplift rates of 0.09 ± 0.03 mm/yr, and (iii) low mean Pleistocene uplift rates of 0.01 mm/yr. Extrapolations of these slow rates combined with geological evidence implies that the formation of the sequences from the Cotentin Peninsula occurred between 3 Ma (Pliocene) and 15 Ma (Miocene), which cannot be narrowed down further without additional research. Along the coasts of Western Europe, sequences of marine terraces and rasas are widespread (169 preserve the MIS 5e benchmark). In Spain, Portugal, S England and other parts of western France, the sequences morphostratigraphy is very similar to that of Cotentin. The onset of such Western European sequences occurred during the Miocene (e.g. Spain) or Pliocene (e.g. Portugal). We interpret this Neogene-Quaternary coastal uplift as a symptom of the increasing lithospheric compression that accompanies Cenozoic orogenies.

Pliocene and Pleistocene chronostratigraphy of continental sediments underlying the Altiplano at La Paz, Bolivia

NASA Astrophysics Data System (ADS)

Roberts, Nicholas J.; Barendregt, René W.; Clague, John J.

2018-06-01

Continental sediments underlying the Altiplano plateau provide insight into the late Cenozoic evolution of the Central Andes. We characterize the magnetostratigraphy and lithostratigraphy of the upper part of this fill sequence along a transect extending southwestward from the Cordillera Real at La Paz, Bolivia, where it is best exposed. Multiple polarity reversals and the locally extensive, 2.74-Ma Chijini Tuff enable correlation between our six sections and three previously reported sections. The tuff ties the composite polarity sequence to the geomagnetic polarity time scale, demonstrating that the stratigraphic record extends from the latest Gilbert Chron (ca. 3.8 Ma) to the late Olduvai subchron (ca. 1.8 Ma), or possibly Jaramillo subchron (ca. 1.0 Ma). The sequence provides Earth's longest known record of low-latitude glaciation and the only record of Pliocene tropical glaciation. It includes evidence for 16 late Pliocene and Early Pleistocene glaciations, separated by interglacials of sufficient length (>103-104 a) to produce mature soil profiles. Successively larger ice caps formed directly before, during, and after the globally warm mid-Piacenzian (3.265-3.025 Ma), and throughout Plio-Pleistocene climate deterioration. The late Pliocene glacial units predate the onset of widespread Northern Hemisphere continental glaciation and in most cases unambiguously correspond to specific cool peaks of the astronomically tuned, benthic oxygen isotope (δ18O) record, including marine isotope stages MG2, M2, KM2, and G10. The glacial events broadly coincide with those nearer both poles, suggesting inter-hemispheric climate linkages. The early formation and subsequent expansion of ice caps beyond glacier margins of the Last Glacial Maximum suggest that the Cordillera Real likely attained its modern height before ca. 3.4 Ma. The number and timing of glaciations, and long-term sediment accumulation and incision rates suggest that the local Altiplano surface formed by ca. 1.8 Ma, after which headwaters of the Amazon River system breached the Cordillera Real and began to incise the fill sequence. The sequence spans at least 2 Ma before and during the first main pulses of the Great American Biotic Interchange, providing an important record of faunal migration. The arrival of savanna-adapted North American mammals in the Central Andes during this period points to the influence of glaciation on faunal migration in the southern tropics, similar to influences proposed in North and Central America.

Streamlined islands and the English Channel megaflood hypothesis

NASA Astrophysics Data System (ADS)

Collier, J. S.; Oggioni, F.; Gupta, S.; García-Moreno, D.; Trentesaux, A.; De Batist, M.

2015-12-01

Recognising ice-age catastrophic megafloods is important because they had significant impact on large-scale drainage evolution and patterns of water and sediment movement to the oceans, and likely induced very rapid, short-term effects on climate. It has been previously proposed that a drainage system on the floor of the English Channel was initiated by catastrophic flooding in the Pleistocene but this suggestion has remained controversial. Here we examine this hypothesis through an analysis of key landform features. We use a new compilation of multi- and single-beam bathymetry together with sub-bottom profiler data to establish the internal structure, planform geometry and hence origin of a set of 36 mid-channel islands. Whilst there is evidence of modern-day surficial sediment processes, the majority of the islands can be clearly demonstrated to be formed of bedrock, and are hence erosional remnants rather than depositional features. The islands display classic lemniscate or tear-drop outlines, with elongated tips pointing downstream, typical of streamlined islands formed during high-magnitude water flow. The length-to-width ratio for the entire island population is 3.4 ± 1.3 and the degree-of-elongation or k-value is 3.7 ± 1.4. These values are comparable to streamlined islands in other proven Pleistocene catastrophic flood terrains and are distinctly different to values found in modern-day rivers. The island geometries show a correlation with bedrock type: with those carved from Upper Cretaceous chalk having larger length-to-width ratios (3.2 ± 1.3) than those carved into more mixed Paleogene terrigenous sandstones, siltstones and mudstones (3.0 ± 1.5). We attribute these differences to the former rock unit having a lower skin friction which allowed longer island growth to achieve minimum drag. The Paleogene islands, although less numerous than the Chalk islands, also assume more perfect lemniscate shapes. These lithologies therefore reached island equilibrium shape more quickly but were also susceptible to total erosion. Our observations support the hypothesis that the islands were initially carved by high-water volume flows via a unique catastrophic drainage of a pro-glacial lake in the southern North Sea at the Dover Strait rather than by fluvial erosion throughout the Pleistocene.

Determining earthquake recurrence intervals from deformational structures in young lacustrine sediments

USGS Publications Warehouse

Sims, John D.

1975-01-01

Examination of the silty sediments in the lower Van Normal reservoir after the 1971 San Fernando, California earthquake revealed three zones of deformational structures in the 1-m-thick sequence of sediments exposed over about 2 km2 of the reservoir bottom. These zones are correlated with moderate earthquakes that shook the San Fernando area in 1930, 1952, and 1971. The success of this study, coupled with the experimental formation of deformational structures similar to those of the Van Norman reservoir, led to a search for similar structures in Pleistocene and Holocene lakes and lake sediments in other seismically active areas. Thus, studies have been started in Pleistocene and Holocene silty and sandy lake sediments in the Imperial Valley, southeastern California; Clear Lake, in northern California; and the Puget Sound area of Washington. The Imperial Valley study has yielded spectacular results: five zones of structures in the upper 10 m of Late Holocene sediments near Brawley have been correlated over an area of approximately 100 km2, using natural outcrops. These structures are similar to those of the Van Norman reservoir and are interpreted to represent at least five moderate to large earthquakes that affected the southern Imperial Valley area during Late Holocene time. The Clear Lake study has provided ambiguous results with respect to determination of earthquake recurrence intervals because the cores studied are in clayey rich in organic material sediments that have low liquefaction potential. A study of Late Pleistocene varved glacio-lacustrine sediments has been started in the Puget Sound area of Washington, and thirteen sites have been examined. One has yielded 18.75 m of sediments that contains 1,804 varves and fourteen deformed zones interpreted as being caused by earthquake, because they are identical to structures formed experimentally by simulated seismic shaking. Correlation of deformational structures with seismic events is based on:(1) proximity to presently active seismic zones;(2) presence of potentially liquefiable sediments;(3) similarity to structures formed experimentally;(4) small-scale internal structures within deformed zones that suggest liquefaction;(5) structures restricted to single stratigraphic intervals;(6) zones of structures correlatable over large areas; and(7) absence of detectable influence by slopes, slope failures, or other sedimentological, biological, or deformational processes.

Geophysical observations on northern part of Georges Bank and adjacent basins of Gulf of Maine

USGS Publications Warehouse

Oldale, R.N.; Hathaway, J.C.; Dillon, William P.; Hendricks, J.D.; Robb, James M.

1974-01-01

Continuous-seismic-reflection and magnetic-intensity profiles provide data for inferences about the geology of the northern part of Georges Bank and the basins of the Gulf of Maine adjacent to the bank.Basement is inferred to be mostly sedimentary and volcanic rocks of Paleozoic age that were metamorphosed and intruded locally by felsic and mafic plutons near the end of the Paleozoic Era. During Late Triassic time, large fault basins formed within the Gulf of Maine and probably beneath Georges Bank. The fault basins and a possible major northeast-trending fault zone beneath the northern part of the bank probably formed as a result of the opening Atlantic during the Mesozoic. Nonmarine sediments, associated with mafic flows and intrusive rocks, were deposited in the fault basins as they formed. The upper surface of the Triassic and pre-Triassic rocks that comprise basement is an unconformity that makes up much of the bottom of the Gulf of Maine. Depth to the basement surface beneath the gulf differ greatly because of fluvial erosion in Tertiary time and glacial erosion in Pleistocene time. Beneath the northern part of Georges Bank the basement surface is smoother and slopes southward. Prominent valleys, cut before Late Cretaceous time, are present beneath this part of the bank.Cretaceous, Tertiary, and possibly Jurassic times were characterized by episodes of coastal-plain deposition and fluvial erosion. During this time a very thick wedge of sediment, mostly of Jurassic(?) and Cretaceous ages, was deposited on the shelf. Major periods of erosion took place at the close of the Cretaceous and during the Pliocene. Fluvial erosion during the Pliocene removed much of the coastal-plain sedimentary wedge and formed the Gulf of Maine.Pleistocene glaciers eroded all but a few remnants of the coastal-plain sediments within the gulf and deposited a thick section of drift against the north slope of Georges Bank and a thin veneer of outwash on the bank. Marine sediments were deposited in the basins of the Gulf of Maine during the retreat of the last ice and the postglacial rise in sea level.

Evidence of climatic variations in upper Pleistocene and Holocene sediments from the lagoon of Venice (Italy and the Bohai Sea (China))

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonardi, M.; Carbognin, L.; Tosi, L.

1996-12-31

An accurate forecasting of environmental impact on sea level and shoreline changes due to global warming, requires a detailed investigation and interpretation of the events that occurred during the past 20,000 years. This time interval in fact corresponds to two significant climatic global changes: the last Wuermian glaciation, during the Upper Pleistocene, and the warming during the Holocene. Examples of the climatic variation impact on paleoenvironments are here evidenced by sedimentological studies, radiocarbon dating, paleobotanic, paleontological, mineralogical and geochemical investigations of two stratigraphic columns that are geographically far apart: the Lagoon of Venice, Italy, and the Bohai Sea, China. Themore » study focuses first on a general overview of the regional paleoclimatic history of these two core locations and their correlation with the sedimentological variations; second on some depositional events, such clay layers and beachrock formations, that carry the imprints of the climatic conditions. The results of this investigation may contribute to a better understanding of diagenetic processes, still not sufficiently described, caused by the climatic changes. Furthermore the study provided information that may be useful to a more complete overview of the environmental impact caused by natural global warming before the anthropogenic input.« less

Active deformation and evolution of the upper forearc slope of the central Ryukyu Arc, northwestern Pacific

NASA Astrophysics Data System (ADS)

Arai, K.; Inoue, T.; Sato, T.

2016-12-01

The Ryukyu Arc, which extend for over 1200 km along the east coast of Asia from Kyushu to Taiwan, and the associated Ryukyu Trench, are products of the subduction of the Philippine Sea Plate beneath the Eurasian Plate. The Okinawa Trough, a back-arc basin located landward of the Ryukyu Arc, formed in the Late Miocene (Gungor et al., 2012) or the Late Pliocene-Early Pleistocene (Sibuet et al., 1998); its formation is a key geologic event associated with complex tectonic movements and changes in the topographic configuration of the Ryukyu Arc. Geological Survey of Japan (GSJ), AIST has started the marine geological mapping project around Ryukyu Arc since the 2008 FY. Multi channel (16 ch) high-resolution seismic profiles were acquired during these cruises by the GI-gun (355cu. inch) or the Cluster-gun (30+30 cu. inch) systems. Survey area in the southeast off Okinawa Island is located on the upper forearc slope along the Ryukyu Trench. Seismic reflections of shelf and the upper forearc slope show no obvious deformation such as the fold and faults parallel to the Ryukyu Trench axis. In contrast, some active faults, which were perpendicular to the Ryukyu Trench axis (NW-SE direction), were observed. An acoustic basement, which is characterized distinct reflector had tilted southeastward (trenchward) and was unconformable overlain by the stratified sediments. These sediments divided into four seismic units. We present the geological history and tectonics of the central Ryukyu Arc.

Dietary traits of the late Early Pleistocene Bison menneri (Bovidae, Mammalia) from its type site Untermassfeld (Central Germany) and the problem of Pleistocene 'wood bison'

NASA Astrophysics Data System (ADS)

van Asperen, Eline N.; Kahlke, Ralf-Dietrich

2017-12-01

Over the course of the Early and early Middle Pleistocene, a climatic cooling trend led to the partial opening up of landscapes in the western Palaearctic. This led to a gradual replacement of browsers by grazers, whilst some herbivore species shifted their diet towards including more grass. Wear patterns of herbivore cheek teeth can inform our understanding of the timing and extent of this change and indicate levels of dietary plasticity. One of the indicator species of the faunal turnover is the first large-sized form of bison in the Palaearctic, Bison menneri. The dental mesowear of the palaeopopulation from the species' late Early Pleistocene type site of Untermassfeld in Central Germany and the Late Pleistocene B. priscus from Taubach, both from habitat mosaics of forested habitats and more open landscapes, have a mixed feeder profile similar to that of North American wood bison, which has a distinct preference for open habitats but occasionally consumes a high amount of browse as a fall-back food. In contrast, the grazer mesowear signature of early Middle Pleistocene B. schoetensacki voigtstedtensis from Voigtstedt indicates these animals likely did not regularly feed in the densely forested area around the site. The mesowear of B. schoetensacki from Süssenborn, in a more open environment, is similar to that of extant European bison. Both Pleistocene and extant bison are grazers to mixed feeders with relatively high tolerance of a suboptimal browsing diet. None of these species can be regarded as true 'wood bison'.

A geometric morphometric analysis of hominin upper premolars. Shape variation and morphological integration.

PubMed

Gómez-Robles, Aida; Martinón-Torres, María; Bermúdez de Castro, José María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2011-12-01

This paper continues the series of articles initiated in 2006 that analyse hominin dental crown morphology by means of geometric morphometric techniques. The detailed study of both upper premolar occlusal morphologies in a comprehensive sample of hominin fossils, including those coming from the Gran Dolina-TD6 and Sima de los Huesos sites from Atapuerca, Spain, complement previous works on lower first and second premolars and upper first molars. A morphological gradient consisting of the change from asymmetric to symmetric upper premolars and a marked reduction of the lingual cusp in recent Homo species has been observed in both premolars. Although percentages of correct classification based on upper premolar morphologies are not very high, significant morphological differences between Neanderthals (and European middle Pleistocene fossils) and modern humans have been identified, especially in upper second premolars. The study of morphological integration between premolar morphologies reveals significant correlations that are weaker between upper premolars than between lower ones and significant correlations between antagonists. These results have important implications for understanding the genetic and functional factors underlying dental phenotypic variation and covariation. Copyright © 2011 Elsevier Ltd. All rights reserved.

A revision of hominin fossil teeth from Fontana Ranuccio (Middle Pleistocene, Anagni, Frosinone, Italy).

PubMed

Rubini, Mauro; Cerroni, Vittorio; Festa, Giulia; Sardella, Raffaele; Zaio, Paola

2014-12-01

The Fontana Ranuccio hominin teeth (FR, Latium, Italy) are dated to the Middle Pleistocene. In previous studies these teeth were classified as two lower (left and right) second molars, one lower left central incisor and a badly worn incisor crown, the exact position of which could not be determined. In 2012 these remains were acquired by the Anthropological Service of S.B.A.L. (Italian Ministry of Culture) and for this reason re-analysed. In a thorough revision we have reassessed them both morphologically and dimensionally as two lower (left and right) first molars, one lower left lateral incisor and a possible upper left canine. The comparison with penecontemporaneous and diachronic samples shows that the Fontana Ranuccio teeth are morphologically similar to Atapuerca-Sima de los Huesos, Arago XIII and Neanderthal samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

A terrestrial vertebrate palaeontological review of Aldabra Atoll, Aldabra Group, Seychelles

PubMed Central

2018-01-01

The Pleistocene vertebrate assemblage of Aldabra Atoll has been comparatively well studied. Three Upper Pleistocene fossil localities have been described yielding birds, reptiles and terrestrial molluscs. Those of Bassin Cabri and Bassin Lebine on Ile Picard are undated but must be in excess of 136,000 YBP, whereas Point Hodoul on Malabar Island is circa 100,000 YBP. Aldabra was seemingly completely submerged between deposition of the Ile Picard and Point Hodoul deposits, resulting in local faunal extinctions. Here we present the results of an ongoing study of fossil material collected on Ile Picard in 1987, which reveals a more diverse assemblage than previously realised. Notable discoveries are an Ardeola heron, three Procellariformes, tropic-bird Phaethon, gull Larus, rail Dryolimnas, harrier Circus and owl Tyto, plus evidence of recolonisation of the atoll by some seabirds, rail, harrier, owl, giant tortoises and lizards after the Ile Picard/Point Hodoul submergence event. PMID:29590117

Chronology of fluvial terrace sequences for large Atlantic rivers in the Iberian Peninsula (Upper Tagus and Duero drainage basins, Central Spain)

NASA Astrophysics Data System (ADS)

Silva, Pablo G.; Roquero, Elvira; López-Recio, Mario; Huerta, Pedro; Martínez-Graña, Antonio M.

2017-06-01

This work analyses the chronology of fluvial terrace sequences of the two most important fluvial basins from central Spain draining to the Atlantic Ocean (Upper Tagus and Duero drainage basins). Both basins evolved under similar Mediterranean climatic conditions throughout the Pleistocene and present comparable number of fluvial terraces (16-17) after excluding the higher terrace levels of the Tagus (T1-T5) entrenched in the Raña surface. These higher ;rañizo terraces; was formed in response to fan-head trenching in this high alluvial piedmont (+220 m) and therefore not properly controlled by Quaternary fluvial downcutting. The study accomplishes the implementation of multiple regression analyses for terrace height-age relationships. To transform relative terrace heights above the present river thalwegs (i.e. +100 m) in numerical ages a ;height-age transference function; has been developed on the basis of preliminary statistical geochronological approaches proposed for Central Spain. The resultant height-age transference function gather 73 published geochronological data for terrace sequences, featuring a 3rd Order Polynomial Function (R2 0.90). This function describes the overall trend of valley downcutting for the last c. 2.3 Ma in Central Spain and is used to assign numerical ages to terrace levels at different relative elevation.

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens.

PubMed

Kupczik, Kornelius; Hublin, Jean-Jacques

2010-11-01

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens. Copyright © 2010 Elsevier Ltd. All rights reserved.

Formation and tectonic evolution of the Pattani Basin, Gulf of Thailand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bustin, R.M.; Chonchawalit, A.

The stratigraphic and structural evolution of the Pattani Basin, the most prolific petroleum basin in Thailand, reflects the extensional tectonic regime of continental Southeast Asia. E-W extension resulting from the northward collision of India with Eurasia since the Early Tertiary resulted in the formation of a series of N-S-trending sedimentary basins, which include the Pattani Basin. The sedimentary succession in the Pattani Basin is divisible into synrift and postrift sequences. Deposition of the synrift sequence accompanied rifting and extension, with episodic block faulting and rapid subsidence. The synrift sequence comprises three stratigraphic units: (1) Upper Eocene to Lower Olikgocene alluvial-fan,more » braided-river, and floodplain deposits; (2) Upper oligocene to Lowe Miocene floodplain and channel deposits; and (3) a Lower Miocene regressive package consisting of marine to nonmarine sediments. Post-rift succession comprises: (1) a Lower to Middle Miocene regressive package of shallow marine sediments through floodplain and channel deposits; (2) an upper Lower Miocene transgressive sequence; and (3) and Upper Miocene to Pleistocene transgressive succession. The post-rift phase is characterized by slower subsidence and decreased sediment influx. The present-day shallow-marine condition in the Gulf of Thailand is the continuation of this latest transgressive phase. The subsidence and thermal history of the Pattani Basin is consistent with a nonuniform lithospheric-stretching model. The amount of extension as well as surface heat flow generally increases from the margin to the basin center. The crustal stretching factor ({beta}) varies form 1.3 at the basin margin to 2.8 in the center. The subcrustal stretching factor ({delta}) ranges from 1.3 at the basin margin to more than 3.0 in the basin center. 31 refs., 13 figs., 4 tabs.« less

Contrasting environmental memories by ancient soils on different parent rocks in the South-western Italian Alps

NASA Astrophysics Data System (ADS)

D'Amico, Michele; Catoni, Marcella; Bonifacio, Eleonora; Zanini, Ermanno

2014-05-01

Ancient soils (pre-Holocenic paleosols and vetusols) are uncommon on the Alps, because of the extensive Pleistocenic glaciations which erased most of the previously existing soils, the slope steepness and climatic conditions favoring soil erosion. However, in few sites, particularly in the outermost sections of the Alpine range, Pleistocene glaciers covered only small and scattered surfaces because of the low altitude reached in the basins, and ancient soils could be preserved for long periods of time on particularly stable surfaces. We described and sampled soils on 11 stable surfaces in the Upper Tanaro valley, Ligurian Alps (Southwestern Piemonte, Italy). The sampling sites were characterized by low steepness and elevation between 600 to 1600 m, under present day lower montane Castanea sativa/Ostrya carpinifolia forests, montane Fagus sylvatica and Pinus uncinata forests or montane heath/grazed grassland, on different substrata. In particular, we sampled soils developed on dolomite, limestone, quartzite, gneiss and shales. The soils were always well representative of the pedogenic trends active on the respective parent materials, i.e. the skeletal fraction in each soil was always composed of just one rock type, despite the proximity of lithological boundaries and the small dimensions of the different outcrops, often coexisting on the same stable surface. All the considered profiles showed signs of extremely long pedogenesis and/or different phases of intense pedogenesis interrupted by the deposition of periglacial cover beds in the steepest sites. Up to four phases of intense pedogenesis were recognized where cover beds were developed, presumably during cold Pleistocene phases, as present-day climate is not cold enough to create such periglacial morphologies. In such cases, each cover bed underwent similar pedogenesis, strongly dependent on the parent material: on quartzite, podzols with thick E horizons and well developed placic ones were formed in all phases except the most superficial one (i.e., Holocene phase), where non cemented spodic horizons or weakly cemented ortstein were formed; placic horizons were never found in Holocene soils. On limestone, each cover bed separated soils with extremely hard petrocalcic horizons overlaid by argillic ones. Where no cover beds were observed, podzols with extremely thick E horizons (up to more than 2 m thick) and a very hard, very thick ortstein were formed on quartzite. Red Nitisols-like or reddish brown Luvisols were formed on limestone and dolomite, while red, extremely acidic Alisols, with or without fragipan horizons were formed on shales. Very large stone circles and other large patterned ground features, which can be interpreted as evidence of past permafrost conditions, were preserved on coarse quartzitic conglomerate. These soils represent excellent pedo-signatures of different specific past climatic or environmental conditions, as a response of different lithologies to specific soil-forming environments, which range from warm and humid climates typical of red Luvisols and Nitisols, to cool and wet climates leading to the formation of Podzols with placic or ortstein horizons, to extremely cold and dry ones characterizing permafrost sites and often associated with fragipan formation, to warm and dry leading to the cementation of petrocalcic horizons. The precise dating and interpretation of these soils are intriguing.

Pleistocene Brawley and Ocotillo Formations: Evidence for initial strike-slip deformation along the San Felipe and San Jacinto fault zonez, Southern California

USGS Publications Warehouse

Kirby, S.M.; Janecke, S.U.; Dorsey, R.J.; Housen, B.A.; Langenheim, V.E.; McDougall, K.A.; Steeley, A.N.

2007-01-01

We examine the Pleistocene tectonic reorganization of the Pacific-North American plate boundary in the Salton Trough of southern California with an integrated approach that includes basin analysis, magnetostratigraphy, and geologic mapping of upper Pliocene to Pleistocene sedimentary rocks in the San Felipe Hills. These deposits preserve the earliest sedimentary record of movement on the San Felipe and San Jacinto fault zones that replaced and deactivated the late Cenozoic West Salton detachment fault. Sandstone and mudstone of the Brawley Formation accumulated between ???1.1 and ???0.6-0.5 Ma in a delta on the margin of an arid Pleistocene lake, which received sediment from alluvial fans of the Ocotillo Formation to the west-southwest. Our analysis indicates that the Ocotillo and Brawley formations prograded abruptly to the east-northeast across a former mud-dominated perennial lake (Borrego Formation) at ???1.1 Ma in response to initiation of the dextral-oblique San Felipe fault zone. The ???25-km-long San Felipe anticline initiated at about the same time and produced an intrabasinal basement-cored high within the San Felipe-Borrego basin that is recorded by progressive unconformities on its north and south limbs. A disconformity at the base of the Brawley Formation in the eastern San Felipe Hills probably records initiation and early blind slip at the southeast tip of the Clark strand of the San Jacinto fault zone. Our data are consistent with abrupt and nearly synchronous inception of the San Jacinto and San Felipe fault zones southwest of the southern San Andreas fault in the early Pleistocene during a pronounced southwestward broadening of the San Andreas fault zone. The current contractional geometry of the San Jacinto fault zone developed after ???0.5-0.6 Ma during a second, less significant change in structural style. ?? 2007 by The University of Chicago. All rights reserved.

Distribution of glacial deposits, soils, and permafrost in Taylor Valley, Antarctica

USGS Publications Warehouse

Bockheim, James G.; Prentice, M.L.; McLeod, M.

2008-01-01

We provide a map of lower and central Taylor Valley, Antarctica, that shows deposits from Taylor Glacier, local alpine glaciers, and grounded ice in the Ross Embayment. From our electronic database, which includes 153 sites from the coast 50 km upvalley to Pearse Valley, we show the distribution of permafrost type and soil subgroups according to Soil Taxonomy. Soils in eastern Taylor Valley are of late Pleistocene age, cryoturbated due to the presence of ground ice or ice-cemented permafrost within 70 cm of the surface, and classified as Glacic and Typic Haploturbels. In central Taylor Valley, soils are dominantly Typic Anhyorthels of mid-Pleistocene age that have dry-frozen permafrost within the upper 70 cm. Salt-enriched soils (Salic Anhyorthels and Petrosalic Anhyorthels) are of limited extent in Taylor Valley and occur primarily on drifts of early Pleistocene and Pliocene age. Soils are less developed in Taylor Valley than in nearby Wright Valley, because of lesser salt input from atmospheric deposition and salt weathering. Ice-cemented permafrost is ubiquitous on Ross Sea, pre-Ross Sea, and Bonney drifts that occur within 28 km of the McMurdo coast. In contrast, dry-frozen permafrost is prevalent on older (???115 ky) surfaces to the west. ?? 2008 Regents of the University of Colorado.

Lithologic interpretation of the De Braga No. 2 and Richard Weishaupt No. 1 geothermal wells, Stillwater project, Churchill County, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sibbett, B.S.; Blackett, R.E.

1982-02-01

Lithologies penetrated throughout the upper 732 to 838 m (2400 to 2750 ft) within the Stillwater prospect area are terrigenous sediments of Pleistocene to Recent age. A sill of dacite to andesite composition with a thickness variable between 122 to 208 m (400 to 680 ft) is present below the terrigenous sediments. Between the base of the sill and the top of the Bunejug Formation are intercalated volcanic and sedimentary rocks. All formations overlying the Bunejug Formation are probably of Pleistocene age. The basalt and basaltic-andesite flows and ash below the depth of approximately 1128 m (3700 ft) are hereinmore » assigned to the Bunejug Formation (Morrison, 1964) of Pliocene and possibly early Pleistocene age. The Bunejug Formation is a thick sequence of basalt to andesite flows and hyaloclastite exposed in the mountains surrounding the south half of the Carson Desert. The De Braga No. 2 well bottomed in Bunejug volcanics at a depth of 2109 m (6920 ft). The Richard Weishaupt No. 1 well penetrated the entire Bunejug sequence and entered felsic volcanics and tuffaceous sediments, which possibly represent part of the Truckee Formation, at a depth of approximately 2412 m (7915 ft).« less

Recycling of Pleistocene valley fills dominates 125 ka of sediment flux, upper Indus River

NASA Astrophysics Data System (ADS)

Munack, Henry; Blöthe, Jan Henrik; Fülöp, Réka-Hajnalka; Codilean, Alexandru T.; Fink, David; Korup, Oliver

2016-04-01

Rivers draining the semiarid Transhimalayan Ranges along the western Tibetan Plateau margin underwent alternating phases of massive valley infill and incision in Pleistocene times. The imprints of these cut-and-fill cycles on long-term sediment fluxes have remained largely elusive. We investigate the timing and geomorphic consequences of headward incision of the Zanskar River, which taps the vast More Plains valley fill that currently impedes drainage of the endorheic high-altitude basins of Tso Kar and Tso Moriri. In situ 10Be exposure dating and topographic analyses indicate that a phase of valley infill gave way to net dissection of the >250-m thick sedimentary stacks ˜125 ka ago, i.e. during the last interglacial (MIS 5e). Rivers eroded >14.7 km3 of sediment from the Zanskar headwaters since then, fashioning specific sediment yields that surpass 10Be-derived denudation rates from neighbouring catchments by factors of two to ten. We conclude that recycling of Pleistocene valley fills has provided Transhimalayan headwater rivers with more sediment than bedrock denudation, at least since the beginning of the last glacial cycle. This protracted liberation of sediment stored in thick valley fills could bias rate estimates of current sediment loads and long-term bedrock denudation.

Upper third molar internal structural organization and semicircular canal morphology in Plio-Pleistocene South African cercopithecoids.

PubMed

Beaudet, Amélie; Dumoncel, Jean; Thackeray, John Francis; Bruxelles, Laurent; Duployer, Benjamin; Tenailleau, Christophe; Bam, Lunga; Hoffman, Jakobus; de Beer, Frikkie; Braga, José

2016-06-01

Despite the abundance of cercopithecoids in the fossil record, especially in South Africa, and the recent development of morphometric approaches, uncertainties regarding the taxonomic identification of isolated cranio-dental specimens remain. Because cercopithecoids, nearly always found in stratigraphic association with hominin remains in Plio-Pleistocene deposits, are considered as sensitive ecological and chronological biomarkers, a significant effort should be made to clarify their palaeobiodiversity by assessing additional reliable morphological diagnostic criteria. Here we test the relevance of both molar crown internal structure and bony labyrinth morphology for discrimination of fossil cercopithecoid species. We use microtomographic-based 3D virtual imaging and quantitative analyses to investigate tooth endostructural organization and inner ear shape in 29 craniodental specimens from the South African sites of Kromdraai, Makapansgat, Sterkfontein and Swartkrans and provide the first detailed description of the internal structural condition characterizing this Plio-Pleistocene primate assemblage. Our preliminary results show that enamel-dentine junction morphology could be informative for discriminating highly autapomorphic taxa such as Theropithecus, while semicircular canal shape is tentatively proposed as an efficient criterion for diagnosing Dinopithecus ingens. Further research in virtual paleoprimatology may contribute to the identification of unassigned isolated fossil remains and shed new light on the internal craniodental morphology of extinct primate taxa. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Menengai Tuff: A 36 ka widespread tephra and its chronological relevance to Late Pleistocene human evolution in East Africa

NASA Astrophysics Data System (ADS)

Blegen, Nick; Brown, Francis H.; Jicha, Brian R.; Binetti, Katie M.; Faith, J. Tyler; Ferraro, Joseph V.; Gathogo, Patrick N.; Richardson, Jonathan L.; Tryon, Christian A.

2016-11-01

The East African Rift preserves the world's richest Middle and Late Pleistocene (∼780-12 ka) geological, archaeological and paleontological archives relevant to the emergence of Homo sapiens. This region also provides unparalleled chronological control for many important sites through tephrochronology, the dating and correlation of volcanic ashes as widespread isochronous markers in the geological record. There are many well-characterized Pliocene-Early Pleistocene tephras that are widespread across East Africa. A comparable framework is lacking for the Middle and Late Pleistocene; a period characterized by spatially and temporally complex patterns of climate change, as well as the emergence of modern Homo sapiens and the dispersal of this species across and out of Africa. Unraveling relationships among these spatial and temporally complex phenomena requires a precise chronology. To this end we report the Menengai Tuff, a widespread volcanic ash produced by the large-scale caldera-forming eruption in Kenya and 40Ar/39Ar dated to 35.62 ± 0.26 ka. Geochemical characterization of 565 glass shards from 36 samples by wavelength-dispersive electron probe microanalysis show the Menengai Tuff was deposited over >115,000 km2 and is found in the Baringo, Chalbi, Elmenteita, Nakuru, Olorgesailie, Turkana, and Victoria basins, all of which preserve rich Late Pleistocene paleoenvironmental and archaeological archives. Correlation and dating of the Menengai Tuff demonstrate that it is the most widespread tephra and largest eruption currently known from the Late Pleistocene of East Africa. As such, it is a valuable marker in establishing a Late Pleistocene chronology for paleoclimatic, archeological, and paleontological records relevant to the study of human evolution.

Shallow structure and stratigraphy of the carbonate West Florida continental slope and their implications to sedimentation and geohazards

USGS Publications Warehouse

Doyle, Larry J.

1983-01-01

An 1800-joule sparker survey of the West Florida continental slope between about 26?N and 29?15?N showed a top bed of Pleistocene age forming an irregular drape over a surface that is probably Pliocene. The contact between the top two layers is unconformable in the south and, in some places, shows karst collapse and solution features. Karst topography grades into a more hummocky erosional surface to the north, which in turn smoothes out; the contact become conformable still further north. A period of folding, which is widespread over the outer portion of the study area and which may be related to large scale mass wasting, occurred at about the same time represented by the unconformity. Significant subsidence has occurred as late as Pleistocene. The surface layer thins to a minimum (0 in the south) at about 525-meters water depth and then thickens again dramatically to the west, downslope. This thinning is interpreted to be due to the Loop Current, which flows from north to south in the area and which acts to block deposition and scour the bottom. Despite the fact that the margin is dominated by carbonates, usually associated with low sedimentation rates, there is widespread evidence of mass wasting affecting ancient and surficial deposits on the outer part of the upper slope. Three potential groups of geohazards identified are: 1. Potential bottom failure in areas where a thin top layer overlies the karst surface. 2. Potential for sliding and slumping. 3. Scour due to currents which could also affect drilling and engineering activities.

Late quaternary environmental changes in the upper Las Vegas valley, Nevada

NASA Astrophysics Data System (ADS)

Quade, Jay

1986-11-01

Five stratigraphic units and five soils of late Pleistocene to Holocene age crop out in dissected badlands on Corn Creek Flat, 30 km northwest of Las Vegas, Nevada, and at Tule Springs, nearer to Las Vegas. The record is dominantly fluvial but contains evidence of several moister, marsh-forming periods: the oldest (Unit B) dates perhaps to the middle Wisconsin, and the more widespread Unit D falls between 30,000 and 15,000 yr B.P. Unit D therefore correlates with pluvial maximum lacustrine deposits elsewhere in the Great Basin. Standing water was not of sufficient depth or extent during either period to form lake strandlines. Between 14,000 and 7200 yr B.P. (Unit E), standing surface water gradually decreased, a trend also apparent in Great Basin pluvial lake chronologies during the same period. Groundwater carbonate cementation and burrowing by cicadas (Cicadae) accompany the moist-phase units. After 7200 yr B.P., increased wind action, decreased biotic activity, and at least 25 m of water-table lowering accompanied widespread erosion of older fine-grained deposits. Based on pack-rat midden and pollen evidence, this coincides with major vegetation changes in the valley, from sagebrush-dominated steppe to lower Mohave desertscrub.

First Asian record of Panthera (Leo) fossilis (Mammalia, Carnivora, Felidae) in the Early Pleistocene of Western Siberia, Russia.

PubMed

Sotnikova, Marina V; Foronova, Irina V

2014-08-01

A lion-like pantherine felid is described as Panthera (Leo) fossilis from the late Early Pleistocene sediments of the Kuznetsk Basin (Western Siberia, Russia). The find of P. fossilis first recorded in Asia considerably extends the current notion of the eastward expansion of the most ancient lions. The Siberian lion is geologically the oldest form and is dimensionally among the largest members of the group of fossil lions on the Eurasian continent. Although known by mandibular remains only, it is readily distinguished from Panthera (Leo) spelaea by a heavy built mandibular corpus with rectangular profile in the cheek teeth area, a deep, well-outlined and narrow anterior section of the masseteric fossa, and a large p4 supported by a big unreduced anterior root. The Siberian lion shares these features with the European Middle Pleistocene P. fossilis and the American Late Pleistocene P. (Leo) atrox, which suggests their close relationship. P. atrox originated from P. fossilis and was isolated in North America south of the Late Pleistocene ice sheets. This explains why the American lion has retained more primitive features than the coeval Eurasian cave lion P. (L.) spelaea. © 2013 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Evolution of middle-late Pleistocene human cranio-facial form: a 3-D approach.

PubMed

Harvati, Katerina; Hublin, Jean-Jacques; Gunz, Philipp

2010-11-01

The classification and phylogenetic relationships of the middle Pleistocene human fossil record remains one of the most intractable problems in paleoanthropology. Several authors have noted broad resemblances between European and African fossils from this period, suggesting a single taxon ancestral to both modern humans and Neanderthals. Others point out 'incipient' Neanderthal features in the morphology of the European sample and have argued for their inclusion in the Neanderthal lineage exclusively, following a model of accretionary evolution of Neanderthals. We approach these questions using geometric morphometric methods which allow the intuitive visualization and quantification of features previously described qualitatively. We apply these techniques to evaluate proposed cranio-facial 'incipient' facial, vault, and basicranial traits in a middle-late Pleistocene European hominin sample when compared to a sample of the same time depth from Africa. Some of the features examined followed the predictions of the accretion model and relate the middle Pleistocene European material to the later Neanderthals. However, although our analysis showed a clear separation between Neanderthals and early/recent modern humans and morphological proximity between European specimens from OIS 7 to 3, it also shows that the European hominins from the first half of the middle Pleistocene still shared most of their cranio-facial architecture with their African contemporaries. Copyright © 2010 Elsevier Ltd. All rights reserved.

Pleistocene climate change and the origin of two desert plant species, Pugionium cornutum and Pugionium dolabratum (Brassicaceae), in northwest China.

PubMed

Wang, Qian; Abbott, Richard J; Yu, Qiu-Shi; Lin, Kao; Liu, Jian-Quan

2013-07-01

Pleistocene climate change has had an important effect in shaping intraspecific genetic variation in many species; however, its role in driving speciation is less clear. We examined the possibility of a Pleistocene origin of the only two representatives of the genus Pugionium (Brassicaceae), Pugionium cornutum and Pugionium dolabratum, which occupy different desert habitats in northwest China. We surveyed sequence variation for internal transcribed spacer (ITS), three chloroplast (cp) DNA fragments, and eight low-copy nuclear genes among individuals sampled from 11 populations of each species across their geographic ranges. One ITS mutation distinguished the two species, whereas mutations in cpDNA and the eight low-copy nuclear gene sequences were not species-specific. Although interspecific divergence varied greatly among nuclear gene sequences, in each case divergence was estimated to have occurred within the Pleistocene when deserts expanded in northwest China. Our findings point to the importance of Pleistocene climate change, in this case an increase in aridity, as a cause of speciation in Pugionium as a result of divergence in different habitats that formed in association with the expansion of deserts in China. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Detrital zircons from the Tananao metamorphic complex of Taiwan: Implications for sediment provenance and Mesozoic tectonics

NASA Astrophysics Data System (ADS)

Yui, T. F.; Maki, K.; Lan, C. Y.; Hirata, T.; Chu, H. T.; Kon, Y.; Yokoyama, T. D.; Jahn, B. M.; Ernst, W. G.

2012-05-01

Taiwan formed during the Plio-Pleistocene collision of Eurasia with the outboard Luzon arc. Its pre-Tertiary basement, the Tananao metamorphic complex, consists of the western Tailuko belt and the eastern Yuli belt. These circum-Pacific belts have been correlated with the high-temperature/low-pressure (HT/LP) Ryoke belt and the high-pressure/low-temperature (HP/LT) Sanbagawa belt of Japan, respectively. To test this correlation and to reveal the architecture and plate-tectonic history of the Tananao metamorphic basement, detrital zircons were separated from 7 metasedimentary rock samples for U-Pb dating by LA-ICPMS techniques. Results of the present study, coupled with previous data, show that (1) the Tailuko belt consists of a Late Jurassic to earliest Cretaceous accretionary complex sutured against a Permian-Early Jurassic marble ± metabasaltic terrane, invaded in the north by scattered Late Cretaceous granitic plutons; the latter as well as minor Upper Cretaceous cover strata probably formed in a circum-Pacific forearc; (2) the Yuli belt is a mid- to Late Cretaceous accretionary complex containing HP thrust sheets that were emplaced attending the Late Cenozoic Eurasian plate-Luzon arc collision; (3) these two Late Mesozoic belts are not coeval, and in part were overprinted by low-grade metamorphism during the Plio-Pleistocene collision; (4) accreted clastic sediments of the Tailuko belt contain mainly Phanerozoic detrital zircons, indicating that terrigenous sediments were mainly sourced from western Cathaysia, whereas in contrast, clastic rocks of the Yuli accretionary complex contain a significant amount of Paleoproterozoic and distinctive Neoproterozoic zircons, probably derived from the North China craton and the Yangtze block ± eastern Cathaysia, as a result of continent uplift/exhumation after the Permo-Triassic South China-North China collision; and (5) the Late Jurassic-Late Cretaceous formation of the Tananao basement complex precludes the possibility that the early Yanshanian (Early Jurassic) granitoids in southern China represent a landward arc contemporaneous with the later, outboard Tananao accretionary event.

Rhone River Valley & Lower Lake Geneva, Switzerland as seen from STS-60

NASA Image and Video Library

1994-02-09

STS060-90-007 (3-11 Feb 1994) --- Parts of the Swiss Cantons of Vaud and Valois and the French province of Chablais are shown. These mountains were created in the last great mountain-building episode in Europe around 50 million years ago. They have been reshaped by glaciers during the Pleistocene. The glaciers created the wide valley of the Rhone River by scouring a pre-existing stream. The fertile Swiss Plateau runs northwest from the shore of Lake Geneva and is visible in the upper right. The Franco-Swiss border is located in the center of the lake and follows a mountain divide east of the Rhone Valley. According to NASA geologists eutrofication is a problem in Lake Geneva. In 1971 a Swiss Commission was formed to try to slow the problem. Strong discharge laws were enacted, but they are hard to enforce due to the multi-national and multi-organizational parties contributing to the problem.

Anomalous topography on the continental shelf around Hudson Canyon

USGS Publications Warehouse

Knebel, H.J.

1979-01-01

Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

Cueva Antón: A multi-proxy MIS 3 to MIS 5a paleoenvironmental record for SE Iberia

NASA Astrophysics Data System (ADS)

Zilhão, João; Ajas, Aurélie; Badal, Ernestina; Burow, Christoph; Kehl, Martin; López-Sáez, José Antonio; Pimenta, Carlos; Preece, Richard C.; Sanchis, Alfred; Sanz, Montserrat; Weniger, Gerd-Christian; White, Dustin; Wood, Rachel; Angelucci, Diego E.; Villaverde, Valentín; Zapata, Josefina

2016-08-01

Overlying a palustrine deposit of unknown age (complex FP), and protected from weathering and erosion inside a large cave/rock-shelter cavity, the sedimentary fill of Cueva Antón, a Middle Paleolithic site in SE Spain, corresponds in most part (sub-complexes AS2-to-AS5) to a ca.3 m-thick Upper Pleistocene terrace of the River Mula. Coupled with the constraints derived from the deposit's paleoclimatic proxies, OSL dating places the accumulation of this terrace in MIS 5a, and radiocarbon dates from the overlying breccia cum alluvium (sub-complex AS1) fall in the middle part of MIS 3; the intervening hiatus relates to valley incision and attendant erosion. The two intervals represented remain largely unknown in Iberia, where the archeology of the early-to-middle Upper Pleistocene is almost entirely derived from karst sites; Cueva Antón shows that this dearth of data, often interpreted in demographic terms, has depositional underpinnings ultimately determined by past climate variation. In early MIS 5a, the paleobotanical evidence indicates climate conditions similar to present, albeit wetter, followed by progressive cooling, reflected in the replacement of Aleppo pine by black pine and, at the very end, juniper-dominated landscapes - the latter characterizing also mid-MIS 3 times. The variation in sedimentary facies and composition of the mollusk assemblages reflects the changing position of the river channel relative to the back wall of the cave. Such changes represented the major constraint for the occupation of the site - most of the time inaccessible to terrestrial mammals, it was used throughout by the eagle-owl, explaining the abundance of rabbit bones. Human occupation occurred during a few, short windows of availability, and is reflected in well-preserved living floors defined by hearths, artefact scatters, and the remains of hunted herbivores. The stone tool assemblages are Middle Paleolithic, which, in Europe, implies a Neandertal identity for their makers and, hence, that Neandertals persisted in the region until GI 8. Cueva Antón's high-resolution record provides unique, critical information on the paleoenvironments and adaptations of humans in two short windows of time during which wetter conditions existed in SE Iberia, where arid or semi-arid climates prevailed through most of the Upper Pleistocene and the Holocene.

Investigation of sea-level changes and shelf break prograding sequences during the Late Quaternary offshore of Kusadasi (West Anatolia) and surroundings by high resolution seismic methods

NASA Astrophysics Data System (ADS)

Gurcay, Savas; Cifci, Gunay; Dondurur, Derman; Okay, Seda; Atgin, Orhan; Ozel, Ozkan; Mert Kucuk, Hilmi

2016-04-01

High Resolution multi-channel seismic reflection and Chirp data were collected by K. Piri Reis, research vessel of Dokuz Eylül University, in the central Aegean coast of the West Anatolia by research cruises carried out in 2005 and 2008, respectively. Submarine stratigraphic and structural features of Sıǧacık Gulf, Kuşadası Gulf and surroundings were investigated under this survey. The data were processed and interpreted in SeisLab, D.E.U. Marine Sciences and Technology seismic laboratory. Thirteen distinct unconformities can be traced below the study area that separate thirteen progradational stacked paleo-delta sequences (Lob1-Lob13) on seismic profiles following and cutting each other. As a result of comparison with the oxygen isotopic stages (δ18), these deltas (Lob1-L13) were interpreted that they have been deposited during the sea-level lowstands within Pleistocene glacial stages. In the study area the basement surface which observed as the lowest unconformity surface of the seismic sections was called 'Acoustic Basement'. This basement which traced approximately all of the seismic sections has generally quite wavy surface and underlain the upper seismic units. It was observed that these seismic units which terminated their formation in Pleistocene (Lob1-Lob13) and Holocene period were cut and uplifted by acoustic basement, like an intrusion. These type deformations were interpreted as a result of magmatic intrusion into these upper seismic units occurred in Late Pleistocene and Holocene period. Tectonic and structural interpretation was carried out to constitute the submarine active tectonic map of the study area by correlated active faults identified on seismic sections. Submarine active tectonic map and, basement topography and sediment thickness map were correlated together to present the relationship between tectonic deformation and stratigraphy.

The Palos Verdes Fault offshore southern California: late Pleistocene to present tectonic geomorphology, seascape evolution and slip rate estimate based on AUV and ROV surveys

USGS Publications Warehouse

Brothers, Daniel S.; Conrad, James E.; Maier, Katherine L.; Paull, Charles K.; McGann, Mary L.; Caress, David W.

2015-01-01

The Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near-seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high-resolution multibeam bathymetric data, and chirp subbottom profiles were acquired with an autonomous underwater vehicle (AUV) along the main trace of PVF in water depths between 250 and 600 m. Radiocarbon dates were obtained from vibracores collected using a remotely operated vehicle (ROV) and ship-based gravity cores. The PVF is expressed as a well-defined seafloor lineation marked by subtle along-strike bends. Right-stepping transtensional bends exert first-order control on sediment flow dynamics and the spatial distribution of Holocene depocenters; deformed strata within a small pull-apart basin record punctuated growth faulting associated with at least three Holocene surface ruptures. An upper (shallower) landslide scarp, a buried sedimentary mound, and a deeper scarp have been right-laterally offset across the PVF by 55 ± 5, 52 ± 4 , and 39 ± 8 m, respectively. The ages of the upper scarp and buried mound are approximately 31 ka; the age of the deeper scarp is bracketed to 17–24 ka. These three piercing points bracket the late Pleistocene to present slip rate to 1.3–2.8 mm/yr and provide a best estimate of 1.6–1.9 mm/yr. The deformation observed along the PVF is characteristic of strike-slip faulting and accounts for 20–30% of the total right-lateral slip budget accommodated offshore Southern California.

Late pleistocene aggradation and degradation of the lower colorado river: Perspectives from the Cottonwood area and other reconnaissance below Boulder Canyon

USGS Publications Warehouse

Lundstrom, S.C.; Mahan, S.A.; Paces, J.B.; Hudson, M.R.; House, P.K.; Malmon, D.V.; Blair, J.L.; Howard, K.A.

2008-01-01

Where the lower Colorado River traverses the Basin and Range Province below the Grand Canyon, significant late Pleistocene aggradation and subsequent degrada tion of the river are indicated by luminescence, paleomagnetic, and U-series data and stratigraphy. Aggradational, finely bedded reddish mud, clay, and silt are underlain and overlain by cross-bedded to plane-bedded fine sand and silt. That sequence is commonly disconformably overlain by up to 15 m of coarse sand, rounded exotic gravel, and angular, locally derived gravel. Luminescence dates on the fine sediments range from ca. 40 ka to 70 ka, considering collective uncertainties. A section of fine grained sediments over a vertical range of 15 m shows normal polarity magnetization and little apparent secular variation beyond dispersion that can be explained by com paction. Aggradation on large local tributaries such as Las Vegas Wash appears to have been coeval with that of the Colorado River. The upper limits of erosional rem nants of the sequence define a steeper grade above the historical river, and these late Pleistocene deposits are greater than 100 m above the modern river north of 35??N. Ter race gravels inset below the upper limit of the aggradational sequence yield 230Th dates that range from ca. 32 ka to 60 ka and indicate that degradation of the river system in this area closely followed aggradation. The thick sequence of rhythmically bedded mud and silt possibly indicates set tings that were ponded laterally between valley slopes and levees of the aggrading river. Potential driving mechanisms for such aggradation and degradation include sediment-yield response to climate change, drought, fire, vegetation-ecosystem dynam ics, glaciation, paleofloods, groundwater discharge, and building and destruction of natural dams produced by volcanism and landslides. ?? 2008 The Geological Society of America.

Cranial base topology and basic trends in the facial evolution of Homo.

PubMed

Bastir, Markus; Rosas, Antonio

2016-02-01

Facial prognathism and projection are important characteristics in human evolution but their three-dimensional (3D) architectonic relationships to basicranial morphology are not clear. We used geometric morphometrics and measured 51 3D-landmarks in a comparative sample of modern humans (N = 78) and fossil Pleistocene hominins (N = 10) to investigate the spatial features of covariation between basicranial and facial elements. The study reveals complex morphological integration patterns in craniofacial evolution of Middle and Late Pleistocene hominins. A downwards-orientated cranial base correlates with alveolar maxillary prognathism, relatively larger faces, and relatively larger distances between the anterior cranial base and the frontal bone (projection). This upper facial projection correlates with increased overall relative size of the maxillary alveolar process. Vertical facial height is associated with tall nasal cavities and is accommodated by an elevated anterior cranial base, possibly because of relations between the cribriform and the nasal cavity in relation to body size and energetics. Variation in upper- and mid-facial projection can further be produced by basicranial topology in which the midline base and nasal cavity are shifted anteriorly relative to retracted lateral parts of the base and the face. The zygomatics and the middle cranial fossae act together as bilateral vertical systems that are either projected or retracted relative to the midline facial elements, causing either midfacial flatness or midfacial projection correspondingly. We propose that facial flatness and facial projection reflect classical principles of craniofacial growth counterparts, while facial orientation relative to the basicranium as well as facial proportions reflect the complex interplay of head-body integration in the light of encephalization and body size decrease in Middle to Late Pleistocene hominin evolution. Developmental and evolutionary patterns of integration may only partially overlap morphologically, and traditional concepts taken from research on two-dimensional (2D) lateral X-rays and sections have led to oversimplified and overly mechanistic models of basicranial evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Appendicular robusticity and the paleobiology of modern human emergence.

PubMed

Trinkaus, E

1997-11-25

The emergence of modern humans in the Late Pleistocene, whatever its phylogenetic history, was characterized by a series of behaviorally important shifts reflected in aspects of human hard tissue biology and the archeological record. To elucidate these shifts further, diaphyseal cross-sectional morphology was analyzed by using cross-sectional areas and second moments of area of the mid-distal humerus and midshaft femur. The humeral diaphysis indicates a gradual reduction in habitual load levels from Eurasian late archaic, to Early Upper Paleolithic early modern, to Middle Upper Paleolithic early modern hominids, with the Levantine Middle Paleolithic early modern humans being a gracile anomalous outlier. The femoral diaphysis, once variation in ecogeographically patterned body proportions is taken into account, indicates no changes across the pre-30,000 years B.P. samples in habitual locomotor load levels, followed by a modest decrease through the Middle Upper Paleolithic.

Large Erosional Features on the Cascadia Accretionary Wedge Imaged with New High-Resolution Multibeam Bathymetry and Seismic Datasets

NASA Astrophysics Data System (ADS)

Beeson, J. W.; Goldfinger, C.

2013-12-01

Utilizing new high resolution multibeam bathymetric data along with chirp sub-bottom and multichannel seismic reflection (MCS) data, we identified remarkable erosional features on the toe of the Cascadia accretionary wedge near Willapa Canyon, offshore Washington, USA. Bathymetric data was compiled from the Cascadia Open-Access Seismic Transects (COAST) cruise and from the site survey cruise for the Cascadia Initiative. These features loosely resemble slope failures of the frontal thrust, but can be distinguished from such failures by several key features: They incise the crest of the frontal thrust and encompass the landward limb; They have floors below the level of the abyssal plain, similar to plunge pool morphology; They show no evidence of landslide blocks at the base of the slope indicative of block sliding. The features where likely formed during the latest Pleistocene based on post event deposition, cross-cutting relationships with Juan de Fuca Channel and the Willapa Channel levees and wave field, and post event slip on the frontal thrust of the Cascadia accretionary prism. The Holocene levees of both Willapa Channel and Juan de Fuca Channel overlap these older features, and clearly place an upper bound on the age of the erosional features in the latest Pleistocene. A lower bound is estimated from a sub-bottom profile that images ~30 meters of post scour sediment fill. Using existing literature of Holocene and Pleistocene sedimentation rates we estimate a lower age bound between ~23,000 - 56,000 y.b.p. We also map a fault scarp within the erosional feature, with ~60 m of vertical offset. Using multi-channel seismic reflection profiles from the COAST cruise we interpret this scarp as the surface expression of the landward vergent frontal thrust fault. The apparent short duration of the erosional event along the seaward margin of the accretionary wedge, coupled with the presence of the fresh fault scarp within the erosion zone, are indicative of a dormant feature with significant time required to develop the scarp after cessation of the causative process. Based on morphology, dissimilarity with other submarine features, and available age constraints, we infer that these features were most likely formed during the glacial lake outpouring in the Pacific Northwest known as the Missoula floods which occurred 13,000-19,500 y.b.p. The features themselves bear a strong resemblance to 'coulees' formed during the same glacial events onshore, and the outpourings through Willapa Channel are consistent with previous inferences of the deposition of Missoula Flood deposits in Escanaba Trough. If this timing is correct, the slip rate along the Cascadia frontal thrust can be estimated using fault geometry and scarp height as 2.8 - 4.1 mm/yr.

Meteoric calcite cementation: diagenetic response to relative fall in sea-level and effect on porosity and permeability, Las Negras area, southeastern Spain

NASA Astrophysics Data System (ADS)

Li, Zhaoqi; Goldstein, Robert H.; Franseen, Evan K.

2017-03-01

A dolomitized Upper Miocene carbonate system in southeast Spain contains extensive upper and lower zones of calcite cementation that cut across the stratigraphy. Cement textures including isopachous and circumgranular, which are consistent with phreatic-zone cementation. Cements in the upper cemented zone are non-luminescent, whereas those in the lower cemented zone exhibit multiple bands of luminescent and non-luminescent cements. In the upper cemented zone, isotopic data show two meteoric calcite lines (MCL) with mean δ18O at - 5.1‰ and - 5.8‰ VPDB, whereas no clear MCL is defined in the lower cemented zone where mean δ18O for calcite cement is at - 6.7‰ VPDB. δ13C values in both cement zones are predominantly negative, ranging from - 10 to + 2‰ VPDB, suggestive of carbon from soil gas or decayed organics. Measurements of Tm ice in primary fluid inclusions yield a mode of 0.0 °C in both zones, indicating calcite cementation from fresh water. These two zones define the positions of two different paleo-water tables that formed during a relative sea-level fall and erosional downcutting during the Plio-Pleistocene. The upper cemented zone pre-dated the lower cemented zone on the basis of known relative sea-level history. Meteoric calcite cementation reduced porosity and permeability, but measured values are inconsistent with simple filling of open pore space. Each texture, boundstone, grainstone, packstone, wackestone, produces a different relationship between percent calcite cement and porosity/permeability. Distribution of cements may be predictable on the basis of known sea-level history, and the effect of the cementation can be incorporated into subsurface geomodels by defining surfaces of rock boundaries that separate cemented zones from uncemented zones, and applying texture-specific relationships among cementation, porosity and permeability.

Hydrogeology and predevelopment flow in the Texas Gulf Coast aquifer systems

USGS Publications Warehouse

Ryder, Paul D.

1988-01-01

Total simulated recharge in the outcrop areas is 269 million cubic feet per day, which is offset by an equal amount of discharge in the outcrop areas. The smallest rates of leakage are across the Vicksburg-Jackson confining unit, with downward and upward rates of less than one million cubic feet per day. The greatest rate of leakage is 47 million cubic feet per day upward into the Holocene-upper Pleistocene permeable zone.

Metric and geometric morphometric analysis of new hominin fossils from Maba (Guangdong, China).

PubMed

Xiao, Dongfang; Bae, Christopher J; Shen, Guanjun; Delson, Eric; Jin, Jennie J H; Webb, Nicole M; Qiu, Licheng

2014-09-01

We present an analysis of a set of previously unreported hominin fossils from Maba (Guangdong, China), a cave site that is best known for the presence of a partial hominin cranium currently assigned as mid-Pleistocene Homo and that has been traditionally dated to around the Middle-Late Pleistocene transition. A more recent set of Uranium series dates indicate that the Maba travertine may date to >237 ka (thousands of years ago), as opposed to the original U-series date, which placed Maba at 135-129 ka. The fossils under study include five upper first and second molars and a partial left mandible with a socketed m3, all recovered from different parts of the site than the cranium or the dated sediments. The results of our metric and 2D geometric morphometric ('GM') study suggest that the upper first molars are likely from modern humans, suggesting a more recent origin. The upper second molars align more closely with modern humans, though the minimum spanning tree from the 2D GM analysis also connects Maba to Homo neanderthalensis. The patterning in the M2s is not as clear as with the M1s. The m3 and partial mandible are morphometrically intermediate between Holocene modern humans and older Homo sapiens. However, a minimum spanning tree indicates that both the partial mandible and m3 align most closely with Holocene modern humans, and they also may be substantially younger than the cranium. Because questions exist regarding the context and the relationship of the dated travertine with the hominin fossils, we suggest caution is warranted in interpreting the Maba specimens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Geologic columns for the ICDP-USGS Eyreville A and C cores, Chesapeake Bay impact structure: Postimpact sediments, 444 to 0 m depth

USGS Publications Warehouse

Edwards, L.E.; Powars, D.S.; Browning, J.V.; McLaughlin, P.P.; Miller, K.G.; ,; Kulpecz, A.A.; Elbra, T.

2009-01-01

A 443.9-m-thick, virtually undisturbed section of postimpact deposits in the Chesapeake Bay impact structure was recovered in the Eyreville A and C cores, Northampton County, Virginia, within the "moat" of the structure's central crater. Recovered sediments are mainly fine-grained marine siliciclastics, with the exception of Pleistocene sand, clay, and gravel. The lowest postimpact unit is the upper Eocene Chickahominy Formation (443.9-350.1 m). At 93.8 m, this is the maximum thickness yet recovered for deposits that represent the return to "normal marine" sedimentation. The Drummonds Corner beds (informal) and the Old Church Formation are thin Oligocene units present between 350.1 and 344.7 m. Above the Oligocene, there is a more typical Virginia coastal plain succession. The Calvert Formation (344.7-225.4 m) includes a thin lower Miocene part overlain by a much thicker middle Miocene part. From 225.4 to 206.0 m, sediments of the middle Miocene Choptank Formation, rarely reported in the Virginia coastal plain, are present. The thick upper Miocene St. Marys and Eastover Formations (206.0-57.8 m) appear to represent a more complete succession than in the type localities. Correlation with the nearby Kiptopeke core indicates that two Pliocene units are present: Yorktown (57.8-32.2 m) and Chowan River Formations (32.2-18.3 m). Sediments at the top of the section represent an upper Pleistocene channel-fill and are assigned to the Butlers Bluff and Occohannock Members of the Nassawadox Formation (18.3-0.6 m). ?? 2009 The Geological Society of America.

Rapid subsidence along the Kerama Gap on the Ryukyu Arc, northwestern Pacific

NASA Astrophysics Data System (ADS)

Arai, K.; Inoue, T.; Sato, T.

2017-12-01

The Ryukyu Arc, which extend for over 1200 km along the east coast of Asia from Kyushu to Taiwan, and the associated Ryukyu Trench, are products of the subduction of the Philippine Sea Plate beneath the Eurasian Plate. The Okinawa Trough, a back-arc basin located landward of the Ryukyu Arc, formed in the Late Miocene (Gungor et al., 2012) or the Late Pliocene-Early Pleistocene (Sibuet et al., 1998); its formation is a key geologic event associated with complex tectonic movements and changes in the topographic configuration of the Ryukyu Arc. Geological Survey of Japan (GSJ), AIST has started the marine geological mapping project around the Ryukyu Arc since the 2008 FY. Multi channel (16 ch) high-resolution seismic profiles were acquired during these cruises by the GI-gun (355cu. inch) or the Cluster-gun (30+30 cu. inch) systems. Our survey area around the Okinawa Island is characterized by the shelf, upper forearc slope and slope to the back-arc basin. Seismic reflections of shelf and the upper forearc slope show a distinct reflector which may represent erosional unconformable surface. The distinct reflector had mainly tilted southeastward and was overlain by the stratified sediments. No obvious deformation such as the fold and faults parallel to the Ryukyu Trench axis was found under the upper forearc slope. In contrast, some active faults which were perpendicular to the Ryukyu Trench axis (NW-SE direction) were observed. The most conspicuous normal faults system under the Kerama Gap located on southwest off the Okinawa Island is formed. We will present the seismic profiles around the Kerama Gap. Seismic profiles show a distinct, irregularly undulated reflector as an acoustic basement around the Kerama Gap. The acoustic basement is overlain by the clear stratified sediments. Many normal faults developed NW-SE direction cut the stratified sediments and are deformed the subsurface along the Kerama Gap. Subsidence of the Kerama Gap resulted from large vertical downthrows of NW-SE trending normal faults.

Late Pleistocene Environments of the Central Ukraine

NASA Astrophysics Data System (ADS)

Rousseau, Denis-Didier; Gerasimenko, Natalia; Matviischina, Zhanna; Kukla, George

2001-11-01

The Vyazivok loess sequence from the Dnieper Plain, Ukraine, documents regional environmental changes during the late Pleistocene and Holocene. Pedological and palynological analyses and low-field magnetic susceptibility document changes from dense temperate forest during the last interglacial maximum to open, harsh, loess-steppe during the latest Pleistocene. The Vyazivok section overlies hillwash derived from a lower Pleistocene terrace and consists of two stratified soil complexes (Kaydaky and Pryluky; marine isotope stage [MIS] 5 equivalent) separated by a layer of eolian dust (Tyasmyn silt). The lower soils in both complexes formed within forest. These soils are overlain by the Uday (MIS4) and Bug (MIS2) loess units, which are separated by boreal soils of the Vytachiv (MIS3) complex. The coldest conditions within the record occurred in the youngest loess. Holocene soils cap the Bug loess. The Vyazivok section shows remarkable similarities with other classical loess sequences in western Europe, the Czech Republic, and Austria. The Kaydaky, Pryluky, and Vytachiv deposits, correlate with the PKIII, PKII, and PKI soil complexes, respectively, of the Czech Republic. The Tyasmyn and Prylyky silt layers correspond to marker horizons from central Europe.

Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance - a case study from the Bełchatów lignite mine

NASA Astrophysics Data System (ADS)

Goździk, Jan; Zieliński, Tomasz

2017-06-01

Deposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.

Palynology of latest Neogene (Middle Miocene to late Pliocene) strata in the Delmarva Peninsula of Maryland and Virginia

USGS Publications Warehouse

Sirkin, L.; Owens, J.P.

1998-01-01

Palynology of Miocene and Pliocene formations in the Delmarva Peninsula of Maryland and Virginia reveals a significant representation of exotic pollen interspersed in pollen assemblages that are otherwise comparable to those from the modern vegetation of the Mid-Alantic coastal plain region. The late Tertiary arboreal pollen (AP) assemblages are dominated by oak, hickory, pine, birch and alder with minor amounts of mid- and southern coastal tree taxa, as well as minor spruce and hemlock and a trace of fir. Nonarboreal pollen (NAP) include grass, sedge, composite and aquatic taxa. Exotic pollen in these assemblages represent plants now foreign to this region. They may be placed in three categories. First, there are extinct forms, such as Labrapollis, Plicatopollis, and Multiporopollenites, that can be traced from the Cretaceous or Early Tertiary into the Late Tertiary. The second group includes forms, such as Podocarpus, Engelhardtia, Pterocarya, Ephedra, Eucommia, Ulmus-Zelkova, Glyptostrobus, Palmae, and Cyathea, that are not found in this region today and not found in early Pleistocene sediments in the eastern United States. Many of these taxa are subtropical or greatly restricted in geographic range. A third group of exotics, mainly Cyrilla, Planera, Gordonia, Jussiaea, and Sapotacaea, including Minusops, are generally found south of the study area or have their northern limit here at this time. The lack of the extinct or distant exotics in early to mid-Pleistocene sediments in the mid-Atlantic coastal plain and the last appearance of Pterocarya, as the last exotic taxon in the early Pleistocene of western Europe, support the stratigraphic assignment of the Pliocene units. The number of exotic taxa diminish markedly between the Miocene pollen assemblages and those of the Late Pliocene. Climatic fluctuations characterize the Late Tertiary environments. The Miocene, for example, incorporates a warming trend between the upper, middle Miocene and the Manokin beds and the late Miocene of the Pokomoke beds. The late Miocene was probably somewhat warner than the present climate in the Delmarva region. This trend is based on the presence of colder climate indicators, mainly spruce and hemlock, in the Manokin pollen record. The two distinct pollen assemblages constitute two pollen zones. Similarly, the Pliocene pollen record also shows a warming trend. The pollen zone of the Yorktown Formation of the early Pliocene age contains the colder climate indicators spruce and hemlock. The Beaverdam and Walston formation of late Pliocene age contain pollen assemblages that reflect climatic conditions warmer than the present time.

Internal nasal floor configuration in Homo with special reference to the evolution of Neandertal facial form.

PubMed

Franciscus, Robert G

2003-06-01

The presence of a steeply sloping or depressed nasal floor within the nasal cavity of Neandertals is frequently mentioned as a likely specialization or autapomorphy. The depressed nasal floor has also been seen as contributing to a relatively more capacious nasal cavity in Neandertals, which is tied to cold-climate respiratory adaptation and energetics. These observations have been limited largely to a relatively few intact crania, and the character states associated with this trait have not been as precisely codified or analyzed as those published for Plio-Pleistocene hominins (McCollum et al., 1993, J. Hum. Evol. 24, 87; McCollum, 2000, Am. J. Phys. Anthrop. 112, 275). This study examines the internal nasal floor topography in complete crania and isolated maxillae in European, west Asian, and African fossil Homo (n=158) including 25 Neandertals, and a wide range of recent humans from Europe, the Near East, and Africa (n=522). The configuration of the internal nasal floor relative to the nasal cavity entrance is codified as: 1) level, forming a smooth continuous plane; 2) sloped or mildly stepped; or 3) bilevel with a pronounced vertical depression. The frequency of these nasal floor configurations, and their relationship to both nasal margin cresting patterning and a comprehensive set of nasofacial metrics is examined. Neandertals show a high frequency of the bilevel (depressed) configuration in both adults and subadults (80%), but this configuration is also present in lower frequencies in Middle Pleistocene African, Late Pleistocene non-Neandertal (Skhul, Qafzeh), and European Later Upper Paleolithic samples (15%-50%). The bilevel configuration is also present in lower frequencies (ca. 10%) in all recent human samples, but attains nearly 20% in some sub-Saharan African samples. Across extinct and extant Homo (excluding Neandertals), internal nasal floor configuration is not associated with piriform aperture nasal margin patterning, but the two are strongly linked in Neandertals. Variation in internal nasal floor configuration in recent humans is primarily associated with internal nasal fossa breadth and nasal bridge elevation, whereas in fossil hominins, it is associated primarily with variation in facial height. Cold-climate and activity-related thermal adaptation as an explanation for the high frequency of pronounced nasal floor depression in Neandertals is inconsistent with all available data. Alternatively, variation in internal nasal floor configuration is more likely related to stochastically derived populational differences in fetal nasofacial growth patterns that do not sharply differentiate genus Homo taxa (i.e., cladistically), but do phenetically differentiate groups, in particular the Neandertals, especially when considered in combination with other nasofacial features.

Morphometric analysis of molars in a Middle Pleistocene population shows a mosaic of 'modern' and Neanderthal features.

PubMed

Martinón-Torres, María; Spěváčková, Petra; Gracia-Téllez, Ana; Martínez, Ignacio; Bruner, Emiliano; Arsuaga, Juan Luis; Bermúdez de Castro, José María

2013-10-01

Previous studies of upper first molar (M1) crown shape have shown significant differences between Homo sapiens and Homo neanderthalensis that were already present in the European Middle Pleistocene populations, including the large dental sample from Atapuerca-Sima de los Huesos (SH). Analysis of other M1 features such as the total crown base area, cusp proportions, cusp angles and occlusal polygon have confirmed the differences between both lineages, becoming a useful tool for the taxonomic assignment of isolated teeth from Late Pleistocene sites. However, until now the pattern of expression of these variables has not been known for the SH sample. This fossil sample, the largest collection from the European Middle Pleistocene, is generally interpreted as being from the direct ancestors of Neanderthals, and thus is a reference sample for assessing the origin of the Neanderthal morphologies. Surprisingly, our study reveals that SH M(1) s present a unique mosaic of H. neanderthalensis and H. sapiens features. Regarding the cusp angles and the relative occlusal polygon area, SH matches the H. neanderthalensis pattern. However, regarding the total crown base area and relative cusps size, SH M(1) s are similar to H. sapiens, with a small crown area, a strong hypocone reduction and a protocone enlargement, although the protocone expansion in SH is significantly larger than in any other group studied. The SH dental sample calls into question the uniqueness of some so-called modern traits. Our study also sounds a note of caution on the use of M(1) occlusal morphology for the alpha taxonomy of isolated M(1) s. © 2013 Anatomical Society.

The massive fossil humerus from the Oldowan horizon of Gombore I, Melka Kunture (Ethiopia, >1.39 Ma)

NASA Astrophysics Data System (ADS)

Di Vincenzo, Fabio; Rodriguez, Laura; Carretero, José Miguel; Collina, Carmine; Geraads, Denis; Piperno, Marcello; Manzi, Giorgio

2015-08-01

A well-preserved distal portion of a left humerus was discovered in 1976 during excavations directed by J. Chavaillon at the Gombore I site, in the Melka Kunture area (Ethiopia). The specimen, labelled Gombore IB-7594 (formally Melka Kunture 3, or MK3), was found in situ within unit 2 of level B, which is dated to >1.39 Ma and includes a rich Oldowan Paleolithic assemblage. Although MK3 has never been described in detail, it appeared in the literature several times and, from a taxonomic point of view, has been alternatively regarded as Homo, Australopithecus or Paranthropus. According to our analysis, MK3 exhibits a suite of features that fit the variability of the genus Homo and does not display any clear Australopithecus/Paranthropus affinity. Nevertheless, MK3 adds a great deal of variability to the genus Homo, at least as far as the Early Pleistocene fossil record is concerned. In particular, our quantitative approach, which combines traditional morphometric analyses and geometric morphometrics, highlights traits that are uncommon among the Plio-Pleistocene fossil record, while affinities with Mid-to-Late Pleistocene representatives of Homo are observed. In addition, the large size of MK3 suggests that this humerus belonged to an individual whose body weight approached 90 kg, far from the range of body size known for Homo representatives in the Early Pleistocene and as big as those of extant humans or even gorillas. We suggest that such peculiar features are of interest when regarded from an ecological perspective; thus, dimension and morphology of MK3 may be considered as an exaptation that became useful when early humans dispersed to high altitudes such as those of the upper Awash basin on the Ethiopian plateau, at heights above 2000 m.

Early Pleistocene hominin deciduous teeth from the Homo antecessor Gran Dolina-TD6 bearing level (Sierra de Atapuerca, Spain).

PubMed

Bermúdez de Castro, José María; Martinón-Torres, María; Martín-Francés, Laura; Martínez de Pinillos, Marina; Modesto-Mata, Mario; García-Campos, Cecilia; Wu, Xiujie; Xing, Song; Liu, Wu

2017-07-01

During the last 13 years, the late Early Pleistocene Gran Dolina-TD6-2 level (Sierra de Atapuerca, northern Spain) has yielded an additional sample of 26 dental specimens attributed to Homo antecessor. In this report, we present a descriptive and comparative study of the six deciduous teeth. We provide external and internal morphological descriptions following classical terminology, as well as the mesiodistal and buccolingual measurements of the teeth. The internal morphology was described by means of micro-CT technique. The TD6 deciduous teeth preserve primitive features regarding the Homo clade, such as the presence of styles in lower and upper canines and developed anterior and posterior foveae in the dm 2 . However, other features related to the complexity of the crown morphology (e.g., cingulum) are not present in this sample. Furthermore, the great reduction of the talonid of the dm 1 s is also noteworthy. Despite the limited comparative evidence, the presence of a remarkably well-developed tuberculum molare in the dm 1 and dm 1 s from TD6 can be also considered a derived feature in the genus Homo. The TD6 hominins exhibit dental dimensions similar to those of other Pleistocene hominins. The dm 1 s are buccolingually elongated and the buccolingual diameter of ATD6-93 is the largest recorded so far in the Homo fossil record. This study expands the list of plesiomorphic features of H. antecessor, and provides some information on the evolutionary status of this species. However, the identification of some advanced traits evinces a step towards the derived morphology of European Pleistocene teeth. The study of the deciduous dentition confirms the mosaic pattern of H. antecessor morphology revealed in previous studies of this hominin sample. © 2017 Wiley Periodicals, Inc.

Late Pleistocene oscillations of the Drau Glacier (southern Austria)

NASA Astrophysics Data System (ADS)

Karnitschar, Christina; Reitner, Jürgen; Draganits, Erich

2016-04-01

The Drau Glacier was the largest Pleistocene glacier in the southeastern part of the Alps and significantly shaped the landscape in this region. The study area is located at the termination of the Drau Glacier in the southern part of Austria (Carinthia). The investigation aims to decipher glacial dynamics during the Late Pleistocene glacial advance, stabilisation and final recession of this glacier based on geological/geomorphological mapping, interpretation of airborne laser scan (ALS) topographic data and lithostratigraphic investigations of glacial and periglacial sediments. Special emphasis is laid on the reconstruction of the maximum extent of the glaciation (LGM). Based on previous mapping by Bobek (1959) and Ucik (1996-1998) more details have been gained for the paleogeographic reconstruction based on glacial and non-glacial erosion and accumulation features. These include traces of pre-Upper Pleistocene glaciation, drumlins, terminal moraines and kettle holes. Paleogeographic reconstruction was done with correlation of different outcrops based on lithostratigraphy and ALS topography. Sequences of gravel related to glacial advance covered by till, followed by periglacial sediments allowed detailed reconstruction of the glacial sequence in this area and the complex succession of various extents of the Drau Glacier. References Bobek, Hans. 1959: Der Eisrückgang im östlichen Klagenfurter Becken. In: Mitteilungen der österreichischen geographischen Gesellschaft, Wien. Ucik, Friedrich Hans. 1996: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 141, S. 340, Wien. Ucik, Friedrich Hans. 1997: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 141, S. 325-326, Wien. Ucik, Friedrich Hans. 1998: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 142, S. 333-334, Wien.

Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests

PubMed Central

Kondraskov, Paulina; Schütz, Nicole; Schüßler, Christina; de Sequeira, Miguel Menezes; Guerra, Arnoldo Santos; Caujapé-Castells, Juli; Jaén-Molina, Ruth; Marrero-Rodríguez, Águedo; Koch, Marcus A.; Linder, Peter; Kovar-Eder, Johanna; Thiv, Mike

2015-01-01

The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data. PMID:26173113

Morphometric analysis of molars in a Middle Pleistocene population shows a mosaic of ‘modern’ and Neanderthal features

PubMed Central

Martinón-Torres, María; Spěváčková, Petra; Gracia-Téllez, Ana; Martínez, Ignacio; Bruner, Emiliano; Arsuaga, Juan Luis; Bermúdez de Castro, José María

2013-01-01

Previous studies of upper first molar (M1) crown shape have shown significant differences between Homo sapiens and Homo neanderthalensis that were already present in the European Middle Pleistocene populations, including the large dental sample from Atapuerca-Sima de los Huesos (SH). Analysis of other M1 features such as the total crown base area, cusp proportions, cusp angles and occlusal polygon have confirmed the differences between both lineages, becoming a useful tool for the taxonomic assignment of isolated teeth from Late Pleistocene sites. However, until now the pattern of expression of these variables has not been known for the SH sample. This fossil sample, the largest collection from the European Middle Pleistocene, is generally interpreted as being from the direct ancestors of Neanderthals, and thus is a reference sample for assessing the origin of the Neanderthal morphologies. Surprisingly, our study reveals that SH M1s present a unique mosaic of H. neanderthalensis and H. sapiens features. Regarding the cusp angles and the relative occlusal polygon area, SH matches the H. neanderthalensis pattern. However, regarding the total crown base area and relative cusps size, SH M1s are similar to H. sapiens, with a small crown area, a strong hypocone reduction and a protocone enlargement, although the protocone expansion in SH is significantly larger than in any other group studied. The SH dental sample calls into question the uniqueness of some so-called modern traits. Our study also sounds a note of caution on the use of M1 occlusal morphology for the alpha taxonomy of isolated M1s. PMID:23914934

Late Pliocene-Early Pleistocene oscillations in Mediterranean Overflow water: a new perspective from the Iberian Margin

NASA Astrophysics Data System (ADS)

Alonso-Garcia, M.; Salgueiro, E.; Rodrigues, T.; Alvarez Zarikian, C. A.; Kuhnert, H.; Roehl, U.; Voelker, A. H. L.; Sierro, F. J.; Abrantes, F. F. G.

2016-12-01

During the Late Pliocene to the Early Pleistocene the Earth experienced a transition from the warm Pliocene climate, with high greenhouse gases concentrations, to a colder climate with significant expansion of ice-sheets in the Northern Hemisphere and alternation between glacial and interglacial periods. Several hypotheses have been put forward to explain this climate transition, and recently, the enhancement of the Mediterranean Overflow Water (MOW) was suggested to have played a major role since it contributes high salinity water to the North Atlantic. Sedimentary records from the last glacial cycle and modelling experiments evidenced this link and suggested that the MOW injection of salty water to intermediate depths may have enhanced the upper branch of NADW, which ultimately reinvigorated the whole Atlantic Meridional overturning circulation. Here we present sedimentological and paleontological data from Site U1391 (37° N; 9° W; 1085 m water depth), recovered on the Southwest Iberian Margin during the Integrated Ocean Drilling Program (IODP) Expedition 339. This site is located in a plastered drift in the path of the MOW and offers high sedimentation rates to perform high resolution studies of past climatic and oceanographic conditions. In this study, we combined XRF geochemical data (from X-ray fluorescence core scanning) with grain-size, benthic foraminifer δ18O and δ13C, and ostracod records to reconstruct deep water circulation and climatic conditions during the Plio-Pleistocene transition. The high-resolution record of the XRF analysis indicates a switch in the response of MOW to climate changes across this transition. Early Pleistocene glacial-interglacial cycles show a stronger coupling between MOW oscillations (as indicated by the Zr/Al ratio) and sea surface temperature conditions (as indicated by the Ca/Ti ratio).

Pleistocene vertical motions of the Costa Rican outer forearc from subducting topography and a migrating fracture zone triple junction

USGS Publications Warehouse

Edwards, Joel H.; Kluesner, Jared W.; Silver, Eli A.; Bangs, Nathan L.

2018-01-01

Understanding the links between subducting slabs and upper-plate deformation is a longstanding goal in the field of tectonics. New 3D seismic sequence stratigraphy, mapped within the Costa Rica Seismogenesis Project (CRISP) seismic-reflection volume offshore southern Costa Rica, spatiotemporally constrains several Pleistocene outer forearc processes and provides clearer connections to subducting plate dynamics. Three significant shelf and/or slope erosional events at ca. 2.5–2.3 Ma, 1.95–1.78 Ma, and 1.78–1.19 Ma, each with notable differences in spatial extent, volume removed, and subsequent margin response, caused abrupt shifts in sedimentation patterns and rates. These shifts, coupled with observed deformation, suggest three primary mechanisms for Pleistocene shelf and slope vertical motions: (1) regional subaerial erosion and rapid subsidence linked to the southeastward Panama Fracture Zone triple-junction migration, with associated abrupt bathymetric variations and plate kinematic changes; (2) transient, kilometer-scale uplift and subsidence due to inferred subducting plate topography; and (3) progressive outer wedge shortening accommodated by landward- and seaward-dipping thrust faults and fold development due to the impinging Cocos Ridge. Furthermore, we find that the present-day wedge geometry (to within ∼3 km along strike) has been maintained through the Pleistocene, in contrast to modeled landward margin retreat. We also observe that deformation, i.e., extension and shortening, is decoupled from net margin subsidence. Our findings do not require basal erosion, and they suggest that the vertical motions of the Costa Rican outer forearc are not the result of a particular continuous process, but rather are a summation of plate to plate changes (e.g., passage of a fracture zone triple junction) and episodic events (e.g., subducting plate topography).

Pleistocene environments and glacial history of the northern North Sea

NASA Astrophysics Data System (ADS)

Reinardy, Benedict; Hjelstuen, Berit; Petter Sejrup, Hans; Augedal, Hans; Jørstad, Arild

2017-04-01

Based on new geochronological and lithological data combined with analyses of 3D seismic data, the Pliocene-Pleistocene development of the central northern North Sea has been investigated. At the start of the Plio-Pleistocene Transition the study area was dominated by a deltaic, shallow marine or tidal depositional environment with sediments mainly sourced from the west with a local provenance. Directly above the base Quaternary a 60 m thick layer of mud-rich sediments of glacimarine origin were deposited at a rate of 12 cm/ka between 2-1.5 Ma and up to 80 cm/ka between 1.5 - 1.2 Ma possibly reflecting glacial ice advancing to the Norwegian coastline. The high rate of deposition in the Early Pleistocene occurred immediately before the initiation of the Norwegian Channel Ice Stream at 1.1 Ma. Following this, a large part of the sediment input from Fennoscandia seems to have been directed away from the study area to the shelf break. At the start of the Mid Pleistocene Transition (MPT), subaerial conditions allowed the formation of a >50 km long fluvial channel across the study area draining water from the east to the south west. The earliest evidence of grounded ice in the investigated area comes from mega scale glacial lineations formed during the MPT, at or just after 1.2 Ma. Following this, a regional unconformity was formed by one or more grounded ice advances across the study area possibly during or directly after the MPT and likely marks the boundary between the Early and Mid Pleistocene glacimarine sediments. The Mid to Late Pleistocene stratigraphy is dominated by glacimarine sediments and tills and is associated with multiple generations of tunnel valleys observed within the seismic data. A high shear strength till containing chalk clasts transported from the west and/or south of the study area was likely deposited during MIS6 and may have been more conducive to tunnel valley formation in comparison to lower shear strength tills deposited by later ice advances. A thick till unit overlain by a sand layer in the study area was deposited by grounded ice during the Last Glacial Maximum and subsequent drainage of an ice dammed lake in the southern North Sea during the last deglaciation (MIS2) of the study area. This study shows that much of the Quaternary age sediments within the northern North Sea were deposited relatively rapidly during short periods of time probably leaving significant hiatuses within the stratigraphic record. This finding has implications for previous studies that use a chronological framework assuming a relatively continuous sedimentation rate and record for the Early Pleistocene within the North Sea.

Middle Pleistocene vertebrate fossils from the Nefud Desert, Saudi Arabia: Implications for biogeography and palaeoecology

NASA Astrophysics Data System (ADS)

Stimpson, Christopher M.; Lister, Adrian; Parton, Ash; Clark-Balzan, Laine; Breeze, Paul S.; Drake, Nick A.; Groucutt, Huw S.; Jennings, Richard; Scerri, Eleanor M. L.; White, Tom S.; Zahir, Muhammad; Duval, Mathieu; Grün, Rainer; Al-Omari, Abdulaziz; Al Murayyi, Khalid Sultan M.; Zalmout, Iyaed S.; Mufarreh, Yahya A.; Memesh, Abdullah M.; Petraglia, Michael D.

2016-07-01

The current paucity of Pleistocene vertebrate records from the Arabian Peninsula - a landmass of over 3 million km2 - is a significant gap in our knowledge of the Quaternary. Such data are critical lines of contextual evidence for considering animal and hominin dispersals between Africa and Eurasia generally, and hominin palaeoecology in the Pleistocene landscapes of the Arabian interior specifically. Here, we describe an important contribution to the record and report stratigraphically-constrained fossils of mammals, birds and reptiles from recent excavations at Ti's al Ghadah in the southwestern Nefud Desert. Combined U-series and ESR analyses of Oryx sp. teeth indicate that the assemblage is Middle Pleistocene in age and dates to ca. 500 ka. The identified fauna is a biogeographical admixture that consists of likely endemics and taxa of African and Eurasian affinity and includes extinct and extant (or related Pleistocene forms of) mammals (Palaeoloxodon cf. recki, Panthera cf. gombaszogenis, Equus hemionus, cf. Crocuta crocuta, Vulpes sp., Canis anthus, Oryx sp.), the first Pleistocene records of birds from the Arabian Peninsula (Struthio sp., Neophron percnopterus, Milvus cf. migrans, Tachybaptus sp. Anas sp., Pterocles orientalis, Motacilla cf. alba) and reptiles (Varanidae/Uromastyx sp.). We infer that the assemblage reflects mortality in populations of herbivorous animals and their predators and scavengers that were attracted to freshwater and plant resources in the inter-dune basin. At present, there is no evidence to suggest hominin agency in the accumulation of the bone assemblages. The inferred ecological characteristics of the taxa recovered indicate the presence, at least periodically, of substantial water-bodies and open grassland habitats.

Paleomagnetic Determination of Vertical-Axis Block Rotation and Magnetostratigraphy in the Coachella Valley, California

NASA Astrophysics Data System (ADS)

Dimitroff, C.; Housen, B. A.; McNabb, J. C.; Dorsey, R. J.; Burmester, R. F.; Messe, G. T.

2015-12-01

Here, we report new paleomagnetism and magnetostratigraphy data from the Palm Spring Fm of the Mecca Hills, the Pleistocene conglomeratic sandstone in Desert Hot Springs and the Plio-Pleistocene San Timoteo beds from Live Oak Canyon. From the Mecca Hills, new data are from 29 sites and 112 samples. The paleomagnetic results yielded well-defined components of magnetization- defining seven polarity zones within the Ocotillo and upper Palm Spring Fm. Correlation to the geomagnetic polarity timescale, using the Bishop Ash near the top of the section as a tie point, places the Brunhes-Matuyama boundary near the base of the Ocotillo Fm, and the Jaramillo, Olduvai, and Reunion normal polarity sub-chrons in the upper Palm Spring Fm. This indicates the upper Palm Spring Fm in the Mecca Hills was deposited between 2.3 and 0.9 Ma. Sites from the Mecca Hills section have mean directions of D = 343, I = 53, α95 =11.3 N = 5 for normal sites, D = 175, I = -50, α95 = 4.9 N = 24 for reverse sites, and normal and reverse sites combined have a mean direction of D = 353, I = 51 α95 = 4.4. This indicates modest (7 degrees) CCW rotation of the section. Results from 19 sites (53 samples) of the Pleistocene conglomeritic sandstone from Desert Hot Springs have very well-defined paleomagnetic components. Six of the sites have normal polarity- 13 sites have reverse polarity. Sites with normal polarity have a mean direction of D = 358, I = 45, α95 = 13 and reverse sites have a mean of D = 182, I = -50, α95 = 6.6.The combined mean direction (in tilt-corrected coordinates) is D = 0.7, I = 49, α95 = 5.6 and indicates that 3.1° ± 2.3° of CW rotation has occurred at this location since ~1 to 1.5 Ma. Results from 8 sites (35 samples) of the upper-most San Timoteo beds from Live Oak Canyon also have well-defined paleomagnetic components for 6 sites. All of the results have normal polarity, and one site has a direction that is >40 degree from the other sites- the mean of the remaining 5 sites is D = 11, I = 49, k=51, a95=11. The paleomagnetic results from the Coachella Valley collectively indicate that this area has experienced modest (in most cases less than 10 degrees) CW or CCW rotation during the past 1-2 Ma. The lack of variation in amount or sense of rotation as a function of age suggest that rotation has been relatively recent (during the past ~ 1 Ma).

Mass wasting deposits in the upper Sehonghong valley, eastern Lesotho: Late Pleistocene climate implications

NASA Astrophysics Data System (ADS)

Mills, S. C.; Grab, S. W.

2009-04-01

Despite considerable research attention on apparent periglacial, glacial and sedimentary phenomena in the Maluti-Drakensberg alpine environment, knowledge on the Quaternary environmental history of this important watershed and climate-divide is still rather rudimentary. The dearth of Quaternary environmental indicators (proxy data) in the high Drakensberg is partly owing to the harsh climate (e.g. high wind speeds and high seasonal precipitation), which offers a poor preservation of past biological remains (e.g. bones, dung, middens, pollen). Possibly the best opportunity to reconstruct high Drakensberg palaeoenvironments is from sedimentary sequences exposed along fluvially-incised valley fills. The upper Sehonghong River (3000 to 3200 m a.s.l.) flows in a westerly direction and is flanked by north- and south-facing slopes reaching 3465 m a.s.l. Sediment is exposed on both the north- and south-facing slopes along the river. Despite uniform regional environmental conditions (geology, topography, climate, vegetation), there is a notable absence of similar north-facing deposits in adjacent upper valley catchments to the north and south of Sehonghong Valley. The upper Sehonghong Valley thus presents somewhat ‘unique' evidence for palaeo-slope mass movement in this alpine region. Thick colluvial deposits are most prominent on the south-facing slopes along the Sehonghong River and occur at altitudes between 3100 m a.s.l. and 3150 m a.s.l. The colluvial mantles are approximately 7 m in thickness, however reach up to 13 m in some areas. Although the north-facing lower valley side-slopes are generally absent of deposits, the notable exception is the thick stratified deposit located a few kilometres upstream. Whilst the south-facing deposits are relatively uniform in nature, the north-facing deposits consist of alternating units of gravel and organic sediment, dated to 36 600 ± 1400 14C yrs BP, and reflecting environmental changes during the Late Pleistocene. Mass wasting deposits support enhanced periglacial activity during the Late Pleistocene, particularly on south-facing slopes, and also where conditions were conducive to enhanced sediment transport on the adjacent north-facing slope of the Sehonghong River. Recent published work has suggested evidence for marginal glaciation in the high Drakensberg within 10 km of the Sehonghong Valley, suggesting that whilst particular environmental settings host deposits classified as glacial moraine, adjacent valleys are occupied by deep (~8 m) valley deposits flanking south-facing slopes. We demonstrate that the variable nature of adjacent valley slope deposits at similar altitudes is a product of a past climate that was within the glacial/periglacial equilibrium zone, and influenced by specific topographic and associated micro-climatic thresholds.

Diversification in the northern neotropics: mitochondrial and nuclear DNA phylogeography of the iguana Ctenosaura pectinata and related species.

PubMed

Zarza, Eugenia; Reynoso, Victor H; Emerson, Brent C

2008-07-01

While Quaternary climatic changes are considered by some to have been a major factor promoting speciation within the neotropics, others suggest that much of the neotropical species diversity originated before the Pleistocene. Using mitochondrial and nuclear sequence data, we evaluate the relative importance of Pleistocene and pre-Pleistocene events within the evolutionary history of the Mexican iguana Ctenosaura pectinata, and related species. Results support the existence of cryptic lineages with strong mitochondrial divergence (> 4%) among them. Some of these lineages form zones of secondary contact, with one of them hybridizing with C. hemilopha. Evolutionary network analyses reveal the oldest populations of C. pectinata to be those of the northern and southern Mexican coastal regions. Inland and mid-latitudinal coastal populations are younger in age as a consequence of a history of local extinction within these regions followed by re-colonization. Estimated divergence times suggest that C. pectinata originated during the Pliocene, whereas geographically distinct mitochondrial DNA lineages first started to diverge during the Pliocene, with subsequent divergence continuing through the Pleistocene. Our results highlight the influence of both Pliocene and Pleistocene events in shaping the geographical distribution of genetic variation within neotropical lowland organisms. Areas of high genetic diversity in southern Mexico were detected, this finding plus the high levels of genetic diversity within C. pectinata, have implications for the conservation of this threatened species.

Holocene Deglaciation, Sea-Level Change, and the Emergence of the Windmill Islands, Budd Coast, Antarctica

NASA Astrophysics Data System (ADS)

Goodwin, Ian D.

1993-07-01

A Holocene deglaciation sequence for the Windmill Islands was determined from the 14C age of raised marine shorelines, lakebottom sediments, and Adelie penguin remains found in abandoned rookeries. A north-south gradient in the elevation of the upper marine limit was observed, with the highest marine limit (31-32 m) observed on Browning Peninsula and Hull Island at the southern edge of the islands. Correspondingly, the southern islands were found to have been deglaciated by 8000 (corr.) yr B.P. while the northern islands were deglaciated by 5500 (corr.) yr B.P. Isostatic uplift rates were calculated as 0.5 to 0.6 m/100 yr, with an estimated total uplift of around 53 m which indicates late Pleistocene ice sheet thicknesses of 200 and 400 m over the islands and adjacent Petersen Bank, respectively. The margin of the Late Pleistocene grounded ice sheet extended an estimated 8-15 km offshore which coincides with the location of the 200 m isobath.

Dancing to the rhythms of the Pleistocene? Early Middle Paleolithic population dynamics in NW Iberia (Duero Basin and Cantabrian Region)

NASA Astrophysics Data System (ADS)

Sánchez Yustos, Policarpo; Diez Martín, Fernando

2015-08-01

The Northwest of Iberia has yielded one of the most complete European Middle Paleolithic records. Despite this wealth of information, very little is known about population dynamics during this period. For that reason, the main concern of this paper is to provide socio-environmental models that may help explain Early Middle Paleolithic (EMP) population dynamics in NW Iberia, assessing to what extent they were shaped by climate forces. The archaeological record is analyzed on the basis of the heuristics of ecological models, already employed in the European Pleistocene record but never at a regional scale, in order to detect long-term changes in the composition of EMP populations, and the environmental, biological and sociocultural process influencing those changes. According to the models proposed, we have detected a long-term population dynamic between MIS 11 and MIS 6, characterized by low environmental stress, high biological productivity, interaction among populations and sociocultural complexity. Eventually, this population dynamic was broken due to an extreme climate phase in late MIS 6 that had a profound impact on populations and sociocultural structures. As a result, the Upper Pleistocene population of NW Iberia was concentrated in the Cantabrian region. This area became an isolated Neanderthal glacial refugium that hosted a population with different origins and fragile long-term demographic stability.

Late Cenozoic History of the Genus Micromys (Mammalia, Rodentia) in Central Europe

PubMed Central

Horáček, Ivan; Knitlová, Markéta; Wagner, Jan; Kordos, László; Nadachowski, Adam

2013-01-01

Molecular phylogeography suggests that Micromys minutus, the sole extant species of the genus, colonized its extensive range quite recently, during the Late Pleistocene-Holocene period. Rich Pliocene and Pleistocene fossil records both from Europe and China suggest rather continuous and gradual in situ phenotype rearrangements from the Pliocene to the Recent periods. To elucidate the discrepancy we reexamined a considerable part of the European fossil record of the genus (14 sites from MN15 to Q3, 0.4–4.2 Ma, including the type series of M. preaminutus from MN15 Csarnóta 2), analyzed them with the aid of detailed morphometric comparisons, and concluded that: (a) The European Pliocene form, M. praeminutus, differs significantly from the extant species; (b) it exhibits a broad phenotypic variation covering the presumptive diagnostic characters of MN16 M. caesaris; (c) despite having smaller dimensions, the Early and Middle Pleistocene forms (MN17-Q3, 2.6–0.4 Ma) seem to be closer to M. praeminutus than to the extant species; (d) the extinction of M. praeminutus during Q3 and the re-occupation of its niche by the recent expansion of M. minutus from E-European – C Asiatic sources (suggested by phylogeographic hypotheses) cannot be excluded. Discussing interpretations of the phylogenetic past of the genus we emphasize the distinct history of the West Palearctic clade (Late Miocene-Early Pleistocene) terminating with M. praeminutus and the East Asiatic clade (chalceus, tedfordi, minutus), and the possible identity of the Western clade with the Late Miocene genus Parapodemus. PMID:23671605

A mongoose remain (Mammalia: Carnivora) from the Upper Irrawaddy sediments, Myanmar and its significance in evolutionary history of Asian herpestids

NASA Astrophysics Data System (ADS)

Egi, Naoko; Thaung-Htike; Zin-Maung-Maung-Thein; Maung-Maung; Nishioka, Yuichiro; Tsubamoto, Takehisa; Ogino, Shintaro; Takai, Masanaru

2011-11-01

A tooth of a mongoose (Mammalia: Carnivora: Herpestidae) was discovered from the Upper Irrawaddy sediments in central Myanmar. The age of the fauna is not older than the mid-Pliocene. It is identified as a right first upper molar of a small species of Urva (formally included in the genus Herpestes) based on its size and shape. The present specimen is the first carnivoran from the Upper Irrawaddy sediments and is the first record of mongooses in the Pliocene and early Pleistocene of Asia. It confirms that mongooses had already dispersed into Southeast Asia by the late Pliocene, being consistent with the previous molecular phylogenetic analyses. The fossil may belong to one of the extant species, but an assignment to a specific species is difficult due to the fragmentary nature of the specimen and the small interspecific differences in dental shape among the Asian mongooses. The size of the tooth suggests that the Irrawaddy specimen is within or close to the clade of Urva auropunctata + javanica + edwardsii, and this taxonomic assignment agrees with the geographical distribution.

Influences of geomorphology and geology on alpine treeline in the American West - More important than climatic influences?

USGS Publications Warehouse

Butler, D.R.; Malanson, G.P.; Walsh, S.J.; Fagre, D.B.

2007-01-01

The spatial distribution and pattern of alpine treeline in the American West reflect the overarching influences of geological history, lithology and structure, and geomorphic processes and landforms, and geologic and geomorphic factors—both forms and processes—can control the spatiotemporal response of the ecotone to climate change. These influences occur at spatial scales ranging from the continental scale to fine scale processes and landforms at the slope scale. Past geomorphic influences, particularly Pleistocene glaciation, have also left their impact on treeline, and treelines across the west are still adjusting to post-Pleistocene conditions within Pleistocene-created landforms. Current fine scale processes include solifluction and changes on relict solifluction and digging by animals. These processes should be examined in detail in future studies to facilitate a better understanding of where individual tree seedlings become established as a primary response of the ecotone to climate change.

The oldest gibbon fossil (Hylobatidae) from insular Southeast Asia: evidence from Trinil, (East Java, Indonesia), Lower/Middle Pleistocene.

PubMed

Ingicco, Thomas; de Vos, John; Huffman, O Frank

2014-01-01

A fossil femur excavated by Eugène Dubois between 1891-1900 in the Lower/Middle Pleistocene bonebed of the Trinil site (Java, Indonesia) was recognised by us as that of a Hylobatidae. The specimen, Trinil 5703 of the Dubois Collection (Leiden, The Netherlands), has the same distinctive form of fossilization that is seen in many of the bonebed fossils from Trinil in the collection. Anatomical comparison of Trinil 5703 to a sample of carnivore and primate femora, supported by morphometric analyses, lead to the attribution of the fossil to gibbon. Trinil 5703 therefore provides the oldest insular record of this clade, one of the oldest known Hylobatidae fossils from Southeast Asia. Because living Hylobatidae only inhabit evergreen rain forests, the paleoenvironment within the river drainage in the greater Trinil area evidently included forests of this kind during the Lower/Middle Pleistocene as revealed here.

The Oldest Gibbon Fossil (Hylobatidae) from Insular Southeast Asia: Evidence from Trinil, (East Java, Indonesia), Lower/Middle Pleistocene

PubMed Central

Ingicco, Thomas; de Vos, John; Huffman, O. Frank

2014-01-01

A fossil femur excavated by Eugène Dubois between 1891–1900 in the Lower/Middle Pleistocene bonebed of the Trinil site (Java, Indonesia) was recognised by us as that of a Hylobatidae. The specimen, Trinil 5703 of the Dubois Collection (Leiden, The Netherlands), has the same distinctive form of fossilization that is seen in many of the bonebed fossils from Trinil in the collection. Anatomical comparison of Trinil 5703 to a sample of carnivore and primate femora, supported by morphometric analyses, lead to the attribution of the fossil to gibbon. Trinil 5703 therefore provides the oldest insular record of this clade, one of the oldest known Hylobatidae fossils from Southeast Asia. Because living Hylobatidae only inhabit evergreen rain forests, the paleoenvironment within the river drainage in the greater Trinil area evidently included forests of this kind during the Lower/Middle Pleistocene as revealed here. PMID:24914951

Hominin teeth from the Middle Pleistocene site of Yiyuan, Eastern China.

PubMed

Xing, Song; Sun, Chengkai; Martinón-Torres, María; Bermúdez de Castro, José María; Han, Fei; Zhang, Yingqi; Liu, Wu

2016-06-01

In 1981-1982, some hominin fossils, including a relatively complete skull and seven isolated teeth, were recovered from the Middle Pleistocene site of Yiyuan in Eastern China. In the present study we provide a detailed metric and morphological comparison of the Yiyuan dental sample in order to characterize better the variability of the human populations that inhabited China during the Middle Pleistocene. Aside from taxonomic and phylogenetic questions, the lack of understanding and/or knowledge about the morphological variability of these populations have caused concern about the human versus non-human nature of some of the hominin dental remains found in East Asia during the Early and the Middle Pleistocene. Thus, our study aims to present a detailed description and comparison of the Yiyuan isolated teeth to 1) discuss and support their human nature and 2) to explore their taxonomic affinities with regard to other penecontemporaneous populations from Asia. Our results clearly differentiate the Yiyuan sample from Pongo specimens and support a human attribution for the Yiyuan material. Our analyses also suggest that the Yiyuan teeth form a morphologically coherent group together with samples from Zhoukoudian, Chaoxian and Hexian. They are different from the more derived specimens from Panxian Dadong, suggesting a pattern of biogeographic isolation and different evolutionary trends between northern and southern China during the Middle Pleistocene. In addition, and despite sharing a common morphological bauplan with Homo erectus sensu stricto (s.s.), the Yiyuan, Zhoukoudian and Hexian teeth are also different from the Indonesian Early Pleistocene samples. In particular, the expression of a highly crenulated or dendritic enamel-dentine surface could be unique to these groups. Our study supports the notion that the taxonomy of the Pleistocene hominins from Asia may have been oversimplified. Future studies should explore the variability of the Asian specimens and reconsider whether all the samples can be attributed to H. erectus s.s. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structural analysis of Nalagarh lobe, NW Himalaya: implication of thrusting across tectonic edge of NW limb of Nahan salient, Himachal Pradesh, India

NASA Astrophysics Data System (ADS)

Bhakuni, S. S.; Philip, G.; Suresh, N.

2017-07-01

The Main Boundary Fault (MBF), convex towards southwest, forms the leading edge of the Nahan salient. Near the southern end of an oblique ramp, a lobe-shaped physiographic front, named in this work as Nalagarh lobe, has developed across NW limb of salient. The lobe has formed across the MBF that separates the hanging wall Lower Tertiary Dharmsala rocks from the footwall Upper Tertiary Siwalik rocks and overlying Quaternaries. In front of lobe, thrust fault splays (Splay-1 and Splay-2) and associated tectonic fabrics have developed within the Late Pleistocene fan deposit. Structural elements developed across the front of Nalagarh lobe are analysed with reference to evolution of lobe. An unweathered 15-m-high hanging wall or wedge top forms the uplifted and rejuvenated bedrock fault scarp of the MBF. Below the MBF, the fan deposit has underthrust along Splay-1. Later the Splay-2 formed within fan deposit near south of Splay-1. Geometry of the overturned limb of tight to isoclinal fault propagation fold, formed on Splay-2 plane, suggests that the fold formed by normal drag, produced by intermittent fault-slips along Splay-2. The displacement along Splay-2 offset the marker bed to 1 m by which some clasts rotated parallel to the traces of brittle axial planes of fold. The variable fold geometry and style of deformation are analysed along length of thrust splays for 5 km. It is revealed that the lobe is bounded by transverse thrust faults along its NW and SE margins. The geometry of salient and oblique ramp suggests that the transverse thrust faults and associated transverse folds formed by right-lateral displacement along the NW limb of the salient. Marking the northern margin of the intermontane piggyback basin of Pinjaur dun, the MBF is interpreted to be an out-of-sequence thrust that has brought up the Lower Tertiary Dharmsala rocks over the Late Pleistocene fan deposit. The geometry of lobe and its bounding transverse faults suggest that faults are intimately associated with the kinematics of the transition between the Nahan salient and Kangra recess. The transition is a transfer zone forming a long pre-Himalayan lineament across which the stratigraphic set of the Tethys and Lesser Himalaya is different. The study suggests that the lateral ramp on the Main Himalayan Thrust does not exist beneath the apex and also beneath the SE limb of the salient in the Sub-Himalayan region. This ramp should be present only beneath near end point of SW limb of the Nahan salient.

Collision-induced tectonism along the northwestern margin of the Indian subcontinent as recorded in the Upper Paleocene to Middle Eocene strata of central Pakistan (Kirthar and Sulaiman Ranges)

USGS Publications Warehouse

Warwick, Peter D.; Johnson, Edward A.; Khan, Intizar H.

1998-01-01

Outcrop data from the Upper Paleocene to Middle Eocene Ghazij Formation of central Pakistan provide information about the depositional environments, source areas, and paleogeographic and tectonic settings along the northwestern margin of the Indian subcontinent during the closing of the Tethys Ocean. In this region, in the lower part of the exposed stratigraphic sequence, are various marine carbonate-shelf deposits (Jurassic to Upper Paleocene). Overlying these strata is the Ghazij, which consists of marine mudstone (lower part), paralic sandstone and mudstone (middle part), and terrestrial mudstone and conglomerate (upper part). Petrographic examination of sandstone samples from the middle and upper parts reveals that rock fragments of the underlying carbonate-shelf deposits are dominant; also present are volcanic rock fragments and chromite grains. Paleocurrent measurements from the middle and upper parts suggest that source areas were located northwest of the study area. We postulate that the source areas were uplifted by the collision of the subcontinent with a landmass during the final stages of the closing of the Tethys Ocean. Middle Eocene carbonate-shelf deposits that overlie the Ghazij record a return to marine conditions prior to the Miocene to Pleistocene sediment influx denoting the main collision with Eurasia.

Initial report for magnetostratigraphy of IODP Site U1490

NASA Astrophysics Data System (ADS)

Kumagai, Y.; Hatfield, R. G.; Nakamura, N.; Yamazaki, T.

2017-12-01

We report preliminary paleomagnetic results from between 175-296 meters composite depth (Miocene in age) of IODP Site U1490 recovered during Expedition 363. Site U1490 is located at 05°48.95´N, 142°39.27´E (the northern edge of the Eauripik Rise in the equatorial Pacific) in 2341 m water depth. A primary objective of Expedition 363 was to reconstruct the regional climate variability within the Western Pacific Warm Pool (WPWP) in a broad spatial coverage and different temporal resolutions through the time interval from the middle Miocene to late Pleistocene. The recovered pelagic sediments contains calcareous and siliceous nannofossils with varying proportions of clay and ash. It is also characterized by current-controlled mud waves with gradually decreasing amplitude upsection (Rosenthal et al., 2017). Since deep water is enriched in dissolved oxygen due to downwelling in polar regions, the mud waves were probably formed in an oxic environment by bottom currents, hindering the dissolution of magnetic minerals in the sediments. Shipboard analysis revealed that magnetic minerals between 20-175 m composite depth at Site U1490 have been dissolved by diagenetic alteration and the paleomagnetic data is uninterpretable. But the upper 20 m and below 175 m have a stable magnetization that spans from present to early Pleistocene (0-1.9 Ma) and middle to late Miocene period ( 9-19 Ma), respectively. The latter is an exceptionally long-time range continuous core sample, so it provides us an opportunity to reveal long-range variations of paleomagnetic field. We will show stepwise alternate-field (AF) demagnetization of the natural remanent magnetization on U-channel samples from the composite stratigraphic section to establish magnetostratigraphy at this site.

10Be dating of late Pleistocene megafloods and Cordilleran Ice Sheet retreat in the northwestern United States

USGS Publications Warehouse

Balbas, Andrea M.; Barth, Aaron M.; Clark, Peter U.; Clark, Jorie; Caffee, Marc A.; O'Connor, Jim E.; Baker, Victor R.; Konrad, Kevin; Bjornstad, Bruce

2017-01-01

During the late Pleistocene, multiple floods from drainage of glacial Lake Missoula further eroded a vast anastomosing network of bedrock channels, coulees, and cataracts, forming the Channeled Scabland of eastern Washington State (United States). However, the timing and exact pathways of these Missoula floods remain poorly constrained, thereby limiting our understanding of the evolution of this spectacular landscape. Here we report cosmogenic 10Be ages that directly date flood and glacial features important to understanding the flood history, the evolution of the Channeled Scabland, and relationships to the Cordilleran Ice Sheet (CIS). One of the largest floods occurred at 18.2 ± 1.5 ka, flowing down the northwestern Columbia River valley prior to blockage of this route by advance of the Okanogan lobe of the CIS, which dammed glacial Lake Columbia and diverted later Missoula floods to more eastern routes through the Channeled Scabland. The Okanogan and Purcell Trench lobes of the CIS began to retreat from their maximum extent at ca. 15.5 ka, likely in response to onset of surface warming of the northeastern Pacific Ocean. Upper Grand Coulee fully opened as a flood route after 15.6 ± 1.3 ka, becoming the primary path for later Missoula floods until the last ones from glacial Lake Missoula at 14.7 ± 1.2 ka. The youngest dated flood(s) (14.0 ± 1.4 ka to 14.4 ± 1.3 ka) came down the northwestern Columbia River valley and were likely from glacial Lake Columbia, indicating that the lake persisted for a few centuries after the last Missoula flood.

Cova del Rinoceront (Castelldefels, Barcelona): a terrestrial record for the Last Interglacial period (MIS 5) in the Mediterranean coast of the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Daura, J.; Sanz, M.; Julià, R.; García-Fernández, D.; Fornós, J. J.; Vaquero, M.; Allué, E.; López-García, J. M.; Blain, H. A.; Ortiz, J. E.; Torres, T.; Albert, R. M.; Rodríguez-Cintas, À.; Sánchez-Marco, A.; Cerdeño, E.; Skinner, A. R.; Asmeron, Y.; Polyak, V. J.; Garcés, M.; Arnold, L. J.; Demuro, M.; Pike, A. W. G.; Euba, I.; Rodríguez, R. F.; Yagüe, A. S.; Villaescusa, L.; Gómez, S.; Rubio, A.; Pedro, M.; Fullola, J. M.; Zilhão, J.

2015-04-01

The Cova del Rinoceront, a site in NE Iberia, contains a thick sedimentary fill preserving a faunal archive from the penultimate glacial and the the last interglacial periods. Layers I to III have been dated to between 74 and 147 ka, coinciding with MIS 5a to 5e, a period poorly represented in the Mediterranean terrestrial record. The results from Cova del Rinoceront are of broader interest for the reconstruction of ecological dynamics during warm stages and the understanding of the evolution and geographical variation of several taxa. The palaeoecological evidence suggests a landscape dominated by mixed wooded vegetation with mild climatic conditions, slightly more humid than today. Several vertebrate taxa, including Haploidoceros mediterraneus, Stephanorhinus hundsheimensis and Glis glis, are documented for the first time in the early Upper Pleistocene of Europe, showing that these species persisted across the region for longer than previously thought. In addition, the recovery of a small lithic assemblage indicates human presence in the surroundings of the site. The 11 m-thick stratigraphic section also provides an ideal setting in which to compare several geochronological methods. U-Th dating of the flowstones that cap the deposit, of speleothems formed along the cave walls, and of speleothems buried by the deposit at different elevations provides minimum and maximum ages of 74 and 175 ka, respectively, for the accumulation. The ages obtained by luminescence, electron spin resonance (ESR), amino acid racemisation (AAR), palaeomagnetism and U-series dating of bone are in good agreement with each other and are stratigraphically consistent. This well-dated faunal succession presents a unique opportunity to assess changes in the Pleistocene fauna of the Mediterranean coast over an interval of more than 100 ka.

Miocene to recent history of the western Altiplano in northern Chile revealed by lacustrine sediments of the Lauca basin (18°15' 18°40' S/69°30' 69°05'W)

NASA Astrophysics Data System (ADS)

Kött, A.; Gaupp, R.; Wörner, G.

1995-12-01

The intramontane Lauca Basin at the western margin of the northern Chilean Altiplano lies to the west of and is topographically isolated from the well-known Plio-Pleistocene lake system of fluvio-lacustrine origin that covers the Bolivian Altiplano from Lake Titicaca to the north for more than 800 km to the Salar de Uyuni in the south. The Lauca Basin is filled by a sequence of some 120 m of mainly upper Miocene to Pliocene elastic and volcaniclastic sediments of lacustrine and alluvial origin. Volcanic rocks, partly pyroelastic, provide useful marker horizons. In the first period (6 4 Ma) of its evolution, the ‘Lago Lauca’ was a shallow ephemeral lake. Evaporites indicate temporarily closed conditions. After 4 Ma the lake changed to a perennial water body surrounded by alluvial plains. In the late Pleistocene and Holocene (2-0 Ma) there was only marginal deposition of alluvial and glacial sediments. The basin formed as a half-graben or by pull-apart between 10 and 15 Ma (tectonic displacement of the basal ignimbrite sequence during the ‘Quechua Phase’) and 6.2 Ma (maximum K/Ar ages of biotites of tuff horizons in the deepest part of the basin). Apart from this early basin formation, there has been surprisingly little displacement during the past 6 Ma close to the Western Cordillera of the Altiplano. Also, climate indicators (pollen, evaporites, sedimentary facies) suggest that an arid climate has existed for the past 6 Ma on the Altiplano. Together, these pieces of evidence indicate the absence of large scale block-faulting, tilt and major uplift during the past 5 6 Ma in this area.

Miocene to Recent history of the western Altiplano in northern Chile revealed by lacustrine sediments of the Lauca Basin (18°15'-18°40'S/69°30'-69°05'W)

NASA Astrophysics Data System (ADS)

Kött, A.; Gaupp, R.; Wörner, G.

The intramontane Lauca Basin at the western margin of the northern Chilean Altiplano lies to the west of and is topographically isolated from the well-known Plio-Pleistocene lake system of fluvio-lacustrine origin that covers the Bolivian Altiplano from Lake Titicaca to the north for more than 800km to the Salar de Uyuni in the south. The Lauca Basin is filled by a sequence of some 120m of mainly upper Miocene to Pliocene clastic and volcaniclastic sediments of lacustrine and alluvial origin. Volcanic rocks, partly pyroclastic, provide useful marker horizons. In the first period (6-4Ma) of its evolution, the 'Lago Lauca' was a shallow ephemeral lake. Evaporites indicate temporarily closed conditions. After 4Ma the lake changed to a perennial water body surrounded by alluvial plains. In the late Pleistocene and Holocene (2-0Ma) there was only marginal deposition of alluvial and glacial sediments. The basin formed as a half-graben or by pull-apart between 10 and 15Ma (tectonic displacement of the basal ignimbrite sequence during the 'Quechua Phase') and 6.2Ma (maximum K/Ar ages of biotites of tuff horizons in the deepest part of the basin). Apart from this early basin formation, there has been surprisingly little displacement during the past 6Ma close to the Western Cordillera of the Altiplano. Also, climate indicators (pollen, evaporites, sedimentary facies) suggest that an arid climate has existed for the past 6Ma on the Altiplano. Together, these pieces of evidence indicate the absence of large scale block-faulting, tilt and major uplift during the past 5-6Ma in this area.

Enhanced East Pacific Rise hydrothermal activity during the last two glacial terminations

NASA Astrophysics Data System (ADS)

Lund, D. C.; Asimow, P. D.; Farley, K. A.; Rooney, T. O.; Seeley, E.; Jackson, E. W.; Durham, Z. M.

2016-01-01

Mid-ocean ridge magmatism is driven by seafloor spreading and decompression melting of the upper mantle. Melt production is apparently modulated by glacial-interglacial changes in sea level, raising the possibility that magmatic flux acts as a negative feedback on ice-sheet size. The timing of melt variability is poorly constrained, however, precluding a clear link between ridge magmatism and Pleistocene climate transitions. Here we present well-dated sedimentary records from the East Pacific Rise that show evidence of enhanced hydrothermal activity during the last two glacial terminations. We suggest that glacial maxima and lowering of sea level caused anomalous melting in the upper mantle and that the subsequent magmatic anomalies promoted deglaciation through the release of mantle heat and carbon at mid-ocean ridges.

Detrital thermochronology of Rhine, Elbe and Meuse river sediment (Central Europe): implications for provenance, erosion and mineral fertility

NASA Astrophysics Data System (ADS)

Glotzbach, C.; Busschers, F. S.; Winsemann, J.

2018-03-01

Here we present detrital apatite fission track (AFT), zircon fission track (ZFT) and a few apatite (U-Th)/He (AHe) data of Middle Pleistocene to modern Rhine, Meuse and Elbe river sediments in order to resolve processes that control detrital age distributions (provenance, erosion and mineral fertility). We used a modelling approach to compare observed with theoretically predicted age distributions from an interpolated in situ AFT and ZFT age map. In situ cooling ages do show large differences in the Rhine drainage basin, facilitating the differentiation between different source regions. Inconsistencies between observed and theoretical age distributions of the Meuse and Elbe samples can be explained by mixing and reworking of sediments with different provenances (Meuse Middle Pleistocene terrace sediment) and a yet unexplored source region with old AFT ages (Elbe samples). Overall, the results show that detrital thermochronology is capable of identifying the provenance of Middle Pleistocene to modern sediments. The AFT age distributions of Rhine sediments are dominated ( 70%) by AFT ages representing the Alps. A possible explanation is higher erosion rates in the Alps as compared to areas outside the Alps. A Late Pleistocene sample from the Upper Rhine Graben contains apatite grains from the Molasse and Hegau volcanics, which we explain with a shift of the headwaters of the Rhine to the north as a result of intense Middle Pleistocene Riss glaciation. Contrary to the observed dominance of Alpine-derived AFT ages in Rhine sediments, the relative contribution of zircon ages with sources in the Alps is lower and significantly decreases downstream, suggesting a major source of zircons outside the Alps. This can be explained by increased zircon fertility of sediments derived from the Rhenish massif. Therefore, we conclude that erosion and mineral fertility are the main processes controlling detrital AFT and ZFT age distributions of the sampled river sediment. In case of the Rhine samples, AFT age distributions are mainly controlled by differences in erosion rates, whereas this impact is completely balanced by differences in mineral fertility for the ZFT data.

Preliminary report on deposit models for sand and gravel in the Cache la Poudre River valley

USGS Publications Warehouse

Langer, W.H.; Lindsey, D.A.

1999-01-01

The stratigraphy, sedimentary features, and physical characteristics of gravel deposits in the Cache la Poudre River valley were studied to establish geologic models for these deposits. Because most of the gravel mined in the valley is beneath the low terraces and floodplain, the quality of these deposits for aggregate was studied in detail at eight sites in a 25.5-mile reach between Fort Collins and Greeley, Colorado. Aggregate quality was determined by field and laboratory measurements on samples collected under a consistent sampling plan. The Broadway terrace is underlain by Pleistocene alluvium and, at some places, by fine-grained wind-blown deposits. The Piney Creek terrace, low terraces, and floodplain are primarily underlain by Holocene alluvium. Pleistocene alluvium may underlie these terraces at isolated locations along the river. Gravels beneath the Piney Creek terrace, low terraces, and floodplain are divisible into two units that are poorly distinguishable at the upstream end of the study area, but are readily distinguishable about 7 miles downstream. Where distinguished, the two gravel units are separated by a sharp, locally erosional, contact. The upper gravel is probably of Holocene age, but the lower gravel is considered to be Holocene and Pleistocene. The primary variation in particle size of the gravels beneath the floodplain and low terraces of the Cache la Poudre River valley is the downstream decrease in the proportion of particles measuring 3/4 inch and larger. Above Fort Collins, about 60 pct of the gravel collects on the 3/4 inch sieve, whereas about 50 pct of gravel collects on the same sieve size at Greeley. For 1.5-inch sieves, the corresponding values are about 50 pct for Fort Collins and only about 30 pct for Greeley. Local differences in particle size and sorting between the upper and lower gravel units were observed in the field, but only the coarsest particle sizes appear to have been concentrated in the lower unit. Field measurements of aggregate quality, pebble lithology, and shape show little significant downstream variation. Pebble lithology is about 25 percent granite; 48 percent pegmatite; 5-7 percent each of gneiss, quartz, and quartzite; and minor amounts of diabase, schist, volcanic porphyry, and sandstone. Among the rock types, only the volcanic porphyries might be reactive with Portland cement. Pebble shape is dominantly equidimensional with a tendency to form thick, disc-shaped particles. Disc-shaped and spherical particles comprise about 39 percent and 31 percent of the pebble-size fraction, respectively. Rod and blade shapes comprise about 18 and 12 percent of the pebble-size fraction, respectively. The relatively large proportion of equidimensional particles in the Cache la Poudre may be due to the small proportion of layered gneiss in gravel. Pebbles having axial ratios less than 0.5, which might be structurally weak, are rare. The two gravel units show subtle local differences and evidence for derivation of the younger gravel from the older gravel. At many sites, the upper gravel unit tends to contain more quartz plus quartzite, has poorer physical quality, and contains more angular pebbles than the lower gravel. Weathering, followed by transport in the river, might be expected to concentrate quartz and quartzite, degrade physical quality, and break pebbles into angular fragments. This conclusion is consistent with local evidence of an erosional contact between the two gravel units.

Hydrogeologic framework of the North Fork and surrounding areas, Long Island, New York

USGS Publications Warehouse

Schubert, Christopher E.; Bova, Richard G.; Misut, Paul E.

2004-01-01

Ground water on the North Fork of Long Island is the sole source of drinking water, but the supply is vulnerable to saltwater intrusion and upconing in response to heavy pumping. Information on the area's hydrogeologic framework is needed to analyze the effects of pumping and drought on ground-water levels and the position of the freshwater-saltwater interface. This will enable water-resource managers and water-supply purveyors to evaluate a wide range of water-supply scenarios to safely meet water-use demands. The extent and thickness of hydrogeologic units and position of the freshwater-saltwater interface were interpreted from previous work and from exploratory drilling during this study.The fresh ground-water reservoir on the North Fork consists of four principal freshwater flow systems (referred to as Long Island mainland, Cutchogue, Greenport, and Orient) within a sequence of unconsolidated Pleistocene and Late Cretaceous deposits. A thick glacial-lake-clay unit appears to truncate underlying deposits in three buried valleys beneath the northern shore of the North Fork. Similar glacial-lake deposits beneath eastern and east-central Long Island Sound previously were inferred to be younger than the surficial glacial deposits exposed along the northern shore of Long Island. Close similarities in thickness and upper-surface altitude between the glacial-lake-clay unit on the North Fork and the glacial-lake deposits in Long Island Sound indicate, however, that the two are correlated at least along the North Fork shore.The Matawan Group and Magothy Formation, undifferentiated, is the uppermost Cretaceous unit on the North Fork and constitutes the Magothy aquifer. The upper surface of this unit contains a series of prominent erosional features that can be traced beneath Long Island Sound and the North Fork. Northwest-trending buried ridges extend several miles offshore from areas southeast of Rocky Point and Horton Point. A promontory in the irregular, north-facing cuesta slope extends offshore from an area southwest of Mattituck Creek and James Creek. Buried valleys that trend generally southeastward beneath Long Island Sound extend onshore northeast of Hashamomuck Pond and east of Goldsmith Inlet.An undifferentiated Pleistocene confining layer, the lower confining unit, consists of apparently contiguous units of glacial-lake, marine, and nonmarine clay. This unit is more than 200 feet thick in buried valleys filled with glacial-lake clay along the northern shore, but elsewhere on the North Fork, it is generally less than 50 feet thick and presumably represents an erosional remnant of marine clay. Its upper surface is generally 75 feet or more below sea level where it overlies buried valleys, and is generally 100 feet or less below sea level in areas where marine clay has been identified.A younger unit of glacial-lake deposits, the upper confining unit, is a local confining layer and underlies a sequence of late Pleistocene moraine and outwash deposits. This unit is thickest (more than 45 feet thick) beneath two lowland areas--near Mattituck Creek and James Creek, and near Hashamomuck Pond--but pinches out close to the northern and southern shores and is locally absent in inland areas of the North Fork. Its upper-surface altitude generally rises to near sea level toward the southern shore.Freshwater in the Orient flow system is limited to the upper glacial aquifer above the top of the lower confining unit. The upper confining unit substantially impedes the downward flow of freshwater in inland parts of the Greenport flow system. Deep freshwater within the lower confining unit in the east-central part of the Cutchogue flow system probably is residual from an interval of lower sea level. The upper confining unit is absent or only a few feet thick in the west-central part of the Cutchogue flow system and does not substantially impede the downward flow of freshwater, but the lower confining unit probably impedes the downward flow of freshwater within a southeast-trending buried valley in this area.

Palaeoclimate characteristics in interior Siberia of MIS 6-2: first insights from the Batagay permafrost mega-thaw slump in the Yana Highlands

NASA Astrophysics Data System (ADS)

Ashastina, Kseniia; Schirrmeister, Lutz; Fuchs, Margret; Kienast, Frank

2017-07-01

Syngenetic permafrost deposits formed extensively on and around the arising Beringian subcontinent during the Late Pleistocene sea level lowstands. Syngenetic deposition implies that all material, both mineral and organic, freezes parallel to sedimentation and remains frozen until degradation of the permafrost. Permafrost is therefore a unique archive of Late Pleistocene palaeoclimate. Most studied permafrost outcrops are situated in the coastal lowlands of northeastern Siberia; inland sections are, however, scarcely available. Here, we describe the stratigraphical, cryolithological, and geochronological characteristics of a permafrost sequence near Batagay in the Siberian Yana Highlands, the interior of the Sakha Republic (Yakutia), Russia, with focus on the Late Pleistocene Yedoma ice complex (YIC). The recently formed Batagay mega-thaw slump exposes permafrost deposits to a depth of up to 80 m and gives insight into a climate record close to Verkhoyansk, which has the most severe continental climate in the Northern Hemisphere. Geochronological dating (optically stimulated luminescence, OSL, and 14C ages) and stratigraphic implications delivered a temporal frame from the Middle Pleistocene to the Holocene for our sedimentological interpretations and also revealed interruptions in the deposition. The sequence of lithological units indicates a succession of several distinct climate phases: a Middle Pleistocene ice complex indicates cold stage climate. Then, ice wedge growth stopped due to highly increased sedimentation rates and eventually a rise in temperature. Full interglacial climate conditions existed during accumulation of an organic-rich layer - plant macrofossils reflected open forest vegetation existing under dry conditions during Marine Isotope Stage (MIS) 5e. The Late Pleistocene YIC (MIS 4-MIS 2) suggests severe cold-stage climate conditions. No alas deposits, potentially indicating thermokarst processes, were detected at the site. A detailed comparison of the permafrost deposits exposed in the Batagay thaw slump with well-studied permafrost sequences, both coastal and inland, is made to highlight common features and differences in their formation processes and palaeoclimatic histories. Fluvial and lacustrine influence is temporarily common in the majority of permafrost exposures, but has to be excluded for the Batagay sequence. We interpret the characteristics of permafrost deposits at this location as a result of various climatically induced processes that are partly seasonally controlled. Nival deposition might have been dominant during winter time, whereas proluvial and aeolian deposition could have prevailed during the snowmelt period and the dry summer season.

Neandertal versus Modern Human Dietary Responses to Climatic Fluctuations

PubMed Central

El Zaatari, Sireen; Grine, Frederick E.; Ungar, Peter S.; Hublin, Jean-Jacques

2016-01-01

The Neandertal lineage developed successfully throughout western Eurasia and effectively survived the harsh and severely changing environments of the alternating glacial/interglacial cycles from the middle of the Pleistocene until Marine Isotope Stage 3. Yet, towards the end of this stage, at the time of deteriorating climatic conditions that eventually led to the Last Glacial Maximum, and soon after modern humans entered western Eurasia, the Neandertals disappeared. Western Eurasia was by then exclusively occupied by modern humans. We use occlusal molar microwear texture analysis to examine aspects of diet in western Eurasian Paleolithic hominins in relation to fluctuations in food supplies that resulted from the oscillating climatic conditions of the Pleistocene. There is demonstrable evidence for differences in behavior that distinguish Upper Paleolithic humans from members of the Neandertal lineage. Specifically, whereas the Neandertals altered their diets in response to changing paleoecological conditions, the diets of Upper Paleolithic humans seem to have been less affected by slight changes in vegetation/climatic conditions but were linked to changes in their technological complexes. The results of this study also indicate differences in resource exploitation strategies between these two hominin groups. We argue that these differences in subsistence strategies, if they had already been established at the time of the first contact between these two hominin taxa, may have given modern humans an advantage over the Neandertals, and may have contributed to the persistence of our species despite habitat-related changes in food availabilities associated with climate fluctuations. PMID:27119336

Neandertal versus Modern Human Dietary Responses to Climatic Fluctuations.

PubMed

El Zaatari, Sireen; Grine, Frederick E; Ungar, Peter S; Hublin, Jean-Jacques

2016-01-01

The Neandertal lineage developed successfully throughout western Eurasia and effectively survived the harsh and severely changing environments of the alternating glacial/interglacial cycles from the middle of the Pleistocene until Marine Isotope Stage 3. Yet, towards the end of this stage, at the time of deteriorating climatic conditions that eventually led to the Last Glacial Maximum, and soon after modern humans entered western Eurasia, the Neandertals disappeared. Western Eurasia was by then exclusively occupied by modern humans. We use occlusal molar microwear texture analysis to examine aspects of diet in western Eurasian Paleolithic hominins in relation to fluctuations in food supplies that resulted from the oscillating climatic conditions of the Pleistocene. There is demonstrable evidence for differences in behavior that distinguish Upper Paleolithic humans from members of the Neandertal lineage. Specifically, whereas the Neandertals altered their diets in response to changing paleoecological conditions, the diets of Upper Paleolithic humans seem to have been less affected by slight changes in vegetation/climatic conditions but were linked to changes in their technological complexes. The results of this study also indicate differences in resource exploitation strategies between these two hominin groups. We argue that these differences in subsistence strategies, if they had already been established at the time of the first contact between these two hominin taxa, may have given modern humans an advantage over the Neandertals, and may have contributed to the persistence of our species despite habitat-related changes in food availabilities associated with climate fluctuations.

Late Pliocene-Pleistocene environments and glacial history of the northern North Sea

NASA Astrophysics Data System (ADS)

Reinardy, Benedict T. I.; Hjelstuen, Berit O.; Sejrup, Hans Petter; Augedal, Hans; Jørstad, Arild

2017-02-01

Based on new geochronological (amino acids and Sr-isotopes) and lithological data combined with analyses of 3D seismic data, the Pliocene-Pleistocene development of the central northern North Sea has been investigated. At the start of the Plio-Pleistocene Transition the study area was dominated by a deltaic, shallow marine or tidal depositional environment with sediments mainly sourced from the west. These sand-rich sediments include green glauconitic grains that belong to the Utsira Sand with a local provenance. Directly above the base Quaternary (R2) a 60 m thick layer of mud-rich sediments of glacimarine origin were deposited at a rate of ∼12 cm/ka between ∼2-1.5 Ma and up to 80 cm/ka between 1.5 and 1.2 Ma possibly reflecting glacial ice advancing to the Norwegian coastline. The high rate of deposition in the Early Pleistocene occurred immediately before the initiation of the Norwegian Channel Ice Stream at ∼1.1 Ma. Following this, a large part of the sediment input from Fennoscandia seems to have been directed away from the study area to the shelf break. At the start of the Mid Pleistocene Transition (MPT), subaerial conditions allowed the formation of a >50 km long fluvial channel across the study area draining water from the east to the south west. The earliest evidence of grounded ice in the investigated area comes from mega scale glacial lineations formed during the MPT, at or just after ∼1.2 Ma. Following this, a regional unconformity (R4) was formed by one or more grounded ice advances across the study area possibly during or directly after the MPT and likely marks the boundary between the Early and Mid Pleistocene glacimarine sediments. The Mid to Late Pleistocene stratigraphy is dominated by glacimarine sediments and tills and is associated with multiple generations of tunnel valleys observed within the seismic data. A high shear strength till containing chalk clasts transported from the west and/or south of the study area was likely deposited during MIS6 and may have been more conducive to tunnel valley formation in comparison to lower shear strength tills deposited by later ice advances. A thick till unit overlain by a sand layer in the study area was deposited by grounded ice during the Last Glacial Maximum and subsequent drainage of an ice dammed lake in the southern North Sea during the last deglaciation (MIS2) of the study area. This study shows that much of the Quaternary age sediments within the northern North Sea were deposited relatively rapidly during short periods of time probably leaving significant hiatuses within the stratigraphic record. This finding has implications for previous studies that use a chronological framework assuming a relatively continuous sedimentation rate and record for the Early Pleistocene within the North Sea.

Geologic map of the Ennis 30' x 60' quadrangle, Madison and Gallatin Counties, Montana

USGS Publications Warehouse

Kellogg, Karl S.; Williams, Van S.

1998-01-01

The Ennis 1:100,000 quadrangle lies within both the Laramide (Late Cretaceous to early Tertiary) foreland province of southwestern Montana and the northeastern margin of the middle to late Tertiary Basin and Range province. The oldest rocks in the quadrangle are Archean high-grade gneiss, and granitic to ultramafic intrusive rocks that are as old as about 3.0 Ga. The gneiss includes a supracrustal assemblage of quartz-feldspar gneiss, amphibolite, quartzite, and biotite schist and gneiss. The basement rocks are overlain by a platform sequence of sedimentary rocks as old as Cambrian Flathead Quartzite and as young as Upper Cretaceous Livingston Group sandstones, shales, and volcanic rocks. The Archean crystalline rocks crop out in the cores of large basement uplifts, most notably the 'Madison-Gravelly arch' that includes parts of the present Tobacco Root Mountains and the Gravelly, Madison, and Gallatin Ranges. These basement uplifts or blocks were thrust westward during the Laramide orogeny over rocks as young as Upper Cretaceous. The thrusts are now exposed in the quadrangle along the western flanks of the Gravelly and Madison Ranges (the Greenhorn thrust and the Hilgard fault system, respectively). Simultaneous with the west-directed thrusting, northwest-striking, northeast-side-up reverse faults formed a parallel set across southwestern Montana; the largest of these is the Spanish Peaks fault, which cuts prominently across the Ennis quadrangle. Beginning in late Eocene time, extensive volcanism of the Absorka Volcanic Supergroup covered large parts of the area; large remnants of the volcanic field remain in the eastern part of the quadrangle. The volcanism was concurrent with, and followed by, middle Tertiary extension. During this time, the axial zone of the 'Madison-Gravelly arch,' a large Laramide uplift, collapsed, forming the Madison Valley, structurally a complex down-to-the-east half graben. Basin deposits as thick as 4,500 m filled the graben. Pleistocene glaciers sculpted the high peaks of the mountain ranges and formed the present rugged topography.

Geologic map of the Ennis 30' x 60' quadrangle, Madison and Gallatin Counties, Montana, and Park County, Wyoming

USGS Publications Warehouse

Kellogg, Karl S.; Williams, Van S.

2000-01-01

The Ennis 1:100,000 quadrangle lies within both the Laramide (Late Cretaceous to early Tertiary) foreland province of southwestern Montana and the northeastern margin of the middle to late Tertiary Basin and Range province. The oldest rocks in the quadrangle are Archean high-grade gneiss, and granitic to ultramafic intrusive rocks that are as old as about 3.0 Ga. The gneiss includes a supracrustal assemblage of quartz-feldspar gneiss, amphibolite, quartzite, and biotite schist and gneiss. The basement rocks are overlain by a platform sequence of sedimentary rocks as old as Cambrian Flathead Quartzite and as young as Upper Cretaceous Livingston Group sandstones, shales, and volcanic rocks. The Archean crystalline rocks crop out in the cores of large basement uplifts, most notably the 'Madison-Gravelly arch' that includes parts of the present Tobacco Root Mountains and the Gravelly, Madison, and Gallatin Ranges. These basement uplifts or blocks were thrust westward during the Laramide orogeny over rocks as young as Upper Cretaceous. The thrusts are now exposed in the quadrangle along the western flanks of the Gravelly and Madison Ranges (the Greenhorn thrust and the Hilgard fault system, respectively). Simultaneous with the west-directed thrusting, northwest-striking, northeast-side-up reverse faults formed a parallel set across southwestern Montana; the largest of these is the Spanish Peaks fault, which cuts prominently across the Ennis quadrangle. Beginning in late Eocene time, extensive volcanism of the Absorka Volcanic Supergroup covered large parts of the area; large remnants of the volcanic field remain in the eastern part of the quadrangle. The volcanism was concurrent with, and followed by, middle Tertiary extension. During this time, the axial zone of the 'Madison-Gravelly arch,' a large Laramide uplift, collapsed, forming the Madison Valley, structurally a complex down-to-the-east half graben. Basin deposits as thick as 4,500 m filled the graben. Pleistocene glaciers sculpted the high peaks of the mountain ranges and formed the present rugged topography.

Rifting Process and Geomorphic Development of the Okinawa Tough, Southwest Japan

NASA Astrophysics Data System (ADS)

Sato, T.; Arai, K.; Inoue, T.; Matsumoto, D.

2012-12-01

The Ryukyu Island Arc extends from Kyushu to Taiwan, a distance of 1,200 km, along the Ryukyu Trench where the Philippine Sea Plate is subducting beneath the Eurasian Plate. The Okinawa Trough, a back arc basin has formed behind the Ryukyu Island Arc in late Pliocene to early Pleistocene. The research cruises of GH11 (from 14 July to 15 August, 2011) and GH12 (from 20 to 30 July, 2012) were carried out around the Okinawa Trough. More than 3,600 miles multi channel high-resolution seismic profiles were acquired during these cruises by the GI-gun (Generator 250 cu inch and Injector 105 cu. inch) systems with 16ch digital streamer cable. As a result, two unconformities and three depositional sequence divided by the unconformities are recognized in the trough. The lower and the midlle sequence are tilted and blocked by many normal faults, on the other hand the upper one is not tilted and shows the pattern of onlap fill. From this result, the upper sequence started to deposit after start of the rifting. Additionally, internal reflection of the upper sequence shows the cyclic activities of the rifting. The position of the rifting axis was revealed based on dip of the normal faults. As a result, rifting axis shows echelon arrangement and the displacement of the faults are varied with the segment of the arrangement. The location of the segment boundaries is correlated with geometrical boundary of the adjacent slope. Steep slope with incised valley is distributed in southwestern part where the displacement of the normal fault is large, on the other hand, gentle slope without incised valley is distributed in northeastern part where the displacement is small. This difference of the displacement strongly controls the geometry of the adjacent slope.

Late cenozoic fluvial stratigraphy of the New Jersey piedmont: A record of glacioeustasy, planation, and incision on a low-relief passive margin

USGS Publications Warehouse

Stanford, S.D.; Ashley, G.M.; Brenner, G.J.

2001-01-01

Late Cenozoic fluvial deposits and erosional landforms in the New Jersey Piedmont record two episodes of valley incision, one in the Late Miocene and one in the Early Pleistocene, separated by periods of planation and fluvial deposition. The upland erosion surface and a fluvial gravel are the remnants of a low-relief Late Miocene landscape. Late Miocene incision was followed by deposition of a fluvial plain and cutting of straths in the Pliocene. Early Pleistocene incision produced the present valleys, which contain Middle to Late Pleistocene fluvial deposits. The two incisions correspond to permanent glacioeustatic lowering during expansion of the Antarctic ice sheet in the Middle to Late Miocene and development of Northern Hemisphere ice sheets in the Late Pliocene. Bordering Coastal Plain marine deposits indicate that the upland erosion surface was formed during a rising sea-level trend between the Late Oligocene and Middle Miocene. The Pliocene plain and straths formed during a period of rising sea level in the Early Pliocene. The stratigraphic record indicates that the oldest preserved landforms are no older than Late Miocene, that landscape planation in coastal regions of low-relief passive margins can be achieved in <20 m.yr., and that these surfaces can be incised and dissected in <5 m.yr.

High-resolution and Deep Crustal Imaging Across The North Sicily Continental Margin (southern Tyrrhenian Sea)

NASA Astrophysics Data System (ADS)

Agate, M.; Bertotti, G.; Catalano, R.; Pepe, F.; Sulli, A.

Three multichannel seismic reflection profiles across the North Sicily continental mar- gin have been reprocessed and interpreted. Data consist of an unpublished high pene- tration seismic profile (deep crust Italian CROP Project) and a high-resolution seismic line. These lines run in the NNE-SSW direction, from the Sicilian continental shelf to the Tyrrhenian abyssal plain (Marsili area), and are tied by a third, high penetration seismic line MS104 crossing the Sisifo High. The North Sicily continental margin represents the inner sector of the Sicilian-Maghrebian chain that is collapsed as con- sequence of extensional tectonics. The chain is formed by a tectonic wedge (12-15 km thick. It includes basinal Meso-Cenozoic carbonate units overthrusting carbonate platform rock units (Catalano et al., 2000). Presently, main culmination (e.g. Monte Solunto) and a number of tectonic depressions (e.g. Cefalù basin), filled by >1000 m thick Plio-Pleistocene sedimentary wedge, are observed along the investigated tran- sect. Seismic attributes and reflector pattern depicts a complex crustal structure. Be- tween the coast and the M. Solunto high, a transparent to diffractive band (assigned to the upper crust) is recognised above low frequency reflective layers (occurring be- tween 9 and 11 s/TWT) that dips towards the North. Their bottom can be correlated to the seismological (African?) Moho discontinuity which is (26 km deep in the Sicilian shelf (Scarascia et al., 1994). Beneath the Monte Solunto ridge, strongly deformed re- flectors occurring between 8 to 9.5 s/TWT (European lower crust?) overly the African (?) lower crust. The resulting geometry suggests underplating of the African crust respect to the European crust (?). The already deformed crustal edifice is dissected by a number of N-dipping normal faults that open extensional basins and are associ- ated with crustal thinning. The Plio-Pleistocene fill of the Cefalù basin can be subdi- vided into three subunits by well-developed unconformities. The stratal pattern of the lower subunit (Early Pliocene?) points out thrust-top basin. The intermediate subunit (Middle-Late Pliocene?) shows a wide sedimentary lateral accretion with syntectonic growth geometries. Upper Pliocene layers are overlain by well-stratified sediments of supposedly Pleistocene to Recent age, which drape and smooth underlying features (Pepe et al., 2000). Crustal thinning is (2 in the Cefalù basin and reach (3.54 north of Sisifo volcano, where crustal separation occurs and oceanic crust emplaced (Marsili 1 basin). In this area the Moho is located at (8 s/TWT, corresponding to 10-km depth. References Catalano R., Franchino A., Merlini S. e Sulli A., 2000. Mem. Soc. Geol. It., 55, 5-16. Pepe F., Bertotti G., Cella F. Marsella E., 2000. Tectonics, 19, 241-257. Scarascia S., Lozej A. Cassinis R., 1994. Boll. Geof. Teor. Appl., 36 (141-144), 5-19. 2

The marine geology of the eastern Santa Barbara Channel, with particular emphasis on the ground water basins offshore from the Oxnard Plain, Southern California

USGS Publications Warehouse

Greene, H. Gary; Wolf, Stephen C.; Blom, Ken G.

1978-01-01

Marine geophysical investigations provide new data concerning the stratigraphy, tectonic and sedimentary history, and the ground water geology of the southeastern Santa Barbara Channel region. The offshore stratigraphy identified in seismic reflection profiles includes a succession of Neogene to Quaternary strata. The middle Miocene Conejo volcanics form an acoustical basement and the overlying late Cenozoic sedimentary rocks attain a thickness greater than 2,500 m. These sedimentary deposits fill a structurally controlled, physiographic and depositional depression called the Ventura Basin. Structure consists generally of a gently folded, east-trending Tertiary synclinorium bordered on the north by a regional thrust fault and on the south by a steep asymmetrical anticlinal ridge. Most structures show evidence of north-south compression that occurred during early Pleistocene time. Three well-defined unconformities represent widespread erosion in late Miocene, early to middle Pleistocene, and late Pleistocene time. The boundaries of Miocene, Pliocene, and lower Pleistocene strata continue uninterrupted eastward along the southern part of Santa Barbara basin to Hueneme Canyon, where they turn northeast and can be traced to the coast near Port Hueneme. These limits probably represent the south edge of the Santa Barbara basin during Pliocene and Pleistocene time. Fresh water-bearing materials of the Oxnard plain are unconsolidated Quaternary sediment laid down on more consolidated Tertiary rocks. Offshore, the total fresh water-bearing materials distinguished in the seismic reflection profiles attain a thickness of about 356 m and have an areal extent of over 760 km2. Strata that contain the offshore continuation of the five major on-land aquifers (Grimes Canyon, Fox Canyon, Hueneme, Mugu, and Oxnard aquifers) are identified in the seismic reflection profiles. These strata make up the two offshore ground-water basins, the Mound and Oxnard plain ground-water basins, which are separated by the east-west trending Oak Ridge fault. Possible entrance areas for salt water intrusion into fresh water aquifers are found along the walls of the submarine canyons and along the northern slopes of Santa Barbara and Santa Monica basins. Hueneme and Mugu aquifers are probably exposed locally in all five submarine canyons of the Oxnard offshore area and may also crop out along the upper northern slope of Santa Monica basin. In all of these areas, salt water readily intrudes the aquifers. A salinity-temperature-depth study made in April, 1971, does not indicate any great dilution of surface ocean water by fresh water that could be 'leaking' from the exposed aquifers along the walls of Hueneme Canyon and the landward slope of Santa Barbara Channel. Earthquakes in the vicinity of the Oxnard plain suggest that the region is seismically active. Epicenters are widely dispersed over the region. No distinct trend or alignment of earthquake epicenters occurs near the trace of any of the faults, although many epicenters are scattered around the Oak Ridge zone of deformation in the northern part of the region. The largest magnitude earthquake recorded in the area was a magnitude 5.7 that occurred on February 21, 1973, offshore of Point Mugu, south of the Oxnard plain.

Active transpression in the northern Calabria Apennines, southern Italy

NASA Astrophysics Data System (ADS)

Ferranti, L.; Santoro, E.; Mazzella, M. E.; Monaco, C.; Morelli, D.

2009-10-01

An integrated analysis of geomorphologic and structural data, offshore seismic profiles and local network seismicity, is used to shed light on the hitherto poorly known active deformation field that affects the Southern Apennines orogen in northern Calabria region. In the Southern Apennines, Middle Pleistocene waning of Miocene-Early Pleistocene thin-skinned frontal thrust belt motion toward the Apulian foreland to the NE was coeval to onset of regional uplift, which is documented by flights of raised marine terraces. Short-wavelength (˜ 5-10 km) and amplitude (˜ 20-50 m) undulations are superposed to the regional uplift (˜ 100 km length and ˜ 500 m amplitude scale) profile of Middle-Upper Pleistocene marine terraces on the Ionian Sea coast of northern Calabria stretching along the borders of the Sila and Pollino mountain ranges and across the intervening Sibari coastal plain. The secondary undulations spatially coincide with the last generation of ˜ W- to ˜ WNW-striking folds traced in bedrock and locally within Early to Middle Pleistocene continental to transitional deposits. The very recent activity of these structures is highlighted by a range of fluvial geomorphic anomalies and by involvement in folding and locally transpressional faulting of the Middle Pleistocene and younger depositional sequences submerged beneath the continental shelf. We argue that the local-scale, but pervasive undulations in the deformation profile of marine terraces represent shallow-crustal folds grown within a recent and still active transpressional field. A major structural culmination bound by fore- and retro-verging transpressional shear zones is represented by the Pollino mountain range and its offshore extension in the Amendolara ridge, and a further SW-directed transpressional belt is found in northern Sila and adjacent sea bottom. Epicenter distribution and focal solutions of low- to moderate crustal earthquakes illuminate the two NW-SE trending structural belts beneath the Amendolara ridge and northern Sila, where partitioning between thrust and left strike-slip motion occurs in response to ˜ E to ˜ NE directed shortening. A local ˜ NW-SE extension is recorded by fault-kinematic analysis on NE-SW striking fault segments parallel to the coast on the eastern flank of Pollino. These small-length normal faults do not form a through-going lineament, rather they accommodate the seaward collapse of the uppermost crust above the deeper shortening compartment. Conversely, the active transpression testified by geomorphic, structural and seismicity data is accommodated along deep-seated oblique back-thrusts that involve the Apulian foreland plate underlying the now inactive thin-skinned accretionary wedge down to near-Moho depths. In light of the tight interlacing between regional and local components of deformation affecting the marine terraces, we suggest that the large-scale uplift in this sector of Calabria may reflect whole crustal-scale folding. The novel seismotectonic frame reconstructed for this region is consistent with GPS velocities suggesting that large part of geodetic shortening detected between the Apennines and the Apulian block on the eastern side of southern Italy might be accommodated in northern Calabria.

The interaction between surface processes and tectonics during the late Quaternary in the Middle Volturno River valley (southern Italy): new morpho-stratigraphic constraints from fluvial terraces

NASA Astrophysics Data System (ADS)

Amato, Vincenzo; Patrizio Ciro Aucelli, Pietro; Cesarano, Massimo; Filocamo, Francesca; Giralt, Santiago; Leone, Natalia; Rosskopf, Carmen Maria; Scorpio, Vittoria

2017-04-01

The Middle Volturno River valley is located in the inner part of the Southern Apennines of Italy, between the SW slope of the Matese Massif and the NE slopes of the Caserta mountains and is underlain by Meso-Cenozoic carbonate rocks and Miocene Flysch deposits. The study sector includes the lower Calore River valley and, below the Calore-Volturno confluence, the valley portion that extends until the Triflisco gorge, from Telese village to the Volturno dam. It is generally E-W, NW-SE and NE-SW elongated and characterized by rectilinear and meandering fluvial patterns. The main infilling of the two valley portions is locally preserved as remnants of fluvial terraces hanging over the local base level up to ca. 30-40 m. It is generally interfingered with and covered by several generations of alluvial fan and travertine deposits. New Ar/Ar datings on tephra layers interbedded in the oldest generations of the alluvial fan deposits and new U/Th datings on travertine deposits, allowed to constrain the main infilling to the late Middle and the early Upper Pleistocene. Both deposits are locally covered by the Campanian Ignimbrite Formation (CI, 39 ky BP) and are interested by high-angle faults generated during extensional tectonic phases that affected this sector of the Apennine chain since the Middle Pleistocene. Furthermore, the geomorphological analyses of aerial photos and topographic maps (1:5000 in scale) highlight the presence of a flight of fluvial terraces younger than the CI deposits that can be grouped into four orders. The stratigraphical data, based on field surveys and boreholes analyses, supported by new tephrostratigraphical constraints and literature data, allow to refer the older orders (I and II) to the late Upper Pleistocene. The III and IV orders, instead, can be referred to the early Holocene and historical times, respectively. These chronological constraints allow to hypothesize that the genesis of the I and II orders seem to be driven by late Quaternary tectonics, while climatic and land use changes played a key role for the formation of the younger orders.

Late Pleistocene and Holocene sedimentary facies on the Ebro continental shelf

USGS Publications Warehouse

Diaz, J.; Nelson, C.H.; Barber, J.H.; Giro, S.

1990-01-01

Late Pleistocene-Holocene history of the Ebro continental shelf of northeastern Spain is recorded in two main sedimentary units: (1) a lower, transgressive unit that covers the shelf and is exposed on the outer shelf south of 40??40???N, and (2) an upper, progradational, prodeltaic unit that borders the Ebro Delta and extends southward along the inner shelf. The lower transgressive unit includes a large linear shoal found at a water depth of 90 m and hardground mounds at water depths of 70-80 m. Some patches of earlier Pleistocene prodelta mud remain also, exposed or covered by a thin veneer of transgressive sand on the northern outer shelf. This relict sand sheet is 2-3 m thick and contains 9000-12,500 yr old oyster and other shells at water depths of 78-88 m. The upper prodelta unit covers most of the inner shelf from water depths of 20-80 m and extends from the present Ebro River Delta to an area to the southwest where the unit progressively thins and narrows. Interpretation of high-resolution seismic reflection data shows the following facies occurring progressively offshore: (1) a thick stratified facies with thin progradational "foresets beds", (2) a faintly laminated facies with sparse reflectors of low continuity, and (3) a thin transparent bottomset facies underlain by a prominent flat-lying reflector. Deposition in the northern half of the prodelta began as soon as the shoreline transgressed over the mid-shelf, but progradation of the southern half did not begin until about 1000-3000 yrs after the transgression. A classic deltaic progradational sequence is shown in the Ebro prodelta mud by (1) gradation of seismic facies away from the delta, (2) coarsening-upward sequences near the delta and fining-upward sequences in the distal mud belt deposits, and (3) thin storm-sand layers and shell lags in the nearshore stratified facies. The boundaries of the prodeltaic unit are controlled by increased current speeds on the outer shelf (where the shelf narrows) and by development of the shoreface sand body resulting from shoaling waves on the inner shelf. ?? 1990.

Snežna jama (Slovenia): Interdisciplinary dating of cave sediments and implication for landscape evolution

PubMed Central

Häuselmann, Philipp; Mihevc, Andrej; Pruner, Petr; Horáček, Ivan; Čermák, Stanislav; Hercman, Helena; Sahy, Diana; Fiebig, Markus; Hajna, Nadja Zupan; Bosák, Pavel

2015-01-01

Caves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps. PMID:26516294

Snežna jama (Slovenia): Interdisciplinary dating of cave sediments and implication for landscape evolution.

PubMed

Häuselmann, Philipp; Mihevc, Andrej; Pruner, Petr; Horáček, Ivan; Čermák, Stanislav; Hercman, Helena; Sahy, Diana; Fiebig, Markus; Hajna, Nadja Zupan; Bosák, Pavel

2015-10-15

Caves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps.

Magnetic polarity stratigraphy of the middle Pleistocene (Ensenadan) Tarija Formation of southern Bolivia

NASA Astrophysics Data System (ADS)

MacFadden, Bruce J.; Siles, Oscar; Zeitler, Peter; Johnson, Noye M.; Campbell, Kenneth E.

1983-03-01

The Tarija Formation of southern Bolivia, which is well known for its classic vertebrate faunas, is of prime importance in understanding of the chronology of the Ensenadan Land Mammal Age. This formation consists of well-exposed and relatively fossiliferous sections of clays, clayey silts, sands, gravels, and tuffs which were deposited in a predominately fluviatile regime in a Pleistocene structural basin. Four stratigraphic sections, each measuring 110 m or less, were studied to establish a magnetic polarity stratigraphy. Paleomagnetic samples were collected from the finer-grained sediments at 100 sites spaced at stratigraphic intervals of 5 m or less. All paleomagnetic specimens were demagnetized in alternating fields of least 250 oersteds (oe). Some specimens were also thermally demagnetized at 200°C or more. Of the 100 sites, 77 were ultimately used to determine the magnetic polarity zonation. Based on the four sections sampled, the Tarija Formation spans a time interval from about 1 my to about 0.7 my B.P. or perhaps younger. The lower half of the composite section is of reversed polarity punctuated by a short normal event. This sequence probably represents the late Matuyama chron with the Jaramillo subchron. The upper part of the section is of normal polarity and represents early Brunhes time. A tuffaceous unit 43 m above the Brunhes-Matuyama boundary yielded a fission track (zircon) age of 0.7 ± 0.2 by B.P. These data indicate that the classic Tarija fauna is middle Pleistocene Ensendan in age.

High-latitude steppe vegetation and the mineral nutrition of Pleistocene herbivores

NASA Astrophysics Data System (ADS)

Davydov, S. P.; Davydova, A.; Makarevich, R.; Loranty, M. M.; Boeskorov, G.

2014-12-01

High-latitude steppes were widespread and zonal in the Late Pleistocene and formed a landscape basis for the Mammoth Biome. Now the patches of these steppes survived on steep slopes under southern aspects. These steppes serve as unique information sources about the Late Pleistocene "Mammoth" steppe. Numerous data obtained by palynological, carpological, and DNA analysis of plant remains from feces and stomach contents of Pleistocene herbivore mummies, as well as from buried soils and enclosing deposits show that they are similar to modern steppe plant assemblage in taxa composition. Plant's nutrient concentrations are of fundamental importance across Pleistocene grass-rich ecosystems because of their role in the support of large herbivores. The average weight of an adult mammoth skeleton (about 0.5 tons) and of a woolly rhinoceros (about 0.2 tons) clearly suggests this. Detailed studies on fossil bone remains showed mineral deficiency in large Pleistocene herbivores. A three-year study of ash and mineral contents of two types of relict steppe vegetation at the Kolyma Lowland, Arctic Siberia has been carried out. Nowadays refugia of similar vegetation are located not far (1 - 15km) from the Yedoma permafrost outcrops were abundant fossil remains are found. Dominant species of the steppe vegetation were sampled. Preliminary studies indicate that the ash-content varied 1.5-2 times in speceies of steppe herbs. The Ca, P, Mg, K element contents was higher for most steppe species than in the local herbaceous vegetation, especially in Ca and P. One of the most important elements of the mineral nutrition, the phosphorus, was always found in higher concentrations in the steppe vegetation than in plants of recently dominant landscapes of the study area. It should be noted that the mineral nutrient content of the modern steppe vegetation of Siberian Arctic is comparable to that of the recent zonal steppe of Transbaikal Region. This study supports the hypothesis that aboveground mineral concentrations of late Pleistocene grass-rich ecosystem were consistently higher than that of the recent common species of Siberian Arctic grassland. The source of mineral nutrients in the Pleistocene high-latitude steppe vegetation served as one of the reasons for the existence and survival of large herbivores in the Mammoth Biome.

The late Quaternary evolution of the Arno Coastal plain (northern Tuscany, Italy): unravelling the interplay between glacio-eustatic and tectonic signals.

NASA Astrophysics Data System (ADS)

Sarti, G.; Rossi, V.; Amorosi, A.; Ciampalini, A.; Molli, G.; Moretti, S.; Solari, L.

2016-12-01

Through the integration of sedimentological, radar interferometry and structural studies, a complex mid-late Quaternary coastal evolution related to Milankovitch-scale glacio-eustatic oscillations and local tectonics was reconstructed for the southern margin of the Arno coastal plain (APC, Tuscany, Italy). A set of 14C and ESR ages combined with SAR data, paleontological and archaeological proxy support the chronological framework. At a regional scale, the ACP straddles at the SW termination of a regional-scale fault, a crustal expression of lithospheric-scale tear segmenting the deep structure of the northern Apennines. GPS data, historical and present-day seismicity testify the activity of the fault zone. The thickness (up to 3000 m) and the age (Upper Miocene-Holocene) of the APC fill deposits reflect the accommodation space through time north of the Livorno-Sillaro line (LSL), in contrast to the recent uplifting documented south of the it. The uppermost 100 m of subsurface in the APC shows a Pleistocene incised-valley system (IVS), ca. 4 km wide and 45 m deep. The IVS fill is composed of floodplain clays passing upwards to estuarine deposits, dated to MIS 7. Above, a succession of amalgamated fluvial-channel sands record both depositional and erosional events of post-MIS 7 age. Upwards, a Holocene alluvial-deltaic succession overlies an indurated horizon related to a younger IVS system that formed at MIS 3/MIS 2 transition. The Holocene succession becomes thin in proximity of an isolated relief, Upper Pleistocene in age, rising up to 15 m above the present-day plain, ca. 6 km south of the Arno River. ERS and Envisat SAR data were acquired between the 1992 and the 2010 and processed by using the PSInSAR technique. The subsidence rates along the southern boundary of the ACP, reach 28 mm/y even if this data may be partially enhanced by water exploitation. Our results document that the transition between the subsiding and uplifting areas does not coincide with the traditionally defined surface trace of LSL, but is located ca. 20 km northward, close to the present day Arno river course. The complex interplay between sediment accumulation and erosional processes documented in the subsurface of ACP reflect changes in the eustatic rate, connected to the Milankovitch cyclicity, and local activity of the surface splay of LSL.

Biogeographic distribution and metric dental variation of fossil and living orangutans (Pongo spp.).

PubMed

Tshen, Lim Tze

2016-01-01

The genus Pongo has a relatively richer Quaternary fossil record than those of the African great apes. Fossil materials are patchy in terms of anatomical parts represented, limited almost exclusively to isolated teeth, jaw and bone fragments. Fossil evidence indicates that the genus Pongo had a broadly continuous distribution across the southern part of the Indomalayan biogeographic region, ranging in time from Early Pleistocene to Holocene: southern China (77 fossil sites), Vietnam (15), Laos (6), Cambodia (2), Thailand (4), Peninsular Malaysia (6), Sumatra (4), Borneo (6) and Java (4). Within this distribution range, there are major geographical gaps with no known orangutan fossils, notably central and southern Indochina, central and southern Thailand, eastern Peninsular Malaysia, northern and southern Sumatra, and Kalimantan. The geological time and place of origin of the genus remain unresolved. Fossil orangutan assemblages usually show greater extent of dental metrical variation than those of modern-day populations. Such variability shown in prehistoric populations has partially contributed to confusion regarding past taxonomic diversity and systematic relationships among extinct and living forms. To date, no fewer than 14 distinct taxa have been identified and named for Pleistocene orangutans. Clear cases suggestive of predation by prehistoric human are few in number, and limited to terminal Pleistocene-Early Holocene sites in Borneo and a Late Pleistocene site in Vietnam.

Population continuity vs. discontinuity revisited: dental affinities among late Paleolithic through Christian-era Nubians.

PubMed

Irish, Joel D

2005-11-01

The present study revisits a subject that has been a source of long-standing bioarchaeological contention, namely, estimation of Nubian population origins and affinities. Using the Arizona State University dental anthropology system, frequencies of 36 crown, root, and intraoral osseous discrete traits in 12 late Pleistocene through early historic Nubian samples were recorded and analyzed. Specifically, intersample phenetic affinities, and an indication of which traits are most important in driving this variation, were determined through the application of correspondence analysis and the mean measure of divergence distance statistic. The results support previous work by the author and others indicating that population discontinuity, in the form of replacement or significant gene flow into an existing gene pool, occurred sometime after the Pleistocene. This analysis now suggests that the break occurred before the Final Neolithic. Samples from the latter through Christian periods exhibit relative homogeneity, which implies overall post-Pleistocene diachronic and regional population continuity. Yet there are several perceptible trends among these latter samples that: 1) are consistent with documented Nubian population history, 2) enable the testing of several existing peopling hypotheses, and 3) allow the formulation of new hypotheses, including a suggestion of two post-Pleistocene subgroups predicated on an age-based sample dichotomy. Copyright 2005 Wiley-Liss, Inc

Revised Geologic Map of the Fort Garland Quadrangle, Costilla County, Colorado

USGS Publications Warehouse

Wallace, Alan R.; Machette, Michael N.

2008-01-01

The map area includes Fort Garland, Colo., and the surrounding area, which is primarily rural. Fort Garland was established in 1858 to protect settlers in the San Luis Valley, then part of the Territory of New Mexico. East of the town are the Garland mesas (basalt-covered tablelands), which are uplifted as horsts with the Central Sangre de Cristo fault zone. The map also includes the northern part of the Culebra graben, a deep structural basin that extends from south of San Luis (as the Sanchez graben) to near Blanca, about 8 km west of Fort Garland. The oldest rocks exposed in the map area are early Proterozic basement rocks (granites in Ikes Creek block) that occupy an intermediate structural position between the strongly uplifted Blanca Peak block and the Culebra graben. The basement rocks are overlain by Oligocene volcanic and volcaniclastic rocks of unknown origin. The volcanic rocks were buried by a thick sequence of basin-fill deposits of the Santa Fe Group as the Rio Grande rift formed about 25 million years ago. The Servilleta Basalt, a regional series of 3.7?4.8 Ma old flood basalts, was deposited within sediment, and locally provides a basis for dividing the group into upper and lower parts. Landslide deposits and colluvium that rest on sediments of the Santa Fe Group cover the steep margins of the mesas. Exposures of the sediment beneath the basalt and within the low foothills east of the Central Sangre de Cristo fault zone are comprised of siltstones, sandstones, and minor fluvial conglomerates. Most of the low ground surrounding the mesas and in the graben is covered by surficial deposits of Quaternary age. The alluvial deposits are subdivided into three Pleistocene-age units and three Holocene-age units. The oldest Pleistocene gravel (unit Qao) is preserved as isolated remnants that cap high surfaces north and east of Fort Garland. The primary geologic hazards in the map area are from earthquakes, landslides, and localized flooding. The Central Sangre de Cristo fault zone shows evidence for latest Pleistocene to possible early Holocene movement. The landslides may have seismogenic origins; that is, they may be stimulated by strong ground shaking during large earthquakes. This revised geologic map is based on previous mapping by Wallace (1997) and new mapping, primarily of the Quaternary deposits, by Machette.

Newly Described Tephra Provide Middle Pleistocene Age Constraints to Stegodon Fossils in West (Indonesian) Timor

NASA Astrophysics Data System (ADS)

Jensen, B. J. L.; Dufrane, A.; Mark, D.; Zaim, Y.; Rizal, Y.; Aswan, A.; Hascaryo, A.; Ciochon, R.; Gunnell, G.; Larick, R.; Zonnveld, J. P.

2017-12-01

As the Asian proboscidian Stegodon dispersed across Island Southeast Asia during the Pleistocene, multiple forms developed. On Timor, a southerly island east of Wallace's Line, the Ainaro gravels have yielded a highly dwarfed S. timorensis and a larger S. `trigonocephalus.' During a half-century of exploration, the age of the fossil bearing gravels remains in question, with only one age determination of >130 ka derived from six 230Th- 238U dates on a tusk fragment found in the Raebia area (Louys et al. 2016). Here we present radiometric ages for two tephra deposits bracketing Ainaro gravels at Raebia, a S. timorensis fossil locality 8 km northeast of Atambua city. The Raebia ravine exposes 2-10 meters of coarse-grained gravels incised into silt and clay deposits, bracketed by two indurated and largely devitrified tephras. Some intact glass was present to geochemically characterize each unit, which are both high-silica rhyolites. Biotite and zircons for 40Ar/39Ar and laser ablation U-Pb dating were extracted from the upper unit (Raebia Tuff 1; RT1), and zircons from the lower unit (Raebia Tuff 2; RT2). RT1 had zircons with two distinct age populations, but the youngest yield a 230Th deficiency corrected 206Pb/238U age of 665 ± 19 ka, (2s, n = 23, MSWD = 0.81), consistent with the 40Ar/39Ar age 614.9 ± 16.4 ka (2s, full external precision). Preliminary zircon dates on RT2 are more problematic, providing a large range that suggests inheritance by xenoliths and/or locally-sourced detrital zircons. However, a single zircon yielded 230Th deficiency corrected 206Pb/238U age of 708 ± 66 ka (2s, n=17, MSWD = 0.41), which is stratigraphically consistent. These are the first reliable age constraints on a higher elevation Ainaro gravel terrace and fossils they contain. The only other direct ages on the gravels are 230Th- 238U dates on lower terraces interbedded with coral, ranging from 130 ka to Holocene in age (Roosmawati and Harris 2009). These two newly described and dated tephra are likely regionally distributed and may represent important stratigraphic horizons for this portion of Southern Wallacea. They also provide useful data for calculating uplift rates for the region from the middle Pleistocene.

δ18O and Carbonate Clumped Isotopes as Proxies of Lake Level Change: Mono Lake Modern Sediments Inform Pleistocene Interpretations

NASA Astrophysics Data System (ADS)

Westacott, S.; Ingalls, M.; Meixnerova, J.; Betts, M.; Lloyd, M. K.; Miller, L. G.; Sessions, A. L.; Trower, L.; Geobiology Course, A.

2017-12-01

In 1941 LA County began diverting water from the Mono Lake basin, causing lake level to fall dramatically until 1994 when diversion was substantially discontinued. High sedimentation rate (0.7 cm/yr) in combination with rapid, well-documented environmental change offers a unique opportunity to investigate the isotopic fingerprint of lake level change at a much finer scale than is typically accessible in the geologic record. δ18Ocarb can record lake level in a closed-basin system, but relies on knowing the relative contributions from carbonate precipitated from lake water and from authigenic carbonates, both of which are expected to exist in alkaline lake sediments. Here, we combine δ18Ocarb with clumped isotope thermometry (T(Δ47)) on a 70 cm sediment core to "unmix" the carbonate sources and reconstruct δ18Owater of Mono Lake over the past 116 years. Carbonate from the upper 10 cm of the sediment core yields a T(Δ47) of 26°C, reflecting surface water carbonate precipitation during late summer. Carbonates from sediment depths greater than 10cm yield a consistent T(Δ47) of 9.6°C, warmer than today's bottom waters, suggesting dissolution and reprecipitation of originally "warm" carbonate deposited from the water column alongside "cold" water of a different δ18Ow than Mono Lake surface water. A clumped isotope mixing model (Defliese & Lohmann, 2015) used to calculate the relative contributions of the two carbonate precipitates, corroborated by mirrored shifts in δ13Corg and δ13Ccarb down-core, suggests that about half of the carbonate found in the lower 60 cm of the sediment core is authigenic. As an example of how this strategy can be applied to older strata with looser constraints on primary composition, we also analysed the Pleistocene Wilson Creek Formation—lake sediments from Mono Lake's predecessor, Lake Russell. Although Pleistocene Lake Russell should have been cooler than modern Mono Lake, T(Δ47) values were similar to those of modern sediments, suggesting that potentially more of Lake Russell carbonates formed at or near the surface. Clumped isotope analysis thus holds significant potential to improve our interpretation of sedimentary carbonates as proxies for lake level and other paleo-environmental conditions.

Geology and Volcanology of Kima'Kho Mountain, Northern British Columbia: A Pleistocene Glaciovolcanic Edifice

NASA Astrophysics Data System (ADS)

Turnbull, M.; Porritt, L. A.; Edwards, B. R.; Russell, K.

2014-12-01

Kima'Kho Mountain is a 1.8 Ma (40Ar/39Ar of 1.82 +/- 40 ka) Pleistocene an alkali-olivine basaltic tuya situated in northern British Columbia. The volcanic edifice rises 460 m from its base and comprises a central vent, dominated by lapilli-tuff and minor pillow lava and dykes; and a surrounding plateau underlain by a sequence of dipping beds of basaltic tuff-breccia and capped by a series of flat-lying, subaerial lava flows. We present a 1:10,000 geological map for Kima'Kho Mountain building on the preliminary work of Ryane et al. (2010). We use the volcanic stratigraphy to explore the implications of three unique features. (1) The central cone comprises massive to crudely-bedded lapilli tuffs containing abundant armoured lapilli - cores of highly-vesicular pyroclasts coated with blocky to cuspate vitric ash. These units suggest an explosive origin from within an ice-enclosed lake, and deposited by wet, dilute pyroclastic surge events. (2) The entire stratigraphic sequence hosts at least two "passage zones" (cf. Jones, 1969); the presence and geometry of these passage zones constrain ice thicknersses at the time of eruption and inform on the englacial lake dynamics. (3) Lastly, our field-based stratigraphic relationships are at odds with the classic tuya model (i.e. an effusive onset to the eruption, forming pillow basalts, followed by explosive activity). Our field mapping suggests an alternative model of tuya architecture, involving a highly-energetic, sustained explosive onset creating a tephra cone that become emergent followed by effusive eruption to create lavas and a subaqueous lava-fed delta. Jones, J. G. Intraglacial volcanoes of the Laugarvatn region, south-west Iceland-I. Geological Society of London Quarterly Journal 124, 197-211 (1969). Ryane, C., Edwards, B. R. & Russell, J. K. The volcanic stratigraphy of Kima'Kho Mountain: A Pleistocene tuya, northwestern British Columbia. Geological Survey of Canada, Current Research 2011-104, 12p, doi:10.4095/289196 (2011). Figure 1. (Upper Figure) Geological cross-section showing projected distribution of volcanic lithofacies used to define 3 passage zones (PZ#). (Lower Figure) Dynamic evolution and interplay between the rates of volcano growth vs. rise of englacial lake and relationship to passage zones (PZ) mapped at Kima'Kho.

The upper lithostratigraphic unit of ANDRILL AND-2A core (Southern McMurdo Sound, Antarctica): local Pleistocene volcanic sources, paleoenvironmental implications and subsidence in the southern Victoria Land Basin

NASA Astrophysics Data System (ADS)

Del Carlo, P.; Panter, K. S.; Bassett, K. N.; Bracciali, L.; di Vincenzo, G.; Rocchi, S.

2009-12-01

We report results from the study of the uppermost 37 meters of the Southern McMurdo Sound (SMS) AND-2A drillcore, corresponding to the lithostratigraphic unit 1 (LSU 1), the most volcanogenic unit within the core. Nearly all of LSU 1 consists of volcanic breccia and sandstone that is a mixture of near primary volcanic material dominated by lava and vitric clasts with minor exotic material derived from distal basement sources. Lava clasts and glass are mafic and range from strongly alkaline (basanite, tephrite) to moderately alkaline (alkali basalt, hawaiite) compositions that are similar to nearby land deposits. 40Ar-39Ar laser step-heating analyses on groundmass separated from lava clasts yield Pleistocene ages (692±38 and 793±63, ±2σ internal errors). Volcanoes of the Dailey Island group, located ~13 km SW of the drillsite, are a possible source for the volcanic materials based on their close proximity, similar composition and age. A basanite lava flow on Juergens Island yields a comparable Pleistocene age of 775±22 ka. Yet there is evidence to suggest that the volcanic source is much closer to the drillsite and that the sediments were deposited in much shallower water relative to the present-day water depth of 384 mbsl. Evidence for local volcanic activity is based in part on the common occurrence of delicate vitriclasts (e.g. glass shards and Pele’s hair) and a minimally reworked ~2 meter thick monomict breccia that is interpreted to have formed by autobrecciating lava. In addition, conical-shaped seamounts and high frequency magnetic anomalies encompass the drillsite and extend south including the volcanoes of the Dailey Islands. Sedimentary features and structures indicate shallow water sedimentation for the whole of LSU 1. Rippled asymmetric cross-laminated sands and hummocky cross-stratification occur intermittently throughout LSU 1 and indicate water depths shallower than 100 meters. The occurrence of ooliths and layers containing siderite and Fe-rich cement, along with the occurrence of shallow water diatoms, all indicate deposition in shallow waters agitated by waves. These results contrast strikingly with the present water depth, and let us infer rapid recent tectonic subsidence within this segment of the Victoria Land Basin (Terror Rift).

Probe into the origin, development and evolution model of shelf desertizational environment in the last stage of Late Pleistocene

NASA Astrophysics Data System (ADS)

Yu, Hong-Jun; Liu, Jing-Pu; Shan, Qiu-Mei

1998-12-01

Based on study of China's shelf paleoenvironment, this paper summarises the definition of shelf desertization that occurred in the last stage of Late Pleistocene, and discusses the background of its formation and evolution process. Study of shallow layer profiler records and core data revealed that cold-dry aeolian erosion was the major exogenic force on the exposed shelf. Under the prevailing paleo-winter monsoon, part of the exposed marine stratum disintegrated into sand and then desertization occurred. The fine sediments were blown away and deposited on the leeward to form derivative loess deposits.

The relationship between shellbed type and sequence architecture: examples from Japan and New Zealand

NASA Astrophysics Data System (ADS)

Kondo, Yasuo; Abbott, Stephen T.; Kitamura, Akihisa; Kamp, Peter J. J.; Naish, Tim R.; Kamataki, Takanobu; Saul, Gordon S.

1998-12-01

Examples of lithology, fossil content and taphonomic features of shellbeds and intervening less fossiliferous intervals are presented from four Plio-Pleistocene successions (Shimosa Group, Boso Peninsula, Omma Formation, Hokuriku area, Japan, and Okehu, Kai-iwi, and Shakespeare groups in Wanganui, and the Rangitikei Group along the Rangitikei River in New Zealand). As for pre-Pliocene 3rd- and 4th-order depositional sequences, Plio-Pleistocene 5th- to 7th-order depositional sequences contain a variety of shellbeds which are often associated with surfaces or intervals that are characterized by sedimentary condensation, omission or erosion (e.g. sequence boundaries, ravinement surfaces, downlap surfaces and condensed sections). Stratigraphic patterns of shellbed type tend to be similar and repetitive within a basin and a locality. This demonstrates that a specific palaeogeography played an important role in determining the nature of shellbeds. For example, shellbeds formed in the context of toplap are common only in the Shimosa Group, which was deposited in a moderately sheltered sea, the palaeo-Tokyo Bay. Toplap shellbeds are rare in other sequences formed in more open conditions. Despite the variability resulting from such basin characteristics, common styles of shellbeds can be recognized that formed under conditions of marine onlap, backlap, downlap and toplap. Each type of shellbed has a characteristic fossil composition and taphonomy. Onlap and toplap shellbeds contain low-diversity macrobenthic associations including Glycymeris, Mercenaria, Paphies or other bivalves having robust shells, which are often abraded or fragmented. Backlap shellbeds, which are equivalent to the condensed section formed at the maximum transgression, are characterized by dominance of epifaunal macrobenthos such as bryozoa, brachiopoda, pectinid and ostreid bivalves, preserved in a slightly cemented, glauconitic muddy matrix. In contrast to fossils in such condensed sections, the shell density and species diversity of downlap shellbed associations are rather low, and in a few examples the macrobenthic association was buried rapidly in a lower unit of the highstand systems tract (HST) stratigraphically located above the condensed sections. Variations in the stratigraphic distribution of shellbed types are reflected in symmetrical and asymmetrical sequence architectures. Symmetrical sequences have roughly the same thickness of transgressive systems tracts (TST) and highstand systems tracts (HST), and have well segregated shellbeds that were formed during marine onlap and backlap. Asymmetrical cycles have very thin TSTs and much thicker HSTs, and are characterized by the amalgamation of condensed onlap and backlap shellbeds. Such contrasting cycle architectures are interpreted to reflect inner (symmetrical) and outer (asymmetrical) shelf palaeodepositional settings. The amalgamated onlap/backlap shellbeds appear to be common in Plio-Pleistocene sequences. Owing to the short duration of glacio-eustatic sea-level changes with dominant frequencies of 20,000, 40,000 or 100,000 years, shellbeds in the Plio-Pleistocene are relatively simple and thin compared to those formed in ordinary third-order depositional sequences. Infauna-dominated benthic associations are generally more common than in third-order cycles, and epifaunal associations facilitated by taphonomic feedback on sediment-starved shell-gravel substrates occur only in the condensed section corresponding to maximum transgression in most Plio-Pleistocene sequences.

Complete mitochondrial genome sequence of a Middle Pleistocene cave bear reconstructed from ultrashort DNA fragments.

PubMed

Dabney, Jesse; Knapp, Michael; Glocke, Isabelle; Gansauge, Marie-Theres; Weihmann, Antje; Nickel, Birgit; Valdiosera, Cristina; García, Nuria; Pääbo, Svante; Arsuaga, Juan-Luis; Meyer, Matthias

2013-09-24

Although an inverse relationship is expected in ancient DNA samples between the number of surviving DNA fragments and their length, ancient DNA sequencing libraries are strikingly deficient in molecules shorter than 40 bp. We find that a loss of short molecules can occur during DNA extraction and present an improved silica-based extraction protocol that enables their efficient retrieval. In combination with single-stranded DNA library preparation, this method enabled us to reconstruct the mitochondrial genome sequence from a Middle Pleistocene cave bear (Ursus deningeri) bone excavated at Sima de los Huesos in the Sierra de Atapuerca, Spain. Phylogenetic reconstructions indicate that the U. deningeri sequence forms an early diverging sister lineage to all Western European Late Pleistocene cave bears. Our results prove that authentic ancient DNA can be preserved for hundreds of thousand years outside of permafrost. Moreover, the techniques presented enable the retrieval of phylogenetically informative sequences from samples in which virtually all DNA is diminished to fragments shorter than 50 bp.

Complete mitochondrial genome sequence of a Middle Pleistocene cave bear reconstructed from ultrashort DNA fragments

PubMed Central

Dabney, Jesse; Knapp, Michael; Glocke, Isabelle; Gansauge, Marie-Theres; Weihmann, Antje; Nickel, Birgit; Valdiosera, Cristina; García, Nuria; Pääbo, Svante; Arsuaga, Juan-Luis; Meyer, Matthias

2013-01-01

Although an inverse relationship is expected in ancient DNA samples between the number of surviving DNA fragments and their length, ancient DNA sequencing libraries are strikingly deficient in molecules shorter than 40 bp. We find that a loss of short molecules can occur during DNA extraction and present an improved silica-based extraction protocol that enables their efficient retrieval. In combination with single-stranded DNA library preparation, this method enabled us to reconstruct the mitochondrial genome sequence from a Middle Pleistocene cave bear (Ursus deningeri) bone excavated at Sima de los Huesos in the Sierra de Atapuerca, Spain. Phylogenetic reconstructions indicate that the U. deningeri sequence forms an early diverging sister lineage to all Western European Late Pleistocene cave bears. Our results prove that authentic ancient DNA can be preserved for hundreds of thousand years outside of permafrost. Moreover, the techniques presented enable the retrieval of phylogenetically informative sequences from samples in which virtually all DNA is diminished to fragments shorter than 50 bp. PMID:24019490

Under the Skin of a Lion: Unique Evidence of Upper Paleolithic Exploitation and Use of Cave Lion (Panthera spelaea) from the Lower Gallery of La Garma (Spain).

PubMed

Cueto, Marián; Camarós, Edgard; Castaños, Pedro; Ontañón, Roberto; Arias, Pablo

2016-01-01

Pleistocene skinning and exploitation of carnivore furs have been previously inferred from archaeological evidence. Nevertheless, the evidence of skinning and fur processing tends to be weak and the interpretations are not strongly sustained by the archaeological record. In the present paper, we analyze unique evidence of patterned anthropic modification and skeletal representation of fossil remains of cave lion (Panthera spelaea) from the Lower Gallery of La Garma (Cantabria, Spain). This site is one of the few that provides Pleistocene examples of lion exploitation by humans. Our archaeozoological study suggests that lion-specialized pelt exploitation and use might have been related to ritual activities during the Middle Magdalenian period (ca. 14800 cal BC). Moreover, the specimens also represent the southernmost European and the latest evidence of cave lion exploitation in Iberia. Therefore, the study seeks to provide alternative explanations for lion extinction in Eurasia and argues for a role of hunting as a factor to take into account.

Under the Skin of a Lion: Unique Evidence of Upper Paleolithic Exploitation and Use of Cave Lion (Panthera spelaea) from the Lower Gallery of La Garma (Spain)

PubMed Central

Camarós, Edgard; Castaños, Pedro; Ontañón, Roberto; Arias, Pablo

2016-01-01

Pleistocene skinning and exploitation of carnivore furs have been previously inferred from archaeological evidence. Nevertheless, the evidence of skinning and fur processing tends to be weak and the interpretations are not strongly sustained by the archaeological record. In the present paper, we analyze unique evidence of patterned anthropic modification and skeletal representation of fossil remains of cave lion (Panthera spelaea) from the Lower Gallery of La Garma (Cantabria, Spain). This site is one of the few that provides Pleistocene examples of lion exploitation by humans. Our archaeozoological study suggests that lion-specialized pelt exploitation and use might have been related to ritual activities during the Middle Magdalenian period (ca. 14800 cal BC). Moreover, the specimens also represent the southernmost European and the latest evidence of cave lion exploitation in Iberia. Therefore, the study seeks to provide alternative explanations for lion extinction in Eurasia and argues for a role of hunting as a factor to take into account. PMID:27783697

Food for thought: Sub-fossil and fossil chelonian remains from Franchthi Cave and Megalopolis confirm a glacial refuge for Emys orbicularis in Peloponnesus (S. Greece)

NASA Astrophysics Data System (ADS)

Vlachos, Evangelos; Delfino, Massimo

2016-10-01

Peloponnesus peninsula (S. Greece) shows a remarkable extant chelonian fauna that has received considerable attention from a molecular and morphological point of view. Here we present new evidence from the fossil and sub-fossil record of two important sites in the area, Franchthi Cave and Megalopolis. The archaeological material from Franchthi Cave (Upper Paleolithic - Neolithic/latest Pleistocene - early Holocene) represents food remains from small game prey of the humans that inhabited the cave. The palaeontological material from Megalopolis (Late Pleistocene) comes from old and new excavations. The studied specimens, combined with information from molecular, climatic and zoological works, provide for the first time direct evidence for the presence of the European pond turtle, Emys orbicularis, in the glacial refuge of South Greece that was hypothesized on the basis of the results of molecular investigations. We also describe other chelonian taxa present in the localities, the Hermann's tortoise Testudo hermanni and the Balkan stripe-necked terrapin Mauremys rivulata, and review previously published chelonian material from Peloponnesus.

Late Pleistocene sediments and fossils near the mouth of Mad River, Humboldt County, California: Facies analysis, sequence development, and possible age correlation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, E.W.

Study of late Pleistocene-age sediments near the mouth of the Mad River revealed a sequence of nearshore marine and shallow bay deposits. This sequence, bounded by unconformities, is informally named the Mouth of Mad unit. The Mouth of mad unit can be divided into four distinct depositional facies at the study site. The lowest facies are the Nearshore Sand and Estuarine Mud, which lie unconformably on a paleosol. The sand facies grades upward into a high-energy, interbedded Nearshore Sand and Gravel facies containing storm and rip-channel deposits. Above the sand and gravel is a Strand-Plain Sand facies. This sand ismore » overlain by a laterally variable sequence of shell-rich Bay facies. The bay deposits can be further divided into five subfacies: (1) a Bioturbated Sand; (2) a Lower Tidal Flat Mud; (3) a Mixed Sand and Mud; (4) an oyster-rich Bay Mud; and (5) an Upper Tidal Flat Mud. The bay sequence is overlain unconformably by younger late Pleistocene-age marine terrace deposits. The depositional environments represented by these facies progress from a shoreline estuary to nearshore deposits, above storm wave base, and slowly back to shoreline and finally shallow bay conditions. The Mouth of Mad unit represents a transgressive-regressive sequence, involving the development of a protective spit. The uppermost mud within the Mouth of Mad unit has been dated, using thermoluminescence age estimation, at 176 [+-] 33 ka, placing it in the late Pleistocene. The Mouth of Mad unit appears to be younger than the fossiliferous deposits at Elk Head, Crannell Junction, Trinidad Head, Moonstone Beach, and the Falor Formation near Maple Creek, and possibly time equivalent with gravel deposits exposed at the western end of School Road in McKinleyville.« less

Plio-pleistocene volcano-tectonic evolution of la Reforma Caldera, Baja California, Mexico

NASA Astrophysics Data System (ADS)

Demant, Alain; Ortlieb, Luc

1981-01-01

La Reforma volcanic complex, in east-central Baja California, shows a characteristic caldera structure, 10 km in diameter. The first eruptive stage, during the Pliocene, was manifested by ash and pumice falls and by subaqueous pumitic flows. In a second stage basic flows were deposited in a near-shore environment (subaerial and pillow lavas). During the early Pleistocene a large ignimbritic eruption, producing mainly pantelleritic tuffs, immediately predated the formation of the caldera itself. Afterwards, along marginal fractures of the caldera, some rhyolitic domes and flows partially covered the thick ignimbritic sheet. A block of Miocene substratum, in the center of the caldera, has been uplifted, nearly 1 km, by "resurgent doming". Small outcrops of diorite might constitute the top of coarse-grained crystallized magmatic bodies, and thus support the "resurgent doming" interpretation. A few basaltic cones were finally built on the flanks of the caldera complex; the latter are not related to the caldera history but to the extension tectonics of the Gulf of California which are also responsible for the Tortuga Island and the Holocene Tres Virgenes tholeiitic cones. South of la Reforma are found the highest (+300 m) Pleistocene marine deposits of the Gulf coast of Baja California. The uplift of this area is due in part to the positive epeirogenic movements of the whole peninsular crustal block, and also to the late doming of the caldera. On the coastal (eastern) flank of La Reforma complex up to seven stepped wave-cut terraces have been preserved, the highest reaching more than +150 m and the lowest ones +25 m. Lateral correlations of the marine terraces along the whole Gulf of California suggest that this volcano-tectonic uplift, that is still active, is of the order of 240 mm/10 3 y. The set of terraces is interpreted to be Middle (700-125 × 10 3y) to Upper (125-80 × 10 3y) Pleistocene, and is tentatively correlated with the paleoclimatic chronology of deep-sea cores.

The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective

NASA Technical Reports Server (NTRS)

Scherer, Reed P.

1993-01-01

Recent glaciological evaluation and modeling of the marine-based West Antarctic Ice Sheet (WAIS) support the possibility that the WAIS disintegrated during one or more Pleistocene interglacial period(s). The magnitude of sea level and oxygen isotope variation during certain late-Pleistocene interglacial periods is also consistent with the possibility of major retreat of the WAIS. Although oxygen isotopes from deep-sea sediments provide the best available proxy record for global ice volume (despite the ambiguities in the record), the source of ice volume changes must be hypothesized. Based on the intensity of interglacial isotopic shifts recorded in Southern Ocean marine sedimentary records, stage 11 (400,000 years ago) is the strongest candidate for WAIS collapse, but the records for stages 9, 7, and 5.5 are all consistent with the possibility of multiple late-Pleistocene collapses. Seismic reflection studies through the WAIS have revealed thick successions of strata with seismic characteristics comparable to upper Tertiary marine sediments. Small samples of glacial diamictons from beneath the ice sheet have been collected via hot-water drilled access holes. These sediments include mixed diatom assemblages of varying ages. Late-Miocene diatoms dominate many samples, probably reflecting marine deposition in West Antarctic basins prior to development of a dominantly glacial phase in West Antarctica. In addition to late-Miocene diatoms, samples from Upstream B (1988/89) contain rare post-Miocene diatoms, many of which imply deposition in the West Antarctic interior during one or more Pleistocene deglaciation periods. Age-diagnostic fossils in glacial sediments beneath ice sheets provide relatively coarse chronostratigraphic control, but they do contain direct evidence of regional deglaciation. Thus, sub-glacial till samples provide the evidence regarding the source of ice sheet variability seen in well-dated proxy records. Combined, these independent data sets can provide a more comprehensive and less speculative interpretation of the history of past glacial minima in currently glaciated polar regions.

Global Miocene tectonics and the modern world

NASA Astrophysics Data System (ADS)

Potter, Paul Edwin; Szatmari, Peter

2009-11-01

An amazing congruence of seemingly unrelated, diverse global events began in the Middle and Upper Miocene and established our modern world. Two global orogenic belts were active, mostly in the Middle and Upper Miocene, while backarc basins formed along the eastern margin of Asia. Coincident with these events global temperatures cooled in both the ocean and atmosphere, desertification occurred from Central Asia into and across most of northern Africa and also in Australia, and in southern South America. Coincident with the expansion of the Antarctic ice cap at 14 Ma, there was initial widespread deep sea erosion and changes in patterns of deep sea sedimentation. Muddy pelagic sedimentation increased six-fold in the North and Central Atlantic and Pacific Oceans and global changes in circulation lead to more diatomites in the Pacific and fewer in the Atlantic. By the end of the Miocene most of the Mediterranean Sea had evaporated. Broadly coincident with these events, many old, large river systems were destroyed and new ones formed as much of the world's landscape changed. Collectively, these global on-shore tectonic and ocean-atmospheric events provide the foundation for our modern world—a mixture of new and rejuvenated orogenic belts and their far-field effects (distant epiorogenic uplift, rain-shadow deserts, large alluvial aprons, and distant deltas) as inherited Gondwanan landscapes persisted remote from plate boundaries. Thus at the end of the Miocene much of the world's landscape, except for that changed by Pleistocene continental glaciation, would be recognizable to us today. We argue that all of these events had the same ultimate common cause-an internal Earth engine-that drove plate motions in two broad ways: first, the opening and closing of seven key gateways to deep-water oceanic currents radically altered global heat transfer and changed a lingering Greenhouse to an Icehouse world; secondly, these events were in part coincident with renewed heat flow in the African and Pacific Superplumes that energized global plate motions in the Middle and Upper Miocene. We hope this global synthesis will stimulate more research on the many global events of the Miocene—to understand better both our modern world and earlier global orogenies.

Biostratigraphy and chronostratigraphy of the area between Sarasota and Lake Okeechobee, southern Florida: An integrated approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wingard, G.L.; Edwards, L.E.; McCartan, L.

1993-03-01

Preliminary analysis of paleontologic and isotopic data from 15 coreholes, integrated with the lithostratigraphic framework, has revealed three chronostratigraphic depositional units in the subsurface of the Arcadia and Sarasota 30 [times] 60-minute quadrangles, in the southern Florida peninsula. (1) An upper Oligocene depositional unit unconformably overlies the lower Oligocene Suwannee Formation and has been dated by using [sup 87]Sr/[sup 86]Sr values and molluscs. (2) A lower and middle Miocene depositional unit has been dated on the basis of [sup 87]Sr/[sup 86]Sr values, molluscs, and dinoflagellates. The upper boundary of this unit is marked by the top of the Venice Claymore » in the western part of the study area. (3) A Pliocene and Pleistocene depositional unit, dated on the basis of [sup 87]Sr/[sup 86]Sr values, molluscs, dinoflagellates, foraminifera, ostracodes, and pollen, unconformably overlies the lower and middle Miocene beds; this unconformity represents approximately a 13-million-year gap in the record. The Pliocene and Pleistocene unit is seen in the surficial deposits of the Caloosahatchee, Tamiami, Bermont, and Fort Thompson Formations. The interpretation of Florida's geologic history is hampered by the interfingering of onlap/offlap cycles from two coastlines, a unique situation in southeastern coastal plain geology. In addition, a complex diagenetic history, mixing of carbonate and siliciclastic regimes, and lack of surface exposures make interpretation of the stratigraphic sequences difficult. The chronostratigraphic depositional units identified cut across lithofacies boundaries and allow correlation across the Florida peninsula, thus leading to the development of coherent, well-defined lithostratigraphic units.« less

First documentation of tidal-channel sponge biostromes (upper Pleistocene, southeastern Florida)

USGS Publications Warehouse

Cunningham, K.J.; Rigby, J.K.; Wacker, M.A.; Curran, H.A.

2007-01-01

Sponges are not a common principal component of Cenozoic reefs and are more typically dominant in deep-water and/or cold-water localities. Here we report the discovery of extensive upper Pleistocene shallow-marine, tropical sponge biostromes from the Mami Limestone of southeastern Florida built by a new ceractinomorph demosponge. These upright, barrel- to vase-shaped sponges occur in monospecific aggregations constructed within the tidal channels of an oolitic tidal-bar belt similar to modern examples on the Great Bahama Bank. The biostromes appear to have a ribbon-like geometry, with densely spaced sponges populating a paleochannel along a 3.5 km extent in the most lengthy biostrome. These are very large (as high as 2 m and 1.8 m in diameter), particularly well-preserved calcified sponges with walls as hard as concrete. Quartz grains are the most common particles agglutinated in the structure of the sponge walls. Where exposed, sediment fill between the sponges is commonly a highly burrowed or cross-bedded ooid-bearing grainstone and, locally, quartz sand. It is postulated that the dense, localized distribution of these particular sponges was due to a slight edge over competitors for food or energy supply and space in a stressed environment of tidal-influenced salinity and nutrient changes, strong currents, and frequently shifting submarine sand dunes. To our knowledge, this represents the first documentation of sponge biostromes composed of very large upright sponges within high-energy tidal channels between ooid shoals. The remarkably well-preserved accumulations provide an alternative example of sponge reefs for comparative paleoenvironmental studies. ?? 2007 The Geological Society of America.

Pleistocene plants from North Carolina

USGS Publications Warehouse

Berry, Edward Wilber

1926-01-01

The field work upon which this report is based was done in 1906 and 1907 as a part of the cooperative study of the Atlantic Coastal Plain, under the direction of the late William Bullock Clark. Associated with the writer in this work were L. W. Stephenson, B. L. Miller, Jr., and J. E. Pogue. Preliminary accounts of the plants collected were published in 1907 and 1909. As has been frequently emphasized, the study of the Pleistocene floras in this country is in an exceedingly backward state as measured by the volume and precision of our knowledge of Pleistocene floras in Europe. Researches in Pleistocene geology in North America have been confined almost entirely to glaciology, and the problem of the correlation of the glacial deposits with those outside the glaciated area has not been solved, nor is there any general agreement regarding the genesis of the Pleistocene deposits south of the terminal moraines. The present account of what is known of the Pleistocene flora of North Carolina and the conclusions that may be legitimately derived from it is offered in the hope that it may stimulate an interest in a neglected field of research and form a small part of the evidence upon which to base future more comprehensive conclusions and generalizations. A word of explanation regarding the illustrations is required. Nearly all of them have been made from leaves preserved as carbonaceous films in the peaty clays. These specimens were carefully washed out, and blue prints were made directly from them. Outlines and as much of the venation as could be seen were inked on the blue prints, which were then bleached. This procedure made it possible to handle a much larger amount of material and prevented any possible damage to the exceedingly fragile specimens, which were mounted on cards or between glass. The accompanying drawings were made from tracings of the original nature prints.

Estimated post-Messinian sediment supply and sedimentation rates on the Ebro continental margin, Spain

USGS Publications Warehouse

Nelson, C.H.

1990-01-01

Because of the extensive data base of seismic profiles, radiometric ages, and stratigraphic time markers such as the subaerial Messinian surface, sedimentation rates and Ebro River sediment discharge can be estimated for different periods and environments of the Ebro continental margin. New values for sediment discharge (i.e., 6.2 versus previous estimates of 2-3.5 million t/yr) for the Holocene highstand are more reliable but remain minimum estimates because a small proportion of Ebro sediment advected to the Balearic Rise and Abyssal Plain cannot be accounted for, especially during lowstands. The general highstand conditions of the Pliocene, which were similar to those of the Holocene, resulted in a low discharge of Ebro River sediment (ca. 6.5 million t/yr) and an even thickness of sediment across the margin that deposited at rates of about 24-40 cm/ky. In contrast, sediment supply increased two-three times during the Pleistocene, the margin prograded rapidly and deposition occurred at rates of 101-165 cm/ky on the outer shelf and slope, but basin floor rates remained anomalously low (21-26 cm/ky) because sediment was drained and broadly dispersed eastward in Valencia Trough. During the late Pleistocene rise of sea level, the main depocenters progressively shifted shoreward and sedimentation rates greatly decreased from 175 cm/ky on the upper slope during the early transgression to 106 cm/ky on the outer shelf and then to 63 cm/ky on the mid-shelf during the late transgression as the river sediment discharge dropped to half by Holocene time. Maximal sedimentation rates occurred in active depocenters of sediment dispersal such as the Holocene delta (370 cm/ky) or the youngest Pleistocene Oropesa channel-levee complex (705 cm/ky) where deposition rates increased by an order of magnitude or more compared to average Ebro shelf (38 cm/ky) or base-of-slope rates in the Pleistocene (21 cm/ky). The sedimentation rates verify the importance of sea-level control on the progressive change in location of depocenters and amount of sediment supply, but Pleistocene climatic change and deforestation alone can be observed to double river sediment discharge. The latter observation helps explain the anomalously high deposition rates in Pleistocene turbidite systems compared with older systems that may be controlled more by tectonic and sea-level changes alone. During the past 2000 years, in contrast, man has controlled deposition in the Ebro margin system, first by deforestation that more than doubled river sediment discharge and shelf deposition rates to equal those of Pleistocene time; and second by dam contruction that reduced sediment discharge to less than 5% of the normal Holocene discharge. Similar recent discharge reductions from the Nile and Rhone Rivers suggest that loss of the majority of the river sediment supply in the Mediterranean Sea may result in significant erosion of biologically and agriculturally important lobate delta areas. ?? 1990.

Mountain front migration and drainage captures related to fault segment linkage and growth: The Polopos transpressive fault zone (southeastern Betics, SE Spain)

NASA Astrophysics Data System (ADS)

Giaconia, Flavio; Booth-Rea, Guillermo; Martínez-Martínez, José Miguel; Azañón, José Miguel; Pérez-Romero, Joaquín; Villegas, Irene

2013-01-01

The Polopos E-W- to ESE-WNW-oriented dextral-reverse fault zone is formed by the North Alhamilla reverse fault and the North and South Gafarillos dextral faults. It is a conjugate fault system of the sinistral NNE-SSW Palomares fault zone, active from the late most Tortonian (≈7 Ma) up to the late Pleistocene (≥70 ky) in the southeastern Betics. The helicoidal geometry of the fault zone permits to shift SE-directed movement along the South Cabrera reverse fault to NW-directed shortening along the North Alhamilla reverse fault via vertical Gafarillos fault segments, in between. Since the Messinian, fault activity migrated southwards forming the South Gafarillos fault and displacing the active fault-related mountain-front from the north to the south of Sierra de Polopos; whilst recent activity of the North Alhamilla reverse fault migrated westwards. The Polopos fault zone determined the differential uplift between the Sierra Alhamilla and the Tabernas-Sorbas basin promoting the middle Pleistocene capture that occurred in the southern margin of the Sorbas basin. Continued tectonic uplift of the Sierra Alhamilla-Polopos and Cabrera anticlinoria and local subsidence associated to the Palomares fault zone in the Vera basin promoted the headward erosion of the Aguas river drainage that captured the Sorbas basin during the late Pleistocene.

Diatoms and stratigraphically significant silicoflagellates from the Atlantic Margin Coring Project and other Atlantic margin sites

USGS Publications Warehouse

Abbott, W.H.

1980-01-01

In 1976, 19 sites were cored along the U.S. Atlantic Continental Shelf and Slope by the Oceanographic Branch of the U.S. Geological Survey aboard the Glomar Conception. Only 6 sites contained siliceous microfossil assemblages of sufficient quantity and quality for biostratigraphic study. Two of the sites, AMCOR (Atlantic Margin Coring Project) 6002 and AMCOR 6011, contained good Miocene assemblages: a small Pleistocene assemblage occurred at the top of AMCOR 6002. A Late Miocene to Early Pliocene assemblage was encountered in AMCOR 6007B. AMCOR 6013, 6019, and 6021 contained Pleistocene assemblages. In addition to the AMCOR cores, 3 additional Atlantic Margin cores were studied. These were the JOIDES 1 (Caldrill) core, and Atlantic Slope Project (ASP) cores 10 and 22. JOIDES 1 contains a Middle Miocene assemblage similar to AMCOR 6002. ASP 10 contains a Lower Pliocene assemblage and ASP 22 contains a Middle to Late Oligocene and a Pleistocene assemblage. Siliceous assemblages at all sites consisted mainly of shallow shelf species, including brackish and marine benthics and occasionally freshwater forms. Although planktonic forms were present, they were few and most were extant cosmopolitan species. This makes it difficult to correlate the biostratigraphy of the sediments with siliceous microfossil zonations from other oceans. The only biostratigraphic zonations for Atlantic Shelf diatom assemblages are for the Miocene.

Finding palaeowaters in a multi-layered aquifer system in the Lom depression of Danubian Plain in Bulgaria

NASA Astrophysics Data System (ADS)

Túri, Marianna; Palcsu, László; Molnár, Mihály; Futó, István; Orehova, Tatiana; Toteva, Aglaida; Hristov, Vladimir; Benderev, Aleksey

2017-04-01

This work is an environmental isotope investigation of groundwater samples from a multi-layered aquifer system in the Lom depression of Danubian Plain in Bulgaria. Our previous studies in the Carpathian-Pannonian Region had been convinced through groundwater researches using noble gas temperatures that the recharge temperature difference between the Holocene and the late Pleistocene recharged waters is 9.13±0.89°C. The aim of this research in Bulgaria is to observe this phenomenon at the outside of the Carpathian-Pannonian Region. The purpose of the sampling campaign was to find out that one of the aquifers of the Lom depression could be a potential site for late Pleistocene, and Holocene paleoclimate reconstruction. There are water samples from the Dacian-Romanian complex, Upper-Pontian aquifer, Meotian-Lower Pontian aquitard and the Sarmatian aquifer as well. The collected water samples were examined for water chemistry, stable carbon, oxygen and hydrogen isotopes, and for noble gas concentrations, and besides them for radiocarbon and tritium. The radiocarbon content of the water samples are in the range from 15.9 pMC to 98.6 pMC. Based on the obtained radiocarbon values it can be stated that tree aquifers of four could be contain such waters which recharged during the early Holocene late Pleistocene (Pontian, Dacian, Sarmatian). There are two wells in the Pontian aquifer (Dolni Tsibar, 20.8 pMC; Agroinvest, 23.8 pMC) with lower radiocarbon content. Based on the stable oxygen composition of the Agroinvest well, which is with -14.2 ‰ more negative than the others so it can be late Pleistocene recharged water. In the Dacian aquifer might be one well, the Valchedram which can be late Pleistocene recharged with 23.7 pMC. In the Sarmatian aquifer can be find the oldest water sample from all with 15.9 pMC of Smirnenski. The obtained noble gas temperatures and tritium values might be stated this hypothesis as well. All measurements were carried out in Hertelendi Laboratory of Environmental Studies, Institute for Nuclear Research, Hungarian Academy of Sciences. The research was supported by the European Union and the State of Hungary, co-financed by the European Regional Development Fund in the project of GINOP-2.3.2.-15-2016-00009 'ICER'.

Transitions or turnovers? Climatically-forced extinctions of Homo sapiens and Neanderthals in the east Mediterranean Levant

NASA Astrophysics Data System (ADS)

Shea, John J.

2008-11-01

The East Mediterranean Levant is a focal point for debate about evolutionary continuity among Late Pleistocene hominin populations. Changes in the Levantine Middle and Upper Palaeolithic archaeological records are almost invariably described in terms of adaptive shifts and behavioural transitions, rather than as changes in hominin populations. This paper examines evidence for hominin evolutionary continuity in the Levant between 130 and 25 ka. Two inflection points, one within the Middle Palaeolithic ca 75 ka and the other between the Middle and Upper Palaeolithic ca 45 ka, are examined in light of recently-discovered evidence for rapid climate change and environmental deterioration. It is proposed that both periods mark regional extinctions and turnovers of hominin populations. The first of these occurred among early Homo sapiens, the second among Neanderthals. Each event was followed by dispersal of hominin populations into the Levant from adjacent regions. Differences in Middle vs. Upper Palaeolithic Homo sapiens' long-term success in the Levant may reflect recently-evolved strategies for coping with rapid climate change and with colder arid habitats.

Quaternary Geologic Map of Connecticut and Long Island Sound Basin

USGS Publications Warehouse

Stone, Janet Radway; Schafer, John P.; London, Elizabeth Haley; DiGiacomo-Cohen, Mary L.; Lewis, Ralph S.; Thompson, Woodrow B.

2005-01-01

The Quaternary geologic map (sheet 1) and explanatory figures and cross sections (sheet 2) portray the geologic features formed in Connecticut during the Quaternary Period, which includes the Pleistocene (glacial) and Holocene (postglacial) Epochs. The Quaternary Period has been a time of development of many details of the landscape and of all the surficial deposits. At least twice in the late Pleistocene, continental ice sheets swept across Connecticut. Their effects are of pervasive importance to the present occupants of the land. The Quaternary geologic map illustrates the geologic history and the distribution of depositional environments during the emplacement of glacial and postglacial surficial deposits and the landforms resulting from those events.

Early Levallois and the beginning of the Middle Paleolithic in central Italy.

PubMed

Soriano, Sylvain; Villa, Paola

2017-01-01

In the second half of the 19th century Pleistocene faunas were discovered in two sites, Sedia del Diavolo and Monte delle Gioie, contained in deposits of the Aniene River in the area of Rome (Latium, Italy). Fieldwork by A.C. Blanc in the late 1930's proved the association of fauna and lithic industry within fluvial deposits interbedded with volcanoclastic layers. A human femoral diaphysis and a metatarsal were later identified in the faunal assemblage from Sedia del Diavolo and evaluated as Neandertal. The lithic assemblages from these two sites were the basis of the definition of the Protopontinian by M. Taschini, which she viewed as a late Middle Pleistocene industry very similar to the later, Upper Pleistocene Pontinian industries, thought to be characteristic of the Latium Mousterian. The chronostratigraphic framework of the Aniene river deposits has been recently updated and the lithic assemblages from these two sites are now confidently dated between 295 and 290 ka, close to the transition from MIS 9 to MIS 8. They fit chronologically between the industries of layers m and d from Torre in Pietra, a site 26 km northwest of Rome. The presence of the Levallois debitage is indisputable yet it occurs within an original technical context, different from what is known in other early occurrences of the Levallois. The date confirms the proposed chronology for the early Levallois in Europe. More importantly these two assemblages demonstrate that this technology can emerge in more diversified contexts than usually described. This suggests that its dispersal in Europe may have been rapid.

Paleo-environments of Late Pliocene to Early Pleistocene Foreland-Basin Deposits in the Western Foothills of South-Central Taiwan

NASA Astrophysics Data System (ADS)

Chiu, Tzu-Hsuan; Tien-Shun Lin, Andrew; Chi, Wen-Rong; Wang, Shih-Wei

2017-04-01

Lithofacies and paleo-environmental analyses of the Pliocene-Pleistocene deposits of Taiwan provide a framework to understand the stratigraphic development of foreland basin to the west of the orogenic belt. In this study, we performed lithofacies analyses and biostratigraphic studies on calcareous nannofossils in two areas in south-central Taiwan, the Jhuoshuei River, and the Hushan Reservoir, respectively. The studied lithostratigraphic units are the Chinshui Shale, the Cholan Formation, and the Toukoshan Formation, in an ascending order, with a total stratigraphic thickness more than 3500 m in central Taiwan. Sixteen lithofacies and four lithofacies associations are identified, pertaining to tide-dominated deltaic systems bordering a shallow marine setting in the foreland basin. A few wide-spread layers of thickly-bedded sandstones featuring ball-and-pillow structures are interpreted as resulting from earthquake shaking (i.e., seismites). In addition, the vertical facies change shows a coarsening and shallowing-upward succession, indicating the gradually filling up of the foreland basin by sediment progradation. The progradation is interpreted to result from westward migrating orogenic belt and an increase in sediment supply. The top 2000-m thick foreland succession (i.e., the uppermost part of the Cholan Formation, and the Toukoshan Formation) is dominantly fluvial deposits with occasional intercalations of shoreface sediments, indicating an extremely rapid and balanced rate of basin subsidence and sediment supply for the past 1.5 Ma. Vertebrate fossils of deer and elephants are identified in the upper Cholan Formation deposited in coastal to fluvial settings. Keywords: Pliocene-Pleistocene Epoch, lithofacies, foreland basin, Taiwan

Early Levallois and the beginning of the Middle Paleolithic in central Italy

PubMed Central

2017-01-01

In the second half of the 19th century Pleistocene faunas were discovered in two sites, Sedia del Diavolo and Monte delle Gioie, contained in deposits of the Aniene River in the area of Rome (Latium, Italy). Fieldwork by A.C. Blanc in the late 1930’s proved the association of fauna and lithic industry within fluvial deposits interbedded with volcanoclastic layers. A human femoral diaphysis and a metatarsal were later identified in the faunal assemblage from Sedia del Diavolo and evaluated as Neandertal. The lithic assemblages from these two sites were the basis of the definition of the Protopontinian by M. Taschini, which she viewed as a late Middle Pleistocene industry very similar to the later, Upper Pleistocene Pontinian industries, thought to be characteristic of the Latium Mousterian. The chronostratigraphic framework of the Aniene river deposits has been recently updated and the lithic assemblages from these two sites are now confidently dated between 295 and 290 ka, close to the transition from MIS 9 to MIS 8. They fit chronologically between the industries of layers m and d from Torre in Pietra, a site 26 km northwest of Rome. The presence of the Levallois debitage is indisputable yet it occurs within an original technical context, different from what is known in other early occurrences of the Levallois. The date confirms the proposed chronology for the early Levallois in Europe. More importantly these two assemblages demonstrate that this technology can emerge in more diversified contexts than usually described. This suggests that its dispersal in Europe may have been rapid. PMID:29053710

Paleoproductivity in the northwestern Pacific Ocean during the Pliocene-Pleistocene climate transition (3.0-1.8 Ma)

NASA Astrophysics Data System (ADS)

Venti, Nicholas L.; Billups, Katharina; Herbert, Timothy D.

2017-02-01

Alkenone mass accumulation rates (MARs) provide a proxy for export productivity in the northwestern Pacific (Ocean Drilling Program Site 1208) spanning the late Pliocene through early Pleistocene (3.0-1.8 Ma). We investigate changes in productivity associated with global cooling during the onset and expansion of Northern Hemisphere glaciation (NHG). Alkenone MARs vary on obliquity timescales throughout, but the amplitude increases at 2.75 Ma concurrent with the intensification of NHG and cooling of the sea surface by 3°C. The obliquity-scale variations in alkenone MARs parallel shipboard measurements of sediment color reflectance (%) with higher MARs significantly correlated (>95%) with darker (opal-rich) intervals. Variations in both lead benthic foraminiferal δ18O values by 1.5-2 kyr suggesting that export productivity may be a contributing factor, rather than a response, to the extent of continental glaciation. The biological pump is therefore a plausible mechanism for transferring atmospheric CO2 into the deep ocean during the onset of NHG and the ensuing obliquity-dominated climate regime. Obliquity-scale correlation between productivity and magnetic susceptibility is consistent with a link via westerly winds delivering terrigenous sediments and mixing the upper water column. Alkenone MARs also contain a 400 kyr modulation. Because this periodicity is a multiple of the residence time of carbon in the ocean, it may reflect inputs of new nutrients associated with eccentricity-forced changes in the terrestrial biosphere and weathering. We ascribe these findings to interactions between the East Asian winter monsoon and productivity in the North Pacific Ocean, perhaps contributing to Plio-Pleistocene climate change.

Paleodistributions and Comparative Molecular Phylogeography of Leafcutter Ants (Atta spp.) Provide New Insight into the Origins of Amazonian Diversity

PubMed Central

Solomon, Scott E.; Bacci, Mauricio; Martins, Joaquim; Vinha, Giovanna Gonçalves; Mueller, Ulrich G.

2008-01-01

The evolutionary basis for high species diversity in tropical regions of the world remains unresolved. Much research has focused on the biogeography of speciation in the Amazon Basin, which harbors the greatest diversity of terrestrial life. The leading hypotheses on allopatric diversification of Amazonian taxa are the Pleistocene refugia, marine incursion, and riverine barrier hypotheses. Recent advances in the fields of phylogeography and species-distribution modeling permit a modern re-evaluation of these hypotheses. Our approach combines comparative, molecular phylogeographic analyses using mitochondrial DNA sequence data with paleodistribution modeling of species ranges at the last glacial maximum (LGM) to test these hypotheses for three co-distributed species of leafcutter ants (Atta spp.). The cumulative results of all tests reject every prediction of the riverine barrier hypothesis, but are unable to reject several predictions of the Pleistocene refugia and marine incursion hypotheses. Coalescent dating analyses suggest that population structure formed recently (Pleistocene-Pliocene), but are unable to reject the possibility that Miocene events may be responsible for structuring populations in two of the three species examined. The available data therefore suggest that either marine incursions in the Miocene or climate changes during the Pleistocene—or both—have shaped the population structure of the three species examined. Our results also reconceptualize the traditional Pleistocene refugia hypothesis, and offer a novel framework for future research into the area. PMID:18648512

Effects of climatic and geological processes during the pleistocene on the evolutionary history of the northern cavefish, Amblyopsis spelaea (teleostei: amblyopsidae).

PubMed

Niemiller, Matthew L; McCandless, James R; Reynolds, R Graham; Caddle, James; Near, Thomas J; Tillquist, Christopher R; Pearson, William D; Fitzpatrick, Benjamin M

2013-04-01

Climatic and geological processes associated with glaciation cycles during the Pleistocene have been implicated in influencing patterns of genetic variation and promoting speciation of temperate flora and fauna. However, determining the factors promoting divergence and speciation is often difficult in many groups because of our limited understanding of potential vicariant barriers and connectivity between populations. Pleistocene glacial cycles are thought to have significantly influenced the distribution and diversity of subterranean invertebrates; however, impacts on subterranean aquatic vertebrates are less clear. We employed several hypothesis-driven approaches to assess the impacts of Pleistocene climatic and geological changes on the Northern Cavefish, Amblyopsis spelaea, whose current distribution occurs near the southern extent of glacial advances in North America. Our results show that the modern Ohio River has been a significant barrier to dispersal and is correlated with patterns of genetic divergence. We infer that populations were isolated in two refugia located north and south of the Ohio River during the most recent two glacial cycles with evidence of demographic expansion in the northern isolate. Finally, we conclude that climatic and geological processes have resulted in the formation of cryptic forms and advocate recognition of two distinct phylogenetic lineages currently recognized as A. spelaea. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Modification of the Quaternary stratigraphic framework of the inner-continental shelf by Holocene marine transgression: An example offshore of Fire Island, New York

USGS Publications Warehouse

Schwab, William C.; Baldwin, Wayne E.; Denny, Jane F.; Hapke, Cheryl J.; Gayes, Paul T.; List, Jeffrey; Warner, John C.

2014-01-01

The inner-continental shelf off Fire Island, New York was mapped in 2011 using interferometric sonar and high-resolution chirp seismic-reflection systems. The area mapped is approximately 50 km long by 8 km wide, extending from Moriches Inlet to Fire Island Inlet in water depths ranging from 8 to 32 m. The morphology of this inner-continental shelf region and modern sediment distribution patterns are determined by erosion of Pleistocene glaciofluvial sediments during the ongoing Holocene marine transgression; much of the shelf is thus an actively forming ravinement surface. Remnants of a Pleistocene outwash lobe define a submerged headland offshore of central Fire Island. East of the submerged headland, relatively older Pleistocene outwash is exposed over much of the inner-continental shelf and covered by asymmetric, sorted bedforms interpreted to indicate erosion and westward transport of reworked sediment. Erosion of the eastern flank of the submerged Pleistocene headland over the last ~ 8000 years yielded an abundance of modern sand that was transported westward and reworked into a field of shoreface-attached ridges offshore of western Fire Island. West of the submerged headland, erosion of Pleistocene outwash continues in troughs between the sand ridges, resulting in modification of the lower shoreface. Comparison of the modern sand ridge morphology with the morphology of the underlying ravinement surface suggests that the sand ridges have moved a minimum of ~ 1000 m westward since formation. Comparison of modern sediment thickness mapped in 1996–1997 and 2011 allows speculation that the nearshore/shoreface sedimentary deposit has gained sediment at the expense of deflation of the sand ridges.

Middle Pleistocene protein sequences from the rhinoceros genus Stephanorhinus and the phylogeny of extant and extinct Middle/Late Pleistocene Rhinocerotidae

PubMed Central

Smith, Geoff M.; Hutson, Jarod M.; Kindler, Lutz; Garcia-Moreno, Alejandro; Villaluenga, Aritza; Turner, Elaine

2017-01-01

Background Ancient protein sequences are increasingly used to elucidate the phylogenetic relationships between extinct and extant mammalian taxa. Here, we apply these recent developments to Middle Pleistocene bone specimens of the rhinoceros genus Stephanorhinus. No biomolecular sequence data is currently available for this genus, leaving phylogenetic hypotheses on its evolutionary relationships to extant and extinct rhinoceroses untested. Furthermore, recent phylogenies based on Rhinocerotidae (partial or complete) mitochondrial DNA sequences differ in the placement of the Sumatran rhinoceros (Dicerorhinus sumatrensis). Therefore, studies utilising ancient protein sequences from Middle Pleistocene contexts have the potential to provide further insights into the phylogenetic relationships between extant and extinct species, including Stephanorhinus and Dicerorhinus. Methods ZooMS screening (zooarchaeology by mass spectrometry) was performed on several Late and Middle Pleistocene specimens from the genus Stephanorhinus, subsequently followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to obtain ancient protein sequences from a Middle Pleistocene Stephanorhinus specimen. We performed parallel analysis on a Late Pleistocene woolly rhinoceros specimen and extant species of rhinoceroses, resulting in the availability of protein sequence data for five extant species and two extinct genera. Phylogenetic analysis additionally included all extant Perissodactyla genera (Equus, Tapirus), and was conducted using Bayesian (MrBayes) and maximum-likelihood (RAxML) methods. Results Various ancient proteins were identified in both the Middle and Late Pleistocene rhinoceros samples. Protein degradation and proteome complexity are consistent with an endogenous origin of the identified proteins. Phylogenetic analysis of informative proteins resolved the Perissodactyla phylogeny in agreement with previous studies in regards to the placement of the families Equidae, Tapiridae, and Rhinocerotidae. Stephanorhinus is shown to be most closely related to the genera Coelodonta and Dicerorhinus. The protein sequence data further places the Sumatran rhino in a clade together with the genus Rhinoceros, opposed to forming a clade with the black and white rhinoceros species. Discussion The first biomolecular dataset available for Stephanorhinus places this genus together with the extinct genus Coelodonta and the extant genus Dicerorhinus. This is in agreement with morphological studies, although we are unable to resolve the order of divergence between these genera based on the protein sequences available. Our data supports the placement of the genus Dicerorhinus in a clade together with extant Rhinoceros species. Finally, the availability of protein sequence data for both extinct European rhinoceros genera allows future investigations into their geographic distribution and extinction chronologies. PMID:28316883

Middle Pleistocene protein sequences from the rhinoceros genus Stephanorhinus and the phylogeny of extant and extinct Middle/Late Pleistocene Rhinocerotidae.

PubMed

Welker, Frido; Smith, Geoff M; Hutson, Jarod M; Kindler, Lutz; Garcia-Moreno, Alejandro; Villaluenga, Aritza; Turner, Elaine; Gaudzinski-Windheuser, Sabine

2017-01-01

Ancient protein sequences are increasingly used to elucidate the phylogenetic relationships between extinct and extant mammalian taxa. Here, we apply these recent developments to Middle Pleistocene bone specimens of the rhinoceros genus Stephanorhinus . No biomolecular sequence data is currently available for this genus, leaving phylogenetic hypotheses on its evolutionary relationships to extant and extinct rhinoceroses untested. Furthermore, recent phylogenies based on Rhinocerotidae (partial or complete) mitochondrial DNA sequences differ in the placement of the Sumatran rhinoceros ( Dicerorhinus sumatrensis ). Therefore, studies utilising ancient protein sequences from Middle Pleistocene contexts have the potential to provide further insights into the phylogenetic relationships between extant and extinct species, including Stephanorhinus and Dicerorhinus . ZooMS screening (zooarchaeology by mass spectrometry) was performed on several Late and Middle Pleistocene specimens from the genus Stephanorhinus , subsequently followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to obtain ancient protein sequences from a Middle Pleistocene Stephanorhinus specimen. We performed parallel analysis on a Late Pleistocene woolly rhinoceros specimen and extant species of rhinoceroses, resulting in the availability of protein sequence data for five extant species and two extinct genera. Phylogenetic analysis additionally included all extant Perissodactyla genera ( Equus , Tapirus ), and was conducted using Bayesian (MrBayes) and maximum-likelihood (RAxML) methods. Various ancient proteins were identified in both the Middle and Late Pleistocene rhinoceros samples. Protein degradation and proteome complexity are consistent with an endogenous origin of the identified proteins. Phylogenetic analysis of informative proteins resolved the Perissodactyla phylogeny in agreement with previous studies in regards to the placement of the families Equidae, Tapiridae, and Rhinocerotidae. Stephanorhinus is shown to be most closely related to the genera Coelodonta and Dicerorhinus . The protein sequence data further places the Sumatran rhino in a clade together with the genus Rhinoceros , opposed to forming a clade with the black and white rhinoceros species. The first biomolecular dataset available for Stephanorhinus places this genus together with the extinct genus Coelodonta and the extant genus Dicerorhinus . This is in agreement with morphological studies, although we are unable to resolve the order of divergence between these genera based on the protein sequences available. Our data supports the placement of the genus Dicerorhinus in a clade together with extant Rhinoceros species. Finally, the availability of protein sequence data for both extinct European rhinoceros genera allows future investigations into their geographic distribution and extinction chronologies.

Nine thousand years of upper montane soil/vegetation dynamics from the summit of Caratuva Peak, Southern Brazil

NASA Astrophysics Data System (ADS)

Scheer, Maurício B.; Pereira, Nuno Veríssimo; Behling, Hermann; Curcio, Gustavo R.; Roderjan, Carlos V.

2014-12-01

Biodiversity loss, climate change, and increased freshwater consumption are some of the main environmental problems on Earth. Mountain ecosystems can reduce these threats by providing several positive influences, such as the maintenance of biodiversity, water regulation, and carbon storage, amongst others. The knowledge of the history of these environments and their response to climate change is very important for management, conservation, and environmental monitoring programs. The genesis of the soil organic matter of the current upper montane vegetation remains unclear and seems to be quite variable depending on location. Some upper montane sites in the very extensive coastal Sea Mountain Range present considerable organic matter from the late Pleistocene and other from only the Holocene. Our study was carried out on three soil profiles (two cores in grassland and one in forest) on the Caratuva Peak of the Serra do Ibitiraquire (a sub-range of Sea Mountain Range - Serra do Mar) in Southern Brazil. The δ13C isotopic analyses of organic matter in soil horizons were conducted to detect whether C3 or C4 plants dominated the past communities. Complementarily, we performed a pollen analysis and 14C dating of the humin fraction to obtain the age of the studied horizons. Except for a short and probably drier period (between 6000 and 4500 cal yr BP), C3 plants, including ombrophilous grasses and trees, have dominated the highlands of the Caratuva Peak (Pico Caratuva), as well as the other uppermost summits of the Serra do Ibitiraquire, since around 9000 cal yr BP. The Caratuva region represents a landscape of high altitude grasslands (campos de altitude altomontanos or campos altomontanos) and upper montane rain/cloud forests with soils that most likely contain some organic matter from the late Pleistocene, as has been reported in Southern and Southeastern Brazil for other sites. However, our results indicate that the studied deposits (near the summit) are from the early to late Holocene, when somewhat wetter and warmer conditions (since around 9000 cal yr BP) enabled a stronger colonization of the ridge of Pico Caratuva by mainly C3 plants, especially grassland species. However, at the same time, even near the summit, the soil core from the forest site already presented the current physiognomy (or a shrubby/elfin or successional forest), indicating that the colonization of the neighboring uppermost saddles and valleys were probably populated mainly by upper montane forest species.

Brief communication: beyond the South African cave paradigm--Australopithecus africanus from Plio-Pleistocene paleosol deposits at Taung.

PubMed

Hopley, Philip J; Herries, Andy I R; Baker, Stephanie Edwards; Kuhn, Brian F; Menter, Colin G

2013-06-01

Following the discovery of the "Taung Child" (Australopithecus africanus) in 1924 in the Buxton-Norlim Limeworks near Taung, the fossil-bearing deposits associated with the Dart and Hrdlička pinnacles have been interpreted as the mined remnants of cave sediments that formed within the Plio-Pleistocene Thabaseek Tufa: either as a younger cave-fill or as contemporaneous carapace caves. When combined with the Plio-Pleistocene dolomitic cave deposits from the "Cradle of Humankind," a rather restricted view emerges that South African early hominins derived from cave deposits, whereas those of east and central Africa are derived from fluvio-lacustrine and paleosol deposits. We undertook a sedimentological and paleomagnetic analysis of the pink-colored deposit (PCS) from which the "Taung Child" is purported to have derived and demonstrate that it is a calcrete, a carbonate-rich pedogenic sediment, which formed on the paleo-land surface. The deposit extends 100 s of meters laterally beyond the Dart and Hrdlička Pinnacles where it is interbedded with the Thabaseek Tufa, indicating multiple episodes of calcrete development and tufa growth. The presence of in situ rhizoconcretions and insect trace fossils (Celliforma sp. and Coprinisphaera sp.) and the distinctive carbonate microfabric confirm that the pink deposit is a pedogenic calcrete, not a calcified cave sediment. Paleomagnetic and stratigraphic evidence indicates that a second, reversed polarity, fossil-bearing deposit (YRSS) is a younger fissure-fill formed within a solutional cavity of the normal polarity tufa and pink calcrete (PCS). These observations have implications for the dating, environment, and taphonomy of the site, and increase the likelihood of future fossil discoveries within the Buxton-Norlim Limeworks. Copyright © 2013 Wiley Periodicals, Inc.

Sediment-Basalt Architecture, Pliocene and Pleistocene Eastern and Central Snake River Plain

NASA Astrophysics Data System (ADS)

Helm-Clark, C. M.; Link, P. K.

2006-12-01

This presentation is a synthesis of known stratigraphic studies of the Pliocene, Pleistocene and Holocene basalts and interbedded sedimentary beds on the Eastern Snake River Plain (ESRP). This information is important for understanding the post-caldera tectonic evolution of the ESRP, especially for tracking patterns of volcanic eruption and changes in topography. Geophysical surveys and existing well logs indicate the depth of the basalt sequence is usually 2 km or less, even near the axis of the Plain. An alteration horizon, the product of high heat-flow in the wake of the Yellowstone hot spot, moderated by cold-water recharge in the thick and highly-transmissive Snake River Aquifer, has variable depth. The surface and near-surface of the lava fields are mainly basalts less than a half a million years old, from Island Park to Twin Falls/Shoshone. Near the junction of the Eastern and Western Snake River Plains, these youngest late Pleistocene basalts, many less than 100,000 years old, overlie early Pleistocene basalts more than a million and a half years old. Most basalt flows have been erupted from NW-trending volcanic rift zones like the Great Rift of Idaho or from the Axial Volcanic High (AVH). The AVH is a constructional axial ridge formed by multiple volcanic vents, small shield volcanoes and rhyolitic domes which run the length of the ESRP. A combination of previous and new stratigraphic and geochronology studies, including U-Pb detrital-zircon geochronology on sediments, reveals several lake sequences, formed by the damming of rivers. These tend to be thickest in upstream, valley-mouth, and Plain-marginal locations where the rivers were trapped. The lake beds generally pinch out toward the AVH. The most notable of these are the Mid-Pleistocene Raft Formation, the Late Pleistocene American Falls Lake Beds, at least two mid-Pleistocene sequences of ponded sediment from the Big Lost River at its egress onto the ESRP, and a 2.5 to 1.6 Ma sequence in the Big Lost Trough (BLT). Argon-argon dating of intercalated basalts demonstrates that the Big Lost River was trapped in the BLT starting about ~2Ma. Egress was blocked by the AVH to the southeast and by constructional volcanic rift zones to the southwest. Channel deposits of the ancestral Big Lost River are present in well logs, with one 20 m thick sequence traceable to the southwest under the Craters of the Moon National Monument (COM) between 1430 and 1380 m MSL. Other lake sequences in the ESRP subsurface include two mid-Pleistocene 30 to 50m thick sequences of clayey sediments in the BLT, near the southeast corner of the Idaho National Laboratory at ~250 to ~300 m depths. Two other fine-grained sediment sequences of unknown age are found at similar depths south of COM. Lake Terreton and its predecessors can be traced from Howe to Menan in the northeastern ESRP. Fluvial sediments here are coarse-grained gravels and sands of the Snake River, exposed near Blackfoot and logged in many well logs. Other notable fluvial sediments include the southwest-trending channel deposits and the two previously-mentioned clay sequences south of COM may prove to be parts of a paleo-Big Lost River that flowed to the southwest before 2 Ma.

Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

USGS Publications Warehouse

Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

2009-01-01

Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake levels have decreased from as high as 1830 m to 1806 m above sea level since the early Pleistocene due to episodic downcutting by the Bear River. The oldest exposed lacustrine sediments in Bear Lake Valley are probably of Pliocene age. Several high-lake phases during the early and middle Pleistocene were separated by episodes of fluvial incision. Threshold incision was not constant, however, because lake highstands of as much as 8 m above bedrock threshold level resulted from aggradation and possibly landsliding at least twice during the late-middle and late Pleistocene. Abandoned stream channels within the low-lying, fault-bounded region between Bear Lake and the modern Bear River show that Bear River progressively shifted northward during the Holocene. Several factors including faulting, location of the fluvial fan, and channel migration across the fluvial fan probably interacted to produce these changes in channel position. Late Quaternary slip rates on the east Bear Lake fault zone are estimated by using the water-level history of Bear Lake, assuming little or no displacement on dated deposits on the west side of the valley. Uplifted lacustrine deposits representing Pliocene to middle Pleistocene highstands of Bear Lake on the footwall block of the east Bear Lake fault zone provide dramatic evidence of long-term slip. Slip rates during the late Pleistocene increased from north to south along the east Bear Lake fault zone, consistent with the tectonic geomorphology. In addition, slip rates on the southern section of the fault zone have apparently decreased over the past 50 k.y. Copyright ?? 2009 The Geological Society of America.

Investigation of aquifer-system compaction in the Hueco basin, El Paso, Texas, USA

USGS Publications Warehouse

Heywood, Charles

1995-01-01

The Pleistocene geologic history of the Rio Grande valley in the Hueco basin included a cycle of sediment erosion and re-aggradation, resulting in unconformable stratification of sediment of contrasting compressibility and stress history. Since the 1950s large groundwater withdrawals have resulted in significant water-level declines and associated land subsidence. Knowledge of the magnitude and variation of specific storage is needed for developing predictive models of subsidence and groundwater flow simulations. Analyses of piezometric and extensometric data in the form of stress-strain diagrams from a 16 month period yield in situ measurements of aquifer-system compressibility across two discrete aquifer intervals. The linear elastic behaviour of the deeper interval indicates over-consolidation of basin deposits, probably resulting from deeper burial depth before the middle Pleistocene. By contrast, the shallow aquifer system displays an inelastic component, suggesting pre-consolidation stress not significantly greater than current effective stress levels for a sequence of late Pleistocene clay. Harmonic analyses of the piezometric response to earth tides in two water-level piezometers provide an independent estimate of specific storage of aquifer sands.

Sedimentary facies and depositional history of the Swan Islands, Honduras

NASA Astrophysics Data System (ADS)

Ivey, Marvin L.; Breyer, John A.; Britton, Joseph C.

1980-10-01

Swan Island is a Honduran possession in the western Caribbean, located on the southeastern side of the Cayman Trench. Two sedimentary assemblages are found on the island: an older bedded sequence of mid-Tertiary age (Aquitanian or Burdigalian) and a younger sedimentary sequence of Late Pleistocene age. The older sequence is composed of a series of calcarenites, calcilutites, and siliciclastic mudstones; capping these are cliff-forming reefal carbonates of the younger sequence. The rocks of the older bedded sequence accumulated in deep water. Sedimentation consisted of a constant rain of pyroclastic debris interrupted by the episodic introduction of upslope carbonate material by turbidity currents. Uplift and deformation of this sequence was initiated sometime after the Early Miocene. By the Late Pleistocene, uplift had brought the rocks into water depths conducive to coral growth. Pleistocene sedimentation on the island was controlled by the interaction between tectonic uplift and eustatic sea-level changes. The primary controlling force on the tectonic history of the island is its proximity to the boundary between the North American and Caribbean plates.

Sequence stratigraphy and environmental background of the late Pleistocene and Holocene occupation in the Southeast Primor'ye (the Russian Far East)

NASA Astrophysics Data System (ADS)

Chlachula, Jiri; Krupyanko, Alexander A.

2016-06-01

The paper presents the results of Quaternary palaeoecology and geoarchaeology studies in the Zerkal'naya Basin, with new insights about sequenced natural shifts during the prehistoric occupation of this marginally explored NE Asian maritime territory. The Basin is part of the continental drainage system and the main physiographic and biotic corridor for peopling of the transitive coastal interior SE Primor'ye Region. The Final Pleistocene and Holocene environmental (biotic and abiotic) proxy records from the Upper/Final Palaeolithic to early historical sites document a dynamic climate change with vegetation cover transformations within riverine and mountain valley ecosystems of the Russian Far East. Most of the archaeological sites located on the low terraces and bedrock promontories along the main river channel and its tributary streams suggest traditional hunter gathered lifestyles based on seasonal salmon-fishing supplemented by pastoral economy. Tundra-forests with larch trees, dwarf birch thickets and polypod ferns from the basal stratigraphic units of the late Last Glacial occupation sites associated with the Upper Palaeolithic micro-blade and bifacial stone tool traditions (14C-dated to 19,000-12,000 cal yrs BP) indicate rather pronounced conditions and much lower MAT comparing today. Following a final Pleistocene cooling event, a major climate warming marked the onset of Holocene accompanied by a regional humidity increase promoting the formation of a mixed broadleaved-coniferous oak-dominant taiga, and culminating in the mid-Holocene Climatic Optimum. The appearance of mosaic parklands ca. 5,000-4,000 cal yrs BP. may be partly attributed to the expansion of the Far Eastern Neolithic cultures practicing forest clearance for pastures and dwellings. A progressing landscape opening indicated by the spread of light-demanding thickets and birch-dominated riverine biotopes with Artemisia suggests a further vegetation cover transformation during the late Neolithic and the early Palaeo-Metal (Bronze Age) periods. This trend corroborates the documented climate deterioration between 3,400 and 2,600 cal yrs BP, causing a regional aridification with a parkland-steppe broadening in the main SE Primor'ye river valleys. The late Holocene climate development persisted until the Little Ice Age which led to formation of the present settlement ecosystems with mixed (oak/cedar/fir-dominated) temperate maritime woodlands.

The comparative phylogeography of fruit bats of the tribe Scotonycterini (Chiroptera, Pteropodidae) reveals cryptic species diversity related to African Pleistocene forest refugia.

PubMed

Hassanin, Alexandre; Khouider, Souraya; Gembu, Guy-Crispin; Goodman, Steven M; Kadjo, Blaise; Nesi, Nicolas; Pourrut, Xavier; Nakouné, Emmanuel; Bonillo, Céline

2015-03-01

The hypothesis of Pleistocene forest refugia was tested using comparative phylogeography of Scotonycterini, a fruit bat tribe endemic to Africa containing four species: Scotonycteris zenkeri, Casinycteris argynnis, C. campomaanensis, and C. ophiodon. Patterns of genetic structure were assessed using 105 Scotonycterini (including material from three holotypes) collected at 37 localities, and DNA sequences from the mitochondrial cytochrome b gene (1140 nt) and 12 nuclear introns (9641 nt). Phylogenetic trees and molecular dating were inferred by Bayesian methods. Multilocus analyses were performed using supermatrix, SuperTRI, and *BEAST approaches. Mitochondrial analyses reveal strong phylogeographical structure in Scotonycteris, with four divergent haplogroups (4.9-8.7%), from Upper Guinea, Cameroon, western Equatorial Africa, and eastern Democratic Republic of the Congo (DRC). In C. argynnis, we identify two mtDNA haplogroups corresponding to western and eastern Equatorial Africa (1.4-2.1%). In C. ophiodon, the mtDNA haplotypes from Cameroon and Ivory Coast differ by only 1.3%. Nuclear analyses confirm the validity of the recently described C. campomaanensis and indicate that western and eastern populations of C. argynnis are not fully isolated. All mtDNA clusters detected in Scotonycteris are found to be monophyletic based on the nuclear dataset, except in eastern DRC. In the nuclear tree, the clade from western Equatorial Africa is closely related to individuals from eastern DRC, whereas in the mitochondrial tree it appears to be the sister-group of the Cameroon clade. Migrate-n analyses support gene flow from western Equatorial Africa to eastern DRC. Molecular dating indicates that Pleistocene forest refugia have played an important role in shaping the evolution of Scotonycterini, with two phases of allopatric speciation at approximately 2.7 and 1.6 Mya, resulting from isolation in three main forest areas corresponding to Upper Guinea, Cameroon, and Equatorial Africa. Two cryptic species and two subspecies are described herein in the genus Scotonycteris. Female philopatry and male biased dispersal are supported for the smallest taxa, i.e., the three species of Scotonycteris and C. argynnis. The Congo, Ntem, and Sanaga rivers are identified as biogeographic barriers to the dispersal of Scotonycteris during interglacial periods. A greater capacity for long-distance dispersal is inferred for the largest species, C. ophiodon. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All rights reserved.

A new fossil cercopithecid tibia from Laetoli and its implications for positional behavior and paleoecology.

PubMed

Laird, Myra F; Kozma, Elaine E; Kwekason, Amandus; Harrison, Terry

2018-05-01

Detailed analyses and comparisons of postcranial specimens of Plio-Pleistocene cercopithecids provide an opportunity to examine the recent evolutionary history and locomotor diversity in Old World monkeys. Studies examining the positional behavior and substrate preferences of fossil cercopithecids are also important for reconstructing the paleoenvironments of Plio-Pleistocene hominin sites. Here we describe a new fossil cercopithecid tibia (EP 1100/12) from the Australopithecus afarensis-bearing Upper Laetolil Beds (∼3.7 Ma) of Laetoli in northern Tanzania. The fossil tibia is attributed to cf. Rhinocolobus sp., which is the most common colobine at Laetoli. In addition to qualitative comparisons, the tibial shape of EP 1100/12 was compared to that of 190 extant cercopithecids using three-dimensional landmarks. Discriminant function analyses of the shape data were used to assess taxonomic affinity and shape variation relating to positional behavior. EP 1100/12 clustered with extant colobines, particularly the large-bodied genera Nasalis and Rhinopithecus. Comparisons reveal that EP 1100/12 belongs to a large-bodied monkey that engaged in arboreal pronograde quadrupedalism. These findings add further support to previous inferences that woodland and forest environments dominated the paleoenvironment of the Upper Laetolil Beds, which supported the diverse community of cercopithecids at Laetoli. The inferred paleoecology and the presence of large-bodied arboreally-adapted monkeys at Laetoli show that A. afarensis had access to a range of diverse habitats, including woodlands and forests. This supports the possibility that A. afarensis, with its potential range of positional capabilities, was able to utilize arboreal settings for food acquisition and refuge from predators. Copyright © 2018 Elsevier Ltd. All rights reserved.

Storm-related sedimentation influenced by coastal configuration in the stratigraphic record of a tectonically active shelf (Upper Pleistocene Le Castella terrace, Italy)

NASA Astrophysics Data System (ADS)

Nalin, Ronald; Massari, Francesco

2018-03-01

Analysis of patterns of coastal circulation and sediment dispersal is an essential step for the study of controlling factors influencing the long-term dynamics of coastal systems. Modern settings offer the possibility to monitor relevant parameters over relatively short time spans. However, geological examples complement this perspective by providing a time-averaged record where longer trends and stratigraphically significant processes can be evaluated. This study investigates the shallow marine deposits of Le Castella terrace (Upper Pleistocene, southern Italy) to document how patterns of circulation influenced by coastline configuration can affect the preserved millennial-scale depositional record of a progradational shoreline system. The regressive portion of the Le Castella terrace deposits, developed during a relative sea-level highstand and falling stage, consists of a progradational wedge mainly composed of redistributed skeletal particles of a coeval shallow water carbonate factory. Preservation of the morphology of the paleocoastline and abundant current-related sedimentary structures allow reconstruction of the predominant sediment dispersal dynamics responsible for the formation of this sedimentary wedge. Facies and paleocurrent analysis indicate offshore and alongshore sediment transport modes, consistent with coastal circulation driven by storms normally incident to the shoreline and a sharp change in coastline orientation. This coastal inflection influenced circulation patterns causing flow separation and eddy formation in the lee of the curved coastline. Syndepositional tectonic deformation also affected the architecture of the preserved deposits, controlling the nucleation and development of a clinostratified body and determining localized lateral stratigraphic variability. This study illustrates how transient but recurrent circulation patterns associated with changes in coastal orientation and related to high-energy storm events can leave a predominant signature in the stratigraphic record of microtidal shallow-marine successions.

The silence of the layers: Archaeological site visibility in the Pleistocene-Holocene transition at the Ebro Basin

NASA Astrophysics Data System (ADS)

Alday, Alfonso; Domingo, Rafael; Sebastián, María; Soto, Adriana; Aranbarri, Josu; González-Sampériz, Penélope; Sampietro-Vattuone, María Marta; Utrilla, Pilar; Montes, Lourdes; Peña-Monné, José Luis

2018-03-01

The Ebro Basin constitutes one of the most representative territories in SW Europe for the study of prehistoric societies during the Pleistocene-Holocene transition. The correlation of palaeoenvironmental and geomorphological proxies obtained from sedimentary records with chronologically well-constrained reference archaeological sites has allowed defining this time frame precisely, such that three main pilot areas haven been broadly depicted: the Alavese region, the Pre-Pyrenees and the Bajo Aragón. Overall, the human imprint in the Ebro Basin was rare during the Upper Palaeolithic, but more visible from the Upper Magdalenian (14500-13500 cal BP) to Neolithic times (up to 5500 cal BP). Local environmental resources were continuously managed by the prehistoric communities in the different areas of study. In fact, the Ebro Basin acted during those millennia as a whole, developing the same cultural trends, industrial techniques and settlement patterns in parallel throughout the territory. However, some gaps exist in the 14C frequency curve (SCDPD curve). This is partially related to prehistoric sites in particular lithologies and geological structures that could have partly been lost by erosional processes, especially during the Early Holocene. In addition, this gap also parallels the reconstructed climate trend for the Pre-Pyrenean and the Bajo Aragón areas, which are defined by high frequencies of xerophilous flora until ca. 9500 cal BP, suggesting that continental climate features could have hampered the presence of well-established human communities in inland regions. The interdisciplinary research (archaeology, geomorphology and palaeoclimatology) discussed in this paper offers clues to understand the existence of fills and gaps in the archaeological record of the Ebro Basin, and can be applied in other territories with similar geographic and climate patterns.

Salt diapirs in the Dead Sea basin and their relationship to Quaternary extensional tectonics

USGS Publications Warehouse

Al-Zoubi, A.; ten Brink, Uri S.

2001-01-01

Regional extension of a brittle overburden and underlying salt causes differential loading that is thought to initiate the rise of reactive diapirs below and through regions of thin overburden. We present a modern example of a large salt diapir in the Dead Sea pull-apart basin, the Lisan diapir, which we believe was formed during the Quaternary due to basin transtension and subsidence. Using newly released seismic data that are correlated to several deep wells, we determine the size of the diapir to be 13 x 10 km. its maximum depth 7.2 km. and its roof 125 m below the surface. From seismic stratigraphy, we infer that the diapir started rising during the early to middle Pleistocene as this section of the basin underwater rapid subsidence and significant extension of the overburden. During the middle to late Pleistocene, the diapir pierced through the extensionally thinned overburden, as indicated by rim synclines, which attest to rapid salt withdrawal from the surrounding regions. Slight positive topography above the diapir and shallow folded horizons indicate that it is still rising intermittently. The smaller Sedom diapir, exposed along the western bounding fault of the basin is presently rising and forms a 200 m-high ridge. Its initiation is explained by localized E-W extension due monoclinal draping over the edge of a rapidly subsiding basin during the early to middle Pleistocene, and its continued rise by lateral squeezing due to continued rotation of the Amazyahu diagonal fault. 

The Gediz River fluvial archive: A benchmark for Quaternary research in Western Anatolia

NASA Astrophysics Data System (ADS)

Maddy, D.; Veldkamp, A.; Demir, T.; van Gorp, W.; Wijbrans, J. R.; van Hinsbergen, D. J. J.; Dekkers, M. J.; Schreve, D.; Schoorl, J. M.; Scaife, R.; Stemerdink, C.; van der Schriek, T.; Bridgland, D. R.; Aytaç, A. S.

2017-06-01

The Gediz River, one of the principal rivers of Western Anatolia, has an extensive Pleistocene fluvial archive that potentially offers a unique window into fluvial system behaviour on the western margins of Asia during the Quaternary. In this paper we review our work on the Quaternary Gediz River Project (2001-2010) and present new data which leads to a revised stratigraphical model for the Early Pleistocene development of this fluvial system. In previous work we confirmed the preservation of eleven buried Early Pleistocene fluvial terraces of the Gediz River (designated GT11, the oldest and highest, to GT1, the youngest and lowest) which lie beneath the basalt-covered plateaux of the Kula Volcanic Province. Deciphering the information locked in this fluvial archive requires the construction of a robust geochronology. Fortunately, the Gediz archive provides ample opportunity for age-constraint based upon age estimates derived from basaltic lava flows that repeatedly entered the palaeo-Gediz valley floors. In this paper we present, for the first time, our complete dataset of 40Ar/39Ar age estimates and associated palaeomagnetic measurements. These data, which can be directly related to the underlying fluvial deposits, provide age constraints critical to our understanding of this sequence. The new chronology establishes the onset of Quaternary volcanism at ∼1320ka (MIS42). This volcanism, which is associated with GT6, confirms a pre-MIS42 age for terraces GT11-GT7. Evidence from the colluvial sequences directly overlying these early terraces suggests that they formed in response to hydrological and sediment budget changes forced by climate-driven vegetation change. The cyclic formation of terraces and their timing suggests they represent the obliquity-driven climate changes of the Early Pleistocene. By way of contrast the GT5-GT1 terrace sequence, constrained by a lava flow with an age estimate of ∼1247ka, span the time-interval MIS42 - MIS38 and therefore do not match the frequency of climate change as previously suggested. The onset of volcanism breaks the simple linkage of terracing to climate-driven change. These younger terraces more likely reflect a localized terracing process triggered by base level changes forced by volcanic eruptions and associated reactivation of pre-existing faults, lava dam construction, landsliding and subsequent lava-dammed lake drainage. Establishing a firm stratigraphy and geochronology for the Early Pleistocene archive provides a secure framework for future exploitation of this part of the archive and sets the standard as we begin our work on the Middle-Late Pleistocene sequence. We believe this work forms a benchmark study for detailed Quaternary research in Turkey.

The impact of periglacial cover beds on runoff generation in a small spring catchment, Ore Mountains

NASA Astrophysics Data System (ADS)

Heller, Katja; Hübner, Rico; Kleber, Arno

2010-05-01

The knowledge of hillslope processes is essential to improve pollutant research and flood prediction. Relic periglacial covers are widespread on slopes of the central European low mountain ranges. Cover beds are assumed to be an important control factor for subcutaneous water flow paths. Periglacial cover beds originated by solifluction, kryoturbation and accumulation of loess during Pleistocene times. Differences in bulk density, sediment type, as well as structure and rate of coarse clasts in the layers result in vertical disparity in hydraulic conductivity (anisotropy), leading to interflow. This hypothesis has been testing in an ongoing study in a small spring catchment (6 ha) in the eastern Ore Mountains, south-eastern Germany, since November 2007. The study area is underlain by gneiss and is formed as a slope hollow. The cover beds consist of a 3-layer complex with upper layer, intermediate layer and basal layer. Soil water tension within the layers is measured with 76 recording tensiometers. Electrical resistivity tomography was used to monitor the spatial dispersal of soil moisture. Results of hydrometrical measurements and of electrical resistivity surveys will be described and new findings on slope water dynamics will be presented.

Digital representation of exposures of Precambrian bedrock in parts of Dickinson and Iron Counties, Michigan, and Florence and Marinette Counties, Wisconsin

USGS Publications Warehouse

Cannon, William F.; Schulte, Ruth; Bickerstaff, Damon

2018-04-04

The U.S. Geological Survey (USGS) conducted a program of bedrock geologic mapping in much of the central and western Upper Peninsula of Michigan from the 1940s until the late 1990s. Geologic studies in this region are hampered by a scarcity of bedrock exposures because of a nearly continuous blanket of unconsolidated sediments resulting from glaciation of the region during the Pleistocene ice ages. The USGS mapping, done largely at a scale of 1:24,000, routinely recorded the location and extent of exposed bedrock to provide both an indication of where direct observations were made and a guide for future investigations to expedite location of observable rock exposures. The locations of outcrops were generally shown as colored or patterned overlays on printed geologic maps. Although those maps have been scanned and are available as Portable Document Format (PDF) files, no further digital portrayal of the outcrops had been done. We have conducted a prototype study of digitizing and improving locational accuracy of the outcrop locations in parts of Dickinson County, Michigan, to form a data layer that can be used with other data layers in geographic information system applications.

The most recent (682-792 CE) volcanic eruption in the Jombolok lava field, East Sayan, Central Asia triggered exodus of Mongolian pre-Chinggis Khaan tribes (778-786 CE)

NASA Astrophysics Data System (ADS)

Arzhannikov, S. G.; Ivanov, A. V.; Arzhannikova, A. V.; Demonterova, E. I.; Jolivet, M.; Buyantuev, V. A.; Oskolkov, V. A.; Voronin, V. I.

2016-08-01

This study presents new data on one of the most recent (historical) volcanic eruptions in Central Asia. The Jombolok lava field located in the East Sayan Mountains (Southern Siberia) was formed during Late Pleistocene and Holocene times. At least four phases of volcanic activity have been identified and evidences associated with the last phase have been found in the upper reaches of the Khi-Gol valley and in the Oka-Jombolok basin. The volcanic activity is represented by young basaltic lava located among older lavas. Live and dead trees have been sampled in the young lava field. Nine fragments of wood have been found embedded in lavas of the latest eruption. Dendrochronological analysis, radiocarbon dating and the analysis of historical chronicles have shown that the latest eruption occurred during the period 682-792 CE. The volcanic activity possibly triggered the migration of Mongolian tribes out of the locality known in historical chronicles as Ergune-Kun towards the Onon River, which, 400 years later, became the place of birth and rise of Chinggis Khaan.

High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State

USGS Publications Warehouse

Clement, C.R.; Pratt, T.L.; Holmes, M.L.; Sherrod, B.L.

2010-01-01

Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with the Olympia structure were imaged beneath Budd and Eld Inlets. Beneath Case Inlet, the Tacoma fault zone includes an ???350-m wide section of south-dipping strata forming the upper part of a fold (kink band) coincident with the southern edge of an uplifted shoreline terrace. An ???2 m change in the depth of the water bottom, onlapping postglacial sediments, and increasing stratal dips with increasing depth are consistent with late Pleistocene to Holocene postglacial growth folding above a blind fault. Geologic data across a topographic lineament on nearby land indicate recent uplift of late Holocene age. Profiles acquired in Carr Inlet 10 km to the east of Case Inlet showed late Pleistocene or Holocene faulting at one location with ???3 to 4 m of vertical displacement, south side up. North of this fault the data show several other disruptions and reflector terminations that could mark faults within the broad Tacoma fault zone. Seismic reflection profiles across part of the Olympia structure beneath southern Puget Sound show two apparent faults about 160 m apart having 1 to 2 m of displacement of subhorizontal bedding. Directly beneath one of these faults, a dipping reflector that may mark the base of a glacial channel shows the opposite sense of throw, suggesting strike-slip motion. Deeper seismic reflection profiles show disrupted strata beneath these faults but little apparent vertical offset, consistent with strike-slip faulting. These faults and folds indicate that the Tacoma fault and Olympia structure include active structures with probable postglacial motion.

Quaternary stratigraphy of Bermuda: A high-resolution pre-Sangamonian rock record

NASA Astrophysics Data System (ADS)

Hearty, Paul J.; Vacher, H. Leonard

Carbonate islands such as Bermuda are created by climatic change. Warm climates and high sea levels stimulate carbonate sediment production that may ultimately result in island growth, while cold glacials expose the platforms to weathering, dissolution and soil formation. Of great importance in Quaternary studies is the ability to decipher this climatic history. Mapping and geochronologic studies have established that Bermuda may have one of the most continuous and detailed Quaternary interglacial depositional records on a carbonate platform. Advances in racemization dating (AAR) have offered a means of deciphering this climatic history and generating a high-resolution stratigraphic and age framework for the Quaternary. Bermudian interglacial units consist predominantly of eolianites, with less voluminous occurrences of beach deposits and calcarenite protosols (Entisols). Glacial or stadial-age terra rossa (aluminous laterite) paleosols, whose degree of development is a function of time of exposure, form boundaries between interglacial units. D-alloiso-leucine/ L-isoleucine ( {A}/{I}) ratios have been determined on marine pelecypods, land snails and whole-rock samples from mapped sections; aminozones have been defined for two Sangamonian and at least five pre-Sangamonian depositional intervals. From kinetic models based on calibration with previously published U-series coral dates, estimated ages of middle Pleistocene and older aminozones are: F = 190,000-265,000 years; G = 300,000-400,000 years; H = 400,000-500,000 years; J = >700,000 years; and K = > 900,000 years. Aminozone G, which is correlated with the upper Town Hill Formation and Isotope Stage 9, is volumetrically the most important depositional event of the middle Pleistocene. The great mass of sediment deposited during this period suggests an interglacial of significant duration and prolonged shelf submergence, during which the island grew to over half its present size. Only the Sangamonian ( sensu lato) rivals Stage 9 in volume of eolianite deposited on the island. Sea-level amplitude, as determined from dated outcrops, appears to correlate well with amplitudinal variations in the oxygen isotope record.

High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State

USGS Publications Warehouse

Odum, Jackson K.; Stephenson, William J.; Pratt, Thomas L.; Blakely, Richard J.

2016-01-01

Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with the Olympia structure were imaged beneath Budd and Eld Inlets. Beneath Case Inlet, the Tacoma fault zone includes an ∼350-m wide section of south-dipping strata forming the upper part of a fold (kink band) coincident with the southern edge of an uplifted shoreline terrace. An ∼2 m change in the depth of the water bottom, onlapping postglacial sediments, and increasing stratal dips with increasing depth are consistent with late Pleistocene to Holocene postglacial growth folding above a blind fault. Geologic data across a topographic lineament on nearby land indicate recent uplift of late Holocene age. Profiles acquired in Carr Inlet 10 km to the east of Case Inlet showed late Pleistocene or Holocene faulting at one location with ∼3 to 4 m of vertical displacement, south side up. North of this fault the data show several other disruptions and reflector terminations that could mark faults within the broad Tacoma fault zone. Seismic reflection profiles across part of the Olympia structure beneath southern Puget Sound show two apparent faults about 160 m apart having 1 to 2 m of displacement of subhorizontal bedding. Directly beneath one of these faults, a dipping reflector that may mark the base of a glacial channel shows the opposite sense of throw, suggesting strike-slip motion. Deeper seismic reflection profiles show disrupted strata beneath these faults but little apparent vertical offset, consistent with strike-slip faulting. These faults and folds indicate that the Tacoma fault and Olympia structure include active structures with probable postglacial motion.

High-precision 14C and 40Ar/39Ar dating of the Campanian Ignimbrite (Y-5) reconciles the time-scales of climatic-cultural processes at 40 ka.

PubMed

Giaccio, Biagio; Hajdas, Irka; Isaia, Roberto; Deino, Alan; Nomade, Sebastien

2017-04-06

The Late Pleistocene Campanian Ignimbrite (CI) super-eruption (Southern Italy) is the largest known volcanic event in the Mediterranean area. The CI tephra is widely dispersed through western Eurasia and occurs in close stratigraphic association with significant palaeoclimatic and Palaeolithic cultural events. Here we present new high-precision 14 C (34.29 ± 0.09 14 C kyr BP, 1σ) and 40 Ar/ 39 Ar (39.85 ± 0.14 ka, 95% confidence level) dating results for the age of the CI eruption, which substantially improve upon or augment previous age determinations and permit fuller exploitation of the chronological potential of the CI tephra marker. These results provide a robust pair of 14 C and 40 Ar/ 39 Ar ages for refining both the radiocarbon calibration curve and the Late Pleistocene time-scale at ca. 40 ka. In addition, these new age constraints provide compelling chronological evidence for the significance of the combined influence of the CI eruption and Heinrich Event 4 on European climate and potentially evolutionary processes of the Early Upper Palaeolithic.

Middle Pleistocene Human Remains from Tourville-la-Rivière (Normandy, France) and Their Archaeological Context

PubMed Central

Faivre, Jean-Philippe; Maureille, Bruno; Bayle, Priscilla; Crevecoeur, Isabelle; Duval, Mathieu; Grün, Rainer; Bemilli, Céline; Bonilauri, Stéphanie; Coutard, Sylvie; Bessou, Maryelle; Limondin-Lozouet, Nicole; Cottard, Antoine; Deshayes, Thierry; Douillard, Aurélie; Henaff, Xavier; Pautret-Homerville, Caroline; Kinsley, Les; Trinkaus, Erik

2014-01-01

Despite numerous sites of great antiquity having been excavated since the end of the 19th century, Middle Pleistocene human fossils are still extremely rare in northwestern Europe. Apart from the two partial crania from Biache-Saint-Vaast in northern France, all known human fossils from this period have been found from ten sites in either Germany or England. Here we report the discovery of three long bones from the same left upper limb discovered at the open-air site of Tourville-la-Rivière in the Seine Valley of northern France. New U-series and combined US-ESR dating on animal teeth produced an age range for the site of 183 to 236 ka. In combination with paleoecological indicators, they indicate an age toward the end of MIS 7. The human remains from Tourville-la-Rivière are attributable to the Neandertal lineage based on morphological and metric analyses. An abnormal crest on the left humerus represents a deltoid muscle enthesis. Micro- and or macro-traumas connected to repetitive movements similar to those documented for professional throwing athletes could be origin of abnormality. PMID:25295956

High-precision 14C and 40Ar/39Ar dating of the Campanian Ignimbrite (Y-5) reconciles the time-scales of climatic-cultural processes at 40 ka

PubMed Central

Giaccio, Biagio; Hajdas, Irka; Isaia, Roberto; Deino, Alan; Nomade, Sebastien

2017-01-01

The Late Pleistocene Campanian Ignimbrite (CI) super-eruption (Southern Italy) is the largest known volcanic event in the Mediterranean area. The CI tephra is widely dispersed through western Eurasia and occurs in close stratigraphic association with significant palaeoclimatic and Palaeolithic cultural events. Here we present new high-precision 14C (34.29 ± 0.09 14C kyr BP, 1σ) and 40Ar/39Ar (39.85 ± 0.14 ka, 95% confidence level) dating results for the age of the CI eruption, which substantially improve upon or augment previous age determinations and permit fuller exploitation of the chronological potential of the CI tephra marker. These results provide a robust pair of 14C and 40Ar/39Ar ages for refining both the radiocarbon calibration curve and the Late Pleistocene time-scale at ca. 40 ka. In addition, these new age constraints provide compelling chronological evidence for the significance of the combined influence of the CI eruption and Heinrich Event 4 on European climate and potentially evolutionary processes of the Early Upper Palaeolithic. PMID:28383570

The paleomagnetism of clastic and precipitate deposits in limestone and dolomite caves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Latham, A.G.; Ford, D.C.

1991-03-01

Clastic sediments and calcite precipitates (stalagmites, flowstones, etc.) are abundant in modern limestone caves and normally are the dominant infillings in buried (paleokarst) caves. Clastic sediment fillings are chiefly of fluviatile or local breakdown origin, but lacustrine, colluvial, eolian, and glacial deposits are known. Paleomagnetism has been studied in the fluviatile and lacustrine types: (1) reversal stratigraphy aids dating of geomorphic and paleoclimatic events in the late Pliocene/Pleistocene; (2) fine magnetostratigraphy has yielded estimates of the westward drift. Calcite precipitates (speleothems) may display natural remanent magnetism of either depositional (DRM) or chemical (CRM) origin. NRMs of modern speleothems are primary,more » not diagenetic; CRMs are invariably associated with the degradation of surface organic matter. (1) Coarse reversal stratigraphy dates geomorphic, etc., events and erosion rates. (2) Fine stratigraphy combined with {sup 230}Th:{sup 234}U dating gives high precision estimates of secular variation, westward drift, and rate of change of geomagnetic anomalies in upper Pleistocene and Holocene deposits. Magnetostratigraphy of paleokarst speleothem fillings associated with hydrocarbons in Ordovician limestones suggest a Permian age for the karstification. Potential applications of magnetostratigraphy to paleokarst deposits of many different scales are considerable.« less

Steppe lion remains imported by Ice Age spotted hyenas into the Late Pleistocene Perick Caves hyena den in northern Germany

NASA Astrophysics Data System (ADS)

Diedrich, Cajus G.

2009-05-01

Upper Pleistocene remains of the Ice Age steppe lion Panthera leo spelaea (Goldfuss, 1810) have been found in the Perick Caves, Sauerland Karst, NW Germany. Bones from many hyenas and their imported prey dating from the Lower to Middle Weichselian have also been recovered from the Perick Cave hyena den. These are commonly cracked or exhibit deep chew marks. The absence of lion cub bones, in contrast to hyena and cave bear cub remains in the Perick Caves, and other caves of northern Germany, excludes the possibility that P. leo spelaea used the cave for raising cubs. Only in the Wilhelms Cave was a single skeleton of a cub found in a hyena den. Evidence of the chewing, nibbling and cracking of lion bones and crania must have resulted from the importation and destruction of lion carcasses (4% of the prey fauna). Similar evidence was preserved at other hyena den caves and open air sites in Germany. The bone material from the Perick and other Central European caves points to antagonistic hyena and lion conflicts, similar to clashes of their modern African relatives.

Infill of tunnel valleys associated with landward-flowing ice sheets: The missing Middle Pleistocene record of the NW European rivers?

NASA Astrophysics Data System (ADS)

Moreau, Julien; Huuse, Mads

2014-01-01

The southern termination of the Middle and Late Pleistocene Scandinavian ice sheets was repeatedly located in the southern North Sea (sNS) and adjacent, north-sloping land areas. Giant meltwater-excavated valleys (tunnel valleys) formed at the southern termination of the ice sheets and contain a hitherto enigmatic succession of northward prograding clinoforms, comprising 1000s km3 of sediment. This study analyses 3D seismic data, covering the entire sNS, and demonstrates for the first time that the formation of these tunnel valleys was separate from their infill. The infill constitutes the postglacial record of the NW European river deltas, which had so far been considered missing.

Sedimentary and structural patterns on the northern Santa Rosa-Cortes Ridge, southern California

USGS Publications Warehouse

Field, M.E.; Richmond, W.C.

1980-01-01

The Santa Rosa-Cortes Ridge is an 1800 m high, 180 km long feature lying approximately 90 km off the coast of southern California and directly south of the northern group of Channel Islands. Geophysical profiling and sampling cruises to the northern part of the ridge, an area of recent and future lease sales for petroleum development, provide a strong data base for interpretation of structural and sedimentary patterns and their relation to potential geologic hazards. The northern part of the ridge is a complexly folded and faulted northwest-trending anticlinorium composed mostly of lower and middle Miocene shale and mudstone. Erosional remnants of upper Miocene and Pliocene rocks unconformably overlie highly folded pre-upper Miocene strata. The major structure of the ridge developed almost continuously from Oligocene or early Miocene time to the end of the Tertiary; many small folds formed between post-late Miocene and pre-late Pleistocene time. Numerous small faults cut the rocks on the ridge top. Faults cut basement rocks on the west side of the ridge along the Ferrelo fault zone. Published data on historical epicenters and evidence of offsets on the seafloor from seismic reflection and side-scan profiles, including limited evidence of possible strike-slip movement along fault traces, indicate that the northern Santa Rosa-Cortes Ridge is tectonically active. The crest of the ridge was truncated as the result of repeated sea-level fluctuations in the Quaternary. A thin veneer of unconsolidated medium to fine sand, less than 3 m thick, mantles most of the ridge; locally in topographically low areas and on the upper flanks of the ridge, thickness exceeds 20 m. The meager sediment cover, coupled with available evidence of relatively strong currents flowing across the ridge top, indicate that the ridge is an area of nondeposition or winnowing of fine sediments. Modern sediments become thicker and finer-grained from the ridge top to the ridge flanks, suggesting active accretion in those areas. Slumps are present at various depths on the flanks, and it seems probable that the thicker deposits (> 20 m) of modern sediments on the upper flanks will be sites of future slumping. ?? 1980.

Holocene aggradation of the Dry Tortugas coral reef ecosystem

USGS Publications Warehouse

Brock, J.C.; Palaseanu-Lovejoy, M.; Poore, R.Z.; Nayegandhi, A.; Wright, C.W.

2010-01-01

Radiometric age dating of reef cores acquired at the Dry Tortugas coral reef ecosystem (DTCRE) was merged with lidar topographic mapping to examine Holocene reef development linked to spatial variation in growth and erosion under the control of sea level. Analysis of variance of lidar topography confirmed the presence of three distinct terraces on all three major DTCRE banks (Loggerhead Bank, Garden Bank, and Pulaski Bank). Reef building on the middle terrace (T2) began atop Pleistocene edifices on Loggerhead Bank by 8.0 ka (thousands of years ago) and on Garden Bank by 7.2 ka at elevations of about −16.0 m and −11.9 m, respectively, relative to present mean sea level. Following this initiation at different elevations, T2 aggraded vertically on both banks at different rates during the early Holocene under foundering conditions until a highstand at 5.2 ka, resulting in a 2.21 m offset in present mean T2 elevation between these banks. Initiation of an upper terrace (T1) occurred on both Loggerhead Bank and Garden Bank in association with sea-level fall to a lowstand at near 4.8 ka. This upper terrace initiated on Garden Bank at about 5.0 ka and then grew upward at rate of 2.5 mm year−1 until approximately 3.8 ka. On Loggerhead Bank, the upper T1 terrace formed after 4.5 ka at a higher vertical aggradation rate of 4.1 mm year−1, but at a lower elevation than on Garden Bank. Terrace T1 aggraded on Loggerhead Bank below the elevation of lowstands during late Holocene sea-level oscillation, and consequently erosion on Loggerhead Bank was minimal and likely limited to the crest of the upper terrace. In contrast, after 3.8 ka terrace T1 on Garden Bank likely tracked sea level and consequently underwent erosion when sea level fell to second, third and fourth lowstands at 3.3, 1.1, and 0.3 ka.

Upper Cenozoic deposits of the central Delmarva Peninsula, Maryland and Delaware

USGS Publications Warehouse

Owens, James Patrick; Denny, Charles Storrow

1979-01-01

The surface and shallow subsurface sediments of the lower Delmarva Peninsula include beds ranging in age from Miocene to Holocene. The oldest beds appear to be typical shelf deposits of the Chesapeake Group (Calvert-Choptank age). These marine units are overlain by deltaic deposits, which range from fluviatile facies in the north (Pensauken Formation) to marginal marine and marine beds in the south ('Yorktown(?) and Cohansey(?)' Formations as used by Rasmussen and Slaughter in 1955). This large deltaic mass underlies most of the Delmarva Peninsula. Fossil age determinations supplemented by some radiometric dates indicate the delta to be largely late Miocene in age. The nonmarine facies of the delta, the Pensauken Formation, previously was considered to be Pleistocene in age. The late Miocene delta and possibly the Yorktown Formation (lower to middle Pliocene) are overlain by a feldspathic sand, the Beaverdam, which is at least in part marginal marine. Microflora recovered from this formation include species no longer indigenous to the Delmarva region ('exotics'). On the basis of existing information, microfloral assemblages containing 'exotics' are pre-Pleistocene in age. The Beaverdam therefore is pre-Pleistocene in age, probably late Pliocene. A highly dissected and weathered unit, the Walston Silt, caps the uplands of the central Delmarva Peninsula, where it overlies the Beaverdam. The Walston has a microflora containing 'exotics' and therefore is considered to be the youngest Tertiary unit (uppermost Pliocene) in this area. Sediments forming a barrier-back-barrier sequence fringe most of the southern Maryland-Delaware part of the Delmarva Peninsula and are found at altitudes of as much as 15 m (50 ft) above sea level. This sequence, the Omar Formation, is Sangamon in age and has been dated radiometrically as 60,000 to about 100,000 years old. The microflora in these beds contains no 'exotics,' and the assemblage suggests a warm-temperate environment. The Omar represents the highest stand of the Quaternary seas in the Delmarva region. The Ironshire and Kent Island Formations overlie or cut into the Omar Formation and are probably late Sangamon and middle Wisconsin, respectively, in age. Near Ocean City, the Ironshire forms a seaward-facing scarp with a toe nearly 4.5 m (15 ft) above sea level. A warm-temperate microfloral assemblage from the fluviatile-estuarine facies of the Ironshire Formation in the Delaware Bay region suggests that the formation is interglacial, probably late Sangamon in age. The Ironshire and Omar Formations are overlain unconformably by the Sinepuxent Formation. The top of this marine unit is slightly above present sea level and has been dated by radiocarbon as about 30,000 years old or middle Wisconsin. The microflora from this formation is a cold to cool-temperate assemblage (high proportion of spruce pollen). The outer fringes of the Delmarva Peninsula are being overlapped by deposits of a Holocene marine transgression.

Structural characteristics of epicentral areas in Central Europe: study case Cheb Basin (Czech Republic)

NASA Astrophysics Data System (ADS)

Bankwitz, P.; Schneider, G.; Kämpf, H.; Bankwitz, E.

2003-03-01

The earthquake distribution pattern of Central Europe differs systematically from the neighbouring areas of NW and southern Europe regarding the fault plane kinematics. Within a belt between the French Massif Central and the northern part of the Bohemian Massif (1000 km) sinistral faulting along N-S zones dominates on the contrary to the Alps and their foreland with common bookshelf shears. One of the prominent N-S structures is the Regensburg-Leipzig-Rostock Zone (A) with several epicentral areas, where the main seismic center occurs in the northern Cheb Basin (NW Bohemia). The study demonstrates new structural results for the swarm-quake region in NW-Bohemia, especially for the Nový Kostel area in the Cheb Basin. There the N-S-trending newly found Počatky-Plesná zone (PPZ) is identical with the main earthquake line. The PPZ is connected with a mofette line between Hartušov and Bublák with evidence for CO 2 degassing from the subcrustal mantle. The morphologically more prominent Mariánské Lázně fault (MLF) intersects the PPZ obliquely under an acuate angle. In the past the MLF was supposed to be the tectonic structure connected with the epicentral area of Nový Kostel. But evidence from the relocated hypocentres along the PPZ (at 7-12 kms depth) indicate that the MLF is seismically non-active. Asymmetric drainage patterns of the Cheb Basin are caused by fault related movement along Palaeozoic basement faults which initiate a deformation of the cover (Upper Pliocene to Holocene basin filling). The PPZ forms an escarpment in Pliocene and Pleistocene soft rock and is supposingly acting as an earthquake zone since late Pleistocene time. The uppermost Pleistocene of 0.12-0.01 Ma deposited only in front of the fault scarp dates the fault activity. The crossing faults envelope crustal wedges under different local stress conditions. Their intersection line forms a zone beginning at the surface near Nový Kostel, dipping south with increasing depth, probably down to about 12 km. The intersection zone represents a crustal anomaly. There fault movements can be blocked up and peculiar stress condition influence the behaviour of the adjacent crust. An ENE-WNW striking dextral wrench fault was detected which is to expect as kinematic counterpart to the ca. N-S striking sinistral shear zones. Nearly E-W striking fracture segments were formerly only known as remote sensing lineaments or as joint density zones. The ENE shear zone is characterized by a set of compressional m-scale folds and dm-scale faults scattered within a 20 m wide wrench zone. It is built up of different sets of cleavage-like clay plate pattern of microscopical scale. The associated shear planes fit into a Riedel shear system. One characteristic feature are tiny channels of micrometer scale. They have originated after shear plane bending and are the sites of CO 2 mantle degassing.

Pliocene-Pleistocene ecological niche evolution shapes the phylogeography of a Mediterranean plant group.

PubMed

Benítez-Benítez, C; Escudero, M; Rodríguez-Sánchez, F; Martín-Bravo, S; Jiménez-Mejías, P

2018-04-01

Estimating species ability to adapt to environmental changes is crucial to understand their past and future response to climate change. The Mediterranean Basin has experienced remarkable climatic changes since the Miocene, which have greatly influenced the evolution of the Mediterranean flora. Here, we examine the evolutionary history and biogeographic patterns of two sedge sister species (Carex, Cyperaceae) restricted to the western Mediterranean Basin, but with Pliocene fossil record in central Europe. In particular, we estimated the evolution of climatic niches through time and its influence in lineage differentiation. We carried out a dated phylogenetic-phylogeographic study based on seven DNA regions (nDNA and ptDNA) and fingerprinting data (AFLPs), and modelled ecological niches and species distributions for the Pliocene, Pleistocene and present. Phylogenetic and divergence time analyses revealed that both species form a monophyletic lineage originated in the late Pliocene-early Pleistocene. We detected clear genetic differentiation between both species with distinct genetic clusters in disjunct areas, indicating the predominant role of geographic barriers limiting gene flow. We found a remarkable shift in the climatic requirements between Pliocene and extant populations, although the niche seems to have been relatively conserved since the Pleistocene split of both species. This study highlights how an integrative approach combining different data sources and analyses, including fossils, allows solid and robust inferences about the evolutionary history of a plant group since the Pliocene. © 2018 John Wiley & Sons Ltd.

Late Pleistocene-Holocene phytoplankton productivity in the Gulf of Alaska, IODP Site U1419

NASA Astrophysics Data System (ADS)

LeVay, L. J.; Romero, O. E.; McClymont, E.; Müller, J.; Penkrot, M. L.; Jaeger, J. M.; Mix, A.; Walczak, M.

2016-12-01

The modern Gulf of Alaska (GoA) is a high-nutrient, low-chlorophyll region that is iron-limited; however, the coastal region of Alaska is macronutrient-limited. Vertical mixing of these shallow coastal and deep basinal waters produce high seasonal productivity across the shelf. Previous studies on the Alaskan shelf showed that productivity varied across the Pleistocene-Holocene transition, likely related to climate and sea level change that brought nutrients from estuaries into the Gulf. Here we explore an extended record through the Late Pleistocene-Holocene to reconstruct the productivity of phytoplankton groups in the GoA and to understand the impact of glacial/interglacial climates on primary production and nutrient availability near the shelf. International Ocean Discovery Program (IODP) Site U1419 was cored during Expedition 341 on the upper continental slope in the GoA. A high-resolution sedimentary sequence was recovered that records Late Pleistocene-Holocene glacial and paleoceanographic dynamics. Both calcareous nannoplankton and diatoms are well-represented at Site U1419. Very few studies have explored the competition of these two phytoplankton groups in the geologic record. Because calcareous nannoplankton and diatoms favor differing nutrient conditions, changes in their abundance can aid in reconstructing shifts in primary productivity as well as the causes, such as stratification or nutrient limitation. We present a multi-proxy record, including the group and species abundance of diatoms and calcareous nannoplankton, biogenic bulk components content, alkenone-based sea surface temperatures, and XRF core scanning elemental composition, which is used to interpret fluctuations in phytoplankton and identify the underlying causes. Initial results show the group abundance of nannoplankton and diatoms fluctuates greatly and appears to covary. Calcareous nannoplankton abundance increases with sea surface temperature and is related to higher alkenone concentrations in the sediments. The occurrence of diatoms is sporadic and could be linked to silica-limitation in surface waters. These findings will provide new insights into the processes governing fossil phytoplankton interactions and how this affects production and carbon cycling on the shelf.

Paleomagnetic Results From the Pleistocene Sediments of Lomonosov Ridge, Central Artic Ocean, IODP Leg 302

NASA Astrophysics Data System (ADS)

King, J. W.; Heil, C.; O'Regan, M.; Moran, K.; Gattacecca, J.; Backman, J.; Jakobsson, M.; Moore, T.

2005-12-01

Two major conclusions can be drawn from magnetic studies of Pleistocene sediments drilled on Lomonosov Ridge, central Arctic Ocean during IODP Leg 302. The first conclusion is that central Arctic Ocean sedimentation rates approach 2 cm/ka during the Pleistocene, thereby resolving the Arctic sedimentation rate controversy in favor of "fast" rates. The second conclusion is that abundant broad intervals of reversed polarity during the Pleistocene are a consistent characteristic of Arctic sedimentary records. These broad reversed intervals have helped perpetuate the Arctic sedimentation rate controversy. The weight of evidence strongly indicates that these reversal intervals are excursions. They do not occur during the late Brunhes Epoch (approximately 0-250,000 BP), but occur during the mid to lower Brunhes Epoch and persist into the upper Matuyama Epoch. We observe a strong correlation between rock magnetic variations, color changes, and physical property stratigraphy and these excursions. The model for Arctic sedimentation indicates that the excursions primarily occur during "interglacial" intervals. Previous high quality paleomagnetic studies of Bermuda Rise sediments have shown that approximately 85 % of Brunhes age excursions occur during interglacial periods (Lund, et al., 2001). In addition, similar excursions do not appear to occur at high southern latitudes (e.g. Acton, et al., 2002). For these reasons, we feel that hypotheses that attribute the interesting observed Arctic paleomagnetic behavior to environmental controls (e.g. sedimentation processes) are favored over those involving geomagnetic field behavior within the tangent cylinder. Acton, G. D., Guyodo, Y., and S. A. Brachfeld, 2002. Magnetostratigraphy of sediment drifts on the continental rise of West Antarctica (ODP Leg 178, Sites 1095, 1096, and 1101). In Barker, P. F., Camerlenghi, A., Acton, G. D., and Ramsay, A.T.S (Eds.), Proc. ODP Sci. Results, v. 178; 1-61 (CD ROM). Lund, S. P., G. D. Acton, B. Clement, M. Okada, and T. Williams. 2001. Brunhes chron magnetics excursions recovered from Leg 172 sediments. In Keigwin, L. D., Rio, D., Acton, G. D., and Arnold, E., (eds.) Proc. ODP Sci. Results, v. 172; p. 1-18 (Online)

The Pleistocene evolution of the East Antarctic Ice Sheet in the Prydz bay region: Stable isotopic evidence from ODP Site 1167

USGS Publications Warehouse

Theissen, K.M.; Dunbar, R.B.; Cooper, A. K.; Mucciarone, D.A.; Hoffmann, D.

2003-01-01

Ocean Drilling Program Leg 188, Prydz Bay, East Antarctica is part of a larger initiative to explore the Cenozoic history of the Antarctic Ice Sheet through direct drilling and sampling of the continental margins. In this paper, we present stable isotopic results from Ocean Drilling Program (ODP) Site 1167 located on the Prydz Channel Trough Mouth Fan (TMF), the first Antarctic TMF to be drilled. The foraminifer-based ??18O record is interpreted along with sedimentary and downhole logging evidence to reconstruct the Quaternary glacial history of Prydz Bay and the adjacent Lambert Glacier Amery Ice Shelf System (LGAISS). We report an electron spin resonance age date of 36. 9 ?? 3.3 ka at 0.45 m below sea floor and correlate suspected glacial-interglacial cycles with the global isotopic stratigraphy to improve the chronology for Site 1167. The ??18O record based on planktonic (Neogloboquadrina pachyderma (s.)) and limited benthic results (Globocassidulina crassa), indicates a trend of ice sheet expansion that was interrupted by a period of reduced ice volume and possibly warmer conditions during the early-mid-Pleistocene (0.9-1.38 Ma). An increase in ?? 18O values after ??? 900 ka appears to coincide with the mid-Pleistocene climate transition and the expansion of the northern hemisphere ice sheet. The ??18O record in the upper 50 m of the stratigraphic section indicates as few as three glacial-interglacial cycles, tentatively assigned as marine isotopic stages (MIS) 16-21, are preserved since the Brunhes/Matuyama paleomagnetic reversal (780 ka). This suggests that there is a large unconformity near the top of the section and/or that there may have been few extreme advances of the ice sheet since the mid-Pleistocene climate transition resulting in lowered sedimentation rates on the Prydz Channel TMF. The stable isotopic record from Site 1167 is one of the few available from the area south of the Antarctic Polar Front that has been linked with the global isotopic stratigraphy. Our results suggest the potential for the recovery of useful stable isotopic records in other TMFs. ?? 2003 Elsevier B.V. All rights reserved.

Ground-water geology of the Gonaives Plain, Haiti

USGS Publications Warehouse

Taylor, George C.; Lemoine, Rémy C.

1950-01-01

The Gonaives Plain lies in northern Haiti at the head of the Gulf of Gonaives. Ground water in the plain is used widely for domestic and stock purposes but only to limited extent for irrigation. The future agricultural development of the plain will depend in large measure on the proper utilization of available ground-water supplies for irrigation. The rocks in the region of the Gonaives Plain belong to the upper (?) Cretaceous series of the Cretaceous system, the Nocene and Oligovene series of the Tertiary system, and the Pleistocene and Recent series of the Quarternary system. The structural depression occupied by the Gonaives Plain was formed in post-Miocene time by the dislocation of Oligocene and older rocks along normal faults and by the tilting of the adjacent crustal blocks. The lower parts of the depression contain a Pleistocene and Recent alluvial fill deposited by streams tributary to the plain. The upper (?) Cretaceous rocks include aniesite and basalt lava flows locally intercalated with some beds of tuff and agglomerate. These rocks are generally dense and impervious but locally small springs rise from fractures and bedding planes or from weathered zones. The Nocene rocks are hard, thin-bedded, cherty limestones with some beds of massive chalky limestone. Considerable ground water circulates through joints, bedding planes, and solution passages in these rocks giving rise to important springs such as Sources Madame Charles. These springs discharge at the rate of about 110 liters per second. The Oligocene rocks include limestone, shely limestone, limy sandstone, marl, and shale. The limestone beds contain solution passages and other openings and these may afford capacity for the circulation of ground water. However, no wells or springs in Oligocene rocks were observed during the present study. The alluvial fill of the plain is composed of interbedded lenses of clay, silt, sand, and gravel. These deposits contain a zone of saturation whose upper limit is marked by a water table. The depth to the water table beneath the alluvial lowland of the plain ranges from less than one meter to about 20 meters. In most places in the plain the depth to water is less that 15 meters. Where present in the zone of saturation the coarse, well-sorted sand and gravel beds of the alluvium will probably yield moderate to large supplies of water to wells and infiltration galleries. The individual yields of existing wells range from a few liters to about 60 liters per second. The most favorable part of the plain for ground-water prospecting and development lies 5 to 10 kilometers northeast of Gonaives. In this area yields of 10 to 50 liters per second could be obtained from the alluvium in simple wells drilled to depths of about 35 to 45 meters. Additional information on the yield and physical character of aquifers in the alluvium would be provided by test wells drilled to depths of 40 to 60 meters.

A record of reversed polarity carries by the iron sulphide greigite in British early Pleistocene sediments

NASA Astrophysics Data System (ADS)

Hallam, D. F.; Maher, B. A.

1994-01-01

Palaeomagnetic measurements were made on samples extracted from a short sequence of early Pleistocene estuarine clays, now exposed in a sea cliff near Sheringham on the north Norfolk coast, UK. On the basis of earlier palynological work, these clays had been ascribed a Pastonian (late Tiglian) age. The clays show marked changes in colour, from reddish-brown at the top of the unit, to blue-grey in the middle, and grey-brown at the base. The palaeomagnetic data vary in close association with these colour changes. The top and basal brown clays show scattered normal directions of low intensity, while the middle blue clays show strongly clustered reversed directions, of much higher intensities. Some samples taken from the boundary between the middle blue clays and upper red clays show upon demagnetisation a normal overprint on a stable reversed polarity. Using high-gradient magnetic extraction, magnetic concentrates have been obtained from the strongly magnetic middle blue clays. The presence of iron sulphide minerals in these concentrates was identified using energy-dispersive X-ray analysis during scanning electron microscopy. More specifically, X-ray diffraction identifies greigite as the only detectable ferrimagnetic mineral in the magnetic concentrates. Rock magnetic measurements show clear qualitative differences in the magnetic mineralogies of the three clay subunits, but absolute identification of the magnetic mineralogy of the weakly magnetic upper and basal brown clays has not yet been possible. We interpret the sequence as a primary reversed polarity record. This record is carried by the iron sulphide greigate as a chemical remanence acquired during `syn'-depositional reduction of iron via the decomposition of organic material in these anoxic tidal clays. Subsequently, the upper and basl subunits of the clay have been oxidised by permeation of groundwater from the adjacent coarse-grained sediments. Most of the griegite in the oxidised margins of the clay has been altered as a result, to a new, less efficient magnetic recording material which thus carries a later, scattered, low-intensity, normal overprint.

The association between mid-facial morphology and climate in northeast Europe differs from that in north Asia: Implications for understanding the morphology of Late Pleistocene Homo sapiens.

PubMed

Evteev, Andrej A; Movsesian, Alla A; Grosheva, Alexandra N

2017-06-01

The climate of northeastern Europe is likely to resemble in many ways Late Pleistocene periglacial conditions in Europe, but there have been relatively few studies exploring the association between climate and morphology in the mid-face of modern northeastern European populations. To fill this gap, we sampled 540 male skulls from 22 European and Near Eastern groups, including 314 skulls from 11 populations from northeastern Europe, to test for possible climate-morphology association at the continental scale. Our results found a moderate and highly significant association (R = 0.48, p = 0.0013, Mantel test) between sets of 23 mid-facial measurements and eight climatic variables. A partial least squares analysis revealed this association to be mostly driven by differences between groups from northeastern Europe and populations from the Mediterranean and the Caucasus. Matrices of between-group genetic distances based on Y-chromosome and mtDNA markers, as well as cranial non-metric and geographic distance matrices, were used to control for the possible influence of shared population history. Irrespective of which measure of neutral between-population distances is taken into account, the association between cranial variables and climate remains significant. The pattern of association between climate and morphology of the mid-face in western Eurasia was then compared to that in east and north Asia. Although differences between the two were found, there were also similarities that support existing functional interpretations of morphology for the bony parts of the upper airways. Last, in a preliminary analysis using a reduced set of measurements, mid-facial morphology of several Upper Paleolithic European Homo sapiens specimens was found to be more similar to groups from northern and northeastern Europe than to southern European populations. Thus, the population of northeastern Europe rather than east and north Asian groups should be used as a model when studying climate-mediated mid-facial morphology of Upper Paleolithic European H. sapiens. Copyright © 2017 Elsevier Ltd. All rights reserved.

Legacy sediment storage in New England river valleys: anthropogenic processes in a postglacial landscape

NASA Astrophysics Data System (ADS)

Snyder, N. P.; Johnson, K. M.; Waltner, M.; Hopkins, A. J.; Dow, S.; Ames, E.; Merritts, D. J.; Walter, R. C.; Rahnis, M. A.

2016-12-01

Walter and Merritts (2008, and subsequent papers) show that legacy sediment associated with deposition in millponds is a common feature in river valleys of the Mid-Atlantic Piedmont region, with 1-5 m of fine sand and silt overlying Holocene soil and Pleistocene periglacial deposits. For this project, we seek to test the hypothesis that these field relationships are seen in New England, a formerly glaciated region with similar history and intensity of forest clearing and milldam construction during the 17-19th centuries. We study three watersheds, using field observations of bank stratigraphy, radiocarbon dating, and mapping of terraces and floodplains using lidar digital elevation models and other GIS datasets. The 68 km2 South River watershed in western Massachusetts exhibits the most extensive evidence for legacy sediment storage. We visited 17 historic dam sites in the watershed and found field evidence for fine sand and silt legacy sediment storage at 14, up to 2.2 m thick. In the 558 km2 Sheepscot River watershed in coastal Maine, we visited 12 historic dam sites, and found likely legacy sediment at six, up to 2.3 m thick. In the 171 km2 upper Charles River watershed in eastern Massachusetts, we investigated 14 dam sites, and found legacy sediment at two, up to 1.8 m thick. Stratigraphically, we identified the base of legacy sediment from a change in grain size to gravel at most sites, or to Pleistocene marine clay at some Sheepscot River sites. In the Sheepscot River, we observed cut timbers underlying historic sediment at several locations, likely associated with sawmill activities. Only at the Charles River were we able to radiocarbon date the underlying gravel (1281-1391 calibrated CE). At no site did we find a buried Holocene soil, in contrast to the field relations commonly observed in the Mid-Atlantic region. This may indicate that the New England sites have eroded to the pre-historic river bed, not floodplain surfaces. We attribute the variation in thickness and presence of legacy sediment at the New England sites to the existence or absence of upstream sediment supply in the form of thick (>5 m) glacial deposits. Of the three study watersheds, the South River has the most extensive glacial sediments, having been occupied by one or more ice-dammed lakes during the late Pleistocene, and the most legacy sediment storage.

Hominin footprints from early Pleistocene deposits at Happisburgh, UK.

PubMed

Ashton, Nick; Lewis, Simon G; De Groote, Isabelle; Duffy, Sarah M; Bates, Martin; Bates, Richard; Hoare, Peter; Lewis, Mark; Parfitt, Simon A; Peglar, Sylvia; Williams, Craig; Stringer, Chris

2014-01-01

Investigations at Happisburgh, UK, have revealed the oldest known hominin footprint surface outside Africa at between ca. 1 million and 0.78 million years ago. The site has long been recognised for the preservation of sediments containing Early Pleistocene fauna and flora, but since 2005 has also yielded humanly made flint artefacts, extending the record of human occupation of northern Europe by at least 350,000 years. The sediments consist of sands, gravels and laminated silts laid down by a large river within the upper reaches of its estuary. In May 2013 extensive areas of the laminated sediments were exposed on the foreshore. On the surface of one of the laminated silt horizons a series of hollows was revealed in an area of ca. 12 m(2). The surface was recorded using multi-image photogrammetry which showed that the hollows are distinctly elongated and the majority fall within the range of juvenile to adult hominin foot sizes. In many cases the arch and front/back of the foot can be identified and in one case the impression of toes can be seen. Using foot length to stature ratios, the hominins are estimated to have been between ca. 0.93 and 1.73 m in height, suggestive of a group of mixed ages. The orientation of the prints indicates movement in a southerly direction on mud-flats along the river edge. Early Pleistocene human fossils are extremely rare in Europe, with no evidence from the UK. The only known species in western Europe of a similar age is Homo antecessor, whose fossil remains have been found at Atapuerca, Spain. The foot sizes and estimated stature of the hominins from Happisburgh fall within the range derived from the fossil evidence of Homo antecessor.

Characterizing the Lower Paleolithic bone industry from Schöningen 12 II: A multi-proxy study.

PubMed

Julien, Marie-Anne; Hardy, Bruce; Stahlschmidt, Mareike C; Urban, Brigitte; Serangeli, Jordi; Conard, Nicholas J

2015-12-01

Although preservation of Paleolithic faunal assemblages from open-air settings is often poor, the Lower Paleolithic sites of Schöningen provide exceptionally well-preserved mammalian faunal material for investigating hominin/animal relationships. Pleistocene fossil assemblages, however, usually reflect a complex taphonomic history in which natural and anthropogenic processes are often superimposed. A number of examples of osseous finds that resemble tools were recently discovered in the MIS 9 deposits of Schöningen 12 II. Non-anthropogenic agents are known to produce surface modifications mimicking human artifacts and the identification of osseous remains used and/or deliberately modified by ancient hominins is often controversial in such old contexts. Multiple lines of evidence are thus useful for distinguishing between osseous artifacts and "eco-facts". In this paper, the recognition of the use of bone for different technological purposes by late Middle Pleistocene hominins is addressed through a multi-proxy study combining geoarcheology, bone taphonomy, zooarcheology, and use-wear analysis. This allowed the identification of the processes and agents responsible for the formation and modification of the different bone assemblages of Schöningen 12 II. Our analysis points to different types of bones having been likely used as tools. These results expand the diversity of the organic technological repertoire of the Middle Pleistocene hominins, making Schöningen 12 II a remarkable new source of information on osseous technology long before the Upper Paleolithic, the period traditionally viewed as the start of the systematic use of bone tools. Together with other observations of bone tools documented during the Lower and Middle Paleolithic, the results from Schöningen show that archeologists may have underestimated the diversity and importance of osseous technology among archaic hominins. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiscalar approach to archaeological site formation at GaJj17, East Turkana, Kenya

NASA Astrophysics Data System (ADS)

Murray, B. M.; Ranhorn, K. L.; Colarossi, D.; Mavuso, S. S.; Dogandžić, T.; Ziegler, M. J.; Warren, S. L.; Braun, D. R.; Harris, J. W. K.

2017-12-01

Kenya's East Turkana region hosts a rich Plio­Pleistocene record of fossils, archaeological artifacts, and sedimentary features whose chronostratigraphic histories are often obscured by landscape changes from erosional events and tectonic activity. The Middle Stone Age (MSA) record of the Koobi Fora Formation (KF Fm.) has particularly been subjected to this complex depositional history, making it a sparse unit and, consequently, widely understudied. Stratigraphically located in between the maximum capping unconformity of the KF Fm.'s Chari tuff ( 1.39 Ma) and that of the Galana Boi Fm. ( 10 ka), the unit provides a unique window into understanding the Late Pleistocene of the region. The MSA surface scatters at archaeological site GaJj17 prompted further study into the site's age and depositional chronology. The GaJj17 ridge is locally distinguished by its cap of Late Pleistocene sands overlying strata containing tuffs likely of the Upper Burgi (2.0­-1.87 Ma) or KBS (1.87­-1.56 Ma) members. To investigate whether GaJj17's preservation is due to tectonic deformation, a broader scale examination of the structural geology was conducted through surveys and aerial imagery. Regions of deformation were identified and mapped to establish the geological history of the locality. Resultant observations and elevation data offer insight into regional faults at the root of prolonged structural alterations which have facilitated the unique preservation of MSA materials. Through a multiscalar approach it is possible to understand both the formation of GaJj17 and the underlying processes behind preservation and destruction in the changing landscape of the Turkana basin, enabling future identification of archaeological sites through proxies of elevation, regional stratigraphy, and fault mapping. This research was supported by IRES grants 1358178 and 1358200 from the U.S. National Science Foundation.

Muzzle of South American Pleistocene ground sloths (Xenarthra, Tardigrada).

PubMed

Bargo, M Susana; Toledo, Néstor; Vizcaíno, Sergio F

2006-02-01

Sloths are among the most characteristic elements of the Cainozoic of South America and are represented, during the Pleistocene, by approximately nine genera of gigantic ground sloths (Megatheriidae and Mylodontidae). A few contributions have described their masticatory apparatus, but almost no attention has been paid to the reconstruction of the muzzle, an important feature to consider in relation to food intake, and particularly relevant in sloths because of the edentulous nature of the muzzle and its varied morphology. The relationship between dietary habits and shape and width of the muzzle is well documented in living herbivores and has been considered an important feature for the inference of alimentary styles in fossils, providing an interesting methodological tool that deserves to be considered for xenarthrans. The goal of this study was to examine models of food intake by reconstructing the appearance and shape of the muzzle in five species of Pleistocene ground sloths (Megatherium americanum, Glossotherium robustum, Lestodon armatus, Mylodon darwini, and Scelidotherium leptocephalum) using reconstructions of the nasal cartilages and facial muscles involved in food intake. The preservation of the nasal septum, and the scars for muscular attachment in the rostral part of the skulls, allow making a conservative reconstruction of muzzle anatomy in fossil sloths. Wide-muzzled ground sloths (Glossotherium and Lestodon) had a square, nonprehensile upper lip and were mostly bulk-feeders. The lips, coupled with the tongue, were used to pull out grass and herbaceous plants. Narrow-muzzled sloths (Mylodon, Scelidotherium, and Megatherium) had a cone-shaped and prehensile lip and were mixed or selective feeders. The prehensile lip was used to select particular plants or plant parts. (c) 2005 Wiley-Liss, Inc.

Stratigraphic Paleobiology of the Taranto Area

NASA Astrophysics Data System (ADS)

Scarponi, Daniele; Angeletti, Lorenzo; Taviani, Marco; Huntley, John Warren; Amorosi, Alessandro; Negri, Alessandra; Battista Vai, Gian

2015-04-01

The area surrounding Taranto, Italy is chronostratigraphically very important, as it is one of the few areas in the world where Upper Pleistocene marine successions are well exposed, easily accessible, and relatively thick. Several outcrops in this area were investigated as suitable marine sections for defining the Late Pleistocene GSSP. At these locations, the late Pleistocene bathymetric history of the Taranto area was depicted using macrobenthic assemblages from a network of outcrops and cores. Outcrops at Pontile, Fronte, and Garitta, along with two cores drilled at Cimino and Cantoro were densely sampled to conduct quantitatively-derived paleobathymetric reconstructions. These deposits yielded relatively diverse mollusk associations (> 250 species and > 9.000 specimens distributed among 55 samples), dominated by extant mollusk species of known bathymetric distribution. Multiple analytical approaches were applied to the macrobenthic dataset in a comparative fashion: (i) direct calibration by weighted averaging of taxa with known preferred depth recovered in a sample, (ii) posteriori-calibrated ordination (DCA) using bathymetric data of key extant taxa. These analyses were conducted at both species and genus level. Regardless of the choice of the analytical method, mollusk assemblages yielded bathymetric trends congruent with previous qualitative and semi-quantitative paleoecological and stratigraphic analyses: the bathymetric range of sampled deposits is bracketed between 140 and 0 meters. Secondly, macrobenthos-derived proxies provided an improved characterization of the marine deposits in terms of sample bathymetry and by discriminating shallowing-upward (regressive) trends from deepening-upward (transgressive) tendencies. Thirdly, mollusk-derived bathymetric inferences suggest spatial bathymetric gradients that are coherent with the morphology of the study area. In conclusion, the results provided an improved characterization of coastal depositional facies in a sequence stratigraphic perspective, which is one of the primary research goals of Stratigraphic Paleobiology.

Sediment composition and texture of Pleistocene deep-sea turbidites in the eastern Nankai Trough gas hydrate field

NASA Astrophysics Data System (ADS)

Egawa, K.; Nishimura, O.; Izumi, S.; Ito, T.; Konno, Y.; Yoneda, J.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Nagao, J.

2013-12-01

In the 2012 JOGMEC/JAPEX pressure coring operation, we collected a totally 60-m-long core sample from the interval of gas hydrate concentration zone at the planned site of the world's first offshore production test of natural gas hydrates in the eastern Nankai Trough area. In this contribution, the cored sediments were sedimentologically, mineralogically, and paleontologically analyzed to know sediment composition and texture of reservoir formation, which are known to provide useful geological information to discuss sedimentation, diagenesis, and permeability. The targeted interval belongs to a Middle Pleistocene deep-sea turbidite sequence distributed around the Daini Atsumi Knoll, east of the Kumano forearc basin, and consists of the lower (thick sand-dominant), middle (thin-bedded sand-and-mud alteration), and upper (mud-dominant) formations in ascending order. X-ray powder diffraction analysis and scanning electron microscopic observation revealed that pore space in turbidite sands is commonly filled with clay fractions (mostly phyllosilicates) in the lower formation. Such a pore filling of clay fractions is reflected in particle size distribution showing high standard deviation and clay content, and thus is expected to have an impact on permeability. There is the older Pliocene to Early Pleistocene fossil coccolith record in the middle formation, indicating sediment reworking probably induced by submarine landslide. The coexistence of authigenic siderite and framboidal pyrite in the middle formation strongly suggests anoxic microbial activity under methane oxidation and sulfide reduction conditions at least before the hydrate cementation. This contribution was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI).

Petroleum systems of the Southeast Tertiary basins and Marbella area, Southeast Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuentes, F.

1996-08-01

This study was done in an area where insufficient organic-rich rocks were available for a reliable oil-source rock correlation. However, oil-rock correlations, molecular characteristics of key horizons, paleofacies maps, maturation and potential migration pathways suggest the Tithonian as a major source rock. Moreover, there is good evidence of high quality source rocks in Oxfordian, Kimmeridgian, Middle-Upper Cretaceous and Paleogene (mainly in the Eocene). Plays were identified in Upper Jurassic oolitic sequences, Early-Middle Cretaceus carbonate platform rocks and breccias, Late Cretaceous basinal fracture carbonates, Paleogene carbonates and breccias, Early-Middle Miocene mounds and submarine fans and isolated carbonate platform sediments and Miocene-Recentmore » turbidites. Seal rocks are shaly carbonates and anhydrites from Tithonian, basinal carbonates and anhydrites from Middle-Upper Cretaceous, basinal carbonates and marls from Upper Cretaceous and Paleogene shales, and bathyal shales from Early Miocene-Recent. The first phase of oil migration from upper Jurassic-Early Cretaceous source rocks occurred in the Early-Middle Cretaceous. In the Upper Cretaceous the Chortis block collided with Chiapas, and as a result mild folding and some hydrocarbons were emplaced to the structural highs. The main phase of structuration and folding of the Sierra de Chiapas started in the Miocene, resulting in well-defined structural traps. Finally, in Plio-Pleistocene the Chortis block was separated, the major compressional period finished and the southern portion of Sierra de Chiapas was raised isostatically. As a result of major subsidence, salt withdrawal and increased burial depth, conditions were created for the generation of liquid hydrocarbons from the Paleogene shales.« less

Geomorphology of the Chippewa River delta of Glacial Lake Saginaw, central Lower Michigan, USA

NASA Astrophysics Data System (ADS)

Connallon, Christopher B.; Schaetzl, Randall J.

2017-08-01

We introduce, characterize, and interpret the geomorphic history of a relict, Pleistocene-aged delta of the Chippewa River in central Lower Michigan. The broad, sandy Chippewa delta developed into various stages of Glacial Lake Saginaw, between ca. ≈ 17 and 15 ka·BP (calibrated ages). Although the delta was first identified in 1955 on a statewide glacial geology map, neither its extent nor its Pleistocene history had been previously determined. The delta is typically forested, owing to its wet, sandy soils, which stand out against the agricultural fields of the surrounding, loamy lake plain sediments. The delta heads near the city of Mt Pleasant and extends eastward onto the Saginaw Lowlands, i.e., the plain of Glacial Lake Saginaw. Data from 3285 water well logs, 180 hand augered sites, and 185 points randomly located in a GIS on two-storied (sand over loam) soils were used to determine the extent, textural properties, and thickness of the delta. The delta is ≈ 18 km wide and ≈ 38 km long and is sandy throughout. Deltaic sediments from neighboring rivers that also drained into Glacial Lake Saginaw merge with the lower Chippewa delta, obscuring its boundary there. The delta is thickest near the delta's head and in the center, but thins to 1-2 m or less on its eastern margins. Mean thicknesses are 2.3-2.9 m, suggestive of a thin sediment body, frequently impacted by the waves and fluctuating waters of the lakes. Although beach ridges are only weakly expressed across the delta because of the sandy sediment, the coarsest parts of the delta are generally coincident with some of these inferred former shorezones and have a broad, incised channel that formed while lake levels were low. The thick upper delta generally lies above the relict shorelines of Glacial Lakes Saginaw and Arkona (≈ 17.1 to ≈ 16 ka·BP), whereas most of the thin, distal delta is associated with Glacial Lake Warren (≈ 15 ka·BP). Together, these data suggest that the Chippewa delta formed and prograded as lake levels in the Saginaw Lowlands alternated and episodically fell. The result is a delta that is comparatively thin, expansive, and sandy. In some places, these sands have subsequently been reworked into fields of small parabolic dunes.

Geochemical characteristics of Holocene laminated sapropel (unit II) and underlying lacustrine unit III in the Black Sea

USGS Publications Warehouse

Dean, Walter E.; Arthur, Michael A.

2011-01-01

eg 1 of the 1988 R/V Knorr expeditions to the Black Sea recovered 90 gravity and box cores. The longest recovery by gravity cores was about 3 meters, with an average of about 2.5 meters, recovering all of the Holocene and upper Pleistocene sections in the Black Sea. During the latest Pleistocene glaciation, sea level dropped below the 35-meters-deep Bosporus outlet sill of the Black Sea. Therefore throughout most of its history the Black Sea was a lake, and most of its sediments are lacustrine. The oldest sediments recovered (older than 8,000 calendar years) consist of massive to coarsely banded lacustrine calcareous clay designated as lithologic Unit III, generally containing less than 1 percent organic carbon (OC). The base of overlying Unit II marks the first incursion of Mediterranean seawater into the Black Sea, and the onset of bottom-water anoxia about 7,900 calendar years. Unit II contains as much as 15 percent OC in cores from the deepest part of the Black Sea (2,200 meters). The calcium carbonate (CaCO3) remains of the coccolith Emiliania huxleyi form the distinctive white laminae of overlying Unit I. The composition of Unit III and Unit II sediments are quite different, reflecting different terrigenous clastic sources and increased contributions from hydrogenous and biogenic components in anoxic Unit II sapropel. In Unit II, positive covariance between OC and three trace elements commonly concentrated in OC-rich sediments where sulfate reduction has occurred (molybdenum, nickel, and vanadium) and a nutrient (phosphorus) suggest a large marine source for these elements although nickel and vanadium also have a large terrigenous clastic source. The marine sources may be biogenic or hydrogenous. A large biogenic source is also suggested for copper and cobalt. Because abundant pyrite forms in the water column and sediments of the Black Sea, we expected to find a large hydrogenous iron component, but a strong covariance of iron with aluminum suggests that the dominant source of iron is from terrigenous clastic material. Most elements in lacustrine Unit III sediments have a strong covariance with Al indicating a very dominant terrigenous source. In Unit II, some elements, especially nickel, molybdenum, vanadium, and zinc, do not correlate with aluminum and have concentrations well above terrigenous clastic material, indicating a marine source.

High-resolution bathymetry and acoustic geophysical data from Santa Maria di Leuca Cold Water Coral province (Northern Ionian Sea—Apulian continental slope)

NASA Astrophysics Data System (ADS)

Savini, A.; Corselli, C.

2010-03-01

A total of 800 km 2 of multibeam echo-sounder coverage, roughly 800 km of chirp-sonar data and 18 km of side-scan sonar profiles (100/500 kHz) were acquired a few km offshore Santa Maria di Leuca (south-eastern Italy), from 200 m to 1300 m water depth. The explored area belongs to the upper slope of the gently south-eastward dipping Apulian continental margin (northern Ionian Sea). Acoustic datasets were collected, by three different oceanographic expeditions, where evidence of living cold-water coral (CWC) colonies were documented by previous surveys and samples. High-resolution multibeam bathymetry indicated an extensive rough seafloor with an irregular faulted upper surface to the west (reflecting large-scale tectonic control on the margin) and a highly disrupted upper slope formed by prominent downslope mass-movements to the north. A broad area in the east was influenced by mass-transport deposition, which resulted in a very complex hummocky seafloor, mainly shaped by detached block-like features and failure-related bedforms (i.e. low scarps, downslope lineations and compressional ridges). From the shallow seismic-stratigraphic data, failure events appeared to be multiple and recurrent and chaotic reflectors, both buried and exposed at the seafloor, affected most of the investigated area. Drift sedimentation was also recognised along a central large ridge, resulting in an interplay between contour currents and downslope turbidity currents. The spatial distribution of the CWC reefs was inferred from the acoustic facies interpretation based on video images and ground-truthed by sediment samples. It appeared that: (1) within the investigated area, living coral frameworks were located along large topographic highs facing the main flow of the bottom currents, where hard and firm substrata and/or failure-related sediment bedforms occurred; (2) CWC mainly settled on clustered (and isolated) mound-like features, tens to a few hundreds of metres long and no more than 25 m high and were located between 600 and 900 m water depth, within the broad area affected by downslope mass-transport deposits. Such mound-like morphologies could thus be interpreted as a result of sediment accreted by coral growth, with the consequent sediment trapping on small-scale positive seafloor irregularities; formed by different types of Pleistocene-exposed mass-transport deposits, their burial prevented by bottom currents.

Revision of Southern Hemisphere taxa referred to Fosterella (Crustacea: Cirripedia), and their extinction in response to Pleistocene cooling.

PubMed

Buckeridge, John

2015-11-01

Extensive barnacle coquinas (barnamols) formed around New Zealand's North and Chatham Islands during the late Pliocene to early Pleistocene. The inner-shelf megabalanine Fosterella is the primary constituent of these lithofacies, which also include epifaunal bivalves, bryozoans and less modified balanids like Notobalanus and Notomegabalanus. The status of genus Fosterella is reviewed, 3 species are retained and a new genus, Porobalanus, is proposed for Fosterella hennigi, a species restricted to the Early Pliocene of Cockburn Island, Antarctica. Significantly, Fosterella did not survive the New Zealand Pleistocene, although Notobalanus and Notomegabalanus, which have fossil records extending back to the Early Miocene, remain important components of present day cool-temperate Southern Hemisphere faunas. Extinction of Fosterella, in shelf waters off Argentina, is explained through a combination of changing circulatory and sedimentary regimes, competition for food and space, predation and physiological constraints. The driver of these factors was rapid regional cooling. Zoobank registration: urn:lsid:zoobank.org:pub:DBB1CB34-83E4-48BA-AA10-81823017F37A. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Mastodon herbivory in mid-latitude late-Pleistocene boreal forests of eastern North America

NASA Astrophysics Data System (ADS)

Teale, Chelsea L.; Miller, Norton G.

2012-07-01

Skeletal remains of the extinct American mastodon have often been found with deposits of short, decorticated twigs intermixed with plant fragments presumed to be gastrointestinal or fecal material. If such deposits are digesta, paleobotanical evidence may be used to analyze mastodon foraging strategy, with implications for assessing habitat selection, ecological roles, and response to environmental change. To identify components of mastodon diet in mid-latitude late-Pleistocene boreall forests of eastern North America, plant macrofossils and pollen from a molar socket (Hyde Park site, New York) were compared with dispersed deposits associated with skeletal remains (Hiscock and Chemung sites, New York). Similar macrofossil condition and twig morphology among samples, but difference from a modern boreal fen analog, confirmed the deposits were digesta. Comparison of twigs with material from other paleontological sites and modern elephants suggested dimensions generally indicative of digesta. Picea formed the bulk of each sample but Pinus may have been locally important. Wintertime browsing of Salix and Populus, and springtime consumption of Alnus, were indicated. Evidence for Cyperaceae, Gramineae, and Compositae was ambiguous. If conifers, broadleaf trees, shrubs, and herbs were necessary to fulfill dietary requirements, mastodons would have been nutritionally stressed by rapid late-Pleistocene decrease in vegetational diversity.

Geological probability calculation of new gas discoveries in wider area of Ivana and Ika Gas Fields, Northern Adriatic, Croatia

NASA Astrophysics Data System (ADS)

Tomislav, Malvić; Josipa, Velić; Režić, Mate

2016-09-01

There are eleven reservoirs in Ivana Gas Field and they are composed of Pleistocene sands, silt sands and siltstones, developed in dominant clays and marls depositional sequences. Ika Gas Field is the only field in Adriatic with gas accumulated in carbonate rocks, which are the deepest reservoir of the total four reservoirs. A carbonate reservoir is defined with tectonical and erosional unconformity, which is placed between Mesozoic and Pliocene rocks. The three younger Ika reservoirs are composed of Pleistocene sands, silt sands and siltstones that are laminated into clays and marls. The goal of our study was to assess the `Probability Of Success' (POS) of finding new gas accumulations within the marginal area of those two fields, either in the form of Mesozoic rocks or Pleistocene deposits. The assessment was successfully completed using the Microsoft Excel POS table for the analyzed areas in the Croatian part of the Po Depression, namely, Northern Adriatic. The methodology was derived and adapted from a similar POS calculation, which was originally used to calculate the geological probability of hydrocarbon discoveries in the Croatian part of the Pannonian Basin System (CPBS).

Cyclical Changes in the Pleistocene Climate from an Analysis of Biogenic Silica in a Bottom Sediment Core Sample of Lake Baikal

NASA Astrophysics Data System (ADS)

Dergachev, V. A.; Dmitriev, P. B.

2017-12-01

An inhomogeneous time series of measurements of the percentage content of biogenic silica in the samples of joint cores BDP-96-1 and BDP-96-2 from the bottom of Lake Baikal drilled at a depth of 321 m under water has been analyzed. The composite depth of cores is 77 m, which covers the Pleistocene Epoch to 1.8 Ma. The time series was reduced to a regular form with a time step of 1 kyr, which allowed 16 distinct quasi-periodic components with periods from 19 to 251 kyr to be revealed in this series at a significance level of their amplitudes exceeding 4σ. For this, the combined spectral periodogram (a modification of the spectral analysis method) was used. Some of the revealed quasi-harmonics are related to the characteristic cyclical oscillations of the Earth's orbital parameters. Special focus was payed to the temporal change in the parameters of the revealed quasi-harmonic components over the Pleistocene Epoch, which was studied by constructing the spectral density of the analyzed data in the running window of 201 and 701 kyr.

Last interglacial reef growth beneath Belize barrier and isolated platform reefs

USGS Publications Warehouse

Gischler, Eberhard; Lomando, Anthony J.; Hudson, J. Harold; Holmes, Charles W.

2000-01-01

We report the first radiometric dates (thermal-ionization mass spectrometry) from late Pleistocene reef deposits from offshore Belize, the location of the largest modern reef complex in the Atlantic Ocean. The results presented here can be used to explain significant differences in bathymetry, sedimentary facies, and reef development of this major reef area, and the results are significant because they contribute to the knowledge of the regional geology of the eastern Yucatán. The previously held concept of a neotectonically stable eastern Yucatán is challenged. The dates indicate that Pleistocene reefs and shallow-water limestones, which form the basement of modern reefs in the area, accumulated ca. 125–130 ka. Significant differences in elevation of the samples relative to present sea level (>10 m) have several possible causes. Differential subsidence along a series of continental margin fault blocks in combination with variation in karstification are probably the prime causes. Differential subsidence is presumably related to initial extension and later left-lateral movements along the adjacent active boundary between the North American and Caribbean plates. Increasing dissolution toward the south during Pleistocene sea-level lowstands is probably a consequence of higher precipitation rates in mountainous southern Belize.

East Cameron Block 270, a Pleistocene field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holland, D.S.; Sutley, C.E.; Berlitz, R.E.

1974-01-01

Exploration of the Plio-Pleistocene in the Gulf of Mexico since 1970 has discovered significant hydrocarbon reserves. One of the better gas fields to date has been the Block 270 E. Cameron field. Utilization of a coordinated exploitation plan with Schlumberger has allowed Pennzoil as operator, to develop and put on production the Block 270 field in a minimum time period. Block 270 field is a N.-S. trending faulted nose at 6,000 ft. At G-Sand depth (8,700 ft), the structure has closed, forming an elongated N.-S. structure with dip in all directions from the Block 270 area. Closure is the resultmore » of contemporaneous growth on the E. bounding regional fault. Structural and stratigraphic interpretations from dipmeters were used to help determine the most favorable offset locations.« less

Neogene marine sedimentary record of the Gulf of Alaska: from the glaciers to the distal submarine fan systems

NASA Astrophysics Data System (ADS)

Ridgway, K. D.; Bahlburg, H.; Childress, L. B.; Cowan, E. A.; Forwick, M.; Moy, C. M.; Müller, J.; Ribeiro, F.; Gupta, S.; Gulick, S. P.; Jaeger, J. M.

2013-12-01

The marine sedimentary record of Miocene to Pleistocene tectonics and glaciation is well preserved along the southern Alaska convergent margin. This margin is well suited for linking proximal to distal sediment transport processes because sediment is being generated by glacial erosion in the highest coastal mountain range on earth and subsequently being transported to the Aleutian subduction zone. We will discuss the sedimentary record from two end members of this system: (1) the proximal marine record now exposed onshore in the high peaks of the coastal ranges, and (2) the offshore distal record preserved in the Surveyor submarine fan system that was cored during the 2013 IODP Expedition 341. Onshore the Miocene non-glacial strata are represented by the Poul Creek Fm. This unit is 2000 m thick and in its upper part consists of mudstone, thin sandstone beds (10-30 cm thick), and thick bedded (1-2 m) highly bioturbated green sandstone beds that contain hummocky stratification. We interpret this unit as being deposited mainly in marine shelf environments. A gradational contact between the Poul Creek and the overlying upper Miocene-Pleistocene Yakataga Formation is marked by a transition to mudstone, thick bedded sandstone and glacial diamictite. This transition to glacial dominated deposition is interpreted to have occurred around 5 Ma based on previous studies. The onshore glacimarine strata are 5 km thick and grade up section from submarine fan to marine shelf strata. In the distal submarine fan record at IODP Site U1417, the upper Miocene strata in the lower part of the Site consist of 340 m of highly bioturbated gray to green mud interbedded with coarse sand and sandy diamict. These coarse-grained units are lithic rich with mainly sedimentary, volcanic, and coal clasts. We interpret these units as being derived from coal-bearing sedimentary strata exposed in the onshore thrust belt. These facies are interbedded with diatom ooze; we interpret this combination of facies as representing deposition of coarse-grained detritus originating from sedimentary gravity flows followed by longer periods of hemipelagic deposition. The first clear record of glacial sediment input in the distal submarine fan environment is late Pliocene - early Pleistocene muddy diamict beds that probably are the products of ice-rafting. This unit is about 30 m in thickness. The overlying 260 m of the core are mainly dark gray mud with thin beds of volcanic ash and sand/silt beds. Lonestones are common and are mainly argillite and metasiltstone clasts suggesting at least a component of sediment derivation from onshore metamorphosed parts of the Mesozoic accretionary prism. In general, the overall Neogene sedimentary record in both the proximal and distal marine settings appears to be similar but requires a sediment link between the proximal strata deposited on the Yakutat microplate and the Surveyor fan system deposited on the Pacific Plate.

Sequence of mammalian fossils, including hominoid teeth, from the Bubing Basin caves, South China.

PubMed

Wang, Wei; Potts, Richard; Baoyin, Yuan; Huang, Weiwen; Cheng, Hai; Edwards, R Lawrence; Ditchfield, Peter

2007-04-01

A Plio-Pleistocene to Holocene faunal sequence has been recovered from four carefully excavated caves in the Bubing Basin, adjacent to the larger Bose Basin of South China. The caves vary in elevation; we suggest that the higher caves were formed and filled with sediments prior to the lower caves. The highest deposits, which are from Mohui Cave, contain hominoid teeth and other fossilized remains of mammalian taxa most similar to late Pliocene and early Pleistocene faunas. Wuyun Cave ( approximately 50m lower in elevation than Mohui) contains a late middle Pleistocene fauna, which is supported by U-series age constraints from 350 to 200ka. Lower Pubu Cave ( approximately 23m below Wuyun) is assigned to the late Pleistocene, while the Cunkong Cave (the lowest, approximately 2m lower elevation than Lower Pubu) preserves a Holocene fauna. The four faunal assemblages indicate species-level changes in Ailuropoda, Stegodon, and Sus, the appearance of Elephas, the local disappearance of Stegodon, and the migration of Equus hemionus to South China. These initial results of our work call into question the continued value of the Stegodon/Ailuropoda Fauna, a category long used to characterize the Pleistocene faunas of South China. Excavation of karstic caves of varying elevation within the basins of South China holds promise for defining local sequences of mammalian fossils that can be used to investigate faunal variations related to climate change, biogeographic events, and evolutionary change over the past two million years. Stable isotopic analysis of a small sample of mammalian teeth from Bubing Basin caves is consistent with 100% C(3) vegetation in the Bubing/Bose region, with certain delta(13)C values consistent with a canopied woodland or forest. A preliminary assessment of the hominoid teeth indicates the presence of diverse molar and premolar morphologies including dental remains of Gigantopithecus blacki and a sample with similarities to the teeth reported from Longgupo.

Climatic, geomorphic, and archaeological implications of a late Quaternary alluvial chronology for the lower Salt River, Arizona, USA

NASA Astrophysics Data System (ADS)

Huckleberry, Gary; Onken, Jill; Graves, William M.; Wegener, Robert

2013-03-01

Recent archaeological excavations along the lower Salt River, Arizona resulted in the unexpected discovery of buried late Pleistocene soils and cultural features dating 5800-7100 cal YBP (Early Archaic), the latter representing the earliest evidence of human activity in the lower Salt River floodplain thus far identified. Because the lower Salt River floodplain has been heavily impacted by recent agriculture and urbanization and contains few stratigraphic exposures, our understanding of the river's geological history is limited. Here we present a late Quaternary alluvial chronology for a segment of the lower Salt River based on 19 accelerator mass spectrometry 14C and four optically stimulated luminescence ages obtained during two previous geoarchaeological investigations. Deposits are organized into allostratigraphic units and reveal a buried late Pleistocene terrace inset into middle-to-late Pleistocene terrace deposits. Holocene terrace fill deposits unconformably cap the late Pleistocene terrace tread in the site area, and the lower portion of this fill contains the Early Archaic archaeological features. Channel entrenchment and widening ~ 900 cal YBP eroded much of the older terrace deposits, leaving only a remnant of fill containing the buried latest Pleistocene and middle-to-late Holocene deposits preserved in the site area. Subsequent overbank deposition and channel filling associated with a braided channel system resulted in the burial of the site by a thin layer of flood sediments. Our study confirms that the lower Salt River is a complex mosaic of late Quaternary alluvium formed through vertical and lateral accretion, with isolated patches of buried soils preserved through channel avulsion. Although channel avulsion is linked to changes in sediment load and discharge and may have climatic linkages, intrinsic geomorphic and local base level controls limit direct correlations of lower Salt River stratigraphy to other large rivers in the North American Southwest.

The discovery and character of Pleistocene calcrete uranium deposits in the Southern High Plains of west Texas, United States

USGS Publications Warehouse

Van Gosen, Bradley S.; Hall, Susan M.

2017-12-18

This report describes the discovery and geology of two near-surface uranium deposits within calcareous lacustrine strata of Pleistocene age in west Texas, United States. Calcrete uranium deposits have not been previously reported in the United States. The west Texas uranium deposits share characteristics with some calcrete uranium deposits in Western Australia—uranium-vanadium minerals hosted by nonpedogenic calcretes deposited in saline lacustrine environments.In the mid-1970s, Kerr-McGee Corporation conducted a regional uranium exploration program in the Southern High Plains province of the United States, which led to the discovery of two shallow uranium deposits (that were not publicly reported). With extensive drilling, Kerr-McGee delineated one deposit of about 2.1 million metric tons of ore with an average grade of 0.037 percent U3O8 and another deposit of about 0.93 million metric tons of ore averaging 0.047 percent U3O8.The west-Texas calcrete uranium-vanadium deposits occur in calcareous, fine-grained sediments interpreted to be deposited in saline lakes formed during dry interglacial periods of the Pleistocene. The lakes were associated with drainages upstream of a large Pleistocene lake. Age determinations of tephra in strata adjacent to one deposit indicate the host strata is middle Pleistocene in age.Examination of the uranium-vanadium mineralization by scanning-electron microscopy indicated at least two generations of uranium-vanadium deposition in the lacustrine strata identified as carnotite and a strontium-uranium-vanadium mineral. Preliminary uranium-series results indicate a two-component system in the host calcrete, with early lacustrine carbonate that was deposited (or recrystallized) about 190 kilo-annum, followed much later by carnotite-rich crusts and strontium-uranium-vanadium mineralization in the Holocene (about 5 kilo-annum). Differences in initial 234U/238U activity ratios indicate two separate, distinct fluid sources.

Global evolution of Equidae and Gomphotheriidae from South America.

PubMed

Prado, José L; Alberdi, María T

2014-08-01

The contemporary South American mammalian communities were determined by the emergence of the Isthmus of Panama and by the profound climatic oscillations during the Pleistocene. Horses and gomphotheres were 2 very conspicuous groups of immigrant mammals from North America that arrived in South America during the Pleistocene. The present study compiles updated data on the phylogeny, systematics and ecology of both groups in South America. The horses in South America are represented by 2 genera, Hippidion and Equus, as are the gomphotheres, represented by Cuvieronius and Stegomastodon. Both genera of horses include small (Hippidion devillei, H. saldiasi, E. andium and E. insulatus) and large forms (Equus neogeus and H. principale), which dispersed into South America using 2 different routes. The possible model for this dispersion indicates that the small forms used the Andes corridor, while larger horses dispersed through the eastern route and through some coastal areas. In the case of gomphotheres, Cuvieronius and Stegomastodon reached South America in 2 independent dispersal events, and Cuvieronius dispersed across the Andean corridor, while large Stegomastodon spread along the eastern route. Horses and gomphotheres present values of δ(13) C from woodlands to C4 grasslands. Hippidion present lower values of δ(13) C than Equus in the late Pleistocene, whereas the gomphotheres diverge from value of δ(18) O, reflecting that Cuvieronius inhabited the Andean corridor and Stegomastodon dispersed through eastern plains. The gomphothere and horse species recorded in South America became extinct around the time that humans arrived. © 2013 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Surficial deposits in the Bear Lake Basin

USGS Publications Warehouse

Reheis, Marith C.; Laabs, Benjamin J.C.; Forester, Richard M.; McGeehin, John P.; Kaufman, Darrell S.; Bright, Jordon

2005-01-01

Mapping and dating of surficial deposits in the Bear Lake drainage basin were undertaken to provide a geologic context for interpretation of cores taken from deposits beneath Bear Lake, which sometimes receives water and sediment from the glaciated Bear River and sometimes only from the small drainage basin of Bear Lake itself. Analyses of core sediments by others are directed at (1) constructing a high-resolution climate record for the Bear Lake area during the late Pleistocene and Holocene, and (2) investigating the sources and weathering history of sediments in the drainage basin. Surficial deposits in the upper Bear River and Bear Lake drainage basins are different in their overall compositions, although they do overlap. In the upper Bear River drainage, Quaternary deposits derived from glaciation of the Uinta Range contain abundant detritus weathered from Precambrian quartzite, whereas unglaciated tributaries downstream mainly contribute finer sediment weathered from much younger, more friable sedimentary rocks. In contrast, carbonate rocks capped by a carapace of Tertiary sediments dominate the Bear Lake drainage basin.

Growth, Failure, and Erosion of Submarine Channel Levees on the Upper Mississippi Fan, Gulf of Mexico

NASA Astrophysics Data System (ADS)

Sawyer, D. E.; Flemings, P. B.; Nikolinakou, M. A.

2011-12-01

Late Pleistocene channel levees on the Mississippi Fan failed repeatedly along deep-seated listric faults. These growth faults begin at the top of the levee, as much as a kilometer away from the channel axis. They plunge 150-200 meters downward reaching their deepest point halfway towards the channel axis (0.5 km) along the base of a regional sand unit. They then rise toward the channel axis where they emerge. The erosion of toe-thrust material coupled with levee growth, promoted a dynamic equilibrium: turbidity currents flushed the channel axis and deposited new levee on the margins, which induced further displacement into the channel. With a geomechanical model we show that deep-seated failure occurred by undrained loading of an underlying low permeability mudstone. Excess pore pressure formed a low-strength layer that localized the detachment at the base of a regional sand. Our results show that deep-seated failure is expected when levee systems form above regional sand bodies that were deposited rapidly above low permeability mudstone. Furthermore, the presence of this failure style in channel-levee systems is a strong indicator that overpressures and low effective stresses were present during formation and thus record paleo-pressures. Understanding these systems is critical for the design of safe well penetrations, predicting hydraulic connectivity of deepwater channel sands, and the growth of submarine channel-levee systems. This study illuminates the linkages between sedimentation, erosion, and the mechanical stability of levees in submarine channel systems.

The palaeogeographic setting and the local environmental impact of the 130 ka Falconiera tuff-cone eruption (Ustica island, Italy)

NASA Astrophysics Data System (ADS)

de Vita, Sandro; Foresta Martin, Franco

2017-04-01

This research focuses on the effects of the last eruption at Ustica (Suthern Tyrrhenian Sea, Italy), which formed the Falconiera tuff-cone at around 130 ka BP in the north-eastern tip of the island. This eruption was mainly explosive and phreatomagmatic, and emplaced a series of pyroclastic surge beds that formed an asymmetric tuff cone. This is the most easily recognizable volcanic edifice on Ustica, although its north-eastern sector has been partially eroded. A section of the feeding conduit is exposed northward, and is composed of lavas that fed the last stages of the eruption characterized by an intracrateric lava lake and a Strombolian scoria-fallout deposit. The eruption occurred during Upper Pleistocene Marine Isotopic Substage 5.5, a warm period characterized by a high sea-level stand (6±3 m above the present sea level in stable areas) and the diffusion of subtropical flora and fauna across the Mediterranean sea. This eruption slightly modified the morphology of Ustica, but impacted both marine and terrestrial environments, burying beach deposits rich in mollusk shells (i.e. Strombus bubonius, Conus testudinarius, Brachidontes puniceus), colonies of corals (Cladocora caespitosa) and subaerial plants (Chamaerops humilis). These organisms, found in some cases in their life position, along with other lines of evidence, provide information on the palaeogeography of this sector of the island at the time of the eruption, and on the local impact of this event on the environment.

Stratigraphic controls on saltwater intrusion in the Dominguez Gap area of coastal Los Angeles

USGS Publications Warehouse

Edwards, Brian D.; Ehman, Kenneth D.; Ponti, Daniel J.; Reichard, Eric G.; Tinsley, John; Rosenbauer, Robert J.; Land, Michael T.

2009-01-01

The Los Angeles Basin is a densely populated coastal area that significantly depends on groundwater. A part of this groundwater supply is at risk from saltwater intrusion-the impetus for this study. High-resolution seismic-reflection data collected from the Los Angeles-Long Beach Harbor Complex have been combined with borehole geophysical and descriptive geological data from four nearby ??400-m-deep continuously cored wells and with borehole geophysical data from adjacent water and oil wells to characterize the Pliocene to Holocene stratigraphy of the Dominguez Gap coastal aquifer system. The new data are shown as a north-south, two- dimensional, sequence-stratigraphic model that is compared to existing lithostratigraphic models of the Los Angeles Basin in an attempt to better understand pathways of saltwater intrusion into coastal aquifers. Intrusion of saltwater into the coastal aquifer system generally is attributed to over-pumping that caused the hydraulic gradient to reverse during the mid-1920s. Local water managers have used the existing lithostratigraphic model to site closely spaced injection wells of freshwater (barrier projects) attempting to hydraulically control the saltwater intrusion. Improved understanding of the stratigraphic relationships can guide modifications to barrier design that will allow more efficient operation. Allostratigraphic nomenclature is used to define a new sequence-stratigraphic model for the area because the existing lithostratigraphic correlations that have been used to define aquifer systems are shown not to be time-correlative. The youngest sequence, the Holocene Dominguez sequence, contains the Gaspur aquifer at its base. The Gaspur aquifer is intruded with saltwater and consists of essentially flat-lying gravelly sands deposited by the ancestral Los Angeles River as broad channels that occupied a paleovalley incised into the coastal plain during the last glacio-eustatic highstand. The underlying sequences are deformed into a broad anticlinal fold that occurs parallel to, but ??2 km north of, the axis of the Pliocene Wilmington anticline. The Dominguez sequence breaches the crest of the young anticline, cuts through the upper Pleistocene Mesa and Pacific sequences, and into the middle Pleistocene Harbor sequence. Saltwater migrates along channels within the Dominguez sequence and into the underlying sequences (composed mostly of shallow marine and tidal sands, silts, and clays) that contain the classically defined Gage and Lynwood aquifers. The newly recognized Pacific Coast Highway fault cuts through the core of this young fold and is downthrown on the northern side, thereby creating accommodation space for a thick succession of middle Pleistocene sediments that constitute the Upper Wilmington sequence. North of the Pacific Coast Highway fault, the Upper Wilmington sequence contains the classic Silverado aquifer (composed of fluviodeltaic deposits); the Silverado is the primary freshwater aquifer for the West Coast and Central Los Angeles Groundwater Basins. Pore fluid and electric log analyses show the upper part of this aquifer to be saline-intruded near the crest of the young fold. This relationship implies that some saltwater is migrating into deeper aquifers from above, across the regional unconformity that marks the base of the Harbor sequence (ca. 240-270 ka). This sequence-stratigraphic model provides new insight into the potential flow paths for saltwater intrusion, and as such, should allow improved characterization of fluidflow that will aid in transport model studies and in managing groundwater resources. ?? 2009 Geological Society of America.

Preliminary geologic map of the Simi 7.5' quadrangle, Southern California, a digital database

USGS Publications Warehouse

Yerkes, R.F.; Campbell, R.H.

1997-01-01

The Simi Quadrangle covers an area of about 62 square miles in southern Ventura County. The Santa Clara River Valley occupies the northwestern corner of the quadrangle. Mountainous terrain of South Mountain and Oak Ridge characterizes the northern and central area. Elevation within the quadrangle ranges from about 250 feet along the arroyo bottoms to over 2200 feet. Steep, highly dissected slopes form much of the boundary of the area. In the southeast, Little Simi Valley, drained by Arroyo Simi/Arroyo Las Posas, separates the southern flank of Oak Ridge from the Las Posas Hills. The Las Posas upland area, a broad elevated region that slopes gently to the south, separates the South Mountain-Oak Ridge highlands from the Las Posas-Camarillo Hills between Little Simi Valley on the east and the Oxnard Plain on the west. This relatively low-lying area is also referred to as the Las Posas Valley. Numerous north-south-trending drainages cut South Mountain and Oak Ridge creating steep narrow canyons on north-facing slopes and wide flat-bottomed canyons with incised streams on south-facing slopes. A network of residential streets and ranch and oilfield roads that traverse the area from U.S. Highway 101 and State Highways 118, 23, and 126 provides access to the area. Current land use includes citrus and avocado orchards, oil well drilling and production, sand and gravel quarries, decorative-rock quarries, cattle grazing, suburban residential development, and golf courses. The oldest geologic unit mapped in the Simi Quadrangle is the upper Eocene to lower Miocene Sespe Formation. The Sespe Formation consists of alluvial fan and floodplain deposits of interbedded pebble-cobble conglomerate, massive to thick-bedded sandstone, and thin-bedded siltstone and claystone. In the northern part of the map area, Sespe Formation is overlain by and interfingers with the upper Oligocene to lower Miocene Vaqueros Formation that is composed of transitional and marine sandstone, siltstone, and claystone with local sandy coquina beds. In the Las Posas Hills, Sespe Formation is unconformably overlain by marine sandstones of the middle Miocene Topanga Group that are interlayered with and intruded by basalt flows, breccia, and diabase dikes of the Conejo Volcanics. Deep-marine strata of the upper Miocene Modelo Formation cover the Vaqueros Formation and Topanga Group along the crests and southern flanks of South Mountain and Oak Ridge. They also occur as isolated outcrops in the Las Posas Hills. Locally, Modelo Formation consists of interbedded diatomaceous shale, claystone, mudstone, and siltstone with minor sandstone, limestone, chert, and tuff beds. The most widely exposed rock units in the area are the Plio-Pleistocene marine and non-marine Pico and Saugus Formations that crop out on the southern flank of South Mountain-Oak Ridge. Locally, the Pico Formation consists of marine siltstone and silty shale with minor sandstone and pebbly sandstone. The Saugus Formation overlies and interfingers with the Pico Formation and is composed of interbedded shallow-marine to brackish water sandstone, siltstone, pebble-to-cobble conglomerate, and coquina beds that grade laterally and vertically into non-marine sandstone, siltstone, and conglomerate. A local member of the Saugus Formation is exposed in the southwest corner of the map area. It is predominantly a volcanic breccia conglomerate that resembles the Conejo Volcanics breccia, but is believed to represent remnants of landslide debris shed from the Conejo Volcanics into a local trough during Saugus time. Quaternary surficial deposits cover the floor and margins of the Little Simi Valley, Santa Clara River Valley in the north, and Arroyo Las Posas in the south, and extend up into the larger canyons that drain South Mountain and Oak Ridge. Extensive surficial deposits are also present in the Las Posas upland area in the southwest. These upper Pleistocene to Holocene sediments consist of older and younger alluvial fan and valley deposits, colluvium, active alluvial fans, and active stream deposits. Pleistocene- to Holocene-age landslide deposits are widespread throughout the Simi Quadrangle, especially in the finer grained Tertiary sedimentary units where bedding planes are dip slopes. In addition, massive slumps are present in the Sespe and Vaqueros Formations on anti-dip slopes. Seismic and well data from the San Fernando Valley (SFV) document evolution of that region from mid-Miocene rifting to north-south contraction. Formations in the western SFV subsurface (Cretaceous to Paleogene strata, and Miocene Topanga and Modelo Formations) trace southward to outcrops in the Santa Monica Mountains that constrain faulting along the valley's south basin edge. Cretaceous strata in the Simi Uplift to the west are over 2 km higher than equivalent strata beneath the western SFV across a boundary marked by the Chatsworth Reservoir fault, and Neogene thinning and offlap. The Simi fault, located at the eastern end of the Simi-Santa Rosa fault system, bounds the northern margins of the Simi and Tierra Rejada Valleys. West of Simi Valley, the Simi fault has placed Miocene Conejo Volcanics over Plio-Pleistocene Saugus Formation rocks. The 15.5 ± 0.8 m.y.a. base of the Conejo Volcanics, identified in oil well logs, is inferred to have a dip-slip separation of about 425 to 550 m, suggesting a low long-term slip rate of about 0.03 mm/yr. However, substantial late Quaternary offset is suggested by the presence of more than 150 m of Pleistocene and younger alluvium that fills the east-west trending, down-dropped bedrock trough beneath western Simi Valley. In addition, trenching within faulted colluvial deposits in Tierra Rejada Valley has revealed evidence of multiple shears within Holocene (?) deposits.

Soil-landscape development and late Quaternary environmental change in coastal Estremadura, Portugal

NASA Astrophysics Data System (ADS)

Daniels, Michael; Haws, Jonathan; Benedetti, Michael; Bicho, Nuno

2015-04-01

This poster integrates soil-landscape analysis with archaeological survey and paleoenvironmental reconstruction. Soils in surface and buried contexts in Estremadura, Portugal, provide evidence of landscape stability and instability, relative age relationships between landforms, and general paleoenvironmental conditions during the late Quaternary. These factors provide insight into the distribution and condition of Paleolithic archaeological sites and help understand the record of human settlement in the region. Late Pleistocene and Holocene dunes extend inland approximately 10 km from coastal source regions. Surface soils in Holocene dunes under maritime pine (Pinus pinaster) forest exhibit A, E, C/Bh and A, C horizon sequences and classify as Quartzipsamments. Surface soils in late Pleistocene dunes exhibit A, E, Bh, Bhs, Bs horizon sequences and classify as Haplorthods. Both Pleistocene and Holocene dunes commonly bury a heavily weathered soil formed in calcareous sandstone. The boundary between underlying buried soils and overlying surface soils is characterized by a lag deposit of medium to coarse, moderately-rounded gravels, underlain immediately by subsurface Bt and Bss horizons. The lag deposit and absence of buried A horizons both indicate intense and/or prolonged surface erosion prior to burial by late Quaternary dunes. Soil-geomorphic relationships therefore suggest at least two distinct episodes of dune emplacement and subsequent landscape stability following an extensive episode late Pleistocene landscape instability and soil erosion. A conceptual model of soil-landscape evolution through the late Quaternary and Holocene results from the integration of soil profile data, proxy paleoenvironmental data, and the partial record of human settled as revealed in the archaeological record.

The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene-Holocene sediments in the Mekong River Delta.

PubMed

Hoang, Truong Minh; van Lap, Nguyen; Oanh, Ta Thi Kim; Jiro, Takemura

2016-11-01

The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene-Holocene deposits in the Mekong River delta (MRD), and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene-Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU). The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

Posterior dental size reduction in hominids: the Atapuerca evidence.

PubMed

Bermúdez de Castro, J M; Nicolas, M E

1995-04-01

In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984-1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution.

Evolutionary History of Saber-Toothed Cats Based on Ancient Mitogenomics.

PubMed

Paijmans, Johanna L A; Barnett, Ross; Gilbert, M Thomas P; Zepeda-Mendoza, M Lisandra; Reumer, Jelle W F; de Vos, John; Zazula, Grant; Nagel, Doris; Baryshnikov, Gennady F; Leonard, Jennifer A; Rohland, Nadin; Westbury, Michael V; Barlow, Axel; Hofreiter, Michael

2017-11-06

Saber-toothed cats (Machairodontinae) are among the most widely recognized representatives of the now largely extinct Pleistocene megafauna. However, many aspects of their ecology, evolution, and extinction remain uncertain. Although ancient-DNA studies have led to huge advances in our knowledge of these aspects of many other megafauna species (e.g., mammoths and cave bears), relatively few ancient-DNA studies have focused on saber-toothed cats [1-3], and they have been restricted to short fragments of mitochondrial DNA. Here we investigate the evolutionary history of two lineages of saber-toothed cats (Smilodon and Homotherium) in relation to living carnivores and find that the Machairodontinae form a well-supported clade that is distinct from all living felids. We present partial mitochondrial genomes from one S. populator sample and three Homotherium sp. samples, including the only Late Pleistocene Homotherium sample from Eurasia [4]. We confirm the identification of the unique Late Pleistocene European fossil through ancient-DNA analyses, thus strengthening the evidence that Homotherium occurred in Europe over 200,000 years later than previously believed. This in turn forces a re-evaluation of its demography and extinction dynamics. Within the Machairodontinae, we find a deep divergence between Smilodon and Homotherium (∼18 million years) but limited diversity between the American and European Homotherium specimens. The genetic data support the hypothesis that all Late Pleistocene (or post-Villafrancian) Homotherium should be considered a single species, H. latidens, which was previously proposed based on morphological data [5, 6]. Copyright © 2017 Elsevier Ltd. All rights reserved.

General geology and ground-water resources of the island of Maui, Hawaii

USGS Publications Warehouse

Stearns, Harold T.; Macdonald, Gordon Andrew

1942-01-01

Maui, the second largest island in the Hawaiian group, is 48 miles long, 26 miles wide, and covers 728 square miles. The principal town is Wailuku. Sugar cane and pineapples are the principal crops. Water is used chiefly for irrigating cane. The purpose of the investigation was to study the geology and the ground-water resources of the island.Maui was built by two volcanoes. East Maui or Haleakala Volcano is 10,025 feet high and famous for its so-called crater, which is a section of Hawaii National Park. Evidence is given to show that it is the head of two amphitheater-headed valleys in which numerous secondary eruptions have occurred and that it is not a crater, caldera, or eroded caldera. West Maui is a deeply dissected volcano 5,788 feet high. The flat Isthmus connecting the two volcanoes was made by lavas from East Maui banking against the West Maui Mountains. Plate 1 shows the geology, wells, springs, and water-development tunnels. Plate 2 is a map and description of points of geologic interest along the main highways. Volcanic terms used in the report are briefly defined. A synopsis of the climate is included and a record of the annual rainfall at all stations is given also. Puu Kukui, on West Maui, has an average annual rainfall of 389 inches and it lies just six miles from Olowalu where only 2 inches of rain fell in 1928, the lowest ever recorded in the Hawaiian Islands. The second rainiest place in the Territory is Kuhiwa Gulch on East Maui where 523 inches fell during 1937. Rainfall averages 2,360 million gallons daily on East Maui and 580 on West Maui. Ground water at the point of use in months of low rainfall is worth about $120 per million gallons, which makes most undeveloped supplies valuable.The oldest rocks on East Maui are the very permeable primitive Honomanu basalts, which were extruded probably in Pliocene and early Pleistocene time from three rift zones. These rocks form a dome about 8,000 feet high and extend an unknown distance below sea level. Covering this dome are the Kula volcanics, extruded probably in early and middle Pleistocene time, and characterized by andesites, andesitic basalts, and picritic basalts. They are 2.000 feet thick on the summit and 50 to 200 feet thick at the periphery. They contain a sufficient number of interbedded soils, thin vitric tuff beds, and lava-filled valleys in their upper part to give rise to valuable perched springs in wet areas. The Kula lavas accumulated during a waning volcanic phase which was followed by a quiescence long enough for the erosion of deep amphitheater-headed valleys in the east or wet half of the mountain. Volcanic activity was renewed in middle (?) to late Pleistocene time and continued until Recent time, during which the Hana volcanic series was laid down. The last lava flow was erupted about 1750. The Hana lavas comprise andesitic, picritic, and olivine basalts. They veneered large areas of the east and south slopes, partly filled the deep amphitheater-headed valleys, and deeply buried the smaller valleys in the eastern half of the mountain. The Hana rocks are exceedingly permeable and much rain sinks into them.The oldest rocks on West Maui are the very permeable primitive Wailuku basalts, which were extruded probably in Pliocene and early Pleistocene time from two rifts and from many radial fissures. The basalts form a dome about 5,600 feet high and extend an unknown distance below sea level. Iao Valley is the eroded caldera of this dome. Forming an incomplete veneer over the dome are the Honolua soda trachytes and oligoclase andesites. They were extruded in late Pliocene (?) or early Pleistocene time, chiefly from bulbous domes. The clinker beds carry some water but the rocks are generally too dense to be good aquifers. During early (?) Pleistocene the West Maui volcano was cut by deep amphitheater-headed valleys and then all of Maui was deeply submerged. Four scattered eruptions occurred on West Maui in middle (?) and late Pleistocene time. The cones and lavas cover only small areas and are called the Lahaina volcanic series. The sedimentary rocks of both East and West Maui are chiefly late Quaternary and comprise fans, landslide debris, delta deposits, and valley fills, mostly of poorly permeable and poorly assorted bouldery alluvium. They are overlain on the Isthmus by extensive calcareous dunes of three ages. A mud flow more than 300 feet thick is exposed in Kaupo Valley. During the fluctuations of the ocean in the Pleistocene, the island was emerged and submerged several times. Calcareous fossiliferous marine conglomerates deposited during this period are found up to an altitude of 250 feet on West Maui. The Homomanu, Wailuku, and Kula lavas are the chief aquifers. They supply 28 irrigation wells which yield an average of 170 million gallons a day of basal water. These wells are mine-like shafts with infiltration tunnels and are called Maui-type wells. Well 16 yields 40,000,000 gallons daily with a 22-foot drawdown, which is the largest amount yielded by any well in the Hawaiian Islands. The largest spring (no. 26) on the island is artesian. It yields 10,400,000 gallons daily and issues from Kula lavas near Nahiku. West Maui has numerous perennial streams supplied by springs from a dike complex. Twenty-three tunnels in West Maui recover 20.5 million gallons a day of high-level water, mostly from this dike complex. East Maui has few perennial streams in proportion to its size, and they are chiefly small due to the water sheds being underlain with permeable lavas. Forty tunnels recover 6 million gallons a day of high-level water in East Maui and all from structures other than dikes. It is estimated that about 100 million gallons a day of basal water wastes into the sea from West Maui and about 700 million gallons a day from East Maui. A number of sites are described where wells could be sunk to recover this water. Sites are also described where tunnels could be driven to recover high-level supplies. The hydrology of East and West Maui is conspicuously different in many respects, mainly because of the difference in the stage of dissection, the extensive veneer of very permeable Hann lavas on East Maui, and the comparatively small area of the Lahaina lavas of similar age on West Maui. The only thermal water known in the Hawaiian Islands, except on the active volcano of Kilauea, is in a well in West Maui.The Nahiku area has been mapped and studied in detail. The upper part of the Honomanu volcanic series, exposed in the sea cliffs, in petrographic character is transitional into the overlying Kula lavas, Kula and Hana time were characterized by a long succession of valley-cutting episodes, each valley being filled by lava erupted from the east rift zone. The lavas include olivine basalts, picritic basalts, and basaltic andesites,In the Nahiku area basal ground water occurs largely in the Honomanu basalts. Perched water occurs in many of the later lavas, generally following the axes of buried valleys. The members which perch the water are mostly ashy soil beds, although an unusually extensive, thick layer of much decomposed clinker also appears to be a supporting member. Most of the water travels through the basal clinker members of aa lavas. Artesian water is encountered in the upper, transitional part of the Honomanu volcanic series. The aquifer is permeable porphyritic pahoehoe; the confining members are relatively impermeable nonporphyritic aa.The lavas of East Maui are described according to stratigraphic groups. The oldest or Honomanu lavas are olivine basalts like the primitive lavas in other Hawaiian volcanoes. The later or Kula and Hana lavas include basalts, basaltic andesites, andesites, and picritic basalts. The normative nepheline of analyzed East Maui lavas has not been identified in the mode. The degree of differentiation is inversely proportional to the frequency of eruptions.The lavas of West Maui volcano are divided into the Wailuku volcanic series, consisting largely of olivine basalts with less abundant olivine-poor basalts, hypersthene basalts, and picritic basalts; the Honolua volcanic series, consisting of oligoclase andesites and soda trachytes; and the Lahaina volcanic series, consisting of nepheline basanite and picritic basalts. Coarse-grained gabbros intrude the Wailuku lavas. Differentiation was undoubtedly partly by crystal settling, but the alkali curves of the variation diagram suggest that volatile transfer was of some importance.

Archaeal diversity and the extent of iron and manganese pyritization in sediments from a tropical mangrove creek (Cardoso Island, Brazil)

NASA Astrophysics Data System (ADS)

Otero, X. L.; Lucheta, A. R.; Ferreira, T. O.; Huerta-Díaz, M. A.; Lambais, M. R.

2014-06-01

Even though several studies on the geochemical processes occurring in mangrove soils and sediments have been performed, information on the diversity of Archaea and their functional roles in these ecosystems, especially in subsurface environments, is scarce. In this study, we have analyzed the depth distribution of Archaea and their possible relationships with the geochemical transformations of Fe and Mn in a sediment core from a tropical mangrove creek, using 16S rRNA gene profiling and sequential extraction of different forms of Fe and Mn. A significant shift in the archaeal community structure was observed in the lower layers (90-100 cm), coinciding with a clear decrease in total organic carbon (TOC) content and an increase in the percentage of sand. The comparison of the archaeal communities showed a dominance of methanogenic Euryarchaeota in the upper layers (0-20 cm), whereas Crenarchaeota was the most abundant taxon in the lower layers. The dominance of methanogenic Euryarchaeota in the upper layer of the sediment suggests the occurrence of methanogenesis in anoxic microenvironments. The concentrations of Fe-oxyhydroxides in the profile were very low, and showed positive correlation with the concentrations of pyrite and degrees of Fe and Mn pyritization. Additionally, a partial decoupling of pyrite formation from organic matter concentration was observed, suggesting excessive Fe pyritization. This overpyritization of Fe can be explained either by the anoxic oxidation of methane by sulfate and/or by detrital pyrite tidal transportation from the surrounding mangrove soils. The higher pyritization levels observed in deeper layers of the creek sediment were also in agreement with its Pleistocenic origin.

Quaternary base-level drops and trigger mechanisms in a closed basin: Geomorphic and sedimentological studies of the Gastre Basin, Argentina

NASA Astrophysics Data System (ADS)

Bilmes, Andrés; Veiga, Gonzalo D.; Ariztegui, Daniel; Castelltort, Sébastien; D'Elia, Leandro; Franzese, Juan R.

2017-04-01

Evaluating the role of tectonics and climate as possible triggering mechanisms of landscape reconfigurations is essential for paleoenvironmental and paleoclimatic reconstructions. In this study an exceptional receptive closed Quaternary system of Patagonia (the Gastre Basin) is described, and examined in order to analyze factors triggering base-level drops. Based on a geomorphological approach, which includes new tectonic geomorphology investigations combined with sedimentological and stratigraphic analysis, three large-scale geomorphological systems were identified, described and linked to two major lake-level highstands preserved in the basin. The results indicate magnitudes of base-level drops that are several orders of magnitude greater than present-day water-level fluctuations, suggesting a triggering mechanism not observed in recent times. Direct observations indicating the occurrence of Quaternary faults were not recorded in the region. In addition, morphometric analyses that included mountain front sinuosity, valley width-height ratio, and fan apex position dismiss tectonic fault activity in the Gastre Basin during the middle Pleistocene-Holocene. Therefore, we suggest here that upper Pleistocene climate changes may have been the main triggering mechanism of base-level falls in the Gastre Basin as it is observed in other closed basins of central Patagonia (i.e., Carri Laufquen Basin).

(40)Ar/(39)Ar dating of Bed I, Olduvai Gorge, Tanzania, and the chronology of early Pleistocene climate change.

PubMed

Deino, Alan L

2012-08-01

(40)Ar/(39)Ar dating of tuffs and lavas of the late Pleistocene volcanic and sedimentary sequence of Olduvai Gorge, north-central Tanzania, provides the basis for a revision of Bed I chronostratigraphy. Bed I extends from immediately above the Naabi Ignimbrite at 2.038 ± 0.005 Ma to Tuff IF at 1.803 ± 0.002 Ma. Tuff IB, a prominent widespread marker tuff in the basin and a key to understanding hominin evolutionary chronologies and paleoclimate histories, has an age of 1.848 ± 0.003 Ma. The largest lake expansion event in the closed Olduvai lake basin during Bed I times encompassed the episode of eruption and emplacement of this tuff. This lake event is nearly coincident with the maximum precessional insolation peak of the entire Bed I/Lower Bed II interval, calculated from an astronomical model of the boreal summer orbital insolation time-series. The succeeding precessional peak also apparently coincides with the next youngest expansion of paleo-Lake Olduvai. The extreme wet/dry climate shifts seen in the upper part of Bed I occur during an Earth-orbital eccentricity maximum, similar to episodic lake expansions documented elsewhere in the East African Rift during the Neogene. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pliocene and early Pleistocene environments and climates of the western Snake River Plain, Idaho

USGS Publications Warehouse

Thompson, R.S.

1996-01-01

Sedimentological, palynological, and magnetic susceptibility data provide paleoenvironmental and paleoclimatic information from a 989 ft (301 m) core of sediments from the upper Glenns Ferry and Bruneau Formations from near the town of Bruneau, Idaho. Chronology is based on stratigraphic position, paleomagnetism, and biostratigraphic data. Palynological data from the Glenns Ferry sediments reveal a pollen flora similar to the modern regional pollen flora, with very rare occurrences of now-extirpated taxa common earlier in the Tertiary. Palynological data from the Pliocene portion of this core indicate conditions more moist than today, with cooler summers and perhaps warmer winters. The pollen spectra from the Bruneau Formation sediments resemble those of the Wisconsinan glacial period on the Snake River Plain, and hence indicate cold and dry conditions during some portion of the early Pleistocene. The deep-water Glenns Ferry lacustrine episode appears to date between approximately 3.5 to 3.3 and 2.5 Ma, and thus occurred during the middle Pliocene period of warmer-than-modern global temperatures. Similar sustained wetter-than-present conditions occurred in the same age range at sites across the western USA. This moist period was apparently followed by an interval of regional arid conditions that persisted for several hundred thousand years. -from Author

Micropaleontologic record of late Pliocene and Quaternary paleoenvironments in the northern Albemarle Embayment, North Carolina, U.S.A.

USGS Publications Warehouse

Culver, S.J.; Farrell, K.M.; Mallinson, D.J.; Horton, B.P.; Willard, D.A.; Thieler, E.R.; Riggs, S.R.; Snyder, S.W.; Wehmiller, J.F.; Bernhardt, C.E.; Hillier, C.

2008-01-01

Micropaleontological data provide a strong actualistic basis for detailed interpretations of Quaternary paleoenvironmental change. The 90??m-thick Quaternary record of the Albemarle Embayment in the mid-Atlantic coastal plain of the USA provides an excellent opportunity to use such an approach in a region where the details of Quaternary environmental change are poorly known. The foraminiferal record in nine cores from the northern Outer Banks, east of Albemarle Sound, North Carolina, indicates the deposition of subhorizontal, mostly open-marine early to late Pleistocene units unconformably upon a basement of late Pliocene reduced-oxygen, fine-grained, shelf-basin deposits. Pollen data record several warm-cool fluctuations within the early to mid-Pleistocene deposits. Diatom data indicate that some fresh and brackish-water units occur within the generally open-marine Pleistocene succession. A channel cut by the paleo-Roanoke River during the last glacial sea-level lowstand occurs in the northern part of the study area. Pollen indicates that the basal fluvial valley fill accumulated in cooler than modern climate conditions in the latest Pleistocene. Overlying silts and muds accumulated under cool climatic, estuarine conditions according to diatom and pollen data. Radiocarbon ages from the estuarine deposits indicate that the bulk of these sediments accumulated during the latest Pleistocene. The estuarine channel-fill deposits are overlain by Holocene open-marine sands deposited as the rising sea transgressed into the estuary approximately 8.5 to 9.0??kyr BP. Within the barrier island drill cores of this study, fully marine sedimentation occurred throughout the Holocene. However, immediately west of the present barrier island, mid- to late Holocene estuarine deposits underlie the modern Albemarle Sound. The islands that currently form a continuous barrier across the mouth of Albemarle Sound have a complex history of Holocene construction and destruction and large portions of them may be less than 3??kyr old. The barrier island sands overlie open-marine sands of Colington Shoal in the north and to the south overlie fluvial and marine sand filling paleo-Roanoke tributary valleys. The Pleistocene sediments underlying the northern Outer Banks study area are mainly of open inner to mid-shelf origin. If, as is likely, sea level continues to rise, a return to such environmental conditions is likely in the near future. ?? 2008 Elsevier B.V.

The Evolution of Northern Hemisphere Glaciation

NASA Astrophysics Data System (ADS)

Wright, J. D.

2001-05-01

For much of the last 50 million years, high-latitude regions remained too warm to allow snow to accumulate and form ice sheets. Shackleton et al. (1984) published a landmark paper correlating the first occurrence of ice-rafted detritus (IRD) observed at Rockall Plateau with a prominent increase in benthic foraminiferal d18O values during the late Pliocene. These late Pliocene to Pleistocene ice sheets were modulated on an orbital frequency and have characterized the global climate over the past 2.6 myr (Shackleton and Opdyke, 1973; Shackleton et al., 1984; Ruddiman, et al., 1986). During the early Pliocene, northern hemisphere glaciation (NHG) variations were less significant (Jansen et al., 1993). Our understanding of the Plio-Pleistocene ice sheet cycles can be viewed from two different perspectives. When viewed from the late Pleistocene, the fundamental question is what changed near the early/late Pliocene boundary to produce the large-scale, glacial-interglacial cycles of the past 2.6 Ma. In contrast, the view from the middle to late Miocene is quite different. Since the pioneering work of Shackleton et al. (1984), the record of NHG has been extended further back in time with drilling in the Norwegian Sea (ODP Leg 104). At Sites 642 and 644, IRD was found throughout the late Miocene and back to ~12 Ma. More recent drilling in the high northern latitudes occurred on ODP Leg 151. Site 909 recovered a middle Miocene section from the Fram Straits with rounded quartz grains that were interpreted as IRD (Wolf-Welling et al., 1996). Age estimates for those sediments place the first northern hemisphere ice sheets at least as old as 14 Ma. The occurrence of sand-sized particles (>1000 μm) and coal below this level indicates the possibility of glacial activity in the Northern Hemisphere as early as 16 Ma. Thus, the late Pliocene to Pleistocene cycles appear to be the resumption of the glacial-interglacial pattern that began during the Miocene. While the Miocene ice sheets were much smaller than their late Pliocene and Pleistocene counterparts, their presence casts the climate dynamics of the Neogene in a new light. Thus, understanding the middle to late Miocene climatic changes is key to understanding the Plio-Pleistocene climates.

Geology of the Knife River area, North Dakota

USGS Publications Warehouse

Benson, William Edward

1953-01-01

The Knife River area, consisting of six 15-minute quadrangles, includes the lower half of the Knife River valley in west-central North Dakota. The area, in the center of the Williston Basin, is underlain by the Tongue River member of the Fort Union formation (Paleocene) and the Golden Valley formation (Eocene). The Tongue River includes beds equivalent to the Sentinel Butte shale; the Golden Valley formation, which receives its first detailed description in this report, consists of two members, a lower member of gray to white sandy kaolin clay and an upper member of cross-bedded micaceous sandstone. Pro-Tongue River rocks that crop out in southwestern North Dakota include the Ludlow member of the Fort Union formation, the Cannonball marine formation (Paleocene) and the Hell Creek, Fox Hills, and Pierre formations, all upper Cretaceous. Post-Golden Valley rocks include the White River formation (Oligocene) and gravels on an old planation surface that may be Miocene or Pliocent. Surficial deposits include glacial and fluvial deposits of Pleistocene age and alluvium, dune sand, residual silica, and landslide blocks of Recent age. Three ages of glacial deposits can be differentiated, largely on the basis of three fills, separated by unconformities, in the Knife River valley. All three are of Wisconsin age and probably represent the Iowan, Tazewell, and Mankato substages. Deposits of the Cary substage have not been identified either in the Knife River area or elsewhere in southern North Dakota. Iowan glacial deposits form the outermost drift border in North Dakota. Southwest of this border are a few scattered granite boulders that are residual from the erosion of either the White River formation or a pre-Wisconsin till. The Tazewell drift border cannot be followed in southern North Dakota. The Mankato drift border can be traced in a general way from the South Dakota State line northwest across the Missouri River and through the middle of the Knife River area. The major land forms of southwestern North Dakota are: (1) high buttes that stand above (2) a gravel-capped planation surface and (3) a gently-rolling upland; below the upland surface are (4) remnants of a broad valley stage of erosion into which (5) modern valleys have been cut. The broad valley profiles of many streams continue east across the Missouri River trench and are part of a former drainage system that flowed into Hudson Bay. Crossing the divides are (6) large trenches, formed when the former northeast-flowing streams were dammed by the glacier and diverted to the southeast. The largest diversion valley is occupied by the Missouri River; another diversion system, now largely abandoned, extends from the Killdeer Mountains southwest to the mouth of Porcupine Creek in Sioux County. By analogy with South Dakota, most of the large diversion valleys are thought to have been cut in Illinoian time. Numerous diversion valleys of Illinoian to late Wisconsin age cut across the divides. Other Pleistocene land forms include ground and moraines, kames, and terraces. Land forms of Recent age include dunes, alluvial terraces, floodplains, and several types of landslide blocks. One type of landslide, called rockslide slump, has not previously been described. Drainage is well adjusted to the structure, most of the streams flowing down the axes of small synclines. The bedrock formations have been gently folded into small domes and synclines that interrupt a gentle northward regional dip into the Williston Basin. Three episodes of deformation affected southwestern North Dakota in Tertiary time: (1) intra-Paleocene, involving warping and minor faulting; (2) post-Eocene, involving uplift and tilting; (2) Oligocene, involving uplift and gentle folding. Mineral resources include ceramic clay, sand and gravel and lignite coal. The Knife River area is the largest lignite-producing district in the United States.

Stratigraphic palaeobiology around the Pliocene-Pleistocene boundary at Altavilla Milicia (Sicily, Italy)

NASA Astrophysics Data System (ADS)

Dominici, Stefano; Benvenuti, Marco; Garilli, Vittorio; Uchman, Alfred; Pollina, Francesco

2017-04-01

The Pliocene-Pleistocene around Altavilla Milicia, near Palermo (Sicily), includes a thick siliciclastic succession rich with shell beds, dominated by molluscs, brachiopods and annelids in fine-grained, totally bioturbated sandstones. Taphonomy of fossil assemblages indicates the importance of taphonomic feedback and within-habitat time-averaging in proximity of maximum flooding intervals. The trace fossil suite is characterized by the abundance of Thalassinoides paradoxicus boxworks and by local occurence of Scalichnus, Piscichnus, ?Scolicia, ?Bichordites, Ophiomorpha, ?Gyrolithes, Palaeophycus, Diopatrichnus and ?Taenidium. These trace fossils are typical of the archetypal Cruziana ichnofacies, with local elements of the proximal Cruziana ichnofacies, which point to deposition mainly below the fairweather wave base. Three depositional sequences, characterized by geometries driven by the interplay of eustatism and regional tectonics, were recognized through sedimentary facies analysis. Biostratigraphic data frame the oldest sequence in the upper Pliocene, whereas the thickest part of the succession, occupied by the second sedimentary sequence, includes biozone NN16b/17 of calcareous nannoplankton stratigraphy, thereby comprising the base of the Pleistocene. Transgressive deposits of the third and uppermost sequence are marked by encrusted and bioeroded pebbles with sparse oyster shells. The whole time interval is characterized by glacio-eustatic fluctuations in the 50-100 m range and with 100 ky-periodicity. We performed a multivariate analysis of 22 samples yielding 92 species of mollusks collected in the first and second sequences. Clustering and ordination analysis allowed to recognize a gradient controlled by depth-related environmental variables. At one end of the continuum we have a very-shallow water assemblage dominated by the bivalve Loripes orbiculatus, indicating an organic-rich seagrass bottom. Opposite in the continuum is an offshore assemblage dominated by Corbula gibba and the extinct gastropod Petaloconchus intortus. Both the shallowest and the deepest assemblages are from the first (Piacenzian) sequence. The gradient at intermediate depths is better characterized by restricting the analysis to 17 collections from the second sequence (Piacenzian-Gelasian). The shallowest assemblage is here dominated by upper shoreface species, such as Tellina spp. and Spisula subtruncata, and the deepest by muddy bottom, offshore transition species, such as Venus nux, the extinct gastropod Nassarius semistriatus and deposit-feeding nuculanoid bivalves. Plotting samples along the composite section allows to recognize two deepening-upward trends and two intervals of maximum flooding, in accordance with the sequence-stratigraphic interpretation. Stratigraphic palaeobiology proves to be a powerful tool to understand factors that control the geologic record during an interval of intense climate change.

Kontekst stratygraficzny zastosowania różnych odmian metody termoluminescencyjnej w datowaniu lessów z terenu Polski południowo-wschodniej i Ukrainy północno-zachodniej

NASA Astrophysics Data System (ADS)

Kusiak, Jarosław

2008-01-01

Loess profiles contain a complex but usually incomplete sequence of deposits. In order to chronologically organize deposit layers accessible in different exposures it is necessary to use absolute dating methods. The 14C, TL and OSL methods are widely used for dating of the Upper Pleistocene deposits whereas to older Pleistocene deposits only luminescence methods are applied. Some attempts are made to use the OSL method for dating of the deposits older than the Upper Pleistocene. However, the OSL ages seem to be consistently lower than the TL ages, and also considerably underestimated with reference to stratigraphic interpretation. This fact indicates that the TL method should be used above all. The possibility of TL dating of loesses is connected with their aeolian origin. The obtained TL age should correspond to geological time when mineral grains constituting deposit were exposed to sunlight before deposition. Such exactly condition is met in case of loess deposits. There are many variants of thermoluminescence method because different measuring procedures can be used. Depending on the used procedure, the TL ages obtained for the same sample can be considerably different. The manner of equivalent dose determination is decisive for the obtained TL ages. The factors influencing the value of equivalent dose are presented in this paper. The equivalent dose is determined by comparison of thermoluminescence measured for a given sample with thermoluminescence of the same sample after irradiation in laboratory with known doses of ionizing radiation. The following criteria should be taken into account: size of mineral grains, relation between thermoluminescence and heating temperature, way of reduction of unstable thermoluminescence, and the results of plateau test. The variant of thermoluminescence method used in the TL Laboratory of the Department of Physical Geography and Palaeogeography, Maria Curie-Skłodowska University in Lublin is as follows. The dose rate is determined by gamma spectrometry. The equivalent dose is determined by the total-bleach technique for the 45-63 μm fraction. Blue light obtained using the BG-28 filter is applied. Samples are preheated at 160°C for 3 hours before measurement. Light sum is read as the maximum height of glow curve. The application of such measurement procedure allows reliable dating of climatic episodes recorded in loess deposits not only related to the last glacial but also in older ones.

SR-XFA as a method of choice in the search of signals of changing palaeoclimates in the sediments of Lake Baikal, compared to INAA and ICP-MS

NASA Astrophysics Data System (ADS)

Phedorin, M. A.; Bobrov, V. A.; Goldberg, E. L.; Navez, J.; Zolotaryov, K. V.; Grachev, M. A.

2000-06-01

Sediments of Lake Baikal obtained on top of the underwater Akademichesky Ridge for reconstruction of the palaeoclimates of Holocene and Upper Pleistocene were subjected to elemental analysis with three methods: (i) synchrotron radiation X-ray fluorescent analysis (SR-XFA); (ii) instrumental neutron activation analysis (INAA); (iii) induction-coupled plasma mass-spectrometry (ICP-MS). Comparison of the results obtained is accompanied by statistical tests and shows that, due to its high sensitivity, simplicity, and non-destructive nature, SR-XFA can be recommended as a method of choice in the search of geochemical signals of changing palaeoclimates.

77 FR 36871 - Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule To List Dunes...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-19

... shinnery oak community. During the late Pleistocene era, wind erosion of the Blackwater Draw formation along with shinnery oak encroachment formed this unique dune system. The prevailing winds blow from the... spatially dynamic system that is altered by natural processes like wind and rain. Over time, these natural...

Seismic stratigraphy of the Mississippi-Alabama shelf and upper continental slope

USGS Publications Warehouse

Kindinger, J.L.

1988-01-01

The Mississippi-Alabama shelf and upper continental slope contain relatively thin Upper Pleistocene and Holocene deposits. Five stages of shelf evolution can be identified from the early Wisconsinan to present. The stages were controlled by glacioeustatic or relative sea-level changes and are defined by the stratigraphic position of depositional and erosional episodes. The stratigraphy was identified on seismic profiles by means of geomorphic pattern, high-angle clinoform progradational deposits, buried stream entrenchments, planar conformities, and erosional unconformities. The oldest stage (stage 1) of evolution occurred during the early Wisconsinan lowstand; the subaerially exposed shelf was eroded to a smooth seaward-sloping surface. This paleosurface is overlain by a thin (< 10 m) drape of transgressive deposits (stage 2). Stage 3 occurred in three phases as the late Wisconsinan sea retreated: (1) fluvial channel systems eroded across the shelf, (2) deposited a thick (90 m) shelf-margin delta, and (3) contemporaneously deposited sediments on the upper slope. Stage 4 included the rapid Holocene sea-level rise that deposited a relatively thin transgressive facies over parts of the shelf. The last major depositional episode (stage 5) was the progradation of the St. Bernard delta over the northwestern and central parts of the area. A depositional hiatus has occurred since the St. Bernard progradation. These Upper Quaternary shelf and slope deposits provide models for analogous deposits in the geologic record. Primarily, they are examples of cyclic sedimentation caused by changes in sea level and may be useful in describing short-term, sandy depositional episodes in prograding shelf and slope sequences. ?? 1988.

First Pleistocene faunas from the Arabian Peninsula: An Nafud desert, Saudi Arabia

NASA Astrophysics Data System (ADS)

Thomas, Herbert; Geraads, Denis; Vaslet, Denis; Memesh, Abdallah; Billiou, Daniel; Bocherens, Hervé; Dobigny, Gauthier; Eisenmann, Véra; Gayet, Mireille; France de Lapparent de Broin; Petter, Germaine; Halawani, Mohammed

1998-01-01

Three Pleistocene vertebrate localities in lacustrine deposits which accumulated in interdune depressions were discovered in the south-western part of the An Nafud sand sea (northern Saudi Arabia). Although the fossil vertebrate fauna is restricted in diversity, its composition and stage of evolution suggest an Early Pleistocene age in contrast with the recent Pleistocene or Holocene lake beds occurring in several other interdune depressions in central and southern An Nafud. The Nafud fauna has clear African affinities whereas faunas from the Levant, dating from the Middle Pleistocene onwards, contain typically European elements.

Geology and ground-water conditions in southern Nassau and southeastern Queens Counties, Long Island, New York

USGS Publications Warehouse

Perlmutter, N.M.; Geraghty, J.J.

1963-01-01

Test drilling, electrical logging, and water sampling of 'outpost' and other wells have revealed the existence of a deep confined body of salt water in the Magothy(?) formation beneath southwestern Nassau and southeastern Queens Counties, Long Island, N.Y. In connection with a test-drilling program, cooperatively sponsored by the U.S. Geological Survey, the Nassau County Department of Public Works, and the New York State Water Resources Commission (formerly Water Power and Control Commission), 13 wells ranging in depth from about 130 to 800 feet were drilled during 1952 and 1953 and screened at various depths in the Magothy(?) formation and Jameco gravel. On the basis of the preliminary geologic, hydrologic, and chemical data from these wells, a detailed investigation of ground-water conditions from the water table to the bedrock was begun in a 200-square-mile area in southern Nassau and southeastern Queens Counties. The Inain purposes of the investigation were to delineate the bodies of fresh and salty ground water in the project area, to relate their occurrence and movement to geologic and hydrologic conditions, to estimate the rate of encroachment, if any, of the salty water, and to evaluate the effectiveness of the existing network of outpost wells as detectors of salt-water encroachment. About a million people in the report area, residing mainly in southern Nassau County, are completely dependent on ground water as a source of supply. Fortunately, precipitation averages about 44 inches per year, of which approximately half is estimated to percolate into the ground-water reservoir. The ground water is contained in and moves through eight differentiated geologic units composed of unconsolidated gravel, sand, and clay, of Late Cretaceous, Pleistocene, and Recent age, having a maximum total thickness of about 1,700 feet. The underlying metamorphic and igneous crystalline basement rocks are of Precambrian age and are not water bearing. The water-yielding units from the surface down are (1) the upper Pleistocene deposits, (2) the principal artesian aquifer, composed of the Jameco gravel and Magothy(?) formation, and (3) the Lloyd sand member of the Raritar formation. The confining units are the '20-foot' clay, the Gardiners clay, and the clay member of the Raritan formation. The upper Pleistocene deposits contain an extensive unconfined body of fresh water. Fresh water under artesian conditions is contained in the principal artesian aquifer and the Lloyd sand member. The piezometric surface of the principal artesian aquifer is similar in shape to the south-ward-sloping water table; it ranges in altitude from about sea level to 55 feet above. The chemical quality of the fresh ground water in most of the area in all aquifers is good to excellent, and concentrations of dissolved solids and of chloride generally are below 100 ppm (parts per million) and 10 ppm, respectively. Analyses of water samples from selected wells show no progressive increase in concentration of chloride in most of the area. The data on quality of water have been used to delineate one major and several minor bodies of salty ground water. The wedgeshaped main confined salt-water body, in which the concentration of chloride reaches about 17,000 ppm, is in the Magothy(?) formation and Jameco gravel in extreme southwestern Nassau County and southeastern Queens County. The base of the salt-water wedge is about at the top of the clay member of the Raritan formation. Beneath the barrier beach in south-central and southeastern Nassau County a shallow extension of the main confined salt-water body contains as much as 4,000 ppm of chloride and is separated from the lower main salt-water body by fresh ground water. Shallow, thin bodies of unconfined salty ground water are common in the upper Pleistocene and Recent deposits adjacent to salty surface water in tidal creeks, bays, and the Atlantic

Dinoflagellate cysts and pollen from the Tjörnes / Breidavik section: a biostratigraphical and palaeoclimatological study of Plio-Pleistocene sediments from northern Iceland.

NASA Astrophysics Data System (ADS)

Verhoeven, Koen; Louwye, Stephen; Eiríksson, Jon

2010-05-01

On the Tjörnes peninsula in northern Iceland, a unique sequence of Plio-Pleistocene shallow marine, continental and glacial sediments is exposed in cliffs near the Tjörnes Fracture Zone. The lowest part of the sequence consists of the more than 500 m thick Tjörnes beds of Pliocene age. In the overlying Breidavik Group, marine interglacial sediments are present together with lava flows and glacial deposits. In this unit, cycles 3, 4, 5 and 7 of the 14 glacial/interglacial cycles were examined for palynomorphs. Sixty eight samples from the sedimentary succession of the Tjörnes beds and 20 samples from the overlying Breidavik Group were palynologicaly investigated for dinoflagellate cysts, pollen and spores. Despite the fact that half of the samples were barren or yielded a very low dinoflagellate cyst concentration (<25 cysts/g), the recovered assemblage holds valuable palaeoecological and biostratigraphical information. The dinoflagellate cyst assemblage from the Tjörnes section reflects a Pliocene flora. Typical Miocene species disappearing at the Miocene - Pliocene boundary (5.33 Ma) such as Selenopemphix armageddonensis are not observed. The combination of the Pliocene record and the lack of typical Miocene species sets a maximum age for the base of the Tjörnes Beds at 5.33 Ma. The nearly continuous occurrence of Batiacasphaera minuta (highest occurrence at 3.8 Ma) and Operculodinium tegillatum (HO at 3.7 Ma) in the upper part of the Tjörnes beds (the Serripes mollusc zone) gives a minimum age of about 3.7 Ma for the top of this zone. These results indicate that the sediments of the Tjörnes beds are older and were deposited faster than previously thought, based on a K/Ar dating of the overlying basalt flows (Albertsson, 1976). In the Serripes zone, the new species Selenopemphix islandicus was recorded. Observations of fragile heterotrophic cysts such as Barssidinium pliocenicum (HO at 2.66 Ma), Echinidinium euaxum (HO at 2.66 Ma), Selenopemphix dionaeacysta (HO at 2.4 to 2.6 Ma) and Trinovantedinium glorianum (HO 2.4 to 2.6 Ma) in the Hörgi Formation sets a minimum age of 2.7 Ma for the third glacial/interglacial cycle. In accordance to the age of the upper Tjörnes beds, this formation has to be older than thought in the present age model of the outcrop. (Símonarson and Eiríksson, 2008). The biostratigraphical analysis indicates an upper Piacenzian age for the Hörgi Formation, instead of the previous Gelasian age. The K/Ar dates of the Höskuldsvik lavas between the Tjörnes beds and the Breidavik Group (2.55+/-0.27Ma; 2.36+/-0.16Ma) appears to be too young. Sea surface temperature reconstruction of the ocean water based on the warm/cold ratio of dinoflagellate cysts indicates higher values for the Tjörnes beds and the Hörgi Formation (3), compared to the colder water of the Svarthamar (5) and Torfhóll (7) Members. The appearance of pollen of temperate plants such as Ilex, Juglans and Tilia in the Tjörnes beds ánd the Hörgi Formation confirms the Pliocene age, and is in agreement with the dinoflagellate cyst biostratigraphy. References: Albertsson, K.J. 1976: K/Ar ages of Pliocene-Pleistocene glaciations in Iceland with special reference to the Tjörnes sequence, northern Iceland. PhD thesis University of Cambridge, 268pp. Símonarson, L.A. and Eiríksson, J. 2008: Tjörnes - Pliocene and Pleistocene sediments and fauna. Jökull 58, 331-342.

Megaliths and Neolithic astronomy in southern Egypt

NASA Astrophysics Data System (ADS)

Malville, J. Mckim; Wendorf, Fred; Mazar, Ali A.; Schild, Romauld

1998-04-01

The Sahara west of the Nile in southern Egypt was hyperarid and unoccupied during most of the Late Pleistocene epoch. About 11,000 years ago the summer monsoons of central Africa moved into Egypt, and temporary lakes or playas were formed. The Nabta Playa depression, which is one of the largest in southern Egypt, is a kidney-shaped basin of roughly 10km by 7km in area. We report the discovery of megalithic alignments and stone circles next to locations of Middle and Late Neolithic communities at Nabta, which suggest the early development of a complex society. The southward shift of the monsoons in the Late Neolithic age rendered the area once again hyperarid and uninhabitable some 4,800 radiocarbon years before the present (years BP). This well-determined date establishes that the ceremonial complex of Nabta, which has alignments to cardinal and solstitial directions, was a very early megalithic expression of ideology and astronomy. Five megalithic alignments within the playa deposits radiate outwards from megalithic structures, which may have been funerary structures. The organization of the megaliths suggests a symbolic geometry that integrated death, water, and the Sun. An exodus from the Nubian Desert at ~4,800 years BP may have stimulated social differentiation and cultural complexity in predynastic Upper Egypt.

Neogene evolution of the North New Guinea basin, Papua New Guinea: New constraints from seismic and subsidence analysis and implications for hydrocarbon exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullen, A.B.; Pigott, J.D.

1990-06-01

The present-day North New Guinea basin is a Plio-Pleistocene successor basin that formed subsequent to accretion of the Finisterre volcanic arc to the Australian Plate. The Ramu, Sepik, and Piore infrabasins formed in a forearc setting relative to the continental Maramuni magmatic arc. The evolution of these infrabasins was strongly influenced by accretion of the composite Torricelli-Prince Alexander terrane to the Australian Plate. Regional reflection seismic data and tectonic subsidence-subsidence rate calculations for seven wells drilled in the North New Guinea basin reveal a complex history. The timing and magnitude of subsidence and changes in subsidence rates differ between eachmore » of the Miocene infrabasins. A diachronous middle to late Miocene unconformity generally truncates infrabasin sequences. The Nopan No. 1 in the Sepik basin, however, has a complete middle Miocene to Pleistocene sedimentary record. This well records late Miocene negative subsidence rates documenting that the Nopan anticline grew as erosion occurred elsewhere in the region. This circumstance suggests that the major, sequence-bounding unconformity results from regional uplift and deformation, rather than changes in global sea level. The Plio-Pleistocene evolution of the North New Guinea basin has two profound implications regarding hydrocarbon exploration. First, the late Pliocene structural inversion of parts of the basin hinders stratigraphic and facies correlation inferred from the present setting. The recognition of basin inversion is particularly important in the Piore basin for predicting the distribution of potential reservoir facies in the Miocene carbonates. Second, the subsidence data suggest that although potential source rocks may be thermally within the oil window, these rocks may not have had sufficient time to mature owing to their recent burial.« less

Stratigraphy, U-Th chronology, and paleoenvironments at Gladysvale Cave: insights into the climatic control of South African hominin-bearing cave deposits.

PubMed

Pickering, Robyn; Hancox, Phillip J; Lee-Thorp, Julia A; Grün, Rainer; Mortimer, Graham E; McCulloch, Malcolm; Berger, Lee R

2007-11-01

Gladysvale Cave is one of the few Plio-Pleistocene hominin-bearing cave sites in South Africa that contains a well-stratified cave fill with clastic sediments interspersed with flowstones. The clastic sediments can be divided into units based on the presence of intercalated flowstones, forming flowstone bounded units (FBU). Ten MC-ICP-MS uranium-series dates on several flowstone horizons in the Gladysvale Internal Deposit fan indicate deposition from the late mid-Pleistocene ( approximately 570 ka) to Holocene ( approximately 7 ka) during limited periods of higher effective moisture. Clastic sedimentation occurred during the interceding, presumably more arid, periods. This sequence is not consistent with earlier models for South African caves that simply assumed interglacial sedimentation and glacial erosion. (13)C/(12)C data suggest that flowstone tended to form during periods with higher proportions of C(3) plants in the local vegetation, while clastic sediments reflect higher proportions of C(4) grasses, although this is not always the case. We argue that flowstones are precipitated during periods of higher effective precipitation and restricted cave entrances, while clastic sediments accumulated during periods with more open vegetation. The sedimentary fill of the fossiliferous deposits are, therefore, highly episodic in nature, with large periods of time unlikely to be represented. This has serious implications for the other hominin-bearing caves close by, as these deposits are likely to be similarly episodic. This is especially pertinent when addressing extinction events and reconstructions of paleoenvironments, as large periods of time may be unrecorded. The Gladysvale Cave fill sediments may serve as a climatically forced chronostratigraphic model for these less well-stratified and well-dated Plio-Pleistocene sites.

Hydrogeology and water quality of the shallow aquifer system at the Explosive Experimental Area, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia

USGS Publications Warehouse

Bell, C.F.

1996-01-01

In October 1993, the U.S. Geological Survey began a study to characterize the hydrogeology of the shallow aquifer system at the Explosive Experimental Area, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia, which is located on the Potomac River in the Coastal Plain Physiographic Province. The study provides a description of the hydrogeologic units, directions of ground-water flow, and back-ground water quality in the study area to a depth of about 100 feet. Lithologic, geophysical, and hydrologic data were collected from 28 wells drilled for this study, from 3 existing wells, and from outcrops. The shallow aquifer system at the Explosive Experimental Area consists of two fining-upward sequences of Pleistocene fluvial-estuarine deposits that overlie Paleocene-Eocene marine deposits of the Nanjemoy-Marlboro confining unit. The surficial hydrogeologic unit is the Columbia aquifer. Horizontal linear flow of water in this aquifer generally responds to the surface topography, discharging to tidal creeks, marshes, and the Potomac River, and rates of flow in this aquifer range from 0.003 to 0.70 foot per day. The Columbia aquifer unconformably overlies the upper confining unit 12-an organic-rich clay that is 0 to 55 feet thick. The upper confining unit conformably overlies the upper confined aquifer, a 0- to 35-feet thick unit that consists of interbedded fine-grained to medium-grained sands and clay. The upper confined aquifer probably receives most of its recharge from the adjacent and underlying Nanjemoy-Marlboro confining unit. Water in the upper confined aquifer generally flows eastward, northward, and northeastward at about 0.03 foot per day toward the Potomac River and Machodoc Creek. The Nanjemoy-Marlboro confining unit consists of glauconitic, fossiliferous silty fine-grained sands of the Nanjemoy Formation. Where the upper confined system is absent, the Nanjemoy-Marlboro confining unit is directly overlain by the Columbia aquifer. In some parts of the Explosive Experimental Area, horizontal hydraulic conductivities of the Nanjemoy-Marlboro confining unit and the Columbia aquifer are similar (from 10-4 to 10-2 foot per day), and these units effectively combine to form a thick (greater than 50 feet) aquifer. The background water quality of the shallow aquifer system is characteristic of ground waters in the Virginia Coastal Plain Physiographic Province. Water in the Columbia aquifer is a mixed ionic type, has a median pH of 5.9, and a median total dissolved solids of 106 milligrams per liter. Water in the upper confined aquifer and Nanjemoy-Marlboro confining unit is a sodium- calcium-bicarbonate type, and generally has higher pH, dissolved solids, and alkalinity than water in the Columbia aquifer. Water in the upper confined aquifer and some parts of the Columbia aquifer is anoxic, and it has high concentrations of dissolved iron, manganese, and sulfide.

Acinonyx pardinensis (Carnivora, Felidae) from the Early Pleistocene of Pantalla (Italy): predatory behavior and ecological role of the giant Plio-Pleistocene cheetah

NASA Astrophysics Data System (ADS)

Cherin, Marco; Iurino, Dawid Adam; Sardella, Raffaele; Rook, Lorenzo

2014-03-01

The site of Pantalla (central Italy) yielded a rich late Villafranchian (Early Pleistocene) faunal assemblage, which includes some well-preserved large mammal skulls. We describe here two nearly complete crania and a left hemimandible of Acinonyx pardinensis from this locality, representing the most complete cranial material of this species in Europe. These finds allowed us to define more clearly the craniodental morphology of A. pardinensis. Similarly to the forms from North Africa and China, the giant cheetah from Pantalla has a more generalized skull than the living Acinonyx jubatus, showing some primitive, pantherine-like features such as the less domed dorsal outline of the cranium, the more developed sagittal and nuchal crests and the less bowed zygomatic arches. High-resolution CT scans of the specimens were used to obtain the first 3D model of a cranium with articulated mandible of A. pardinensis. Starting from the insertion areas on this model we reconstructed the jaw muscles of the Pantalla felid, confirming its affinities with pantherine felines. In the light of the musculoskeletal skull anatomy and the average body mass (about 80 kg), it is likely that A. pardinensis could kill large prey through a hunting strategy more similar to pantherine cats than to the living cheetah.

Ancient DNA and the tropics: a rodent's tale.

PubMed

Gutiérrez-García, Tania A; Vázquez-Domínguez, Ella; Arroyo-Cabrales, Joaquín; Kuch, Melanie; Enk, Jacob; King, Christine; Poinar, Hendrik N

2014-06-01

Most genetic studies of Holocene fauna have been performed with ancient samples from dry and cold regions, in which preservation of fossils is facilitated and molecular damage is reduced. Ancient DNA work from tropical regions has been precluded owing to factors that limit DNA preservation (e.g. temperature, hydrolytic damage). We analysed ancient DNA from rodent jawbones identified as Ototylomys phyllotis, found in Holocene and Late Pleistocene stratigraphic layers from Loltún, a humid tropical cave located in the Yucatan peninsula. We extracted DNA and amplified six short overlapping fragments of the cytochrome b gene, totalling 666 bp, which represents an unprecedented success considering tropical ancient DNA samples. We performed genetic, phylogenetic and divergence time analyses, combining sequences from ancient and modern O. phyllotis, in order to assess the ancestry of the Loltún samples. Results show that all ancient samples fall into a unique clade that diverged prior to the divergence of the modern O. phyllotis, supporting it as a distinct Pleistocene form of the Ototylomys genus. Hence, this rodent's tale suggests that the sister group to modern O. phyllotis arose during the Miocene-Pliocene, diversified during the Pleistocene and went extinct in the Holocene. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Early and Middle Pleistocene vegetation history of the Médoc region, southwest France

NASA Astrophysics Data System (ADS)

O'Brien, C. E.; Jones, R. L.

2003-09-01

Pleistocene deposits, together with their pollen, plant macrofossil, foraminiferal, dinoflagellate and coleopteran remains, from five sites along the Atlantic coast of the Médoc Peninsula are described and discussed. Sediments making up the Négade Formation are shown to have been laid down under either estuarine or lagoonal conditions when closed Quercus-Pinus-Tsuga canadensis regional woodland existed. Comparison with plant records from The Netherlands indicates that these deposits are most likely attributable to either the Early Pleistocene Bavel Interglacial (marine oxygen isotope stage (MIS) 31), or an interglacial of the Waalian (MIS 37-49) or Tiglian (MIS 63-79). In addition, clays assigned to the Argiles du Gurp sensu stricto, were similarly deposited in either an estuary or lagoon, which subsequently was cut off from the sea. A freshwater lake with vegetation dominated by Azolla filiculoides then developed. This was succeeded by reedswamp and an organic mud (termed Lignite in the corresponding French stratigraphical records) formed. Regional Quercus-Abies woodland was replaced by one with Pinus dominant and Pterocarya a minor component. Comparison with plant records from France and other parts of Europe suggest that the clays and organic mud might be correlated with the Holsteinian (Praclaux) Interglacial (MIS 11c). Copyright

Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska

USGS Publications Warehouse

Coombs, Michelle L.; Larsen, Jessica F.; Neal, Christina A.

2018-02-14

Semisopochnoi Island, located in the Rat Islands group of the western Aleutian Islands and Aleutian volcanic arc, is a roughly circular island composed of scattered volcanic vents, the prominent caldera of Semisopochnoi volcano, and older, ancestral volcanic rocks. The oldest rocks on the island are gently radially dipping lavas that are the remnants of a shield volcano and of Ragged Top, which is an eroded stratocone southeast of the current caldera. None of these oldest rocks have been dated, but they all are likely Pleistocene in age. Anvil Peak, to the caldera’s north, has the morphology of a young stratocone and is latest Pleistocene to early Holocene in age. The oldest recognized Holocene deposits are those of the caldera-forming eruption, which produced the 7- by 6-km caldera in the center of the island, left nonwelded ignimbrite in valleys below the edifice, and left welded ignimbrite high on its flanks. The caldera-forming eruption produced rocks showing a range of intermediate whole-rock compositions throughout the eruption sequence, although a majority of clasts analyzed form a fairly tight cluster on SiO2-variation diagrams at 62.9 to 63.4 weight percent SiO2. This clustering of compositions at about 63 weight percent SiO2 includes black, dense, obsidian-like clasts, as well as tan, variably oxidized, highly inflated pumice clasts. The best estimate for the timing of the eruption is from a soil dated at 6,920±60 14C years before present underlying a thin facies of the ignimbrite deposit on the island’s north coast. Shortly after the caldera-forming eruption, two scoria cones on the northwest flank of the volcano outside the caldera, Ringworm crater and Threequarter Cone, simultaneously erupted small volumes of andesite.The oldest intracaldera lavas, on the floor of the caldera, are andesitic to dacitic, but are mostly covered by younger lavas and tephras. These intracaldera lavas include the basaltic andesites of small Windy cone, as well as the more voluminous basaltic andesites of three-peaked Mount Cerberus, which takes up most of the west half of the caldera and has erupted lavas that flowed to the sea on the southwestern coast of the island. Apparently active at the same time as Mount Cerberus, extracaldera Sugarloaf Peak at the southern point of the island has exclusively erupted basalts. Its young satellite peak, Sugarloaf Head, has erupted morphologically young lavas and cinder cones and may be the source of the last historical eruption in 1987. Several tephra sections on the east half of the island record as many as 50 tephras, mostly from Mount Cerberus, Sugarloaf Peak, and Sugarloaf Head, over the past several thousand years.Eruptive products of Semisopochnoi Island show an overall compositional range of basalt to dacite, though basaltic andesite and andesite constitute the largest proportions of rock types. They are tholeiitic, low to medium K, and have geochemical characteristics typical of magmatic arcs. The earliest Pleistocene lavas are mostly basalts that show the greatest geochemical diversity, as illustrated by, for example, LaN/YbN ratios of 1.9 to 3.5, suggesting fluctuations in the magma source region over the hundreds of thousands of years recorded by these older lavas. The Holocene rocks, in contrast, follow arrays in compositional space that suggest crystallization differentiation from discrete, subtly different batches of magma under varying pressure and temperature conditions. Increasingly negative Eu anomalies and an only modestly increasing alumina saturation index value with differentiation suggest that plagioclase and mafic silicates (amphibole and pyroxene) were involved to varying degrees in fractional crystallization to produce Semisopochnoi’s magmatic diversity. The crystal-poor, andesitic magmas that erupted during caldera formation likely separated from a plagioclase-, amphibole-, and clinopyroxene-dominated crystal residue in the upper crust at less than 900 °C, possibly following a period of decreased magmatic flux. During the Holocene, basaltic Sugarloaf Peak appears to bypass any upper crustal magmatic storage region and erupt crystal-rich basalts. Recent seismic swarms and long-lived warm springs attest to ongoing magmatic activity.The Holocene eruptive record at Semisopochnoi volcano is one of diverse eruptive styles as well as frequent eruptions from multiple vents located within and outside the caldera. The number and diversity of postcaldera vents means that the sites of future eruptions cannot be predicted with certainty. Future eruptions of ash similar in magnitude to the VEI 3 or less eruptions recorded in the documented tephra deposits would pose a hazard to aircraft in the region.

Spectroscopic Studies on Organic Matter from Triassic Reptile Bones, Upper Silesia, Poland

PubMed Central

Surmik, Dawid; Boczarowski, Andrzej; Balin, Katarzyna; Dulski, Mateusz; Szade, Jacek; Kremer, Barbara; Pawlicki, Roman

2016-01-01

Fossil biomolecules from an endogenous source were previously identified in Cretaceous to Pleistocene fossilized bones, the evidence coming from molecular analyses. These findings, however, were called into question and an alternative hypothesis of the invasion of the bone by bacterial biofilm was proposed. Herewith we report a new finding of morphologically preserved blood-vessel-like structures enclosing organic molecules preserved in iron-oxide-mineralized vessel walls from the cortical region of nothosaurid and tanystropheid (aquatic and terrestrial diapsid reptiles) bones. These findings are from the Early/Middle Triassic boundary (Upper Roetian/Lowermost Muschelkalk) strata of Upper Silesia, Poland. Multiple spectroscopic analyses (FTIR, ToF-SIMS, and XPS) of the extracted "blood vessels" showed the presence of organic compounds, including fragments of various amino acids such as hydroxyproline and hydroxylysine as well as amides, that may suggest the presence of collagen protein residues. Because these amino acids are absent from most proteins other than collagen, we infer that the proteinaceous molecules may originate from endogenous collagen. The preservation of molecular signals of proteins within the "blood vessels" was most likely made possible through the process of early diagenetic iron oxide mineralization. This discovery provides the oldest evidence of in situ preservation of complex organic molecules in vertebrate remains in a marine environment. PMID:26977600

Spectroscopic Studies on Organic Matter from Triassic Reptile Bones, Upper Silesia, Poland.

PubMed

Surmik, Dawid; Boczarowski, Andrzej; Balin, Katarzyna; Dulski, Mateusz; Szade, Jacek; Kremer, Barbara; Pawlicki, Roman

2016-01-01

Fossil biomolecules from an endogenous source were previously identified in Cretaceous to Pleistocene fossilized bones, the evidence coming from molecular analyses. These findings, however, were called into question and an alternative hypothesis of the invasion of the bone by bacterial biofilm was proposed. Herewith we report a new finding of morphologically preserved blood-vessel-like structures enclosing organic molecules preserved in iron-oxide-mineralized vessel walls from the cortical region of nothosaurid and tanystropheid (aquatic and terrestrial diapsid reptiles) bones. These findings are from the Early/Middle Triassic boundary (Upper Roetian/Lowermost Muschelkalk) strata of Upper Silesia, Poland. Multiple spectroscopic analyses (FTIR, ToF-SIMS, and XPS) of the extracted "blood vessels" showed the presence of organic compounds, including fragments of various amino acids such as hydroxyproline and hydroxylysine as well as amides, that may suggest the presence of collagen protein residues. Because these amino acids are absent from most proteins other than collagen, we infer that the proteinaceous molecules may originate from endogenous collagen. The preservation of molecular signals of proteins within the "blood vessels" was most likely made possible through the process of early diagenetic iron oxide mineralization. This discovery provides the oldest evidence of in situ preservation of complex organic molecules in vertebrate remains in a marine environment.

The geology and chronology of the Acheulean deposits in the Mieso area (East-Central Ethiopia).

PubMed

Benito-Calvo, Alfonso; Barfod, Dan N; McHenry, Lindsay J; de la Torre, Ignacio

2014-11-01

This paper presents the Quaternary sequence of the Mieso area of Central-East Ethiopia, located in the piedmont between the SE Ethiopian Escarpment and the Main Ethiopian Rift-Afar Rift transition sector.In this region, a piedmont alluvial plain is terraced at þ25 m above the two main fluvial courses, the Mieso and Yabdo Rivers. The piedmont sedimentary sequence is divided into three stratigraphic units separated by unconformities. Mieso Units I and II contain late Acheulean assemblages and a weakly consolidated alluvial sequence, consisting mainly of fine sediments with buried soils and, to a lesser degree, conglomerates. Palaeo-wetland areas were common in the alluvial plain, represented by patches of tufas, stromatolites and clays. At present, the piedmont alluvial surface is preserved mainly on a dark brown soil formed at the top of Unit II. Unit III corresponds to a fluvial deposit overlying Unit II, and is defined by sands, silty clays and gravels, including several Later Stone Age (LSA) occurrences. Three fine-grained tephra levels are interbedded in Unit I (tuffs TBI and TA) and II (tuff CB), and are usually spatially-constrained and reworked. Argon/argon (40Ar/39Ar) dating from tuff TA, an ash deposit preserved in a palustrine environment, yielded an age of 0.212 ± 0.016 Ma (millions of years ago). This date places thetop of Unit I in the late Middle Pleistocene, with Acheulean sites below and above tuff TA. Regional correlations tentatively place the base of Unit I around the Early-Middle Pleistocene boundary, Unit II inthe late Middle Pleistocene and within the Late Pleistocene, and the LSA occurrences of Unit III in the LatePleistoceneeHolocene.

Ostracoda (Crustacea) association and a new species (Dolerocypris anatolia nov. sp.) from the Pliocene-Pleistocene Afşin-Elbistan (Kahraman Maraş) Coal Basin of Turkey

NASA Astrophysics Data System (ADS)

Tunoǧlu, Cemal; Besbelli, Berk; Ertekin, İbrahim Kadri

2012-04-01

The Afşin-Elbistan Coal Basin, which is one of the largest and most important Pliocene-Pleistocene lignite basins of Turkey, is located in Eastern Anatolia. The basin was formed between two normal faults having NE-SW direction and these faults controlled both the sedimentation and the subsidence. The coal horizon of over 50 meters in thickness indicates the balance between the sedimentation and subsidence rates, and was preserved during peat deposition. Coals were generated in this extensive and shallow freshwater lake and evolved from the Pliocene to Pleistocene. Typical faunal and floral assemblages of this ancient Afşin-Elbistan freshwater lake are Ostracoda, Mollusca (Gastropoda and Pelecypoda), spore-pollen and Characeae (gyrogonites). Eleven Cypridoidea species were identified from the investigation area. Eight of them are already known (Candona neglecta Sars, Candona iliensis Mandelstam, Candona aff. candida (Müller), Pseudocandona compressa (Koch), Cyclocypris ovum (Jurine), Ilyocypris gibba (Ramdohr), Cypris pubera Müller, Heterocypris salina (Brady)), whereas three belong to open nomenclature — Candona sp. and Eucypris sp.; Dolerocypris anatolia nov. sp. is proposed as a new species. Dolerocypris Kaufmann is one of the largest genera among the freshwater Ostracoda. It has a very wide geographical distribution. Representatives of this genus are actively swimming species found in shallow zones of freshwater lakes and reported from small grassy water bodies with megascopic plants. Dolerocypris anatolia nov. sp. is recorded from core samples of the Pliocene-Pleistocene Afşin-Elbistan Coal Basin for the first time.

Upper Middle Pleistocene climate and landscape development of Northern Germany

NASA Astrophysics Data System (ADS)

Urban, B.

2009-04-01

The Pleistocene sequence of the Schöningen lignite mine contains a number of interglacial and interstadial limnic and peat deposits, travertine tuff, soils, tills and fluvioglacial sediments as well as loess deposits. The complex Quaternary sequence contains six major cycles with evidence of four interglacials younger than the Elsterian glaciation and preceding the Holocene. The sequence begins with Late Elsterian glacial and three interstadial deposits formed in shallow basins. Cycle I is assigned to late parts of the Holsteinian interglacial. A strong cooling is recorded by a significant increase of Artemisia and grasses during the following Buschhaus A Stadial, which is considered to mark the onset of the Saalian Complex sensu lato (penultimate glacial-complex). The lacustrine sediments of Cycle II, Reinsdorf interglacial sequence (Urban, 1995), have been found to occur at archaeological sites Schöningen 12 and 13 (Thieme,1997). Recent investigations give evidence for at least 13 Local Pollen Assemblage Zones showing a five-fold division of the interglacial and a sequence of five climatic oscillations following the interglacial (Urban, 2006). From the relative high values for grasses and herbs in the inferred forested periods of the interglacial, a warm dry forest steppe climate can be deduced. The stratigraphic position of throwing spears (Thieme, 1997), can clearly be allocated to Reinsdorf Interstadial B (level II-4) characterized by an open pine-birch forest. Uppermost parts (level II-5) represent the transition into a periglacial environment indicating the definite end of cycle II. The Schöningen Interglacial (Cycle III) represents the youngest of the pre-Drenthe (Early Saalian Stadial) interglacials (Urban, 1995). In summary, it can be concluded that the Middle Pleistocene terrestrial pollen record of the Schöningen sequence represents tentative correlatives of MIS 7, 9 and 11. North of Leck (North Friesland, Schleswig-Holstein) sediments of the centre and the margin of a 286 m deep channel, subglacially eroded during the Elsterian, have recently been investigated by 9 counter flash or cored drillings (Stephan et al., in press). Studies focussed on the uppermost 50 m, made up of a series of approximately 9 m thick fluviatile sediments ("Leck-Folge") with intercalations of organic sand layers and a gyttja band, up to 1.5 m thick. This sequence is overlain by several metres of mainly decalcified groundmoraine, that, itself, is overlain by glaciofluvial and periglacial sediments. The palynological investigations of the gyttja reveal a floral development of interglacial character ("Leck-Thermomer"). Compared to other Middle Pleistocene warm periods in North Germany, correlations of the Leck-Thermomer with the Holsteinian and with the warm periods of the Reinsdorf and Wacken (Dömnitz) interglacials are precluded or appear rather implausible. The Leck-Thermomer is most likely a correlative of the marine oxigen isotope stage 7 c (MIS 7). Stephan, H.-J., Urban, B., Lüttig, G., Menke, B. und M. Sierralta: Palynologische, petrographische und geochronologische Untersuchungen der Leck-Warmzeit (spätes Mittelpleistozän) und ihrer begleitenden Sedimente.- [Palynological, petrographical, and geochronological investigations of deposits of the "Leck-Thermomer" and accompanying sediments].- Geologisches Jahrbuch, in press. Thieme, H., 1997. Lower Paleolithic hunting spears from Germany. Nature 385, 807-810. Urban, B. 1995. Palynological evidence of younger Middle Pleistocene Interglacials (Holsteinian, Reinsdorf, Schöningen) in the Schöningen open cast lignite mine (eastern Lower Saxony/Germany). Mededelingen Rijks Geologische Dienst 52, 175-186. Urban, B. 2006. Interglacial pollen records from Schöningen, north Germany.- In: THE CLIMATE OF PAST INTERGLACIALS. Sirocko, F., Litt, T., Claussen, M., Sanchez-Goni, M.F. (eds.), Springer Verlag; in press.

Search for clues to Mesozoic graben on Long Island

USGS Publications Warehouse

Rogers, W.B.; Aparisi, M.; Sirkin, L.

1989-01-01

The position of Long Island between the Hartford Basin of Connecticut and graben structures reported from seismic reflection studies offshore to the south of the island suggests the possibility that other grabens associated with the early Mesozoic rifting might be buried beneath central Long Island. The hypothesis that post-rift tectonic activity would be related to the rift grabens and that such activity would be expressed in the post-rift sedimentary deposits led to a study of the Cretaceous and Pleistocene section to seek clues for buried grabens on Long Island. The Pleistocene glacial deposits in central and eastern Long Island have been mapped and a pollen zonation in the Upper Cretaceous section in the central part established. This work, combined with literature research, suggests the following: 1. (1) In central Long Island, the spacing of wells which reach basement enables a NE- striking zone free of basement samples to be defined where a buried graben could occur. This zone is referred to as the "permissible zone" because within it the data permit the existence of a hidden graben. 2. (2) The abrupt changes in the thickness of some pollen zones in the Upper Cretaceous deposits of central Long Island may be related to Cretaceous faulting. 3. (3) Buried preglacial valleys, the confluence of glacial lobes and major glacial outwash channels seem concentrated in west central and central Long Island. The loci of these drainage features may reflect structural control by a basement depression. 4. (4) The "permissible zone" is aligned with the zone of structures in an offshore zone south of central Long Island and with the Hartford Basin in Connecticut. Geophysical anomalies also fit into this pattern. 5. (5) A definitive answer to the question of a buried graben on Long Island will require a seismic line across the "permissible zone", or further drilling. ?? 1989.

The dating and interpretation of a Mode 1 site in the Luangwa Valley, Zambia.

PubMed

Barham, Lawrence; Phillips, William M; Maher, Barbara A; Karloukovski, Vassil; Duller, Geoff A T; Jain, Mayank; Wintle, Ann G

2011-05-01

Flake based assemblages (Mode 1) comprise the earliest stone technologies known, with well-dated Oldowan sites occurring in eastern Africa between ~2.6-1.7 Ma, and in less securely dated contexts in central, southern and northern Africa. Our understanding of the spread and local development of this technology outside East Africa remains hampered by the lack of reliable numerical dating techniques applicable to non-volcanic deposits. This study applied the still relatively new technique of cosmogenic nuclide burial dating ((10)Be/(26)Al) to calculate burial ages for fluvial gravels containing Mode 1 artefacts in the Luangwa Valley, Zambia. The Manzi River, a tributary of the Luangwa River, has exposed a 4.7 m deep section of fluvial sands with discontinuous but stratified gravel layers bearing Mode 1, possibly Oldowan, artefacts in the basal layers. An unconformity divides the Manzi section, separating Mode 1 deposits from overlying gravels containing Mode 3 (Middle Stone Age) artefacts. No diagnostic Mode 2 (Acheulean) artefacts were found. Cosmogenic nuclide burial dating was attempted for the basal gravels as well as exposure ages for the upper Mode 3 gravels, but was unsuccessful. The complex depositional history of the site prevented the calculation of reliable age models. A relative chronology for the full Manzi sequence was constructed, however, from the magnetostratigraphy of the deposit (N>R>N sequence). Isothermal thermoluminescence (ITL) dating of the upper Mode 3 layers also provided consistent results (~78 ka). A coarse but chronologically coherent sequence now exists for the Manzi section with the unconformity separating probable mid- or early Pleistocene deposits below from late Pleistocene deposits above. The results suggest Mode 1 technology in the Luangwa Valley may post-date the Oldowan in eastern and southern Africa. The dating programme has contributed to a clearer understanding of the geomorphological processes that have shaped the valley and structured its archaeological record. Copyright © 2010 Elsevier Ltd. All rights reserved.

Stratigraphic record of Pliocene-Pleistocene basin evolution and deformation within the Southern San Andreas Fault Zone, Mecca Hills, California

NASA Astrophysics Data System (ADS)

McNabb, James C.; Dorsey, Rebecca J.; Housen, Bernard A.; Dimitroff, Cassidy W.; Messé, Graham T.

2017-11-01

A thick section of Pliocene-Pleistocene nonmarine sedimentary rocks exposed in the Mecca Hills, California, provides a record of fault-zone evolution along the Coachella Valley segment of the San Andreas fault (SAF). Geologic mapping, measured sections, detailed sedimentology, and paleomagnetic data document a 3-5 Myr history of deformation and sedimentation in this area. SW-side down offset on the Painted Canyon fault (PCF) starting 3.7 Ma resulted in deposition of the Mecca Conglomerate southwest of the fault. The lower member of the Palm Spring Formation accumulated across the PCF from 3.0 to 2.6 Ma during regional subsidence. SW-side up slip on the PCF and related transpressive deformation from 2.6 to 2.3 Ma created a time-transgressive angular unconformity between the lower and upper members of the Palm Spring Formation. The upper member accumulated in discrete fault-bounded depocenters until initiation of modern deformation, uplift, and basin inversion starting at 0.7 Ma. Some spatially restricted deposits can be attributed to the evolution of fault-zone geometric complexities. However, the deformation events at ca. 2.6 Ma and 0.7 Ma are recorded regionally along 80 km of the SAF through Coachella Valley, covering an area much larger than mapped fault-zone irregularities, and thus require regional explanations. We therefore conclude that late Cenozoic deformation and sedimentation along the SAF in Coachella Valley has been controlled by a combination of regional tectonic drivers and local deformation due to dextral slip through fault-zone complexities. We further propose a kinematic link between the 2.6-2.3 Ma angular unconformity and a previously documented but poorly dated reorganization of plate-boundary faults in the northern Gulf of California at 3.3-2.0 Ma. This analysis highlights the potential for high-precision chronologies in deformed terrestrial deposits to provide improved understanding of local- to regional-scale structural controls on basin formation and deformation along an active transform margin.

The dating and interpretation of a Mode 1 site in the Luangwa Valley, Zambia

USGS Publications Warehouse

Barham, L.; Phillips, W.M.; Maher, B.A.; Karloukovski, V.; Duller, G.A.T.; Jain, M.; Wintle, A.G.

2011-01-01

Flake based assemblages (Mode 1) comprise the earliest stone technologies known, with well-dated Oldowan sites occurring in eastern Africa between ??? 2.6-1.7 Ma, and in less securely dated contexts in central, southern and northern Africa. Our understanding of the spread and local development of this technology outside East Africa remains hampered by the lack of reliable numerical dating techniques applicable to non-volcanic deposits. This study applied the still relatively new technique of cosmogenic nuclide burial dating (10Be/26Al) to calculate burial ages for fluvial gravels containing Mode 1 artefacts in the Luangwa Valley, Zambia. The Manzi River, a tributary of the Luangwa River, has exposed a 4.7 m deep section of fluvial sands with discontinuous but stratified gravel layers bearing Mode 1, possibly Oldowan, artefacts in the basal layers. An unconformity divides the Manzi section, separating Mode 1 deposits from overlying gravels containing Mode 3 (Middle Stone Age) artefacts. No diagnostic Mode 2 (Acheulean) artefacts were found. Cosmogenic nuclide burial dating was attempted for the basal gravels as well as exposure ages for the upper Mode 3 gravels, but was unsuccessful. The complex depositional history of the site prevented the calculation of reliable age models. A relative chronology for the full Manzi sequence was constructed, however, from the magnetostratigraphy of the deposit (N>R>N sequence). Isothermal thermoluminescence (ITL) dating of the upper Mode 3 layers also provided consistent results (???78 ka). A coarse but chronologically coherent sequence now exists for the Manzi section with the unconformity separating probable mid- or early Pleistocene deposits below from late Pleistocene deposits above. The results suggest Mode 1 technology in the Luangwa Valley may post-date the Oldowan in eastern and southern Africa. The dating programme has contributed to a clearer understanding of the geomorphological processes that have shaped the valley and structured its archaeological record. ?? 2010 Elsevier Ltd.

Record of late Pleistocene glaciation and deglaciation in the southern Cascade Range. I. Petrological evidence from lacustrine sediment in Upper Klamath Lake, southern Oregon

USGS Publications Warehouse

Reynolds, R.L.; Rosenbaum, J.G.; Rapp, J.; Kerwin, M.W.; Bradbury, J.P.; Colman, S.; Adam, D.

2004-01-01

Petrological and textural properties of lacustrine sediments from Upper Klamath Lake, Oregon, reflect changing input volumes of glacial flour and thus reveal a detailed glacial history for the southern Cascade Range between about 37 and 15 ka. Magnetic properties vary as a result of mixing different amounts of the highly magnetic, glacially generated detritus with less magnetic, more weathered detritus derived from unglaciated parts of the large catchment. Evidence that the magnetic properties record glacial flour input is based mainly on the strong correlation between bulk sediment particle size and parameters that measure the magnetite content and magnetic mineral freshness. High magnetization corresponds to relatively fine particle size and lower magnetization to coarser particle size. This relation is not found in the Buck Lake core in a nearby, unglaciated catchment. Angular silt-sized volcanic rock fragments containing unaltered magnetite dominate the magnetic fraction in the late Pleistocene sediments but are absent in younger, low magnetization sediments. The finer grained, highly magnetic sediments contain high proportions of planktic diatoms indicative of cold, oligotrophic limnic conditions. Sediment with lower magnetite content contains populations of diatoms indicative of warmer, eutrophic limnic conditions. During the latter part of oxygen isotope stage 3 (about 37-25 ka), the magnetic properties record millennial-scale variations in glacial-flour content. The input of glacial flour was uniformly high during the Last Glacial Maximum, between about 21 and 16 ka. At about 16 ka, magnetite input, both absolute and relative to hematite, decreased abruptly, reflecting a rapid decline in glacially derived detritus. The decrease in magnetite transport into the lake preceded declines in pollen from both grass and sagebrush. A more gradual decrease in heavy mineral content over this interval records sediment starvation with the growth of marshes at the margins of the lake and dilution of detrital material by biogenic silica and other organic matter.

Sedimentological imprints of environmental variability at the Balkan Peninsula on the sediment sequence of Lake Ohrid (Macedonia, Albania) between the Mid Pleistocene Transition and present days: The ICDP SCOPSCO project

NASA Astrophysics Data System (ADS)

Francke, Alexander; Wagner, Bernd; Leicher, Niklas; Raphael, Gromig; Leng, Melanie; Lacey, Jack; Vogel, Hendrik; Baumgarten, Henrike; Thomas, Wonik; Zanchetta, Giovanni; Roberto, Sulpizio; Krastel, Sebastian; Lindhorst, Katja

2015-04-01

The UNESCO World Heritage site of Lake Ohrid in the Balkans is thought to be the oldest, continuously existing lake in Europe. In order to unravel the geological and evolutionary history of the lake, a deep drilling campaign was conducted in spring 2013 under the umbrella of the ICDP SCOPSCO project. At the coring site "DEEP" in central parts of the lake, more than 1,500 m of sediments were recovered down to a penetration depth of 569 m blf. This sediment sequence is assumed to be more than 1.2 Ma old and likely covers the entire lacustrine deposits of the Lake Ohrid Basin. Currently, an age model for the upper 260m of the DEEP- site sequence is available. This age model is based on chronological tie points (tephrochronology), and wiggle matching of down hole logging data and (bio-)geochemistry data (XRF, TIC, TOC) from the core sequence to the global benthic stack LR04 and local insolation patterns. The data suggests that the upper 260 m of the DEEP-site sequence corresponds to the time period between the Mid Pleistocene Transition (MPT) and present days. During this period, the sedimentological properties of the sediments show a strong dependency on environmental variability in the area. Interglacial deposits appear massive or marbled, contain up to 80 % of CaCO3 (high TIC), high amounts of organic matter (high TOC) and biogenic silica (high BSi), and low contents of clastic material. Glacial deposits are predominantly marbled and calcite is generally absent. Similarly, the amounts of organic matter and biogenic silica are low, and glacial sediments predominately consist of clastic matter. Distinct layers of siderite and uniformly distributed Fe- or Mn- oxides occur in the glacial deposits, vivianite concretions occur in both the glacial and interglacial periods. High CaCO3 contents in deposits formed during warm (interglacial) periods are also known from studies on short pilot cores from Lake Ohrid and are triggered by increased productivity in the lake, such as also indicated by enhanced contents of organic matter and biogenic silica. Thereby, CaCO3 precipitation is caused by photosynthesis induced calcite precipitation during algae blooms in spring and early summer. Negligible contents of TIC in deposits formed during glacial periods can be explained by an overall low productivity (low TOC and BSi) and, in addition, by dilution of CaCO3. Dilution of CaCO3 might be a result of more acid bottom water conditions, triggered by improved mixing conditions (less thermal stratification), oxidation of OM and CO2 release from the surface sediments. Oxygenated surface sediments and degradation of organic matter are indicated by the marbled structure of the glacial sediments implying intensive bioturbation, and by TOC/TN ratios around 4, respectively. The high amount of clastic material in deposits from cold (glacial) periods can be a result of mutual dilution with calcite, organic matter and biogenic silica, but might also indicate more intensive erosion in the catchment due to a less dense vegetation cover.

Geologic map of the Silt Quadrangle, Garfield County, Colorado

USGS Publications Warehouse

Shroba, R.R.; Scott, R.B.

2001-01-01

New 1:24,000-scale geologic mapping in the Silt 7.5' quadrangle, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area of the southwest flank of the White River uplift, the Grand Hogback, and the eastern Piceance Basin. The Wasatch Formation was subdivided into three formal members, the Shire, Molina, and Atwell Gulch Members. Also a sandstone unit within the Shire Member was broken out. The Mesaverde Group consists of the upper Williams Fork Formation and the lower Iles Formation. Members for the Iles Formation consist of the Rollins Sandstone, the Cozzette Sandstone, and the Corcoran Sandstone Members. The Cozzette and Corcoran Sandstone Members were mapped as a combined unit. Only the upper part of the Upper Member of the Mancos Shale is exposed in the quadrangle. From the southwestern corner of the map area toward the northwest, the unfaulted early Eocene to Paleocene Wasatch Formation and underlying Mesaverde Group gradually increase in dip to form the Grand Hogback monocline that reaches 45-75 degree dips to the southwest (section A-A'). The shallow west-northwest-trending Rifle syncline separates the northern part of the quadrangle from the southern part along the Colorado River. Geologic hazards in the map area include erosion, expansive soils, and flooding. Erosion includes mass wasting, gullying, and piping. Mass wasting involves any rock or surficial material that moves downslope under the influence of gravity, such as landslides, debris flows, or rock falls, and is generally more prevalent on steeper slopes. Locally, where the Grand Hogback is dipping greater than 60 degrees and the Wasatch Formation has been eroded, leaving sandstone slabs of the Mesa Verde Group unsupported over vertical distances as great as 500 m, the upper part of the unit has collapsed in landslides, probably by a process of beam-buckle failure. In the source area of these landslides strata are overturned and dip shallowly to the northeast. Landslide deposits now armor Pleistocene pediment surfaces and extend at least 1 km into Cactus Valley. Gullying and piping generally occur on more gentle slopes. Expansive soils and expansive bedrock are those unconsolidated materials or rocks that swell when wet and shrink when dry. Most floods are restricted to low-lying areas. Several gas-producing wells extract methane from coals from the upper part of the Iles Formation.

Applying modern measurements of Pleistocene loads to model lithospheric rheology

NASA Astrophysics Data System (ADS)

Beard, E. P.; Hoggan, J. R.; Lowry, A. R.

2011-12-01

The remnant shorelines of Pleistocene Lake Bonneville provide a unique opportunity for building a dataset from which to infer rheological properties of the lower crust and upper mantle. Multiple lakeshores developed over a period of around 30 kyr which record the lithosphere's isostatic response to a well-constrained load history. Bills et al. (1994) utilized a shoreline elevation dataset compiled by Currey (1982) in an attempt to model linear (Maxwell) viscosity as a function of depth beneath the basin. They estimated an effective elastic thickness (Te) for the basin of 20-25 km which differs significantly from the 5-15 km estimates derived from models of loading on geologic timescales (e.g., Lowry and Pérez-Gussinyé, 2011). We propose that the discrepancy in Te modeled by these two approaches may be resolved with dynamical modeling of a common rheology, using a more complete shoreline elevation dataset applied to a spherical Earth model. Where Currey's (1982) dataset was compiled largely from observations of depositional shoreline features, we are developing an algorithm for estimating elevation variations in erosional shorelines based on cross-correlation and stacking techniques similar to those used to automate picking of seismic phase arrival times. Application of this method to digital elevation models (DEMs) will increase the size and accuracy of the shoreline elevation dataset, enabling more robust modeling of the rheological properties driving isostatic response to unloading of Lake Bonneville. Our plan is to model these data and invert for a relatively small number of parameters describing depth- and temperature-dependent power-law rheology of the lower crust and upper mantle. These same parameters also will be used to model topographic and Moho response to estimates of regional mass variation on the longer loading timescales to test for inconsistencies. Bills, B.G., D.R. Currey, and G.A. Marshall, 1994, Viscosity estimates for the crust and upper mantle from patterns of lacustrine shoreline deformation in the Eastern Great Basin, Journal of Geophysical Research, 99, B11, 22,059-22,086. Currey, D.R., 1982, Lake Bonneville: Selected features of relevance to neotectonic analysis, U.S. Geological Survey Open File Report, 82-1070, 31pp. Lowry, A.R., and M. Pérez-Gussinyé, 2011, The role of crustal quartz in controlling Cordilleran deformation, Nature, 471, pp. 353-357.

Potential Interference Among The Campanian Ignimbrite Eruption, Heinrich Event 4 and The Middle/upper Palaeolithic Shift In Late Pleistocene Europe

NASA Astrophysics Data System (ADS)

Fedele, F. G.; Giaccio, B.; Isaia, R.; Orsi, G.

The Campanian Ignimbrite (CI) eruption (Phlegraean Fields Caldera) was the largest volcanic eruption in the Greater Mediterranean area over the past 200 Ka (at least 150 km3 DRE). Ash layers correlated with CI have been found in sediments of the eastern Mediterranean Sea (Y5) and East Europe, from Italy to the former USSR. The recent dating of the CI eruption at 39.3 Ka BP draws attention to the coincidence be- tween this volcanic catastrophe and the suite of coeval biocultural modifications in Old World prehistory, here termed the European Late Pleistocene shift (ELPS). These included the Middle to Upper Palaeolithic cultural transition and the supposed change from Neanderthal to "modern" Homo sapiens anatomy, still a subject of sustained de- bate. The first results of our investigations show that: (1) at several archaeological sites of peninsular Italy a distinct tephra layer corresponding to the CI is regularly interbedded between the last documented Middle Palaeolithic and the earliest appear- ance of unquestionable Upper Palaeolithic assemblages; (2) at the same sites the CI tephra coincides with a interruption of occupation, several millennia long; (3) in the GISP2 Greenland ice-core, Lago Grande di Monticchio (southern Italy) lacustrine se- quences, and KET 8003 Tyrrhenian sea-core, a large volcanogenic sulfate signal (375 ppb, at 40,062 yr BP) to be correlated with the CI eruption and/or CI tephra layer occurs just before a sharp climatic shift which coincides with the onset of Heinrich event 4 (HE4). The concurrence of the CI eruption, Palaeolithic site abandonment and beginning of HE4 suggests that the overlapping of CI eruption and HE4 climatic im- pacts induced ecosystem crisis on a fairly large scale - human systems included - and well beyond the direct-impact zone. Moreover, the occurrence of the CI eruption just before HE4 probably corroborates the positive climate-volcanism feedback supposed for other high magnitude eruptions (e.g. Toba, 74 Ka). Without obviously claiming for the CI an overall evolutionary relevance within the ELPS, on the available data we nevertheless suggest that it deserves careful consideration as a contributing factor to the regional expression - or re-orientation - of cultural and population change.

Sedimentary Carbon, Sulfur, and Iron Relationships in Modern and Ancient Diagenetic Environments of the Eel River Basin (U.S.A.)

USGS Publications Warehouse

Sommerfield, C.K.; Aller, R.C.; Nittrouer, C.A.

2001-01-01

Depositional and diagenetic controls on the distributions of carbon, sulfur, and iron (C-S-Fe) in modern sediments and upper Pleistocene mudrocks of the Eel River Basin (ERB), northern California continental margin, were investigated using a combination of geochemical, radioisotopic, and sedimentological methods. A mass balance based on down-core profiles of porewater and solid-phase constituents and diagenetic modeling suggests that only 12-30% of the pyrite-S produced via SO4-2 reduction during burial is retained in modern shelf and upper slope deposits of the ERB. Bioturbational reoxidation of initially reduced S is inferred to be the major control on S preservation, on the basis of an observed inverse relationship between pyrite-S retention and biological mixing intensity, estimated from profiles of excess 234Th. Importantly, these findings argue that massive depositional episodes on the shelf following floods of the Eel River have a negligible long-term impact on bioturbating macrofauna and the potential to affect geochemical properties of the sediments. Down-core profiles of reactive Fe3+and Py-Fe(II) for the modern deposits suggest that highly reactive Fe phases are sulfidized well within ∼ 500-2000 years of burial, thereby limiting later pyritization, which could occur through sulfidation of less reactive phases. This result explains the low (≤ 0.4) degree of pyritization (DOP) values exhibited by both modern and ancient deposits of the ERB and lends support to the notion that pyritization in aerobic continental-margin sediments is largely associated with highly reactive detrital Fe oxides. Comparable mean C/S weight ratios for modern sediments (5.4 ± 3.3, 1σ) and mudrocks (6.9 ± 4.5) of the ERB suggest that the upper Pleistocene strata reflect a geochemical environment analogous to that of the modern margin. Specifically, the C-S-Fe signatures shared by the modern and ancient deposits are a consequence of similar detrital Fe mineralogies, initial organic-matter content (Corg ≤ 1%) and composition (C/N = 13 to 17, δ13Corg = -22 to -25‰), burial rate, and importantly, bioturbation intensity. The findings of this study have important implications for the use of C-S-Fe signatures as indicators of diagenetic processes in dynamic, continental-margin environments.

Refining the timing of the MIS 5e signal, West Caicos, Bristish West Indies:implications for paleoclimatic interpretation of the stratigraphic record

NASA Astrophysics Data System (ADS)

Kerans, C.; Zahm, C.; Bachtel, S.; Hearty, P.; Cheng, H.

2017-12-01

The progressive refinement of the Last Interglacial (LIG) tropical carbonate record has focused attention on the dramatically abrupt and episodic nature of this critical approximate 12 ka time window. From initial carbonate platform flooding at 133 ka to rapid sea level fall and exposure at 118 ka, the majority of present-day Bahamian and Caribbean strata were produced in a remarkably similar pattern extending from Bermuda and the Bahamas through the Cayman Islands, Yucatan, and south to the Dominican Republic. The position of coral reefs and oolitic sands of the LIG to a first order fit the global insolation-driven climate warming signal. Less well accepted/resolved is the existence of two distinct SL peaks with an intervening sea level fall implying a non-orbitally forced climate shift during this broader highstand. West Caicos, a 10 x 5 km leeward island on the Caicos Platform is an excellent example of LIG carbonate stratigraphic complexity. We collected sub-meter-resolution whole-island airborn LIDAR and decimeter-resolution UAV-constructed DEM's of the western and southern coastal outcrops to serve as a base for decimeter-scale mapping of the MIS 11, 7?, 5e, and Holocene units of the island, with particular focus on the continuous 8.4 km west coast outcrop of the MIS 5e. Seventy-five AAR relative age assignments from ooid separates, pinned by 16 U/Th dates from corals coming from MIS stage 11, lower MIS 5e, and upper MIS 5e reefs helped establish the age model for the Pleistocene-Holocene stratigraphy. The lower MIS 5e reef system averages 128 ka with an onset age of 133 ka. Upper MIS 5e corals ranges from 123 ka to 116 ka, bracketing the intra-MIS 5e sea-level fall between to approximately 125 ka. The intra-MIS 5e fall is a distinct erosional unconformity across 5 km of continuous outcrop, truncating the upper 2.5 m of lower 5e reef. The complexity of MIS 5e record on West Caicos and in the Northern Atlantic and Caribbean platforms regionally provides important insights for those using the Pleistocene as a model for older stratigraphic successions and their linked paleoclimatic records.

Streams as Entanglement of Nature and Culture: European Upper Paleolithic River Systems and Their Role as Features of Spatial Organization.

PubMed

Hussain, Shumon T; Floss, Harald

2016-01-01

Large river valleys have long been seen as important factors to shape the mobility, communication, and exchange of Pleistocene hunter-gatherers. However, rivers have been debated as either natural entities people adapt and react to or as cultural and meaningful entities people experience and interpret in different ways. Here, we attempt to integrate both perspectives. Building on theoretical work from various disciplines, we discuss the relationship between biophysical river properties and sociocultural river semantics and suggest that understanding a river's persona is central to evaluating its role in spatial organization. By reviewing the literature and analyzing European Upper Paleolithic site distribution and raw material transfer patterns in relation to river catchments, we show that the role of prominent rivers varies considerably over time. Both ecological and cultural factors are crucial to explaining these patterns. Whereas the Earlier Upper Paleolithic record displays a general tendency toward conceiving rivers as mobility guidelines, the spatial consolidation process after the colonization of the European mainland is paralleled by a trend of conceptualizing river regimes as frontiers, separating archaeological entities, regional groups, or local networks. The Late Upper Paleolithic Magdalenian, however, is characterized again by a role of rivers as mobility and communication vectors. Tracing changing patterns in the role of certain river regimes through time thus contributes to our growing knowledge of human spatial behavior and helps to improve our understanding of dynamic and mutually informed human-environment interactions in the Paleolithic.

Integrated biostratigraphic zonation for the Malay Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yakzan, A.M.; Nasib, B.Md.; Harun, A.

1994-07-01

This study presents a detailed biostratigraphic scheme for the Malay Basin based on the examination of 10 wells by PRSS, and the review of data from 12 wells, which were previously studied by service companies. For each of the wells reviewed, foraminiferal, nannofossil, and quantitative palynological data were available. This paper demonstrates that through the integration of data from all three biostratigraphic disciplines and through taking careful accounts of lithologies, it is possible to make accurate correlations within the Malay Basin, which would not be possible using data from a single discipline. Stratigraphic relationships within upper Oligocene fluvial and lacustrinemore » sediments are best determined from their rich miospore and freshwater algal content. Miospores are also of importance for correlation in the paralic lower Miocene, but in addition, marine flooding surfaces may be characterized by benthic foraminifera, which although not age diagnostic, may permit accurate correlations. These marine pulses sometimes contain age-diagnostic nannofossils, which permit palynological and foraminiferal events to be dated. The lower/middle Miocene boundary is represented by a marine transgressive unit, which can be dated by nannofossils; benthic foraminiferal and palynological events again provide a basis for detailed correlations. The remainder of the middle Miocene, and most of the upper Miocene, consists of paralic sediments for which correlations can be achieved using benthic foraminifera and miospores. Again age-diagnostic nannofossils may be associated with marine flooding surfaces. The upper part of the upper Miocene and the Pliocene-Pleistocene is marine and readily dated using planktonic foraminifera and nannofossils.« less

Geology of the Western Part of Los Alamos National Laboratory (TA-3 to TA-16), Rio Grande Rift, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

C.J.Lewis; A.Lavine; S.L.Reneau

2002-12-01

We present data that elucidate the stratigraphy, geomorphology, and structure in the western part of Los Alamos National Laboratory between Technical Areas 3 and 16 (TA-3 and TA-16). Data include those gathered by geologic mapping of surficial, post-Bandelier Tuff strata, conventional and high-precision geologic mapping and geochemical analysis of cooling units within the Bandelier Tuff, logging of boreholes and a gas pipeline trench, and structural analysis using profiles, cross sections, structure contour maps, and stereographic projections. This work contributes to an improved understanding of the paleoseismic and geomorphic history of the area, which will aid in future seismic hazard evaluationsmore » and other investigations. The study area lies at the base of the main, 120-m (400-ft) high escarpment formed by the Pajarito fault, an active fault of the Rio Grande rift that bounds Los Alamos National Laboratory on the west. Subsidiary fracturing, faulting, and folding associated with the Pajarito fault zone extends at least 1,500 m (5,000 ft) to the east of the main Pajarito fault escarpment. Stratigraphic units in the study area include upper units of the Tshirege Member of the early Pleistocene Bandelier Tuff, early Pleistocene alluvial fan deposits that predate incision of canyons on this part of the Pajarito Plateau, and younger Pleistocene and Holocene alluvium and colluvium that postdate drainage incision. We discriminate four sets of structures in the area between TA-3 and TA-16: (a) north-striking faults and folds that mark the main zone of deformation, including a graben in the central part of the study area; (b) north-northwest-striking fractures and rare faults that bound the eastern side of the principal zone of deformation and may be the surface expression of deep-seated faulting; (c) rare northeast-striking structures near the northern limit of the area associated with the southern end of the Rendija Canyon fault; and (d) several small east-west-striking faults. We consider all structures to be Quaternary in that they postdate the Tshirege Member (1.22 million years old) of the Bandelier Tuff. Older mesa-top alluvial deposits (Qoal), which may have a large age range but are probably in part about 1.13 million years old, are clearly faulted or deformed by many structures. At two localities, younger alluvial units (Qfo and Qfi) appear to be truncated by faults, but field relations are obscure, and we cannot confirm the presence of fault contacts. The youngest known faulting in the study area occurred in Holocene time on a down-to-the-west fault, recently trenched at the site of a new LANL Emergency Operations Center (Reneau et al. 2002).« less

Quaternary glacial landforms and evolution in the Cantabrian Mountains (Northern Spain): a synthesis from current data

NASA Astrophysics Data System (ADS)

Serrano, Enrique; José González-Trueba, Juan; Pellitero, Ramón; González-García, María; Gómez-Lende, Manuel

2014-05-01

In Northern Iberian Peninsula are located the Cantabrian Mountains, a mountain system of 450 km length, reaching 2648 m in the Picos de Europa. It is an Atlantic mountain in the North slope, with a Atlantic Mediterranean transitional climate in the South slope.More than thirty-five massifs developed glaciers during the Pleistocene. Studies on glacial morphology are known from the XIX century and they have focused mainly on the maximum extent of glaciers. Nowadays there are detailed geomorphological maps, morphostratigraphic surveys and estimation of Equilibrium Line Altitude in different massifs and on different stages. During the last decade studies on glacial evolution and glaciation phases have been made, and the first chronological data have been published. In this work we presents the reconstruction of the glacial evolution in the Cantabrian Mountains during the Pleistocene and Holocene, based on recent chronological data (30 dates made using OSL, AMS and C14) and morphostratigraphic correlations obtained by several research groups. The number of reconstructed glacial stages varies among the different massifs, form one to four different stages. The highest massifs located in the central portion of the Cantabrian Mountains have the most complex glacial features, with at least four different moraine complexes stepped between the 400 m a.s.l in the Northern slope and 800 m a.s.l. in the Southern slope for the lowest moraine complexes, and the highest and youngest, located above 2100 m a.s.l. An ancient glacial phase has been pointed to MIS 12 -more than 400 ka-, disconnected from the present day glacial morphology. During Upper Pleistocene three main stages have been identified. The first one, the local glacial maximum, could be prior to the LGM, as all dates refer to chronologies prior to 28-38 ka. Some authors locate this stage prior to 45 and 65 ka, during the 50-70 ka cold stage. It could be a wet stage, when the main fronts reached the Iberian Peninsula from the SW. The second stage is located to around 30 ka, and point to a dryer stage when glaciers was shorter but thicker. The third stage is located at 20-18 ka, contemporary from the LGM. Glaciers are located inside of glacier-shaped mountain valleys. A few moraine complexes located in the highest massif have been related to Lateglacial, coinciding with cold phases (Dryas) recorded in the Picos de Europa lakes and paleolakes. Finally, during the Holocene only small glaciers developed in the Picos de Europa, which have been assigned to LIA. Nowadays there are still glacial ice remains in four glacial cirques of Picos de Europa, close to the LIA moraines.

Borehole and High-Resolution Seismic Reflection Evidence for Holocene Activity on the Compton Blind-Thrust Fault, Los Angeles Basin, California

NASA Astrophysics Data System (ADS)

Leon, L. A.; Dolan, J. F.; Shaw, J. H.; Pratt, T. L.

2006-12-01

Newly collected borehole and high-resolution seismic reflection data from a site ~6 km south of downtown Los Angeles demonstrate that the Compton blind-thrust fault has generated multiple large-magnitude earthquakes during the Holocene. This large blind thrust fault, which was originally identified by Shaw and Suppe (1996) using industry seismic reflection profiles and well data, extends northwest-southeast for 40 km beneath the western edge of the Los Angeles basin. The industry seismic reflection data define a growth fault-bend fold associated with the thrust ramp, which, combined with well data, reveal compelling evidence for Pliocene and Pleistocene activity. The industry data, however, do not image deformation in the uppermost few hundred meters. In order to bridge this gap, we acquired high-resolution seismic reflection profiles at two scales across the back limb active axial surface of the fault-bend fold above the Compton thrust ramp, using a truck-mounted weight drop and sledgehammer sources. These profiles delineate the axial surfaces of the fold from <20 m depth downward to overlap with the upper part of the industry reflection data within the upper 500 m. The seismic reflection data reveal an upward-narrowing zone of folding that extends to <100 m of the surface. These data, in turn, allowed us to accurately and efficiently site a fault-perpendicular transect of eight continuously cored boreholes across the axial surface of the fold observed in both industry and high-resolution seismic reflection data. The borehole data reveal folding within a discrete kink band that is <~150 m wide in the shallow subsurface. Preliminary analysis of the deformed, shallow growth strata reveals evidence for a number of discrete uplift events, which we interpret as having occurred during several large-magnitude (M >7) earthquakes on the Compton fault. Although we do not as yet have age control for this transect, numerous organic-rich clay and silt layers, as well as abundant detrital charcoal, should yield 14C dates that will allow us to accurately date these uplift events. A stratigraphically abrupt downward transition from an upper section dominated by clays, silts, and sands into a gravel-dominated lower section occurs at ~25 m depth. If this transition is similar in age to well-dated sections elsewhere in the Los Angeles region (e.g. our Carfax site along the Puente Hills Thrust fault), then it marks the Pleistocene-Holocene change in climate and stream power at ~9.5 ¨C 10 ka. The total uplift across the Holocene/Pleistocene boundary is ~8 m, yielding a minimum uplift rate of ~0.8 mm/yr, which in turn suggests a slip rate on the blind thrust of 1.5 to 2 mm/yr. The depth of the shallowest buried fold scarp (1 m) attests to the recency of the youngest large-magnitude earthquake on the Compton blind-thrust fault. These observations clearly indicate that the Compton fault is active and capable of producing damaging, large-magnitude earthquakes directly beneath metropolitan Los Angeles.

Coastal eolian sand-ramp development related to paleo-sea-level changes during the Latest Pleistocene and Holocene (21–0 ka) in San Miguel Island, California, U.S.A.

USGS Publications Warehouse

Peterson, Curt D.; Erlandson, Jon M.; Stock, Errol; Hostetler, Steven W.; Price, David M.

2017-01-01

Coastal eolian sand ramps (5–130 m elevation) on the northern slope (windward) side of the small San Miguel Island (13 km in W-E length) range in age from late Pleistocene to modern time, though a major hiatus in sand-ramp growth occurred during the early Holocene marine transgression (16–9 ka). The Holocene sand ramps (1–5 m measured thicknesses) currently lack large dune forms, thereby representing deflated erosional remnants, locally covering thicker late Pleistocene sand-ramp deposits. The ramp sand was initially supplied from the adjacent island-shelf platform, extending about 20 km north of the present coastline. The sand-ramp deposits and interbedded loess soils were 14C dated using 112 samples from 32 archaeological sites and other geologic sections. Latest Pleistocene sand ramps (66–18 ka) were derived from across-shelf eolian sand transport during marine low stands. Shoreward wave transport supplied remobilized late Pleistocene sand from the inner shelf to Holocene beaches, where dominant NW winds supplied sand to the sand ramps. The onset dates of the sand-ramp deposition in San Miguel are 7.2 ± 1.5 ka (sample n = 14). The internal strata dates in the vertically accreting sand ramps are 3.4 ± 1.7 ka (n = 34). The sand ramps in San Miguel show wide-scale termination of sand supply in the latest Holocene time. The sand-ramp top dates or burial dates are 1.7 ± 0.9 ka (n = 28). The latest Holocene sand ramps are truncated along most of the island's northern coastline, indicating recent losses of nearshore sand reserves to onshore, alongshore, and, possibly, offshore sand sinks. The truncated sand ramps in San Miguel Island and in other sand-depleted marine coastlines provide warnings about future beach erosion and/or shoreline retreat from accelerated sea-level rise accompanying predicted global warming.

Genic diversity, genetic structure, and biogeography of Pinus sabiniana Dougl.

Treesearch

F. Thomas Ledig

1999-01-01

Pinus sabiniana Dougl. (grey pine) forms savanna forests in the foothills surrounding California’s Great Central Valley. However, its fossil record, which dates from the late Miocene through the Pliocene and Pleistocene, is found exclusively in southern California, south of the species’ present range. A total of twenty-nine isozyme loci, representing eighteen enzyme...

Freshwater Fossil Pearls from the Nihewan Basin, Early Early Pleistocene.

PubMed

Li, Su-Ping; Yao, Pei-Yi; Li, Jin-Feng; Ferguson, David Kay; Min, Long-Rui; Chi, Zhen-Qing; Wang, Yong; Yao, Jian-Xin; Sha, Jin-Geng

2016-01-01

Fossil blister pearls attached to the shells of an Anodonta mollusk from China, early Early Pleistocene, are reported here for the first time. The pearls were investigated in detail using a variety of methods. Micro-CT scanning of the fossil pearls was carried out to discover the inner structure and the pearl nucleus. Using CTAn software, changes in the gray levels of the biggest pearl, which reflect the changing density of the material, were investigated. The results provide us with some clues on how these pearls were formed. Sand grains, shell debris or material with a similar density could have stimulated the development of these pearls. X-ray diffraction analysis of one fossil pearl and the shell to which it was attached reveals that only aragonite exists in both samples. The internal structures of our fossil shells and pearls were investigated using a Scanning Electron Microscope. These investigations throw some light on pearl development in the past.

Geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles, Clark County, Washington, and Multnomah County, Oregon

USGS Publications Warehouse

O'Connor, Jim E.; Cannon, Charles M.; Mangano, Joseph F.; Evarts, Russell C.

2016-06-03

IntroductionThis is a 1:24,000-scale geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles in the States of Washington and Oregon. The map area is within the Portland Basin and includes most of the city of Vancouver, Washington; parts of Clark County, Washington; and a small part of northwestern Multnomah County, Oregon. The Columbia River flows through the southern part of the map area, generally forming the southern limit of mapping. Mapped Quaternary geologic units include late Pleistocene cataclysmic flood deposits, eolian deposits, and alluvium of the Columbia River and its tributaries. Older deposits include Miocene to Pleistocene alluvium from an ancestral Columbia River. Regional geologic structures are not exposed in the map area but are inferred from nearby mapping.

Temporal evolution of the Roccamonfina volcanic complex (Pleistocene), Central Italy

NASA Astrophysics Data System (ADS)

Rouchon, V.; Gillot, P. Y.; Quidelleur, X.; Chiesa, S.; Floris, B.

2008-10-01

The Roccamonfina volcanic complex (RVC), in southern Italy, is an Early to Middle Pleistocene stratovolcano sharing temporal and morphological characteristics with the Somma-Vesuvius and the Alban Hills; both being associated with high volcanic hazard for the cities of Naples and Rome, respectively. The RVC is important for the understanding of volcanic evolution in the Roman and Campanian volcanic provinces. We report a comprehensive study of its evolution based on morphological, geochemical and K-Ar geochronological data. The RVC was active from c.a. 550 ka to 150 ka. Its evolution is divided into five stages, defining a volcanic pulse recurrence time of c.a. 90-100 kyr. The two initial stages, consisted in the construction of two successive stratovolcanoes of the tephrite-phonolite, namely "High-K series". The first stage was terminated by a major plinian eruption emplacing the trachytic Rio Rava pumices at 439 ± 9 ka. At the end of the second stage, the last High-K series stratovolcano was destroyed by a large sector collapse and the emplacement of the Brown Leucitic Tuff (BLT) at 353 ± 5 ka. The central caldera of the RVC is the result of the overlapping of the Rio Rava and of the BLT explosions. The plinian eruption of the BLT is related to the emptying of a stratified, deep-seated HKS magma chamber during the upwelling of K series (KS) magma, marking a major geochemical transition and plumbing system re-organization. The following stage was responsible for the emplacement of the Lower White Trachytic Tuff at 331 ± 2 ka, and of basaltic-trachytic effusive products erupted through the main vent. The subsequent activity was mainly restricted to the emplacement of basaltic-shoshonitic parasitic cones and lava flows, and of minor subplinian deposits of the Upper White Trachytic Tuff between 275 and 230 ka. The northern crater is most probably a maar that formed by the phreatomagmatic explosion of the Yellow Trachytic Tuff at 230 ka. The latest stage of activity featured the edification of the central shoshonitic domes at c.a. 150 ka.

Rapid anthropogenic response to short-term aeolian-fluvial palaeoenvironmental changes during the Late Pleistocene-Holocene transition in the northern Negev Desert, Israel

NASA Astrophysics Data System (ADS)

Roskin, Joel; Katra, Itzhak; Agha, Nuha; Goring-Morris, A. Nigel; Porat, Naomi; Barzilai, Omry

2014-09-01

Archaeological investigations along Nahal Sekher on the eastern edge of Israel's northwestern Negev Desert dunefield revealed concentrations of Epipalaeolithic campsites associated respectively with ancient water bodies. This study, aimed at better understanding the connections between these camps and the water bodies, is concerned with a cluster of Natufian sites. A comprehensive geomorphological study integrating field mapping, stratigraphic sections, sedimentological analysis and optically stimulated luminescence (OSL) ages was conducted in the vicinity of a recently excavated Natufian campsite of Nahal Sekher VI whose artifacts directly overlay aeolian sand dated by OSL to 12.4 ± 0.7 and 11.7 ± 0.5 ka. Residual sequences of diagnostic silty sediments, defined here as low-energy fluvial fine-grained deposits (LFFDs), were identified within the drainage system of central Nahal Sekher around the Nahal Sekher VI site. LFFD sections were found to represent both shoreline and mid-water deposits. The thicker mid-water LFFD deposits (15.7 ± 0.7-10.7 ± 0.5 ka) date within the range of the Epipalaeolithic campsites, while the upper and shoreline LFFD units that thin out into the sands adjacent to the Nahal Sekher VI site display slightly younger ages (10.8 ± 0.4 ka-7.6 ± 0.4 ka). LFFD sedimentation by low-energy concentrated flow and standing-water developed as a result of proximal downstream dune-damming. These water bodies developed as a result of encroaching sand that initially crossed central Nahal Sekher by 15.7 ± 0.7 ka and probably intermittently blocked the course of the wadi. LFFD deposition was therefore a response to a unique combination of regional sand supply due to frequent powerful winds and does not represent climate change in the form of increased precipitation or temperature change. The chronostratigraphies affiliate the Natufian sites to the adjacent ancient water bodies. These relations reflect a rapid, but temporary anthropogenic response to a transient ‘window' of improved local aeolian-fluvial palaeoenvironmental conditions during the Late Pleistocene-Holocene transition, but don't necessarily point to a wetter or drier palaeoclimate.

A Long Pleistocene Paleoclimate Record from Stoneman Lake, Arizona

NASA Astrophysics Data System (ADS)

Fawcett, P. J.; Anderson, R. S.; Brown, E. T.; Werne, J. P.; Jimenez-Moreno, G.; Toney, J. L.; Garcia, D.; Garrett, H. L.; Dunbar, N. W.

2015-12-01

Long continuous lake sediment cores provide enormous potential for interpreting climate change. In the American Southwest, long records are revolutionizing our understanding of megadroughts, which have occurred in the past and will most certainly occur in the future with rapidly changing climate. One site with the potential to study ancient megadroughts is Stoneman Lake, central Arizona, whose basin is a circular depression formed by a collapse in late Tertiary volcanics. The lake is spring fed, most recently alternating between a marsh and a lake, with water levels having fluctuated by > 3 meters over the last 25 years. Its small closed drainage basin (ca. 2.5 km2) with one small inflowing stream is key to the sensitivity of the record. Two parallel lacustrine sediment cores (70 m and 30 m deep) were recovered in October of 2014. Our preliminary chronology includes 8 AMS dates in the upper 7 m and two distinct tephras at 30.8 m depth and 36.3 m depth. Radiocarbon dates show a 2.7-m-thick Holocene section, and then a low Pleistocene SAR with an age of 11,000 cal yr B.P. at ~2.8 m to an age of 46,500 cal yr B.P. at 4.2 m depth. We estimate that the 70-m deep hole will provide a climate record back to ~1.3 million years ago. Of particular interest are the interglacials that serve as good analogs for future climate including MIS 11 and MIS 19. Initial core description includes MS, bulk density and high-resolution images. Holocene sediments are characterized by massive, dark organic rich silty clays with no distinct lamination. Sediments from the Last Glacial Maximum are well-laminated, light brown silty clays with few organics present. The distinctive laminations probably represent a very deep lake and therefore a wet cold climate, also verified by pollen data. There are several repeated intervals of laminated sediments deeper in the core that may represent older glacial maxima. Future work will include detailed pollen, plant macrofossil and charcoal analysis, scanning XRF, TOC and carbon isotopic analyses as well as compound specific carbon and hydrogen work.

The contribution of lateritization processes to the formation of the kaolin deposits from eastern Amazon

NASA Astrophysics Data System (ADS)

da Costa, Marcondes Lima; Sousa, Daniel José Lima; Angélica, Rômulo Simões

The eastern region of the Amazon is home to the most important kaolin bauxite producing district in Brazil, referred to as the Paragominas-Capim kaolin bauxite district, which has a reserve of at least 1.0 billion tons of high-quality kaolin used in the paper coating industry. The kaolin deposits are closely related to sedimentary rocks of the Parnaíba basin and their lateritic cover. Two large deposits are already being mined: IRCC (Ipixuna) and PPSA (Paragominas). The geology of the IRCC mine is comprised of the kaolin-bearing lower unit (truncated mature laterite succession derived from the Ipixuna/Itapecuru formation) and the upper unit (immature lateritized Barreiras formation). The lower kaolin unit is characterized by a sandy facies at the bottom and a soft (ore) with flint facies at the top. It is formed by kaolinite, quartz, some iron oxi-hydroxides, mica and several accessories and heavy minerals. The <2 μm kaolinite crystallites only correspond to 41.3-58.3% of the soft kaolin, and large booklets of 15-300 μm are common. The degree of structure order of kaolinite decreases towards the flint kaolin. The chemical composition of the soft kaolin is similar to the theoretical chemical composition of kaolinite, with low iron content, and can be well correlated to most kaolin deposits in the region. The distribution pattern of chemical elements from sandy to flint kaolin (lower unit) suggests a lateritic evolution and erosive truncation. This is quite distinct from the upper unit, which has a mineralogical and chemical pathway relating it to a complete immature lateritic profile. The geological evolution of the IRCC kaolin is similar to that of other deposits in the eastern Amazon region, being comprised of: parent rocks formed in an estuarine marine and fluvio-laccustrine environment during the early Cretaceous; establishment of mature lateritization with the formation of kaolin in the Eocene; marine transgression and regression - (Pirabas and Barreiras formation) with kaolin profile erosion and forward movement of deferruginization and flintization during the Miocene after partial mangrove covering; and immature lateritization - partial kaolin ferruginization during the Pleistocene.

Climatic Implications of Macro- and Microfossil Assemblages from Late Pleistocene Deposits in Northern New Zealand

NASA Astrophysics Data System (ADS)

Ogden, John; Newnham, Rewi M.; Palmer, Jonathan G.; Serra, Richard G.; Mitchell, Neil D.

1993-01-01

Twenty-two plant species were identified from leaves, fruits, or flowers, and 41 taxa from pollen, present in a macrofossil (leaf) layer in a peat swamp formed on Pleistocene dunes on the Aupouri Peninsula in northern New Zealand. Eight genera of gymnosperms are represented. With the exception of Lagarostrobos colensoi, all tree species abundant as macrofossils are also common as pollen. Macrofossils enabled the on-site flora to be compared with the regional flora, represented by the pollen rain. Studies on leaf decomposition rates indicate bias toward sclerophyllous species in the macrofossils. Identification to species level and treering data from preserved kauri logs allow quantitative comparisons with similar extant communities. Current climatic conditions at those analogue sites are cooler (2° to 3°C), cloudier (11%), and much wetter (85%) than those currently prevailing on the Aupouri Peninsula. Dendrochronological results also suggest that the far north of New Zealand had a cooler, cloudier, and wetter climate at the time the fossil leaf assemblage was formed. Radiocarbon dates from possibly contaminated samples suggest that a diverse mixed gymnosperm/angiosperm forest, dominated by kauri ( Agathis australis), was present about (or sometime before) 41,00034,000 yr B.P., when the leaf layer was formed. Similar temperature reductions have been postulated for this period in New Zealand by other authors.

Quaternary Geochronology, Paleontology, and Archaeology of the Upper San Pedro River Valley, Sonora, Mexico

NASA Astrophysics Data System (ADS)

Gaines, E. P.

2013-12-01

This poster presents the results of multi-disciplinary investigations of the preservation and extent of Quaternary fossil-bearing strata in the San Pedro River Valley in Sonora, Mexico. Geologic deposits in the portions of the San Pedro Valley in southern Arizona contain one of the best late Cenozoic fossil records known in North America and the best record of early humans and extinct mammals on the continent. The basin in the U.S. is one of the type locations for the Blancan Land Mammal Age. Hemiphilian and Irvingtonian fossils are common. Rancholabrean remains are widespread. Strata in the valley adjacent to the international border with Mexico have yielded the densest concentration of archaeological mammoth-kill sites known in the western hemisphere. Despite more than 60 years of research in the U.S., however, and the fact that over one third of the San Pedro River lies south of the international boundary, little has been known about the late Cenozoic geology of the valley in Mexico. The study reported here utilized extensive field survey, archaeological documentation, paleontological excavations, stratigraphic mapping and alluvial geochronology to determine the nature and extent of Quaternary fossil-bearing deposits in the portions of the San Pedro Valley in Sonora, Mexico. The results demonstrate that the Plio-Pleistocene fossil -bearing formations known from the valley in Arizona extend into the uppermost reaches of the valley in Mexico. Several new fossil sites were discovered that yielded the remains of Camelids, Equus, Mammuthus, and other Proboscidean species. Late Pleistocene archaeological remains were found on the surface of the surrounding uplands. AMS radiocarbon dating demonstrates the widespread preservation of middle- to late- Holocene deposits. However, the late Pleistocene deposits that contain the archaeological mammoth-kill sites in Arizona are absent in the valley in Mexico, and are now known to be restricted to relatively small portions of the valley immediately north of the international border.

Chronology and ancient feeding ecology of two upper Pleistocene megamammals from the Brazilian Intertropical Region

NASA Astrophysics Data System (ADS)

de Melo França, Lucas; Trindade Dantas, Mário André; Bocchiglieri, Adriana; Cherckinsky, Alexander; de Souza Ribeiro, Adauto; Bocherens, Hervé

2014-09-01

In Brazilian Intertropical Region (BIR) fossil remains of the giant ground sloth Eremotherium laurillardi (Lund, 1842) and of the proboscidean Notiomastodon platensis (Ameghino, 1888) are the most abundant among megaherbivores. However, the paleoecology of both species needs to be better understood to enlighten why these species disappear in the end of the Pleistocene, an issue that is still debated. During the last decades, the carbon and oxygen stable isotopes have been increasingly being used to obtain paleoecological information about extinct animals, although this information is in most cases dissociated from chronological data. Thus, the main objective of this study is to contribute to the knowledge about feeding ecology and chronology of E. laurillardi and N. platensis within BIR. For each fossil sample we performed stable isotopes analyses (δ13C/δ18O) and radiocarbon dating (14C with AMS). The results showed that N. platensis occurred between 12,125 and 19,594 cal yr BP and exhibited a grazer diet (δ13C = -1.1‰-1.3‰), while E. laurillardi lived between 11,084 and 27,690 cal yr BP, with a mixed feeder diet (C3/C4 plants; values ratio δ13C = -7.7‰ to -3.3‰). The δ18O values of N. platensis ranged between 2.20‰ and 3.60‰, while the values of E. laurillardi ranged between -3.10‰ and -1.10‰. Neither species did exhibit differences in its diet through time, which suggests that the vegetational composition of this locality did not vary in the late Pleistocene. Both species were living in an open environment, rich in herbaceous plants (C4 plants) and with tree and shrub with disjoint distribution, maybe similar to some parts of recent Caatinga, where they have partitioned the spatial and feeding niches.

An initial examination of carbonate production in the western equatorial Pacific: XRF results from the Pliocene-Pleistocene of IODP Site U1490

NASA Astrophysics Data System (ADS)

Chapman, J.; Kulhanek, D. K.; Rosenthal, Y.; Holbourn, A. E.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 363 sought to determine the nature of and driving forces behind climate variability in the Western Pacific Warm Pool (WPWP) region throughout the Neogene on millennial, orbital, and geologic timescales. Our research focuses on the Pliocene to recent (4-0 Ma) sediment record from IODP Site U1490 to examine changes in carbonate production and burial in the WPWP as a record of variations in the regional/global carbon cycle. This interval is of particular interest because it spans the Middle Pliocene Warm Period, the initiation of Northern Hemisphere Glaciation, and the Mid-Pleistocene Transition. Site U1490 is located on the northern edge of Eauripik Rise at 05°58.95'N, 142°39.27'E in the northern part of the WPWP. At 2341 m water depth, today the site is bathed in Upper Circumpolar Deepwater. Pliocene to recent sediment primarily consists of foraminifer-rich nannofossil ooze, with the sedimentation rate varying between 1.5 and 3 cm/kyr. Initial shipboard measurement of calcium carbonate content shows little variation at low resolution (1 sample every few meters), varying between 90 and 95 wt%. We collected X-ray fluorescence (XRF) data at 2 cm resolution along the composite stratigraphic section to obtain a qualitative measure of the bulk chemistry of the sediment. We will use the weight percent calcium carbonate of discrete samples to calibrate the XRF data to generate a high-resolution carbonate record. We observe cyclical variations in the Ca/Ba, which may reflect variations in productivity and/or dissolution through this interval, although additional work is needed to fully interpret these data. Ultimately our research will allow for comparison between records obtained from these cores located in the western equatorial Pacific to those obtained in the eastern and central Pacific, which will better elucidate the nature of the carbon system during the Plio-Pleistocene.

Trace element evidence for abrupt changes in deep South Atlantic Ocean nutrient and carbonate chemistry across the Mid-Pleistocene Transition

NASA Astrophysics Data System (ADS)

Farmer, J. R.; Hoenisch, B.; Haynes, L.; Kroon, D.; Bell, D. B.; Jung, S.; Seguí, M. J.; Raymo, M. E.; Goldstein, S. L.; Pena, L. D.

2016-12-01

Pleistocene glaciations underwent a profound transition from lower amplitude 40 kyr cycles to high amplitude 100 kyr cycles between 1.2 and 0.8 Ma, an interval termed the Mid-Pleistocene Transition (MPT). While the underlying causes of the MPT are uncertain, previous studies show quasi-contemporaneous reductions in North Atlantic Deep Water (NADW) export1 and glacial atmospheric pCO22 around 0.9 Ma. Although this suggests a possible role for enhanced deep-ocean carbon storage in amplifying climate change across the MPT, few direct records of deep ocean carbonate chemistry exist for this interval to test this hypothesis. Here we present South Atlantic benthic foraminiferal B/Ca and Cd/Ca records from International Ocean Discovery Program Sites 1088, 1264 and 1267 (2.1 to 4.3 km water depth) as part of a larger study of Atlantic-wide changes in deep ocean chemistry and circulation spanning the MPT. Results show an abrupt 15-20% decrease in benthic B/Ca and 40-50% increase in Cd/Ca at 4.3 km depth (Site 1267) between 1.0 and 0.9 Ma. Site 1088, which at 2.1 km depth is sensitive to input of southern-sourced Upper Circumpolar Deep Water, shows a prolonged 25% decrease in B/Ca and 50% increase in Cd/Ca from 1.0 to 0.6 Ma. In contrast, at Site 1264 ( 2.5 km depth within the core of modern NADW) B/Ca and Cd/Ca changes across the MPT are more modest (-5% and +10%, respectively). These observations reflect on the accumulation of regenerated carbon and nutrients in the deep South Atlantic, and varying contributions of northern- and southern-sourced watermasses to each core site. Implications for deep-ocean carbon storage and forcing of the MPT will be discussed. 1Pena, L. and Goldstein, S. (2014), Science 345, 318 2Hönisch, B. et al. (2009), Science 324, 1551

Anisotropy of magnetic susceptibility as a tool for recognizing core deformation: reevaluation of the paleomagnetic record of Pleistocene sediments from drill hole OL-92, Owens Lake, California

USGS Publications Warehouse

Rosenbaum, Joseph; Reynolds, Richard T.; Smoot, Joseph; Meyer, Robert

2000-01-01

At Owens Lake, California, paleomagnetic data document the Matuyama/Brunhes polarity boundary near the bottom of a 323-m core (OL-92) and display numerous directional fluctuations throughout the Brunhes chron. Many of the intervals of high directional dispersion were previously interpreted to record magnetic excursions. For the upper ~120 m, these interpretations were tested using the anisotropy of magnetic susceptibility (AMS), which typically defines a subhorizontal planar fabric for sediments deposited in quiet water. AMS data from intervals of deformed core, determined from detailed analysis of sedimentary structures, were compared to a reference AMS fabric derived from undisturbed sediment. This comparison shows that changes in the AMS fabric provide a means of screening core samples for deformation and the associated paleomagnetic record for the adverse effects of distortion. For that portion of core OL-92 studied here (about the upper 120 m), the combined analyses of sedimentary structures and AMS data demonstrate that most of the paleomagnetic features, previously interpreted as geomagnetic excursions, are likely the result of core deformation.

Hunter-gatherer mobility and embedded raw-material procurement strategies in the mediterranean upper paleolithic.

PubMed

Tomasso, Antonin; Porraz, Guillaume

2016-05-06

Since the early 1980s, the sourcing of lithic raw materials has become central to studies of the territorial range and mobility strategies of Pleistocene foraging societies. Results have been fruitful but somehow repetitive. We will discuss the embedded procurement strategy, which presumes that raw material acquisition was part of other subsistence activities rather than an autonomous technological task. We argue that this theoretical assumption, when taken as dogma, restricts the role of technology in human history and also underestimates the way some lithic resources may have affected the organization of past hunter-gatherers. We base our discussion on the Upper Paleolithic (UP) from the Liguro-Provençal arc, with examples from the Proto-Aurignacian and the Epigravettian. Our regional record shows that in this context the movement of rocks over distances greater than 100 km was the norm rather than the exception. We argue that these long-distance procurements mirror technical needs that were oriented toward the selection of high-quality flints. We support the hypothesis that indirect procurement was an important component of regional socio-economic networks. © 2016 Wiley Periodicals, Inc.

Hydrocarbon reservoirs of Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, P.K.

1988-01-01

The statistical distribution of over 12,000 producible hydrocarbon reservoirs from various biostratigraphic intervals of the Gulf of Mexico is presented. The average number, thickness, volume, subsurface depth, and ecozone of depositional environments of the reservoirs are grouped according to biostratigraphic intervals, trends, and geographic areas. The upper Pliocene and Pleistocene reservoirs account for more than 77% of the total number. Within the Miocene trend, Bigenerina H in the western Gulf of Bigenerina A and Bigenerina 2 in the central Gulf show significant concentration of reservoirs. The average depth of production for all trends gets deeper, both from west and east,more » toward Ship Shoal-South Timbalier areas. The average thickness varies slightly between trends; however, variation between areas is more significant. A significant majority of the reservoirs of all trends in the entire Gulf is reported from the outer shelf-upper slope ecozones (E3 and E4). According to volume, the E3-E5 reservoirs can be classified into three groups; larger than 10,000 acre-ft/reservoir, 5,000 to 10,000 acre-ft/reservoir, and smaller than 5,000 acre-ft/reservoir.« less

Compositions, ages, and diagenetic histories of the carbonate, sulfide, oxide, and phosphatic concretions at Gay Head, Massachusetts

USGS Publications Warehouse

Poppe, L.J.; Commeau, R.F.; O'Leary, Dennis W.

1988-01-01

The calcite/ankerite concretions were formed in a hot, seasonally arid, caliche-prone environment of early Raritan age; the pyrite, marcasite, and siderite concretions precipitated in sediments deposited in low-energy, marshy, estuarine environments of late Raritan age. The phosphate concretions formed in a middle to inner shelf environment. The goethite and lepidocrocite concretions are secondary oxidation or alteration products of the prexistent Cretaceous concretions that were excavated during the Pleistocene and incorporated into the glacial drift. -from Authors

Regional implications of heat flow of the Snake River Plain, Northwestern United States

NASA Astrophysics Data System (ADS)

Blackwell, D. D.

1989-08-01

The Snake River Plain is a major topographic feature of the Northwestern United States. It marks the track of an upper mantle and crustal melting event that propagated across the area from southwest to northeast at a velocity of about 3.5 cm/yr. The melting event has the same energetics as a large oceanic hotspot or plume and so the area is the continental analog of an oceanic hotspot track such as the Hawaiian Island-Emperor Seamount chain. Thus, the unique features of the area reflect the response of a continental lithosphere to a very energetic hotspot. The crust is extensively modified by basalt magma emplacement into the crust and by the resulting massive rhyolite volcanism from melted crustal material, presently occurring at Yellowstone National Park. The volcanism is associated with little crustal extension. Heat flow values are high along the margins of the Eastern and Western Snake River Plains and there is abundant evidence for low-grade geothermal resources associated with regional groundwater systems. The regional heat flow pattern in the Western Snake River Plains reflects the influence of crustal-scale thermal refraction associated with the large sedimentary basin that has formed there. Heat flow values in shallow holes in the Eastern Snake River Plains are low due to the Snake River Plains aquifer, an extensive basalt aquifer where water flow rates approach 1 km/yr. Below the aquifer, conductive heat flow values are about 100 mW m -2. Deep holes in the region suggest a systematic eastward increase in heat flow in the Snake River Plains from about 75-90 mW m -2 to 90-110 mW m -2. Temperatures in the upper crust do not behave similarly because the thermal conductivity of the Plio-Pleistocene sedimentary rocks in the west is lower than that in the volcanic rocks characteristic of the Eastern Snake River Plains. Extremely high heat loss values (averaging 2500 mW m -2) and upper crustal temperatures are characteristic of the Yellowstone caldera.

Pleistocene phylogeographic effects on avian populations and the speciation process.

PubMed Central

Avise, J C; Walker, D

1998-01-01

Pleistocene biogeographic events have traditionally been ascribed a major role in promoting speciations and in sculpting the present-day diversity and distributions of vertebrate taxa. However, this paradigm has recently come under challenge from a review of interspecific mtDNA genetic distances in birds: most sister-species separations dated to the Pliocene. Here we summarize the literature on intraspecific mtDNA phylogeographic patterns in birds and reinterpret the molecular evidence bearing on Pleistocene influences. At least 37 of the 63 avian species surveyed (59%) are sundered into recognizable phylogeographic units, and 28 of these separations (76%) trace to the Pleistocene. Furthermore, use of phylogroup separation times within species as minimum estimates of 'speciation durations' also indicates that many protracted speciations, considered individually, probably extended through time from Pliocene origins to Pleistocene completions. When avian speciation is viewed properly as an extended temporal process rather than as a point event, Pleistocene conditions appear to have played an active role both in initiating major phylogeographic separations within species, and in completing speciations that had been inaugurated earlier. Whether the Pleistocene was exceptional in these regards compared with other geological times remains to be determined. PMID:9569664

Pleistocene megafaunal interaction networks became more vulnerable after human arrival.

PubMed

Pires, Mathias M; Koch, Paul L; Fariña, Richard A; de Aguiar, Marcus A M; dos Reis, Sérgio F; Guimarães, Paulo R

2015-09-07

The end of the Pleistocene was marked by the extinction of almost all large land mammals worldwide except in Africa. Although the debate on Pleistocene extinctions has focused on the roles of climate change and humans, the impact of perturbations depends on properties of ecological communities, such as species composition and the organization of ecological interactions. Here, we combined palaeoecological and ecological data, food-web models and community stability analysis to investigate if differences between Pleistocene and modern mammalian assemblages help us understand why the megafauna died out in the Americas while persisting in Africa. We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks would have increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations. Our findings suggest that the basic aspects of the organization of ecological communities may have played an important role in major extinction events in the past. Knowledge of community-level properties and their consequences to dynamics may be critical to understand past and future extinctions. © 2015 The Author(s).

Pleistocene megafaunal interaction networks became more vulnerable after human arrival

PubMed Central

Pires, Mathias M.; Koch, Paul L.; Fariña, Richard A.; de Aguiar, Marcus A. M.; dos Reis, Sérgio F.; Guimarães, Paulo R.

2015-01-01

The end of the Pleistocene was marked by the extinction of almost all large land mammals worldwide except in Africa. Although the debate on Pleistocene extinctions has focused on the roles of climate change and humans, the impact of perturbations depends on properties of ecological communities, such as species composition and the organization of ecological interactions. Here, we combined palaeoecological and ecological data, food-web models and community stability analysis to investigate if differences between Pleistocene and modern mammalian assemblages help us understand why the megafauna died out in the Americas while persisting in Africa. We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks would have increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations. Our findings suggest that the basic aspects of the organization of ecological communities may have played an important role in major extinction events in the past. Knowledge of community-level properties and their consequences to dynamics may be critical to understand past and future extinctions. PMID:26336175

Geologic framework of the northern North Carolina, USA inner continental shelf and its influence on coastal evolution

USGS Publications Warehouse

Thieler, E. Robert; Foster, David S.; Himmelstoss, Emily A.; Mallinson, David J.

2013-01-01

The inner continental shelf off the northern Outer Banks of North Carolina was mapped using sidescan sonar, interferometric swath bathymetry, and high-resolution chirp and boomer subbottom profiling systems. We use this information to describe the shallow stratigraphy, reinterpret formation mechanisms of some shoal features, evaluate local relative sea-levels during the Late Pleistocene, and provide new constraints, via recent bedform evolution, on regional sediment transport patterns. The study area is approximately 290 km long by 11 km wide, extending from False Cape, Virginia to Cape Lookout, North Carolina, in water depths ranging from 6 to 34 m. Late Pleistocene sedimentary units comprise the shallow geologic framework of this region and determine both the morphology of the inner shelf and the distribution of sediment sources and sinks. We identify Pleistocene sedimentary units beneath Diamond Shoals that may have provided a geologic template for the location of modern Cape Hatteras and earlier paleo-capes during the Late Pleistocene. These units indicate shallow marine deposition 15–25 m below present sea-level. The uppermost Pleistocene unit may have been deposited as recently as Marine Isotope Stage 3, although some apparent ages for this timing may be suspect. Paleofluvial valleys incised during the Last Glacial Maximum traverse the inner shelf throughout the study area and dissect the Late Pleistocene units. Sediments deposited in the valleys record the Holocene transgression and provide insight into the evolutionary history of the barrier-estuary system in this region. The relationship between these valleys and adjacent shoal complexes suggests that the paleo-Roanoke River did not form the Albemarle Shelf Valley complex as previously proposed; a major fluvial system is absent and thus makes the formation of this feature enigmatic. Major shoal features in the study area show mobility at decadal to centennial timescales, including nearly a kilometer of shoal migration over the past 134 yr. Sorted bedforms occupy ~ 1000 km2 of seafloor in Raleigh Bay, and indicate regional sediment transport patterns between Capes Hatteras and Lookout that help explain long-term sediment accumulation and morphologic development. Portions of the inner continental shelf with relatively high sediment abundance are characterized by shoals and shoreface-attached ridges, and where sediment is less abundant, the seafloor is dominated by sorted bedforms. These relationships are also observed in other passive margin settings, suggesting a continuum of shelf morphology that may have broad application for interpreting inner shelf sedimentation patterns.

Comparative phylogeography of Mississippi embayment fishes.

PubMed

Egge, Jacob J D; Hagbo, Taylor J

2015-01-01

The Mississippi Embayment is a prominent physiographic feature of eastern North America consisting of primarily lowland aquatic habitats and a fish fauna that is largely distinct from nearby highland regions. Numerous studies have demonstrated that both pre-Pleistocene and Pleistocene events have had a strong influence on the distributions and relationships of highland fishes in eastern North America. However, the extent to which these same events affected Embayment distributed taxa remains largely unexplored. The purpose of this study was to investigate the relative roles of pre-Pleistocene and Pleistocene events in shaping phylogeographic relationships of four stream dwelling fishes in the Mississippi Embayment. Molecular genetic analyses of the mitochondrial gene cytochrome b were performed for three ictalurid catfish species (Noturus miurus, n = 67; Noturus hildebrandi, n = 93, and Noturus phaeus, n = 44) and one minnow species (Cyprinella camura, n = 78), all distributed in tributary streams of the Mississippi Embayment. Phylogenetic relationships and divergence times among haplotypes for each species were estimated using maximum likelihood and Bayesian methods. Phylogenetic analyses recovered 6 major haplotype clades within N. miurus, 5 within N. hildbrandi, 8 within N. phaeus, and 8 within C. camura. All three Noturus species show a high degree of isolation by drainage, which is less evident in C. camura. A clade of haplotypes from tributaries in the southern portion of the Mississippi Embayment was consistently recovered in all four species. Divergence times among clades spanned the Pleistocene, Pliocene, and Miocene. Novel relationships presented here for C. camura and N. phaeus suggest the potential for cryptic species. Pre-Pleistocene and Pleistocene era sea level fluctuations coincide with some divergence events, but no single event explains any common divergence across all taxa. Like their highland relatives, a combination of both pre-Pleistocene and Pleistocene era events have driven divergences among Embayment lineages.

Lava dome morphometry and geochronology of the youngest eruptive activity in Eastern Central Europe: Ciomadul (Csomád), East Carpathians, Romania

NASA Astrophysics Data System (ADS)

Karátson, D.; Telbisz, T.; Harangi, Sz.; Magyari, E.; Kiss, B.; Dunkl, I.; Veres, D.; Braun, M.

2012-04-01

Volcanic evolution of the Ciomadul (Csomád) lava dome complex, site of the youngest (Late Pleistocene, late Marine Isotope Stage 3) eruptive activity in the Carpathians, has been studied by advanced morphometry and radiometric (U/Pb, U/He and 14C) geochronology. The volcano produced alternating effusive and intermittent explosive eruptions from individual domes, typical of common andesitic-dacitic lava domes. A comparative morphometry shows steep ≥30° mean slopes of domes' upper flank and the Csomád domes fit well to the 100-200 ka domes worldwide. Morphometric ages obtained from the mean slope vs age precipitation correlation results in ≤100 ka ages. The morphometric approach is supported by U/Pb and U/He chronology: preliminary results of zircon dating indicate ages ranging between 200(250) and 30 ka. The youngest ages of the data set obtained both from lavas and pumiceous pyroclastics argue for a more or less coeval effusive and explosive volcanism. Based also on volcanological data, we propose vulcanian eruptions and explosive dome collapses especially toward the end of volcanic activity. Moreover, radiometric chronology suggests that, possibly subsequently to the peripheral domes, a central lava dome complex built up ≤100 ka ago. This dome complex, exhibiting even more violent, up to sub-plinian explosions, emplaced pumiceous pyroclastic flow and fall deposits as far as 17 km. We propose that the explosive activity produced caldera-forming eruptions as well, creating a half-caldera. This caldera rim is manifested by the asymmetric morphology of the central edifice: the present-day elevated ridge of Ciomadul Mare (Nagy Csomád), encompassing the twin craters of Mohoş (Mohos) peat bog and Sf. Ana (Szent [St.] Anna). These latter craters may have been formed subsequently, ca. ~100-30 ka ago, after the caldera formation. Drilling of lacustrine sediments in the St. Anna crater shows that beneath the Holocene gyttja several meters of Late Pleistocene sediment occurs. Although we did not reach the very bottom of the crater, radiometric dating of the lowest layer indicates that the formation of the crater exceeds 26,000 cal yr BP. This is in accordance with magnetic susceptibility curves and pollen results from the lake sediments, as well as the 31,450 cal yr BP radiocarbon age of the youngest dated eruption at Csomád. Research has been funded by Hungarian National Grants OTKA K68587 and NF101362.

Various environments of interglacials recorded by Pleistocene paleosoils in Hungary (Central Europe)

NASA Astrophysics Data System (ADS)

Varga, György; Kis, Éva

2015-04-01

Based on stable isotope analyses of worldwide reference curves from deep sea, ice core and speleothem records, it has long been apparent that duration, intensity and climatic conditions of different interglacial periods were significantly diverse. As a consequence of negligible fresh, detrital material admixture during interglacials, the soil formation intensity and maturity of various kinds of past soils have been holding vital information on the environmental conditions at the time the soils formed. This, in turn, means that several physical and chemical properties of soils allow us to reconstruct past climatic regimes. Loess-paleosol sequences in Hungary (Central Europe) provide insight into the cyclic nature of glacial-interglacial variations of the last 1 million years. The paleosoils have been recognized as the product of warmer and moister interglacials, when the (glacial) loess material was altered by chemical weathering and pedogenic processes. 12 pedogene units from MIS-19 to MIS-5 strata were analysed in the course of this study, with a special attention to MIS-11 and MIS-19 periods, because of these can be regarded as analogues of the Holocene interglacial (due to the similarities in obliquity and eccentricity). Grain size, geochemical and (clay)mineralogical studies were elaborated and were gathered from previously published papers to quantify past weathering intensity and paleoenvironmental conditions by geochemical climofunctions. The Upper and partly, the Middle Pleistocene loess deposits are intercalated by steppe, forest-steppe and brown forest soils, while the older pedogene horizons are different kinds; these are red, Mediterranean-type soils. The MIS-5 pedocomplex consist of three parts at several Hungarian sites, however the pedogene units cannot be correlated unequivocally with the three MIS-5 warmer substages, due to the scarce absolute age data. The MIS-7 and MIS-9 stages are represented by three forest steppe soils. The MIS-11 pedocomplex and MIS-17 and MIS-19 units are thick and well-developed forest soils, formed under a more humid climate compared to the younger pedogene strata. The geochemical data and climofunctions have been supported well these findings. Contrary to the global loess-paleosoil sequences, the MIS-13 and MIS-15 soils are not so dominant in the Hungarian series. Support of the Hungarian Research Fund OTKA under contract PD108708 (for G. Varga) is gratefully acknowledged. It was additionally supported (for G. Varga) by the Bolyai János Research Scholarship of the Hungarian Academy of Sciences.

Direct radiocarbon dating and DNA analysis of the Darra-i-Kur (Afghanistan) human temporal bone.

PubMed

Douka, Katerina; Slon, Viviane; Stringer, Chris; Potts, Richard; Hübner, Alexander; Meyer, Matthias; Spoor, Fred; Pääbo, Svante; Higham, Tom

2017-06-01

The temporal bone discovered in the 1960s from the Darra-i-Kur cave in Afghanistan is often cited as one of the very few Pleistocene human fossils from Central Asia. Here we report the first direct radiocarbon date for the specimen and the genetic analyses of DNA extracted and sequenced from two areas of the bone. The new radiocarbon determination places the find to ∼4500 cal BP (∼2500 BCE) contradicting an assumed Palaeolithic age of ∼30,000 years, as originally suggested. The DNA retrieved from the specimen originates from a male individual who carried mitochondrial DNA of the modern human type. The petrous part yielded more endogenous ancient DNA molecules than the squamous part of the same bone. Molecular dating of the Darra-i-Kur mitochondrial DNA sequence corroborates the radiocarbon date and suggests that the specimen is younger than previously thought. Taken together, the results consolidate the fact that the human bone is not associated with the Pleistocene-age deposits of Darra-i-Kur; instead it is intrusive, possibly re-deposited from upper levels dating to much later periods (Neolithic). Despite its Holocene age, the Darra-i-Kur specimen is, so far, the first and only ancient human from Afghanistan whose DNA has been sequenced. Copyright © 2017 Elsevier Ltd. All rights reserved.

Paleoenvironmental evolution based on benthic foraminifera biofacies of the Paraíba do Sul Deltaic Complex, eastern Brazil

NASA Astrophysics Data System (ADS)

Gasparini, Sarah Pereira; Vilela, Claudia Gutterres

2017-12-01

The paleoecology and distribution of benthic foraminiferal assemblages were analyzed in the core 2-MU-1-RJ well, drilled in the Paraíba do Sul Deltaic Complex, Rio de Janeiro (Brazil). An abundant assemblage was found in the upper portion of the well core, inferred to be pleistocenic deposits. The coastal dynamic was recognized from five biofacies based on clusters, the Planktonic/Benthic (P/B) ratios and indicator species distribution in the core. Several biofacies were identified along the core depending on the species dominance. From the bottom to the top of the core, the biofacies succession represents the environmental changes in the coastal area associated to sea-level oscillations. The biofacies ABP dominated by Ammonia parkinsoniana and Bolivina spp. and Pararotalia cananeiaensis represents an inner shelf environment; biofacies QP dominated by shelf miliolids species; biofacies PGH, dominated by P. cananeiaensis, Gavelinopsis praegeri, and Hanzawaia nitidula, represents the estuary complex with middle or outer shelf influence; biofacies QL represents hypersaline waters dominated by lagoonal miliolids; and biofacies HP characterized by Haynesina germanica and P. cananeiaensis is associated with paralic environments. Marine ingressions are recorded and those biofacies show the pleistocenic coastal hydrodinamic in the deltaic complex. The foraminiferal biofacies contribute with detailed information to sedimentary facies previously characterized in the study area by the reconstruction of paleoenvironment succession.

Upper Cretaceous and Lower Jurassic strata in shallow cores on the Chukchi Shelf, Arctic Alaska: Chapter C in Studies by the U.S. Geological Survey in Alaska, vol. 15

USGS Publications Warehouse

Houseknecht, David W.; Craddock, William H.; Lease, Richard O.

2016-02-12

Shallow cores collected in the 1980s on the Chukchi Shelf of western Arctic Alaska sampled pre-Cenozoic strata whose presence, age, and character are poorly known across the region. Five cores from the Herald Arch foreland contain Cenomanian to Coniacian strata, as documented by biostratigraphy, geochronology, and thermochronology. Shallow seismic reflection data collected during the 1970s and 1980s show that these Upper Cretaceous strata are truncated near the seafloor by subtle angular unconformities, including the Paleogene mid-Brookian unconformity in one core and the Pliocene-Pleistocene unconformity in four cores. Sedimentary structures and lithofacies suggest that Upper Cretaceous strata were deposited in a low accommodation setting that ranged from low-lying coastal plain (nonmarine) to muddy, shallow-marine environments near shore. These observations, together with sparse evidence from the adjacent western North Slope, suggest that Upper Cretaceous strata likely were deposited across all of Arctic Alaska.A sixth core from the Herald Arch contains lower Toarcian marine strata, indicated by biostratigraphy, truncated by a Neogene or younger unconformity. These Lower Jurassic strata evidently were deposited south of the arch, buried structurally to high levels of thermal maturity during the Early Cretaceous, and uplifted on the Herald thrust-fault system during the mid to Late Cretaceous. These interpretations are based on regional stratigraphy and apatite fission-track data reported in a complementary report and are corroborated by the presence of recycled palynomorphs of Early Jurassic age and high thermal maturity found in Upper Cretaceous strata in two of the foreland cores. This dataset provides evidence that uplift and exhumation of the Herald thrust belt provided sediment to the foreland during the Late Cretaceous.

Ceramic substrate including thin film multilayer surface conductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Joseph Ambrose; Peterson, Kenneth A.

2017-05-09

A ceramic substrate comprises a plurality of ceramic sheets, a plurality of inner conductive layers, a plurality of vias, and an upper conductive layer. The ceramic sheets are stacked one on top of another and include a top ceramic sheet. The inner conductive layers include electrically conductive material that forms electrically conductive features on an upper surface of each ceramic sheet excluding the top ceramic sheet. The vias are formed in each of the ceramic sheets with each via being filled with electrically conductive material. The upper conductive layer includes electrically conductive material that forms electrically conductive features on anmore » upper surface of the top ceramic sheet. The upper conductive layer is constructed from a stack of four sublayers. A first sublayer is formed from titanium. A second sublayer is formed from copper. A third sublayer is formed from platinum. A fourth sublayer is formed from gold.« less

Pleistocene lake level changes in Western Mongolia

NASA Astrophysics Data System (ADS)

Borodavko, P. S.

2009-04-01

Global cooling in the Early Pleistocene caused extensive continental glaciation in the northern hemisphere including the arid areas of Central Asia. The reduction of temperatures (particularly summer temperatures) reduced evaporation and strengthened the importance of precipitation. The simultaneity of "lakes periods" (pluvials) and stages of glaciation is established experience confirmed by investigations in the west of North America and Russia. In the Mongolian Great Lakes Depression new evidence for similar conditions is found. The Great Lakes Depression is one of the largest in Central Asia, and is divided into 2 main Lakes basins: Hyargas Lake Basin and Uvs Lake Basin. The basin is 600-650 km in length with a width of 200-250 km in the north and 60-100 km in the south. Total catchment area is about 186600 km2. The elevation of the basin floor is from 1700 m a.s.l. to 760 m a.s.l., decreasing to the north and south-east. The depression extends south-north and is bounded by mountains: Tannu-Ola to the north, Hangai to the east; Gobi Altai to the south and Mongolian Altay to the west. The maximum elevation of the mountains is 4000 m a.s.l. There are some mountains with an elevation between 2000 and 3000 m a.s.l in the lake catchment. These mountains are not glaciated today. The geological record [1] suggests the Great Lakes Depression already existed in the Mesozoic, but assumed its modern form only during the Pliocene-Quaternary when tectonic movements caused the uplift of the surrounding mountains. A phase of tectonic stability occurred during the Late Quaternary. The depression is filled by Quaternary fluvial, aeolian and lacustrine deposits (e.g. sand, pebbles). The Neogene deposits are represented by coloured clay, marl, sand and sandstone [1]. Hyargas Lake is the end base level of erosion of the lake group consisting of the Hara-Us Nur, Dorgon, Hara Nur and Airag lakes. Hyargas is one of the largest lakes in Mongolia, with a water surface of 1,407 km2. The lake is 75 km long and 31 km wide. Its mean depth is 47 m, with the deepest point reaching 80 m, and its total water volume is 66,034 km3 and drainage basin 115,500 km2. The only water flowing into it is Galbiyn Hooloi. Hara-Us Nur Lake is a fresh-water (mineralization ca 107-348 mg/l, pH -7.8) basin situated in the Mongolian Great Lakes Depression [2]. Hara-Us Nur is fed by the Kobdo and Buyant rivers, which start in the Mongolian Altay, and outflows via the Chano-Hairkhan River into Hara-Us Nur Lake. Hara-Us Nur is divided by the Ak-Bashi Island into two subbasins. It has a water area of 1857 km2 with a length of 72.2 km and a maximum width of 27 km [4]. The maximum depth is 4 m and the average depth is ca 2 m [5,6]. The terraced lake shores are covered by steppe and desert vegetation. Pharagmites is abundant in the river deltas and close to the shore-line and the shallow-water littoral is covered by rich aquatic vegetation, including Myriophyllum verticulatum, Zannichelia pedunculata, Utricularia vulgaris [3]. Hara-Nur Lake is situated in the desert steppe subzone of the Mongolian Great Lakes Depression. The fresh-water Hara-Nur Lake receives inflow from Hara-Us Nur Lake via the Chano-Hairkhan River. There are two outflows from the lake one outflow is via a 10 km-long channel which flows to the Dzabhan River, which in turn flows into the closed Hyargas Lake. The other outflow is a small semi-permanent stream with flows southward into the closed brackish-water Dorgon Lake. Hara-Nur has a water area of 57,500 ha, with a length of 37 km and a maximum width of ca 24 km. The maximum depth is 7 m and the average depth is ca 4 m. The mean water mineralization is 260 mg/l and the pH is 8.0 [5]. The catchment area is ca 7,200,000 ha. Lake Ureg located in the Mongolian Altay at an altitude of 1425 m.a.s.1., this lake has an area 237.6 km2 and maximum depth of 48 m. Secchi disk transparency is to 8 m. Macrophyte beds cover up to 20 per cent of the lake area, with the common cane sedges and horsetails dominant. The benthic fauna is poor, and only single pecimens of molluscs and amphipods are met. The ichtyofauna is represented by Oreoleuciscus Pewzowi. Previous and modern investigations of these lakes, their morphologies and deposits, allow to specify periods of extension of the lakes and palaeogeographical conditions. Two clear extension periods can be determined in the Mongolian Great Lakes Basin, corresponding to Mid-and Late Pleistocene transgressions. During the Mid-Pleistocene transgression the current Lakes Har-Us Nur, Dorgon Nur, Hara Nur, Airag Nur and Hyargas were integrated to a united lake, with a maximal level at 1265 m. and total water area about 23 158 km2 . The maximal thickness of Mid-Pleistocene lake deposits is 70 m. Late Pleistocene lake sediments are investigated in sections near Dzabhan River and Hyargas Nuur shorelines. They consist of laminated sand, clay and gravel with cryogenic structures at the base and upper part of sections. The mean thickness of Late Pleistocene lake deposits is 20-35 m. The main characteristics of Late Pleistocene lake features are represented by a very bright "lake relief" — obvious steps of shorelines, gravel bands, bars and spits. The specific structure of Late Pleistocene lake cross-sections allows to separate two transgressions within this period. In the first half of the Holocene a minor regression of several meters occurred. Elements of the modern time aeolian relief were still inundated on the north shore of Lake Har-Us Nur. Researches funded by RFBR (Grant 08-05-00037-a) References 1. Geomorfologiya Mongol'skoi Narodnoi Respubliki (Geomorphology of the Mongolian People Republic). M.: Nauka, pp. 135-148. 2. Ozera MNR i ikh mineral'nye resursy (Lakes of MPR and their mineral resources), 1991. Moscow, Nauka, 136 p. 3. Sevastyanov, D.V., Shuvalov, V.F. and Neustrueva, I. Yu. (Eds.), 1994. Limnologiya i paleolimnologiya Mongolii (Limnology and Palaeolimnology of Mongolia). St.Petersburg, Nauka, 304 p. 4. Tarasov, P.E., Harrison, S.P., Saarse, L., Pushenko, M.Ya., Andreev, A.A., Aleshinskaya, Z.V., Davydova, N.N., Dorofeyuk, N.I., Efremov, Yu.V., Khomutova, V.I., Sevastyanov, D.V., Tamosaitis, J., Dorofeyuk, N.I., Efremov, Yu.V., Khomutova, V.I., Sevastyanov, D.V., Tamosaitis, J.,Uspenskaya, O.N., Yakushko, O.F. and Tarasova, I.V., 1994. Lake status records from the Former Soviet Union and Mongolia: Data Base Documentation, World Data Center -A for Paleoclimatology NOAA Paleoclimatology Program, Paleoclimatology Publications Series Report No 2, Boulder, Colorado USA, 274 p. 5. Tserensodnom, Zh., 1971. Mongol orny Nuur. Ulaanbaatar, TUAH, 202 p. 6. Vipper, P., Dorofeyuk, N., Liiva, A., Meteltseva, E., and Sokolovskaya, V., 1981. Palaeogeography of the Central Mongolia during the upper Pleistocene and Holocene. Izv. Akad. Nauk ESSR, Ser. Biol., vol. 30, no. 1, pp. 74-82.

Geology, vegetation, and hydrology of the 52 bog at the MEF: 12,000 years in northern Minnesota. Chapter 4.

Treesearch

Elon S. Verry; Joannes Jansenns

2011-01-01

A clear understanding of geology and landscape setting is fundamental to the interpretation of water and solute movement among landscape forms. This understanding allows us to assess how land use affects water, soils, and vegetation as well as assess the fate of acids, nutrients, trace metals, and organic compounds deposited from the atmosphere. Pleistocene Glaciation...

Geologic history of the Black Hills caves, South Dakota

USGS Publications Warehouse

Palmer, Arthur N.; Palmer, Margaret; Paces, James B.

2016-01-01

The caves reveal four phases of calcite deposition: eogenetic ferroan calcite (Mississippian replacement of sulfates); white scalenohedra in paleovoids deposited during deep post-Mississippian burial; palisade crusts formed during blockage of springs by Oligocene–Miocene continental sediments; and laminated crusts from late Pleistocene water-table fluctuations. The caves reveal more than 300 m.y. of geologic history and a close relationship to regional geologic events.

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins

PubMed Central

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-01-01

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male–female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on fossil hominin tooth crowns. Importantly, our data on early hominin cross striation variation may now contribute towards solving difficult taxonomic diagnoses where much may depend on fragmentary molar remains and enamel structure. PMID:19172730

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins.

PubMed

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-08-01

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male-female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on fossil hominin tooth crowns. Importantly, our data on early hominin cross striation variation may now contribute towards solving difficult taxonomic diagnoses where much may depend on fragmentary molar remains and enamel structure.

Surface ages and rates of erosion at the Calico Archaeological Site in the Mojave Desert, Southern California

NASA Astrophysics Data System (ADS)

Owen, Lewis A.; Davis, Teresa; Caffee, Marc W.; Budinger, Fred; Nash, David

2011-01-01

Erosion rates and surface exposure ages were determined at the Calico Archaeological Site in the Calico Hills of the Mojave Desert, California, using 10Be terrestrial cosmogenic nuclides (TCN) methods. The Calico Hills are composed of Miocene lacustrine deposits of the Barstow Formation and fanglomerates/debris flows of the Pleistocene Yermo Deposits. These deposits are highly denuded and dissected by arroyos that have surfaces armored with chert. Surface erosion rates based on cosmogenic 10Be concentrations in stream sediments range from 19 to 39 m/Ma, with an average of 30.5 ± 6.2 m/Ma. Surface boulders have 10Be TCN ages that range from 27 ka to 198 ka, reflecting significant erosion of the Calico Hills. The oldest boulder age (197 ± 20 ka) places a minimum limit on the age of Yermo deposits. Depth profile ages at four locations within the study area have minimum ages that range from 31 to 84 ka and erosion rate-corrected surface exposure ages ranging from 43 to 139 ka. These surface exposure ages support the view that the surfaces in Yermo deposits formed during the Late Pleistocene to latest Middle Pleistocene. This chronology has important implications for interpreting the context of possible artifacts/geofacts at the site that might provide evidence for early human occupation of North America, and for reconstructing paleoenvironment change and landscape evolution in the region.

Evidence for late Pliocene deglacial megafloods in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Wang, Z.; Gani, M. R.

2017-12-01

The paleoclimatic significance of giant sedimentary structures developed under unconfined Froude-supercritical sediment gravity flows in subaqueous settings is considerably under-examined. This research, for the first time, extensively documents >20-km-wide and 200-m-thick Plio-Pleistocene giant sediment waves in the northern Gulf of Mexico continental slope using 3D seismic data, showing waveform morphology in unprecedented detail. Published biostratigraphic data help constraining the geologic age of these deposits. The results of numerical and morphological analyses suggest that such large-scale bedforms were formed under sheet-like unconfined Froude-supercritical turbidity currents as cyclic steps. Paleohydraulic reconstruction (e.g., flow velocity, discharge, and unit flux), in association with other evidence like geologic age, published stable isotope records, and temporal rarity, points out that the responsible Froude-supercritical turbidity currents were most likely triggered by deglacial catastrophic outburst floods during the late Pliocene to early Pleistocene. Laurentide Ice Sheet outburst floods to the Gulf of Mexico have previously been documented based mainly on deep-sea cores during the last several interglacial episodes in the late Pleistocene. Our megaflood events constitute, by far, the oldest record of the glacial outburst floods during the Quaternary Ice Age anywhere in the world. This study suggests that such pervasive occurrence of large-scale sediment waves likely serve as a proxy for extreme events like catastrophic megafloods.

Microbial Habitability and Pleistocene Aridification of the Asian Interior.

PubMed

Wang, Jiuyi; Lowenstein, Tim K; Fang, Xiaomin

2016-06-01

Fluid inclusions trapped in ancient halite can contain a community of halophilic prokaryotes and eukaryotes that inhabited the surface brines from which the halite formed. Long-term survival of bacteria and archaea and preservation of DNA have been reported from halite, but little is known about the distribution of microbes in buried evaporites. Here we report the discovery of prokaryotes and single-celled algae in fluid inclusions in Pleistocene halite, up to 2.26 Ma in age, from the Qaidam Basin, China. We show that water activity (aw), a measure of water availability and an environmental control on biological habitability in surface brines, is also related to microbe entrapment in fluid inclusions. The aw of Qaidam Basin brines progressively decreased over the last ∼1 million years, driven by aridification of the Asian interior, which led to decreased precipitation and water inflow and heightened evaporation rates. These changes in water balance produced highly concentrated brines, which reduced the habitability of surface lakes and decreased the number of microbes trapped in halite. By 0.13 Ma, the aw of surface brines approached the limits tolerated by halophilic prokaryotes and algae. These results show the response of microbial ecosystems to climate change in an extreme environment, which will guide future studies exploring deep life on Earth and elsewhere in the Solar System. Halite fluid inclusions-Ancient microbes-Water activity-Qaidam Basin-Pleistocene aridification. Astrobiology 16, 379-388.

Effects of late quaternary climate change on Palearctic shrews.

PubMed

Prost, Stefan; Klietmann, Johannes; van Kolfschoten, Thijs; Guralnick, Robert P; Waltari, Eric; Vrieling, Klaas; Stiller, Mathias; Nagel, Doris; Rabeder, Gernot; Hofreiter, Michael; Sommer, Robert S

2013-06-01

The Late Quaternary was a time of rapid climatic oscillations and drastic environmental changes. In general, species can respond to such changes by behavioral accommodation, distributional shifts, ecophenotypic modifications (nongenetic), evolution (genetic) or ultimately face local extinction. How those responses manifested in the past is essential for properly predicting future ones especially as the current warm phase is further intensified by rising levels of atmospheric carbon dioxide. Here, we use ancient DNA (aDNA) and morphological features in combination with ecological niche modeling (ENM) to investigate genetic and nongenetic responses of Central European Palearctic shrews to past climatic change. We show that a giant form of shrew, previously described as an extinct Pleistocene Sorex species, represents a large ecomorph of the common shrew (Sorex araneus), which was replaced by populations from a different gene-pool and with different morphology after the Pleistocene Holocene transition. We also report the presence of the cold-adapted tundra shrew (S. tundrensis) in Central Europe. This species is currently restricted to Siberia and was hitherto unknown as an element of the Pleistocene fauna of Europe. Finally, we show that there is no clear correlation between climatic oscillations within the last 50 000 years and body size in shrews and conclude that a special nonanalogous situation with regard to biodiversity and food supply in the Late Glacial may have caused the observed large body size. © 2013 Blackwell Publishing Ltd.

Comparative morphology and paleobiology of Middle Pleistocene human remains from the Bau de l'Aubesier, Vaucluse, France.

PubMed

Lebel, S; Trinkaus, E; Faure, M; Fernandez, P; Guérin, C; Richter, D; Mercier, N; Valladas, H; Wagner, G A

2001-09-25

The discovery of later Middle Pleistocene human remains from the Bau de l'Aubesier, France reinforces an evolutionary model of the gradual accumulation of Neandertal-derived facial and dental features during the Middle Pleistocene of the northwestern Old World. The pronounced maxillary incisor beveling of Aubesier 4 helps to extend the antiquity of nondietary use of the anterior dentition. The interproximal "toothpick" groove on the Aubesier 10 molar increases the sample for these lesions. The pathological loss of the mandibular dentition of Aubesier 11 indicates advanced antemortem masticatory impairment, at a level previously undocumented before the Late Pleistocene. These remains support a view of later Middle Pleistocene humans able to support debilitated individuals despite the considerable use of their bodies to accomplish routine activities.

Continuity versus discontinuity of the human settlement of Europe between the late Early Pleistocene and the early Middle Pleistocene. The mandibular evidence

NASA Astrophysics Data System (ADS)

Bermúdez de Castro, José María; Martinón-Torres, María; Rosell, Jordi; Blasco, Ruth; Arsuaga, Juan Luís; Carbonell, Eudald

2016-12-01

One of the most interesting aspects of the settlement of Europe is the possible continuity or discontinuity of the populations living in this continent during the Early and Middle Pleistocene. In this paper we present an analysis of the mandibular fossil record from four important Pleistocene European sites, Gran Dolina-TD6-2 (Sierra de Atapuerca), Mauer, Arago, and Atapuerca-Sima de los Huesos. We focus this study in the recognition of key derived mandibular features that may be useful to assess the relationship among the populations represented at these sites. In order to make an approach to the ecological scenario, we also present a short review and discussion of the archaeological and paleoenvironmental evidences at that time. Our results suggest that probably there was a demographic discontinuity between the late Early Pleistocene populations (MIS 21-MIS 19), and those dated to the MIS 15. Hybridization between residents and new settlers cannot be discarded. However, some features of the Gran Dolina-TD6 hominins point to some relationship between the population represented in this site (probably dated to the MIS 21) and the European Middle Pleistocene and early Late Pleistocene populations. A hypothetical scenario is presented in order to understand this apparent contradiction with the model of discontinuity.

A critical appraisal of allometric growth among alpine cirques based on multivariate statistics and spatial analysis

NASA Astrophysics Data System (ADS)

Delmas, Magali; Gunnell, Yanni; Calvet, Marc

2015-01-01

When considering the morphometric attributes of a glacial cirque, imbalances between length, width, and amplitude have been deemed relevant tools for discriminating between two possible pathways of cirque growth: downwearing by glaciers or backwearing by freeze-thaw processes. Based on a sample of 1071 cirques in the French Pyrenees, we reframe the concern for climatic variables by also granting systematic consideration to cirque lithology. Insight into the factors that control cirque shape is gained from Principal Component Analysis, where maps of eigenvalues assigned to six classes of bedrock display spatial patterns of cirque form as a function of position along the regional climatic gradient. Among crystalline rocks (granite, gneiss, migmatite), cirque form is predominantly determined by climatic controls. This is highlighted in the contrast between the elevated core of the Pleistocene icefield, where cirque isometry prevails, and the more peripheral areas (external sierras of the Atlantic precipitation zone and high sierras of the drier Mediterranean zone) where the lighter imprint of glaciation on the landscape has failed to erase (through glacial deepening) the allometric signature of pre-Pleistocene topographic features such as shallow valley heads and etch-basins. As a result, wide and shallow cirques occur in these settings. Among schist outcrops, in contrast, cirque form appears randomly distributed, suggesting that bedrock characteristics (e.g., structure) rather than climate are the key controls on cirque growth patterns. Given the importance of geological structure and preglacial topographic inheritance, cirques are complex landforms for which assumptions of allometric growth may be spurious. It follows that form is not always a reliable guide to process.

A paleomagnetic and paleointensity study on Pleistocene and Pliocene basaltic flows from the Djavakheti Highland (Southern Georgia, Caucasus)

NASA Astrophysics Data System (ADS)

Calvo-Rathert, Manuel; Goguitchaichvili, Avto; Bógalo, María-Felicidad; Vegas-Tubía, Néstor; Carrancho, Ángel; Sologashvili, Jemal

2011-08-01

New paleomagnetic, rock-magnetic and paleointensity results obtained on samples from 23 basaltic lava flows belonging to four different flow sequences (Mashavera, Kvemo Orozmani, Zemo Karabulaki and Diliska) of Pleistocene and Pliocene age from the eastern Djavakheti Highland, in southern Georgia, are presented. Radiometric dating of these sequences yields ages between 1.8 and 2.18 Ma for Mashavera, 2.07 and 2.58 Ma for Zemo-Karabulakhi and 2.12 and 3.27 for Diliska. No radiometric ages are available for the Kvemo Orozmani sequence, which is considered to be coeval to the Mashavera sequence. Rock-magnetic experiments including measurement of thermomagnetic, hysteresis and IRM-acquisition curves suggest low-Ti titanomagnetite as main carrier of remanence, although a lower Curie-temperature component was also observed in several cases. Reversible and non-reversible curves were recorded in thermomagnetic experiments. Paleomagnetic analysis generally indicated the presence of a single component (mainly in the Mashavera sequence), but also two more or less superimposed components in some other cases. In 21 sites a characteristic component could be determined and all except one were characterised by normal-polarity directions. Flows from the Mashavera sequence had a rather steep inclination (73.1°). Nevertheless, a mean paleomagnetic direction of all four sequences is obtained ( D = 8.5°, I = 60.8°, N = 4, α95 = 11.7°, k = 62.7) which agrees with the Plio-Quaternary directions obtained in previous studies in Georgia. The paleomagnetic pole obtained (latitude ϕ = 82.1°, longitude λ = 118.2°, A95 = 8.0°, k = 240.7) agrees with the pole values of both the 0 Ma and the 5 Ma windows of the synthetic Eurasian polar wander path from Besse and Courtillot (2002). In order to analyse the behaviour of secular variation, the scatter of paleosecular variation of virtual geomagnetic poles of both the Mashavera flow and all 18 studied flows of Pleistocene age was calculated. It could be observed that both data-sets seem to fit well the expected scatter at latitude 41°N. Paleointensity experiments were carried out with the Coe modification of the Thellier method. Twenty-five out of 84 samples (30%) provided reliable paleointensity results. These successful results were mainly obtained in the Mashavera sequence. Most flows yielded paleointensity results in the 30-45 μT range, in accordance with expected Pliocene to present day intensities. Two flows, however, located near the top of the Mashavera sequence yield high paleointensity values around 60 μT. Anomalous paleointensity results in the upper-lying Mashavera flows together with the steep inclinations observed in that sequence, could perhaps signal the near onset of the Olduvai-Matuyama reversal.

Spotted hyena and steppe lion predation behaviours on cave bears of Europe - ?Late Quaternary cave bear extinction as result of predator stress

NASA Astrophysics Data System (ADS)

Diedrich, Cajus G.

2010-05-01

Cave bears hibernated in caves all over Eurasia (e.g. Rabeder et al., 2000) including alpine regions using mainly larger caves for this purpose. Late Quaternary spotted hyenas Crocuta crocuta spelaea instead occupied mainly areas close to the cave entrances as their dens (Diedrich and Žák 2006, Diedrich 2010). The largest predator, the steppe lion Panthera leo spelaea was only a sporadic cave dweller (Diedrich 2007b, 2009b). His presence and its remains from caves all over Europe can be recently explained best as result of imported carcasses after killing by their largest antagonists, the Late Quaternary spotted hyenas. In some cases the kill might have happened in the hyena den cave itself during the theft of prey remains by lions (Diedrich 2009a). Another reason of their remains in caves of Europe is the hunting onto the herbivorous cave bears, especially during hibernation times, when megafauna prey was less available in the open environments (Diedrich 2009c). These lion remains from caves of Europe, nearly all of which were from adult animals, provide evidence of active predation by lions onto cave bears even in medium high alpine regions (Diedrich 2009b, in review). Lion skeletons in European cave bear dens were therefore often found amongst originally articulated cave bear skeletons or scattered cave bear remains and even close to their hibernation nests (Diedrich et al. 2009c, in review). Not only lions fed on cave bears documented mainly by the large quantities of chewed, punctured and crushed cave bear long-bones; even damaged skulls reveal that hyenas scavenged primarily on cave bear carcasses which were mainly responsible for the destruction of their carcasses and bones (Diedrich 2005, 2009d). Predation and scavenging on cave bears by the two largest Late Quaternary predators C. c. spelaea and P. l. spelaea explains well the large quantity of fragmented cave bear bones over all European caves in low to medium high mountainous elevations, whereas in high alpine regions the leopard Panthera pardus seem to have used the ecological niche of the absent hyenas (Diedrich 2009d, in review a). At open air sites cave bear scavenging by the largest Late Quaternary predators were proven, too (Diedrich 2006, 2009e). The predation stress caused by the three main and largest Late Quaternary predators seem to have provided cave bears to hibernate often deeply in many European caves, and here especially in larger and longer cave systems (e.g. Diedrich et al 2009, in review, Diedrich and Moldovan 2010) to protect themselves against the largest Quaternary predators. In conflicts with those large felids must have been killed by adult cave bears, which explains why those predator carcasses remained as complete skeletons or as partly disarticulated ones even deep in caves all over Europe which were finally not scavenged by the herbivorous cave bears (Diedrich in review). In such cave bear den caves the amount of lion bones generally take only 1-3% of the total bone amount being highly dominated by cave bear bones (Diedrich 2009c, in review). Lions and hyenas seem to have focussed onto the hunt of cave bears all over Europe, especially with the reduction of the biomass in the open environments at the maximum cold period during around 26.000-24.000 BP (Solutrean). The slow extinction of their largest prey was an important motor of the predation pressure onto cave bears. This might be one reason for the cave bear extinction in the final Late Quaternary (early Late Weichselian, maximum cold period) at least in northern Europe, but it seem to have happened in a combination of climatic change, and also human impact (cf. Diedrich, this volume). References Diedrich, C., 2005. Cracking and nibbling marks as indicators for the Upper Pleistocene spotted hyena as a scavenger of cave bear (Ursus spelaeus Rosenmüller, 1794) carcasses in the Perick Caves den of Northwest Germany. Abhandlungen der Naturhistorischen Gesellschaft Nürnberg, 45, 73-90. Diedrich, C., 2006. Ice age spotted hyenas ?hunting or only scavenging on a cave bear Ursus spelaeus Rosenmüller at the Ice Age spotted hyena freeland den and prey deposit site Bad Wildungen-Biedensteg (Hessia, Germany). Scientific Annals, School of Geology Aristotle University of Thessaloniki (AUTH) special volume, 98, 193-199. Diedrich, C., 2007b. The fairy tale about the "cave lions" Panthera leo spelaea (Goldfuss 1810) of Europe - Late Ice Age spotted hyenas and Ice Age steppe lions in conflict - lion killers and scavengers around Prague (Central Bohemia). Scripta Facultatis Scientiarum Universitatis Masarykianae Geology, 35 (2005), 107-112. Diedrich, C., 2009a. Steppe lion remains imported by Ice Age spotted hyenas into the Late Pleistocene Perick Caves hyena den in Northern Germany. Quaternary Research, 71 (3), 361-374. Diedrich, C., 2009b. Upper Pleistocene Panthera leo spelaea (Goldfuss, 1810) remains from the Bilstein Caves (Sauerland Karst) and contribution to the steppe lion taphonomy, palaeobiology and sexual dimorphism. Annales de Paléontologie, 95, 117-138. Diedrich, C. 2009c. Steppe lion predation - another reason for cave bears to protect during hibernation against carnivores in deepest parts of large cave systems in Europe. Abstractc 15th International Cave Bear Symposium, Spisska Nova Ves Slovakia, 8-9. Diedrich, C., 2009d. Cave bear killers, scavengers between the Scandinavian and Alpine Ice shields - the last hyenas and cave bears in antagonism - and the reason why cave bears hibernated deeply in caves. Stalactite, 58(2), 54-63. Diedrich, C. 2009e. Late Pleistocene Cave bear remains from the open air hyena den Emscher River terrace site Bottrop (NW Germany). - Stalactite, 58 (2): 42-47. Diedrich, C. 2010. The Crocuta crocuta spelaea (GOLDFUSS 1823) population from the Late Pleistocene Rösenbeck Cave den in NW Germany and contribution to the sexual dimorphism and palaeobiogeography of the last hyenas of Europe. - Annales de Paléontologie. Diedrich, C. (in review). Cave bear killers and scavengers from the last European Ice Age. Palaeogeography Palaeoclimatology Palaeoecology. Diedrich, C., Žák, K. 2006. Prey deposits and den sites of the Upper Pleistocene hyena Crocuta crocuta spelaea (Goldfuss, 1823) in horizontal and vertical caves of the Bohemian Karst (Czech Republic). Bulletin of Geosciences, 81 (4), 237-276. Diedrich, C., Robu, M., Dragusin, V., Constantin, S., Moldovan, O., 2009. New Upper Pleistocene steppe lion skeleton finds between the cave bear hibernation plateaus of the Ursilor Cave bear den, Romania. Abstractc 15th International Cave Bear Symposium, Spisska Nova Ves Slovakia, 10. Diedrich, C., Moldovan, O., Constantin, S. 2009. Cave bear tracks, scratch marks, hair traces and hibernation nests in the Ursilor Cave (Transylvania, Romania) - preliminary report from a famous European cave bear den. - Stalactite, 58 (2): 48-52. Diedrich, C., Moldovan, O. 2010. Ichnological and ethological studies in one of Europe's famous bear den in the Ursilor Cave (Carpathians, Romania). - Quarternary International (accepted). Rabeder, G., Nagel, D., Pacher, M., 2000. Der Höhlenbär. Stuttgart: Thorbecke.

Pleistocene reefs of the Egyptian Red Sea: environmental change and community persistence

PubMed Central

2017-01-01

The fossil record of Red Sea fringing reefs provides an opportunity to study the history of coral-reef survival and recovery in the context of extreme environmental change. The Middle Pleistocene, the Late Pleistocene, and modern reefs represent three periods of reef growth separated by glacial low stands during which conditions became difficult for symbiotic reef fauna. Coral diversity and paleoenvironments of eight Middle and Late Pleistocene fossil terraces are described and characterized here. Pleistocene reef zones closely resemble reef zones of the modern Red Sea. All but one species identified from Middle and Late Pleistocene outcrops are also found on modern Red Sea reefs despite the possible extinction of most coral over two-thirds of the Red Sea basin during glacial low stands. Refugia in the Gulf of Aqaba and southern Red Sea may have allowed for the persistence of coral communities across glaciation events. Stability of coral communities across these extreme climate events indicates that even small populations of survivors can repopulate large areas given appropriate water conditions and time. PMID:28674659

Pleistocene reefs of the Egyptian Red Sea: environmental change and community persistence.

PubMed

Casazza, Lorraine R

2017-01-01

The fossil record of Red Sea fringing reefs provides an opportunity to study the history of coral-reef survival and recovery in the context of extreme environmental change. The Middle Pleistocene, the Late Pleistocene, and modern reefs represent three periods of reef growth separated by glacial low stands during which conditions became difficult for symbiotic reef fauna. Coral diversity and paleoenvironments of eight Middle and Late Pleistocene fossil terraces are described and characterized here. Pleistocene reef zones closely resemble reef zones of the modern Red Sea. All but one species identified from Middle and Late Pleistocene outcrops are also found on modern Red Sea reefs despite the possible extinction of most coral over two-thirds of the Red Sea basin during glacial low stands. Refugia in the Gulf of Aqaba and southern Red Sea may have allowed for the persistence of coral communities across glaciation events. Stability of coral communities across these extreme climate events indicates that even small populations of survivors can repopulate large areas given appropriate water conditions and time.

Isochron burial dating of Danube terraces in the course of an interlaboratory comparison on sample preparation in Vienna and Budapest

NASA Astrophysics Data System (ADS)

Neuhuber, Stephanie; Ruszkiczay-Rüdiger, Zsófia; Decker, Kurt; Braucher, Regis; Fiebig, Markus; Braun, Mihály; Häuselmann, Philipp; Aster Team

2016-04-01

The Neogene development of the Vienna Basin's tectonic history is well-documented in seismic sections and hydrocarbon wells. The late Neogene to Quaternary history is less well preserved due to a gap in the sediment record starting from the Late Pannonian due to a large-scale uplift during a phase of basin inversion [1]. Quaternary sediments in the Vienna Basin form prominent Pleistocene terraces north and south of the Danube's recent floodplain. The Danube's course currently shifts to the south where it erodes into its own gravel terraces that were presumably accumulated during the Pliocene and Early to Middle Pleistocene. North of the Danube, a wide alluvial plain has developed with one prominent Middle Quaternary terrace level 17-25 m above the river (Gänserndorf and Schlosshof Terraces). The most recent tectonic events related to the sinistral movement of the Vienna Basin transform fault system are recorded north of the Danube by faulted terrace segments that were identified by paleoseismological trenching in combination with OSL [2]. In contrast, terraces south of the Danube form a staircase with altitudes ranging between 25 and 130 m above todays water level. The terraces in the south have also been strongly dissected by faults [3], each fault block preserved a slightly different succession of terraces. The fault-related vertical displacements south of the Danube have not yet been quantified. To better understand the Quaternary terrace sequence and its displacement in the southern zone, we use the cosmogenic nuclide pair of 26Al and 10Be for isochron burial dating of a Danube terrace at Haslau an der Donau (~40 m above river level). This terrace is locally the lowest of a staircase of a total of 6 different levels. Based on published geomorphological works, the expected age is Middle Pleistocene. The isochron burial dating method is therefore well-suited to date this sedimentary setting due to the presence of large individual clasts that share the same post-depositional history, but have different pre-exposure and transport histories [4]. The sandy gravel of the Haslau terrace was sampled in an active gravel pit. At this location, two major sedimentary units are separated by an erosional hiatus of unknown duration. The upper sequence was sampled at 5.5 m depth and the lower one was sampled at 11.8 m depth. From both depths six quartzite or quartz-bearing cobbles were taken together with a bulk sample from the matrix for isochron burial duration determination. Five samples were split after crushing and sieving and were processed at both the Cosmogenic Nuclide Sample Preparation Laboratory at Vienna and at Budapest (http://www.geochem.hu/kozmogen/Lab_en.html), in order to assess and compare the sample processing preocedures of these recently operating sample preparation laboratories. AMS measurements were performed at the French national facility ASTER (CEREGE (Aix-en-Provence, France). Thanks to OTKA PD83610, NKM-96/2014, NKM-31/2015; OMAA 90öu17; LP2012-27/2012. INSU/CNRS, the ANR through the program "EQUIPEX Investissement d'Avenir", IRD and CEA. [1] Decker et al., 2005. QSR 24, 307-322 [2] Hintersberger et al, 2013, EGU2013-12755 [3] Salcher et al. 2012. Tectonics, 31, TC3004, doi:10.1029/2011TC002979 [4] Balco and Rovey, 2008. AJS 908, 1083-1114 [5] Fuchs and Grill, 1984, Geologische Gebietskarte der Republik Österreich 1:200 000 Wien und Umgebung

Chronology of Terra Firme formation in western Amazonia and implications for the diversification of Amazonian biota

NASA Astrophysics Data System (ADS)

Pupim, Fabiano do N.; Sawakushi, André O.; Hartmann, Gelvam A.; Savian, Jairo F.; Kern, Andrea K.; Mineli, Thays D.; Cruz, Francisco W.; Almeida, Renato P.; Grohmann, Carlos H.; Ribas, Camila C.; d'Horta, Fernando M.; Bertassoli, Dailson J.; Marconato, André; Nogueira, Luciana; Lohmann, Lúcia G.

2017-04-01

The shift from a large wetland dominated by avulsive channels and flooded forests to the incised transcontinental Amazon River valley (Várzea) bounded by non-flooded forests (Terra Firme) is suggested as one of the main drivers of diversification of the mega diverse Amazonian Biota. Nonetheless, there is no consensus about the timing of this landscape shift, with the current literature suggesting a period that ranges from the Miocene (11 Ma) and the Late Pleistocene (100 ka). This uncertainty may be due to a lack of absolute ages for the sediments forming Terra Firme forest substrates in western Amazonian lowlands. In Brazil, the Içá Formation represents the uppermost fluvial deposits of Terra Firme forests substrates in western Amazonia. Therefore, a reliable chronology for the last depositional stage of the Içá Formation is key for an improved understanding of the formation of the current Terra Firme-Várzea system. Four sediment profiles were sampled along the margins of the Solimões and Içá rivers for Optically Stimulated Luminescence (OSL) dating, geomagnetic excursions, and palynological analysis. OSL dating was performed in twelve samples using a Single Aliquot Regeneration (SAR) protocol in quartz sand grains. The equivalent doses ranged from 47 to 130 Gy (Central Age Model) and the dose rate values ranged from 0.4 to 2.0 Gy/ka. The resulting sediment burial ages range from 48 to 112 ka. Paleomagnetic data were obtained from samples collected at same profiles sampled for OSL dating and results suggest the presence of Post-Blake geomagnetic excursion ( 100 ka). The age of 100 ka for Post-Blake excursion are adopted for the Geomagnetic Instability Time Scale. Pollen assemblage data show a similarity to a more modern flora and the presence of Alnus clearly points towards Pleistocene deposition as it is unknown before in South America. The combined OSL, paleomagnetism and pollen data is a robust geochronological dataset that indicates Late Pleistocene ages for the last stage of built up of the Terra Firme in a broad region of the western Brazilian Amazonian lowlands. Therefore, the present-day unconformity between Terra Firme and Várzea deposits were formed by fluvial incision during the late Pleistocene and Holocene, which seems to be related with precipitation changes in the South American monsoon system. Our geochronological dataset point to important landscape changes during the late Pleistocene, with expansion of non-flooded Terra Firme and retraction of Várzea floodplain forests. This transition probably had important implications for the development of modern phylogeographical and biogeographical patterns in western Amazonia during the Quaternary. Future efforts will focus on dating drill-core sediment records using cosmogenic nuclides to extend the age range. Financial support: FAPESP 2009/53988-8, 2012/50260-6, 2014/23334-4, 2014/09800-2, 2016/09293-9; 2016/02656-9; CNPq 3009223/2014-8, 307647/2015-3; NSF DEB 1241066 and NASA.

Anatomy of biocalcarenitic units in the Plio-Pleistocene record of the Northern Apennines (Italy)

NASA Astrophysics Data System (ADS)

Cau, Simone; Roveri, Marco; Taviani, Marco

2017-04-01

The Castell'Arquato Basin (CAB) in the foothills of the thrust-belt Northern Apennines is a foreland basin infilled by Plio-Quaternary sediments and a reference area for Plio-Pleistocene biostratigraphy. The CAB exposes plurimetric biodetrital carbonate units at discrete temporal intervals. Such shell-rich units are at places lithified, turning into conspicuous biodetritral carbonate rocks (biocalcarenites) that display a cyclical stacking motif highlighted by the regular alternation with finer-grained marine deposits. The cyclical nature of thick biocalcarenites has been hypothesized to be orbitally-controlled by obliquity and/or precession cyclicity. Furthermore, biocalcarenite-mudstone couplets form distinct clusters governed by 100-400 ka eccentricity maxima starting from 3.1 Ma at the inception of the Northern Hemisphere glaciation. They correlate with sapropels cycles formed at times of maximum insolation (precession minima). The CAB calcarenites are poorly known with respect to their environmental genetic context what motivated a detailed paleoecological analysis to unravel at best their formative context. Five distinct biofacies arranged in stacking patterns are identified through two-way cluster analysis based on the macrofossil content. Our quantitative and qualitative results suggest that these polytaxic shell concentrations and their bracketing marine mudstones developed in middle shelf settings being sensitive to climatically-driven changes.

Geologic evolution of the Bering Sea Komandorksy deep basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogdanov, N.A.

1986-07-01

The deep-water Komandorsky basin is located in the southwestern part of the Bering Sea. On the east, it is separated from the Aleutian basin by the submerged Shirshov Ridge; on the west, it is bordered by structures of the north Kamchatka accretionary prism. The Komandorsky basin is characterized by strongly dissected relief of it acoustic basement, which is overlain by a 1.5 to 2.0-km thick sedimentary cover. The western part of the basin is occupied by a rift zone, which is characterized by modern seismicity and high heat flow. It is considered to be the axial zone of Miocene-Pleistocene spreading.more » On the north terrace of the Komandorsky island arc, traced active volcanos provide evidence that subduction is occurring under the arc from the north. The spreading rift zone is reflected on the continent in Miocene-Pleistocene volcanic rocks, characterized by typical oceanic tholeiitic composition. The Komandorsky basin formed as a result of spreading during the Maestrichtian. Spreading within the basin occurred during the early and middle Oligocene and the late Miocene. East and west of the spreading axis, accretionary prisms formed. The latter are observed along the western flank of the Shirshov Ridge and on the eastern sides of the Kamchatka Peninsula and Koraginsky Island.« less

Geology of the dry creek site; a stratified early man site in Interior Alaska

USGS Publications Warehouse

Thorson, R.M.; Hamilton, T.D.

1977-01-01

The Dry Creek archeologic site contains a stratified record of late Pleistocene human occupation in central Alaska. Four archeologic components occur within a sequence of multiple loess and sand layers which together form a 2-m cap above weathered glacial outwash. The two oldest components appear to be of late Pleistocene age and occur with the bones of extinct game animals. Geologic mapping, stratigraphic correlations, radiocarbon dating, and sediment analyses indicate that the basal loess units formed part of a widespread blanket that was associated with an arctic steppe environment and with stream aggradation during waning phases of the last major glaciation of the Alaska Range. These basal loess beds contain artifacts for which radiocarbon dates and typologic correlations suggest a time range of perhaps 12,000-9000 yr ago. A long subsequent episode of cultural sterility was associated with waning loess deposition and development of a cryoturbated tundra soil above shallow permafrost. Sand deposition from local source areas predominated during the middle and late Holocene, and buried Subarctic Brown Soils indicate that a forest fringe developed on bluff-edge sand sheets along Dry Creek. The youngest archeologic component, which is associated with the deepest forest soil, indicates intermittent human occupation of the site between about 4700 and 3400 14C yr BP. ?? 1977.

N zooming into the Mediterranean outflow fossil moat during the 1.2-1.8 million years period (Early-Pleistocene) - An approach by radiogenic and stable isotopes

NASA Astrophysics Data System (ADS)

Lebreiro, Susana M.; Antón, Laura; Reguera, M. Isabel; Fernández, Marta; Conde, Estefanía; Barrado, Ana I.; Yllera, Abel

2015-12-01

The fossil Alvarez Cabral erosive Moat contains hemipelagite, contourite and turbidite facies where oceanography changes in the Mediterranean outflow are archived over the 1.2-1.8 Myr time period. Here we used Pb and Sr radiogenic isotopes to trace water masses and sediment source changes, for the first time in twenty glacial-interglacial (G-I) cycles of the Early-Pleistocene interval, and the last Glacial Maximum through Holocene cycle (including the Younger Dryas and Heinrich Stadial-1). A mixing line of Pb isotopes gives reliable low radiogenic 208Pb/204Pb, 206Pb/204Pb, and 206Pb/207Pb typical of Mediterranean Outflow Water (MOW) in one end-member and the signature of high radiogenic isotopes of Atlantic Waters (AW) towards the second end-member. The 87Sr/86Sr isotopes also display two end-members of the mixing line between eolian transport/dust source (0.71) and fluvial transport/weathering source (0.73) previously proposed in the Gulf of Cadiz. Combination of Pb and Sr radiogenic isotopes with O and C stable isotopes of planktonic and benthic foraminifera, and the response of foraminifera benthos over the Early-Pleistocene interval, reveals a direct link between water masses circulation and shifts in G-I. We found a persistent cyclic pattern of MOW circulation and fluvial deposition during glaciations and AW and aeolian influence during interglaciations. On site U1386B/C, the upper-MOW was less ventilated but productive and with high flux of organic flux matter during glacials, while Atlantic Waters were better ventilated, enriched in O, but less productive during interglacials. We infer that shifts in ocean and atmospheric processes in the Gulf of Cadiz were strongly controlled by Earth's obliquity (41 kyr-cycle) and 35°NH insolation during the Early-Pleistocene. We propose a correlation in changes in phase-relationship between precession and obliquity. In general terms, physical properties of fine sediments (glacials) show lower NGR, low reflectance and high magnetic susceptibility. These curves measured in a 20 cm sampling interval, on board ship, present a number of gaps due to non-recovery of sediment. To overcome this problem and obtain a complete lithological record the point-sensor curves of physical properties were correlated with down-hole logs of HSGR (standard total Gamma-ray in gAPI units) (Suppl. Fig. 1) and HROM (high resolution corrected bulk density in g/cm3) (IODP Expedition 339 by the Scientific Party, Logging Summaries).

Genetic variation in the southern pines: evolution, migration, and adaptation following the pleistocene

Treesearch

Ronald Schmidtling

2007-01-01

Climate has certainly changed over time, requiring genetic change or migration of forest tree species. Little is known about the location of the southern pines during the Pleistocene glaciation, which ended around 14,000 years ago. Macrofossils of spruce (Picea spp.) dating from the late Pleistocene, which are typical of climates much cooler than...

Size variation in Middle Pleistocene humans.

PubMed

Arsuaga, J L; Carretero, J M; Lorenzo, C; Gracia, A; Martínez, I; Bermúdez de Castro, J M; Carbonell, E

1997-08-22

It has been suggested that European Middle Pleistocene humans, Neandertals, and prehistoric modern humans had a greater sexual dimorphism than modern humans. Analysis of body size variation and cranial capacity variation in the large sample from the Sima de los Huesos site in Spain showed instead that the sexual dimorphism is comparable in Middle Pleistocene and modern populations.

Plastic and adaptive responses of plant respiration to changes in atmospheric CO(2) concentration.

PubMed

Gonzàlez-Meler, Miquel A; Blanc-Betes, Elena; Flower, Charles E; Ward, Joy K; Gomez-Casanovas, Nuria

2009-12-01

The concentration of atmospheric CO2 has increased from below 200 microl l(-1) during last glacial maximum in the late Pleistocene to near 280 microl l(-1) at the beginning of the Holocene and has continuously increased since the onset of the industrial revolution. Most responses of plants to increasing atmospheric CO2 levels result in increases in photosynthesis, water use efficiency and biomass. Less known is the role that respiration may play during adaptive responses of plants to changes in atmospheric CO2. Although plant respiration does not increase proportionally with CO2-enhanced photosynthesis or growth rates, a reduction in respiratory costs in plants grown at subambient CO2 can aid in maintaining a positive plant C-balance (i.e. enhancing the photosynthesis-to-respiration ratio). The understanding of plant respiration is further complicated by the presence of the alternative pathway that consumes photosynthate without producing chemical energy [adenosine triphosphate (ATP)] as effectively as respiration through the normal cytochrome pathway. Here, we present the respiratory responses of Arabidopsis thaliana plants selected at Pleistocene (200 microl l(-1)), current Holocene (370 microl l(-1)), and elevated (700 microl l(-1)) concentrations of CO2 and grown at current CO2 levels. We found that respiration rates were lower in Pleistocene-adapted plants when compared with Holocene ones, and that a substantial reduction in respiration was because of reduced activity of the alternative pathway. In a survey of the literature, we found that changes in respiration across plant growth forms and CO2 levels can be explained in part by differences in the respiratory energy demand for maintenance of biomass. This trend was substantiated in the Arabidopsis experiment in which Pleistocene-adapted plants exhibited decreases in respiration without concurrent reductions in tissue N content. Interestingly, N-based respiration rates of plants adapted to elevated CO2 also decreased. As a result, ATP yields per unit of N increased in Pleistocene-adapted plants compared with current CO2 adapted ones. Our results suggest that mitochondrial energy coupling and alternative pathway-mediated responses of respiration to changes in atmospheric CO2 may enhance survival of plants at low CO2 levels to help overcome a low carbon balance. Therefore, increases in the basal activity of the alternative pathway are not necessarily associated to metabolic plant stress in all cases.

The role of neurocranial shape in defining the boundaries of an expanded Homo erectus hypodigm.

PubMed

Baab, Karen L

2016-03-01

The main goals of this study were to evaluate the distinctiveness of Homo erectus neurocranial shape relative to other closely related species, and assess the likelihood that particular fossils were correctly attributed to H. erectus given how shape variation related to geography, time and brain size. This was accomplished through analyses of several sets of landmarks designed to maximize the fossil sample, including 24 putative H. erectus fossils. The question of taxonomic differentiation was initially assessed for the type specimen (Trinil II) and morphologically similar Sangiran fossils and subsequently for increasingly inclusive definitions of H. erectus. Results indicated that H. erectus fossils from China, Indonesia, Georgia and East Africa shared a neurocranial shape that was distinct from that of other Plio-Pleistocene Homo taxa, a pattern only partially accounted for by brain size. Early Indonesian H. erectus formed a morphological "bridge" between earlier and later populations assigned to H. erectus from Africa and Asia, respectively. These results were combined with discrete characters to create a more complete species definition for H. erectus. There were two notable exceptions to the general pattern of H. erectus uniqueness. The 0.8-1.0 Ma (millions of years ago) Daka calvaria from Ethiopia consistently grouped with mid-Pleistocene Homo, including Bodo and Kabwe, rather than African or Asian H. erectus. In addition, Daka also exhibited several traits derived for mid-Pleistocene Homo, and its scaling pattern mirrored mid-Pleistocene Homo rather than H. erectus. Daka may have belonged to an "advanced" H. erectus population close to the root of Homo heidelbergensis sensu lato (s.l.), or to an early population of H. heidelbergensis s.l.. The 1.5 Ma KNM-ER 42700 specimen from Kenya exhibited a unique calvarial shape distinct from H. erectus despite the exclusion of problematic landmarks from the frontal bone. These unique aspects of shape were not present in two other subadult fossils, KNM-WT 15000 and D2700. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pleistocene range shifts, refugia and the origin of widespread species in western Palaearctic water beetles.

PubMed

García-Vázquez, David; Bilton, David T; Foster, Garth N; Ribera, I

2017-09-01

Quaternary glacial cycles drove major shifts in both the extent and location of the geographical ranges of many organisms. During glacial maxima, large areas of central and northern Europe were inhospitable to temperate species, and these areas are generally assumed to have been recolonized during interglacials by range expansions from Mediterranean refugia. An alternative is that this recolonization was from non-Mediterranean refugia, in central Europe or western Asia, but data on the origin of widespread central and north European species remain fragmentary, especially for insects. We studied three widely distributed lineages of freshwater beetles (the Platambus maculatus complex, the Hydraena gracilis complex, and the genus Oreodytes), all restricted to running waters and including both narrowly distributed southern endemics and widespread European species, some with distributions spanning the Palearctic. Our main goal was to determine the role of the Pleistocene glaciations in shaping the diversification and current distribution of these lineages. We sequenced four mitochondrial and two nuclear genes in populations drawn from across the ranges of these taxa, and used Bayesian probabilities and Maximum Likelihood to reconstruct their phylogenetic relationships, age and geographical origin. Our results suggest that all extant species in these groups are of Pleistocene origin. In the H. gracilis complex, the widespread European H. gracilis has experienced a rapid, recent range expansion from northern Anatolia, to occupy almost the whole of Europe. However, in the other two groups widespread central and northern European taxa appear to originate from central Asia, rather than the Mediterranean. These widespread species of eastern origin typically have peripherally isolated forms in the southern Mediterranean peninsulas, which may be remnants of earlier expansion-diversification cycles or result from incipient isolation of populations during the most recent Holocene expansion. The accumulation of narrow endemics of such lineages in the Mediterranean may result from successive cycles of range expansion, with subsequent speciation (and local extinction in glaciated areas) through multiple Pleistocene climatic cycles. Copyright © 2017 Elsevier Inc. All rights reserved.

Late Cenozoic surficial deposits and valley evolution of unglaciated northern New Jersey

USGS Publications Warehouse

Stanford, S.D.

1993-01-01

Multiple alluvial, colluvial, and eolian deposits in unglaciated northern New Jersey, and the eroded bedrock surfaces on which they rest, provide evidence of both long-term valley evolution driven by sustained eustatic baselevel lowering and short-term filling and excavation of valleys during glacial and interglacial climate cycles. The long-term changes occur over durations of 106 years, the short-term features evolve over durations of 104 to 105 years. Direct glacial effects, including blockage of valleys by glacial ice and sediment, and valley gradient reversals induced by crustal depression, are relatively sudden changes that account for several major Pleistocene drainage shifts. After deposition of the Beacon Hill fluvial gravel in the Late Miocene, lowering of sea level, perhaps in response to growth of the Antarctic ice sheet, led to almost complete dissection of the gravel. A suite of alluvial, colluvial, and eolian sediments was deposited in the dissected landscape. The fluvial Bridgeton Formation was deposited in the Raritan lowland, in the Amboy-Trenton lowland, and in the Delaware valley. Following southeastward diversion of the main Bridgeton river, perhaps during Late Pliocene or Early Pleistocene glaciation, northeastward drainage was established on the inactive Bridgeton fluvial plain. About 30 to 45 m of entrenchment followed, forming narrow, incised valleys within which Late Pleistocene deposits rest. This entrenchment may have occurred in response to lowered sea level caused by growth of ice sheets in the northern hemisphere. Under periglacial conditions in the Middle and Late Pleistocene, valleys were partially filled with alluvium and colluvium. During interglacials slopes were stabilized by vegetation and the alluvial and colluvial valley-fill was excavated by gullying, bank erosion, and spring sapping. During Illinoian and late Wisconsinan glaciation, the lower Raritan River was diverted when glacial deposits blocked its valley, and the Delaware River was partially diverted down the isostatically-steepened lower Millstone valley. ?? 1993.

The Middle Pleistocene archaeological record of Greece and the role of the Aegean in hominin dispersals: new data and interpretations

NASA Astrophysics Data System (ADS)

Tourloukis, Vangelis; Karkanas, Panagiotis

2012-06-01

In the debate about hominin dispersals, Greece is expected to have been among the core areas for the peopling of Eurasia, serving as a 'refugium' and source region for (re)colonizations. Yet, its early Pleistocene record is still scarce, forming a conspicuous 'gap' in the early human geography of the Mediterranean. Here we investigate this gap and provide for the first time a synthesis of the Lower Palaeolithic record of Greece. Our study adopts a geoarchaeological approach to explain the current status of the record and argues that the 'absence of evidence' should be understood as the result of the biasing effects of erosional geomorphic processes and not as an indication of a former absence of hominins. In this line, the potential for archaeological preservation and recovery is assessed as a function of landscape dynamics. Climatic seasonality, tectonic activity, high relief and marine inundations have altogether contributed to significant reworking and/or total loss of archaeological sites: in spatial terms, only about 2-5% of the Lower Palaeolithic record of Greece may have survived up to the present. On the other hand, we interpret recent geological data, which show that half of the Aegean Sea would have been subaerially exposed for most of the early Pleistocene. Our results emphasize the potentially central role of the Aegean region in hominin dispersals, both as a biogeographical landbridge and as a highly productive landscape for occupation. This conclusion opens up new prospects for future fieldwork in an area that was hitherto essentially neglected. Finally, in showing how geomorphic processes bias site distribution patterns, the results and methodological perspective developed here can be seen as having implications that are wider than the geographical limits of the Greek Peninsula: they are pertinent to the investigation and interpretation of the early Pleistocene archaeological records in the highly dynamic landscapes of southern Europe - if not in even broader scales.

External auditory exostoses and hearing loss in the Shanidar 1 Neandertal

PubMed Central

2017-01-01

The Late Pleistocene Shanidar 1 older adult male Neandertal is known for the crushing fracture of his left orbit with a probable reduction in vision, the loss of his right forearm and hand, and evidence of an abnormal gait, as well as probable diffuse idiopathic skeletal hyperostosis. He also exhibits advanced external auditory exostoses in his left auditory meatus and larger ones with complete bridging across the porus in the right meatus (both Grade 3). These growths indicate at least unilateral conductive hearing (CHL) loss, a serious sensory deprivation for a Pleistocene hunter-gatherer. This condition joins the meatal atresia of the Middle Pleistocene Atapuerca-SH Cr.4 in providing evidence of survival with conductive hearing loss (and hence serious sensory deprivation) among these Pleistocene humans. The presence of CHL in these fossils thereby reinforces the paleobiological and archeological evidence for supporting social matrices among these Pleistocene foraging peoples. PMID:29053746

Magmatic inclusions in rhyolites, contaminated basalts, and compositional zonation beneath the Coso volcanic field, California

USGS Publications Warehouse

Bacon, C.R.; Metz, J.

1984-01-01

Basaltic lava flows and high-silica rhyolite domes form the Pleistocene part of the Coso volcanic field in southeastern California. The distribution of vents maps the areal zonation inferred for the upper parts of the Coso magmatic system. Subalkalic basalts (<50% SiO2) were erupted well away from the rhyolite field at any given time. Compositional variation among these basalts can be ascribed to crystal fractionation. Erupted volumes of these basalts decrease with increasing differentiation. Mafic lavas containing up to 58% SiO2, erupted adjacent to the rhyolite field, formed by mixing of basaltic and silicic magma. Basaltic magma interacted with crustal rocks to form other SiO2-rich mafic lavas erupted near the Sierra Nevada fault zone. Several rhyolite domes in the Coso volcanic field contain sparse andesitic inclusions (55-61% SiO2). Pillow-like forms, intricate commingling and local diffusive mixing of andesite and rhyolite at contacts, concentric vesicle distribution, and crystal morphologies indicative of undercooling show that inclusions were incorporated in their rhyolitic hosts as blobs of magma. Inclusions were probably dispersed throughout small volumes of rhyolitic magma by convective (mechanical) mixing. Inclusion magma was formed by mixing (hybridization) at the interface between basaltic and rhyolitic magmas that coexisted in vertically zoned igneous systems. Relict phenocrysts and the bulk compositions of inclusions suggest that silicic endmembers were less differentiated than erupted high-silica rhyolite. Changes in inferred endmembers of magma mixtures with time suggest that the steepness of chemical gradients near the silicic/mafic interface in the zoned reservoir may have decreased as the system matured, although a high-silica rhyolitic cap persisted. The Coso example is an extreme case of large thermal and compositional contrast between inclusion and host magmas; lesser differences between intermediate composition magmas and inclusions lead to undercooling phenomena that suggest smaller ??T. Vertical compositional zonation in magma chambers has been documented through study of products of voluminous pyroclastic eruptions. Magmatic inclusions in volcanic rocks provide evidence for compositional zonation and mixing processes in igneous systems when only lava is erupted. ?? 1984 Springer-Verlag.

Geology, geohydrology, and soils of NASA, Kennedy Space Center: A review

NASA Technical Reports Server (NTRS)

Schmalzer, Paul A.; Hinkle, C. Ross

1990-01-01

Sediments underlying Kennedy Space Center (KSC) have accumulated in alternating periods of deposition and erosion since the Eocene. Surface sediments are of Pleistocene and Recent ages. Fluctuating sea levels with the alternating glacial-interglacial cycles have shaped the formation of the barrier island. Merritt Island is an older landscape whose formation may have begun as much as 240,000 years ago, although most of the surface sediments are not that old. Cape Canaveral probably dates from less than 7,000 years B.P. (before present) as does the barrier strip separating Mosquito Lagoon from the Atlantic Ocean. Merritt Island and Cape Canaveral have been shaped by progradational processes but not continuously so, while the Mosquito Lagoon barrier has been migrating landward. Deep acquifers beneath KSC are recharged inland but are highly mineralized in the coastal region and interact little with surface vegetation. The Surficial acquifer has formed in the Pleistocene and Recent deposits and is recharged by local rainfall. Sand ridges in the center of Merritt Island are important to its recharge.

Late Cenozoic regional collapse due to evaporite flow and Dissolution in the Carbondale Collapse Center, West-Central Colorado

USGS Publications Warehouse

Kirkham, R.M.; Streufert, R.K.; Budahn, J.R.; Kunk, Michael J.; Perry, W.J.

2001-01-01

Dissolution and flow of Pennsylvanian evaporitic rocks in west-central Colorado created the Carbondale Collapse Center, a 450 mi2 structural depression with about 4,000 ft of vertical collapse during the late Cenozoic. This paper describes evidence of collapse in the lower Roaring Fork River valley. Both the lateral extent and amount of vertical collapse is constrained by deformed upper Cenozoic volcanic rocks that have been correlated using field mapping, 40Ar/39Ar geochronology, geochemistry, and paleomagnetism. The Carbondale Collapse Center is one of at least two contiguous areas that have experienced major evaporite tectonism during the late Cenozoic. Historic sinkholes, deformed Holocene deposits, and modern high-salinity loads in the rivers and thermal springs indicate the collapse process continues today. Flow of evaporitic rocks is an important element in the collapse process, and during initial stages of collapse it was probably the primary causative mechanism. Dissolution, however, is the ultimate means by which evaporite is removed from the collapse area. As the Roaring Fork River began to rapidly down-cut through a broad volcanic plateau during the late Miocene, the underlying evaporite beds were subjected to differential overburden pressures. The evaporitic rocks flowed from beneath the upland areas where overburden pressures remained high, toward the Roaring Fork River Valley where the pressures were much lower. Along the valley the evaporitic rocks rose upward, sometimes as diapirs, forming or enhancing a valley anticline in bedrock and locally upwarping Pleistocene terraces. Wherever the evaporites encountered relatively fresh ground water, they were dissolved, forming underground voids into which overlying bedrock and surficial deposits subsided. The saline ground water eventually discharged to streams and rivers through thermal springs and by seepage into alluvial aquifers.

Flowing Dunes of Shangri-La

NASA Image and Video Library

2016-09-07

The Shangri-La Sand Sea on Titan is shown in this image from the Synthetic Aperture radar (SAR) on NASA's Cassini spacecraft. Hundreds of sand dunes are visible as dark lines snaking across the surface. These dunes display patterns of undulation and divergence around elevated mountains (which appear bright to the radar), thereby showing the direction of wind and sand transport on the surface. Sands being carried from left to right (west to east) cannot surmount the tallest obstacles; instead, they are directed through chutes and canyons between the tall features, evident in thin, blade-like, isolated dunes between bright some features. Once sands have passed around the obstacles, they resume their downwind course, at first collecting into small, patchy dunes and then organizing into larger, more pervasive linear forms, before being halted once again by obstacles. These patterns reveal the effects not only of wind -- perhaps even modern winds if the dunes are actively moving today -- but also the effects of underlying bedrock and surrounding topography. Dunes across the solar system aid in our understanding of underlying topography, winds and climate, past and present. Similar patterns can be seen in dunes of the Great Sandy Desert in Australia, where dunes undulate broadly across the uneven terrain and are halted at the margins of sand-trapping lakes. The dune orientations correlate generally with the direction of current trade winds, and reveal that winds must have been similar back when the dunes formed, during the Pleistocene glacial and interglacial periods. An annotated version of this radar image is also available.at the Photojournal. North on Titan is up in the image. Radar illuminates the scene from upper right at a 27-degree incidence angle. http://photojournal.jpl.nasa.gov/catalog/PIA20710

Ages of Quaternary Rio Grande terrace-fill deposits, Albuquerque area, New Mexico

USGS Publications Warehouse

,; Mahan, Shannon; Stone, Byron D.; Shroba, Ralph R.

2007-01-01

Results from luminescence dating on 13 samples from the Albuquerque area show that major-drainage fluvial deposits represent significant periods of aggradation that formed paired, correlatable terraces on the east and west margins of the Rio Grande valley . The youngest terrace fills (Primero Alto) formed during late Pleistocene as a result of streamflow variations with climate cooling during Marine Oxygen-Isotope Stage 3; our ages suggest aggradation of the upper part of the fill occurred at about 47–40 ka . Deposits of the second (Segundo Alto) terraces reached maximum height during climate cooling in the early part of Marine Oxygen-Isotope Stage 5 as late as 90–98 ka (based on dated basalt flows) . Our luminescence ages show considerable scatter and tend to be younger (range from 63 ka to 162 ka) . The third (Tercero Alto) and fourth (Cuarto Alto) terraces are dated on the basis of included volcanic tephra. Tercero Alto terrace-fill deposits contain the Lava Creek B tephra (639 ka), and Cuarto Alto terrace-fill deposits contain tephra of the younger Bandelier Tuff eruption (1 .22 Ma), the Cerro Toledo Rhyolite (1 .47 Ma), and the older Bandelier Tuff eruption (1 .61 Ma). These periods of aggradation culminated in fluvial terraces that are preserved at maximum heights of 360 ft (Cuarto Alto), 300 ft. (Tercero Alto), 140 ft (Segundo Alto), and 60 ft. (Primero Alto) above the modern floodplain. Despite lithologic differences related to local source-area contributions, these terracefill deposits can be correlated across the Rio Grande and up- and down-valley for tens of miles based on maximum height of the terrace above the modern floodplain.

Volcanic history and 40Ar/39Ar and 14C geochronology of Terceira Island, Azores, Portugal

USGS Publications Warehouse

Calvert, Andrew T.; Moore, Richard B.; McGeehin, John P.; Rodrigues da Silva, Antonio

2006-01-01

Seven new 40Ar/39Ar and 23 new radiocarbon ages of eruptive units, in support of new geologic mapping, improve the known chronology of Middle to Late Pleistocene and Holocene volcanic activity on the island of Terceira, Azores and define an east-to-west progression in stratovolcano growth. The argon ages indicate that Cinco Picos Volcano, the oldest on Terceira, completed its main subaerial cone building activity by about 370–380 ka. Collapse of the upper part of the stratovolcanic edifice to form a 7 × 9 km caldera occurred some time after 370 ka. Postcaldera eruptions of basalt from cinder cones on and near the caldera floor and trachytic pyroclastic flow and pumice fall deposits from younger volcanoes west of Cinco Picos have refilled much of the caldera. The southern portion of Guilherme Moniz Volcano, in the central part of the island, began erupting prior to 270 ka and produced trachyte domes, flows, and minor pyroclastic deposits until at least 111 ka. The northern part of Guilherme Moniz Caldera is less well exposed than the southern part, but reflects a similar age range. The northwest portion of the caldera was formed sometime after 44 ka. Several well-studied ignimbrites that blanket much of the island likely erupted from Guilherme Moniz Volcano. The Pico Alto Volcanic Center, a tightly spaced cluster of trachyte domes and short flows, is a younger part of Guilherme Moniz Volcano. Stratigraphic studies and our new radiocarbon ages suggest that most of the Pico Alto eruptions occurred during the period from about 9000 to 1000 years BP. Santa Barbara Volcano is the youngest stratovolcano on Terceira, began erupting prior to 29 ka, and has been active historically.

Paleo-Environment and C-14 Dating: The Key to the Depositional Age of the Tha Chang and Related Sand Pits, Northeastern Thailand

NASA Technical Reports Server (NTRS)

Putthapiban, P.; Zolensky, M.; Jull, T.; Demartino, M.; Salyapongse, S.

2012-01-01

Tha Chang sand pits, Nakhon Ratchasima Province and many other sand pits in the area adjacent to the Mun River are characterized by their fluviatile environment in association with mass wasting deposits, along the paleo-river channel and the flood plain of the Mun River. Sediments of these deposits are characterized by clasts of various rock types especially the resistant ones with frequent big tree trunks, logs and wood fragments in different sizes and various stages of transformation from moldering stage to lignification and petrification. Widespread pyritization of the lower horizon suggests strongly reducing environment during burial. The Tha Chang deposits have been received much attention from geoscientists especially paleontologist communities, as they contain fragments of some distinct vertebrate species such as Stegadon sp., hominoid primate, rhinoceros Aceratherium and others. Based on the associated mammal fauna and hominoid fossils, the late Miocene ( 9 - 6 Ma) was given for the time of deposition of this sand and gravel unit. Some other reports believed that sediments and materials of these sand and gravel quarries (pits) were deposited by high-energy flood pulses contemporaneous with the tektites forming event during mid-Pleistocene at c. 0.8 Ma. Interpretation from Palynostratigraphical study suggested that the lower horizon of Tha Chang sand pit was deposited during Pliocene/Pleistocene period and the upper horizons are Pleistoncene/Holocene. It is crystal clear that all the fluviatile sediments including tektites and almost all fossil fragments being deposited in these sand pits were, likely a multiple times reworked materials. Only some old bamboo trees, some old crowling trees and fossils grasses observed on the old river bank are considered in situ. C-14 dating of 5 old wood specimens from Tha Chang Sand Pits, 15 old wood specimens from Chumpuang Sand Pits and one sample of old pottery from a Chumpuang Sand Pit were carried out in the NSF- Arizona AMS Laboratory. Although, there is no sharp boundary between the unconsolidated sedimentary horizons in the pits, C-14 ages obtained from the Tha Chang vary from 34,340 BP at the middle horizon (approx 10 m below ground zero) to >49,900 BP at the lower horizon with unknown basal formation (highly pyritized zone approx 20 - 25 m below ground zero). The ages for the Chumpuang vary from 41,700 BP, >45,900 BP and >49,900 BP from the upper most to the lower most of a broad horizon (approx 8 m to approx 12 m below ground zero). The C-14 age of the pottery collected from layer approximately 5 m below ground zero is 2,514 BP. The nature of fluviatile together with occasional mass wasting characteristics of all sand pits studies suggest the relatively faster depositional rate of the lower horizon which involved more flooding and mass wasting deposits than those of the upper horizons. The apparent of some mixing of the wood ages may indicate reworking and lag deposits nature of the area. The depositional rate of the upper most sand and soil horizon (5 m thick) is approximately 1 m per 500 years which mean both erosion and deposition had played a significant role during that time period. In term of the true age of the formation, we argue that since most of the materials deposited are reworked materials, all ages obtained from fossil fragments could not be the age of sand and gravel formation. Furthermore, the maximum age of all the tektite bearing horizons cannot be older than 0.8 Ma. The oldest C-14 age of 49,900 BP is interpreted as the minimum age of the Tha Chang and related sand pits formation when geomorphology of the area was a lot more hilly and much higher gradient than that of the present day.

A regional assessment of potential environmental hazards to and limitations on petroleum development of the Southeastern United States Atlantic continental shelf, slope, and rise, offshore North Carolina

USGS Publications Warehouse

Popenoe, Peter; Coward, E.L.; Cashman, K.V.

1982-01-01

More than 11,000 km of high-resolution seismic-reflection data, 325 km of mid-range sidescan-sonar data, and 500 km of long-range sidescan-sonar data were examined and used to construct an environmental geology map of the Continental Shelf, Slope, and Rise for the area of the U.S. Atlantic margin between lats. 32?N. and 37?N. Hardgrounds and two faults described in previous literature also are shown on the map. On the Continental Shelf, at least two faults, the Helena Banks fault and the White Oak lineament, appear to be tectonic in origin. However, a lack of historical seismicity associated with these faults indicates that they are probably not active at the present time. Hardgrounds are widely scattered but are most abundant in Onslow Bay. Although paleostream channels are common nearshore, they do not appear to be common on the central and outer shelf except off Albemarle Sound where extensive Pleistocene, Pliocene, and late Miocene channels extend across the shelf. Mobile bottom sediments are confined mainly to the shoals off Cape Romain, Cape Fear, Cape Lookout, and Cape Hatteras. Elsewhere the sand cover is thin, and older more indurated rocks are present in subcrop. No slope-instability features were noted on the Florida-Hatteras slope off North Carolina. The lack of features indicates that this slope is relatively stable. Evidence for scour by strong currents is ubiquitous on the northern Blake Plateau although deep-water reefs are sparse. The outer edge of the plateau is dominated by a major growth fault and numerous splay and antithetic faults. These faults are the product of salt tectonism in the Carolina trough and thus are not associated with seismicity. Displacements observed near the sea floor and breached diapirs offshore indicate that the main fault is still moving. Associated with the faults are collapse features that are interpreted to be caused by karst solution and cavernous porosity in Eocene and Oligocene limestones at depth. Major slumps have taken place in two large areas of the Continental Slope. Seismic-reflection profiles of the southern area, centered on the lower slope at 1at. 33?N., long. 76?W., show a 80-m-hlgh scarp in which bedding has been truncated. Rotational slump faults are present in this area on the middle and upper slope. Sidescan images show that large blocks have slid downslope from the scarp face, furrowing the bottom. High-resolution (3.5-kHz) records show that the rotational slump faults upslope are active. The association of these slumps and the scarps with salt diapirs suggests subsidence accompanying salt tectonism as the cause. Seismic-reflection records over the northern area, at about fat. 36?20'N., long. 74?40'W., show two steep scarps, each about 225 m high on the upper and middle-slope. These slump scars and an absence of Pleistocene sediments indicate that large blocks of the slope have been removed by slumping. The slope north of fat. 35?N. is highly dissected by canyons. Mid-range sidescan-sonar records suggest that the canyons are the product of mass wasting and have probably formed largely by slumping. Sediments in a wide zone on the upper rise are highly disturbed and faulted owing to salt tectonism. Twenty-six salt diapirs are mapped, as is a zone of disturbed bottom related to salt tectonism. An area of frozen bottom (clathrate) under which shallow free gas is trapped underlies the outer Blake Plateau, the slope, and the upper rise. Although the hazards of drilling into or through clathrates have not been tested, the release of gas from beneath this frozen layer may prove to be a primary hazard to exploration.

Serial population extinctions in a small mammal indicate Late Pleistocene ecosystem instability

PubMed Central

Brace, Selina; Palkopoulou, Eleftheria; Dalén, Love; Lister, Adrian M.; Miller, Rebecca; Otte, Marcel; Germonpré, Mietje; Blockley, Simon P. E.; Stewart, John R.; Barnes, Ian

2012-01-01

The Late Pleistocene global extinction of many terrestrial mammal species has been a subject of intensive scientific study for over a century, yet the relative contributions of environmental changes and the global expansion of humans remain unresolved. A defining component of these extinctions is a bias toward large species, with the majority of small-mammal taxa apparently surviving into the present. Here, we investigate the population-level history of a key tundra-specialist small mammal, the collared lemming (Dicrostonyx torquatus), to explore whether events during the Late Pleistocene had a discernible effect beyond the large mammal fauna. Using ancient DNA techniques to sample across three sites in North-West Europe, we observe a dramatic reduction in genetic diversity in this species over the last 50,000 y. We further identify a series of extinction-recolonization events, indicating a previously unrecognized instability in Late Pleistocene small-mammal populations, which we link with climatic fluctuations. Our results reveal climate-associated, repeated regional extinctions in a keystone prey species across the Late Pleistocene, a pattern likely to have had an impact on the wider steppe-tundra community, and one that is concordant with environmental change as a major force in structuring Late Pleistocene biodiversity. PMID:23185018

Effects of Pleistocene environmental changes on the distribution and community structure of the mammalian fauna of Mexico

NASA Astrophysics Data System (ADS)

Ceballos, Gerardo; Arroyo-Cabrales, Joaquín; Ponce, Eduardo

2010-05-01

Biological communities in Mexico experienced profound changes in species composition and structure as a consequence of the environmental fluctuations during the Pleistocene. Based on the recent and fossil Mexican mammal checklists, we determine the distribution, composition, diversity, and community structure of late Pleistocene mammalian faunas, and analyze extinction patterns and response of individual species to environmental changes. We conclude that (1) differential extinctions occurred at family, genus, and species level, with a major impact on species heavier than 100 kg, including the extinction all proboscideans and several ruminants; (2) Pleistocene mammal communities in Mexico were more diverse than recent ones; and (3) the current assemblages of species are relatively young. Furthermore, Pleistocene relicts support the presence of biogeographic corridors; important refugia existed as well as centers of speciation in isolated regions. We identified seven corridors: eastern USA-Sierra Madre Oriental corridor, Rocky Mountains-Sierra Madre Occidental corridor, Central United States-Northern Mexico corridor, Transvolcanic Belt-Sierra Madre del Sur corridor, western USA-Baja California corridor, Tamaulipas-Central America gulf lowlands corridor, and Sonora-Central America Pacific lowlands corridor. Our study suggests that present mammalian assemblages are very different than the ones in the late Pleistocene.

The paleohydrology of unsaturated and saturated zones at Yucca Mountain, Nevada, and vicinity

USGS Publications Warehouse

Paces, James B.; Whelan, Joseph F.; Stuckless, John S.

2012-01-01

Surface, unsaturated-zone, and saturated-zone hydrologic conditions at Yucca Mountain responded to past climate variations and are at least partly preserved by sediment, fossil, and mineral records. Characterizing past hydrologic conditions in surface and subsurface environments helps to constrain hydrologic responses expected under future climate conditions and improve predictions of repository performance. Furthermore, these records provide a better understanding of hydrologic processes that operate at time scales not readily measured by other means. Pleistocene climates in southern Nevada were predominantly wetter and colder than the current interglacial period. Cyclic episodes of aggradation and incision in Fortymile Wash, which drains the eastern slope of Yucca Mountain, are closely linked to Pleistocene climate cycles. Formation of pedogenic cement is favored under wetter Pleistocene climates, consistent with increased soil moisture and vegetation, higher chemical solubility, and greater evapotranspiration relative to Holocene soil conditions. The distribution and geochemistry of secondary minerals in subsurface fractures and cavities reflect unsaturated-zone hydrologic conditions and the response of the hydrogeologic system to changes in temperature and percolation flux over the last 12.8 m.y. Physical and fluid-inclusion evidence indicates that secondary calcite and opal formed in air-filled cavities from fluids percolating downward through connected fracture pathways in the unsaturated zone. Oxygen, strontium, and carbon isotope data from calcite are consistent with a descending meteoric water source but also indicate that water compositions and temperatures evolved through time. Geochronological data indicate that secondary mineral growth rates are less than 1–5 mm/m.y., and have remained approximately uniform over the last 10 m.y. or longer. These data are interpreted as evidence for hydrological stability despite large differences in surface moisture caused by climate shifts between the Miocene and Pleistocene and between Pleistocene glacial-interglacial cycles. Secondary mineral distribution and δ18O profiles indicate that evaporation in the shallower welded tuffs reduces infiltration fluxes. Several near-surface and subsurface processes likely are responsible for diverting or dampening infiltration and percolation, resulting in buffering of percolation fluxes to the deeper unsaturated zone. Cooler and wetter Pleistocene climates resulted in increased recharge in upland areas and higher water tables at Yucca Mountain and throughout the region. Discharge deposits in the Amargosa Desert were active during glacial periods, but only in areas where the modern water table is within 7–30 m of the surface. Published groundwater models simulate water-table rises beneath Yucca Mountain of as much as 150 m during glacial climates. However, most evidence from Fortymile Canyon up gradient from Yucca Mountain limits water-table rises to 30 m or less, which is consistent with evidence from discharge sites in the Amargosa Desert. The isotopic compositions of uranium in tuffs spanning the water table in two Yucca Mountain boreholes indicate that Pleistocene water-table rises likely were restricted to 25–50 m above modern positions and are in approximate agreement with water-table rises estimated from zeolitic-to-vitric transitions in the Yucca Mountain tuffs (less than 60 m in the last 11.6 m.y.).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lighty, R.G.; Russell, K.L.

Transect mapping and petrologic studies reveal a new depositional model and limited diagenesis of a well-exposed Pleistocene reef outcrop at Ambergris Cay, northern Belize. This emergent shelf-edge reef forms a rocky wave-washed headland at the northern terminus of the present-day 250 km long flourishing Belize Barrier Reef. Previously, the Belize reef outcrop was thought to extend southward in the subsurface beneath the modern barrier reef as a Pleistocene equivalent. The authors study indicate that this outcrop is a large, coral patch reef and not part of a barrier reef trend. Sixteen transects 12.5 m apart described in continuous cm incrementsmore » from fore reef to back reef identified: extensive deposits of broken Acropora cervicornis; small thickets of A. palmata with small, oriented branches; and muddy skeletal sediments with few corals or reef rubble. Thin section and SEM studies show three phases of early submarine cementation: syntaxial and rosette aragonite; Mg-calcite rim cement and peloids; and colloidal Mg-calcite geopetal fill. Subaerial exposure in semi-arid northern Belize caused only minor skeletal dissolution, some precipitation of vadose whisker calcite, and no meteoric phreatic diagenesis. Facies geometry, coral assemblages, lack of rubble deposits, coralline algal encrustations and Millepora framework, and recognition of common but discrete submarine cements, all indicate that this Pleistocene reef was an isolated, coral-fringed sediment buildup similar to may large patch reefs existing today in moderate-energy shelf environments behind the modern barrier reef in central and southern Belize.« less

The carnivore remains from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain).

PubMed

García, N; Arsuaga, J L; Torres, T

1997-01-01

Remains of carnivores from the Sima de los Huesos site representing at least 158 adult individuals of a primitive (i.e., not very speleoid) form of Ursus deningeri Von Reichenau 1906, have been recovered through the 1995 field season. These new finds extend our knowledge of this group in the Sierra de Atapuerca Middle Pleistocene. Material previously classified as Cuoninae indet, is now assigned to Canis lupus and a third metatarsal assigned in 1987 to Panthera of gombaszoegensis, is in our opinion only attributable to Panthera sp. The family Mustelidae is added to the faunal list and includes Martes sp. and a smaller species. The presence of Panthera leo cf. fossilis, Lynx pardina spelaea and Felis silvestris, is confirmed. The presence of a not very speloid Ursus deningeri, together with the rest of the carnivore assemblage, points to a not very late Middle Pleistocene age, i.e., oxygen isotope stage 7 or older. Relative frequencies of skeletal elements for the bear and fox samples are without major biases. The age structure of the bear sample, based on dental wear stages, does not follow the typical hibernation mortality profile and resembles a catastrophic profile. The site was not a natal or refuge den. The hypothesis that the site was a natural trap is the most plausible. If the Sima de los Huesos functioned as a natural trap (without an egress out), the human accumulation cannot be attributed to carnivore: activities and must be explained differently.

Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California

USGS Publications Warehouse

Lundstrom, Scott C.; Mahan, Shannon; Blakely, Richard J.; Paces, James B.; Young, Owen D.; Workman, Jeremiah B.; Dixon, Gary L.

2003-01-01

The Mound Spring quadrangle, the southwestern-most 7.5' quadrangle of the area of the Las Vegas 1:100,000-scale quadrangle, is entirely within the Pahrump Valley, spanning the Nevada/California State line. New geologic mapping of the predominantly Quaternary materials is combined with new studies of gravity and geochronology in this quadrangle. Eleven predominantly fine-grained units are delineated, including playa sediment, dune sand, and deposits associated with several cycles of past groundwater discharge and distal fan sedimentation. These units are intercalated with 5 predominantly coarse-grained alluvial-fan and wash gravel units mainly derived from the Spring Mountains. The gravel units are distinguished on the basis of soil development and associated surficial characteristics. Thermoluminescence and U-series geochronology constrain most of the units to the Holocene and late and middle Pleistocene. Deposits of late Pleistocene groundwater discharge in the northeast part of the quadrangle are associated with a down-to-the-southwest fault zone that is expressed by surface fault scarps and a steep gravity gradient. The gravity field also defines a northwest-trending uplift along the State line, in which the oldest sediments are poorly exposed. About 2 km to the northeast a prominent southwest-facing erosional escarpment is formed by resistant beds in middle Pleistocene fine-grained sediments that dip northeast away from the uplift. These sediments include cycles of groundwater discharge that were probably caused by upwelling of southwesterly groundwater flow that encountered the horst.

Soil development on a Pleistocene terrace sequence, Boise Valley, Idaho

USGS Publications Warehouse

Othberg, K.L.; McDaniel, P.A.; Fosberg, M.A.

1997-01-01

Study of a sequence of terraces in the western Snake River Plain of Idaho reveals a record of at least seven terraces, the ages of which span the Pleistocene. In the Boise Valley, the youngest terraces are less than -14,500 yr and the oldest terraces are -1.7 Ma. Within this sequence, several relationships exist between soil morphology and terrace chronology. On terraces older than -14,500 yr, argillic horizon development generally increases with terrace age with maximum development occurring in soils of the oldest terraces. CaCO3- and SiO2-cemented duripans are found in soils on terraces that are late middle Pleistocene and older. By virtue of their physical and chemical properties, duripans are very resistant to erosion, and therefore provide stable records of CaCO3 and SiO2 accumulation throughout multiple cycles of loess deposition onto the terrace treads, pedogenesis, and partial erosion. Mean duripan thickness increases with age to a maximum of 0.66 m on the oldest terraces. Our results suggest that a geomorphic surface age of approximately 130,000 yr is required to form the initial plugged horizon that is characteristic of a duripan. CaCO3 and SiO2 accumulation is most rapid in duripans occupying geomorphic surfaces with ages ranging from 130,000 to 300,000 yr. After this, apparent accumulation rates decrease and little additional accumulation of these cementing agents occurs with time.

The impact of large terrestrial carnivores on Pleistocene ecosystems

PubMed Central

Van Valkenburgh, Blaire; Ripple, William J.; Meloro, Carlo; Roth, V. Louise

2016-01-01

Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes. PMID:26504224

Middle and Late Pleistocene glaciations in the southwestern Pamir and their effects on topography [Topography of the SW Pamir shaped by middle-late Pleistocene glaciation

DOE PAGES

Stübner, Konstanze; Grin, Elena; Hidy, Alan J.; ...

2017-03-27

Glacial chronologies provide insight into the evolution of paleo-landscapes, paleoclimate, topography, and the erosion processes that shape mountain ranges. In the Pamir of Central Asia, glacial morphologies and deposits indicate extensive past glaciations, whose timing and extent remain poorly constrained. Geomorphic data and 15 new 10Be exposure ages from moraine boulders and roches moutonnées in the southwestern Pamir document multiple Pleistocene glacial stages. The oldest exposure ages, View the MathML source113 ± 10ka, underestimate the age of the earliest preserved glacial advance and imply that the modern relief of the southwestern Pamir (peaks at ~5000–6000 m a.s.l.; valleys at ~2000–3000more » m a.s.l.) already existed in the late Middle Pleistocene. Younger exposure ages (~40–80 ka, ~30 ka) complement the existing Central Asian glacial chronology and reflect successively less extensive Late Pleistocene glaciations. The topography of the Pamir and the glacial chronologies suggest that, in the Middle Pleistocene, an ice cap or ice field occupied the eastern Pamir high-altitude plateau, whereas westward flowing valley glaciers incised the southwestern Pamir. Since the Late Pleistocene deglaciation, the rivers of the southwestern Pamir adjusted to the glacially shaped landscape. As a result, localized rapid fluvial incision and drainage network reorganization reflect the transient nature of the deglaciated landscape.« less

Middle and Late Pleistocene glaciations in the southwestern Pamir and their effects on topography [Topography of the SW Pamir shaped by middle-late Pleistocene glaciation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stübner, Konstanze; Grin, Elena; Hidy, Alan J.

Glacial chronologies provide insight into the evolution of paleo-landscapes, paleoclimate, topography, and the erosion processes that shape mountain ranges. In the Pamir of Central Asia, glacial morphologies and deposits indicate extensive past glaciations, whose timing and extent remain poorly constrained. Geomorphic data and 15 new 10Be exposure ages from moraine boulders and roches moutonnées in the southwestern Pamir document multiple Pleistocene glacial stages. The oldest exposure ages, View the MathML source113 ± 10ka, underestimate the age of the earliest preserved glacial advance and imply that the modern relief of the southwestern Pamir (peaks at ~5000–6000 m a.s.l.; valleys at ~2000–3000more » m a.s.l.) already existed in the late Middle Pleistocene. Younger exposure ages (~40–80 ka, ~30 ka) complement the existing Central Asian glacial chronology and reflect successively less extensive Late Pleistocene glaciations. The topography of the Pamir and the glacial chronologies suggest that, in the Middle Pleistocene, an ice cap or ice field occupied the eastern Pamir high-altitude plateau, whereas westward flowing valley glaciers incised the southwestern Pamir. Since the Late Pleistocene deglaciation, the rivers of the southwestern Pamir adjusted to the glacially shaped landscape. As a result, localized rapid fluvial incision and drainage network reorganization reflect the transient nature of the deglaciated landscape.« less

Debris Flows and Record Floods from Extreme Mesoscale Convective Thunderstorms over the Santa Catalina Mountains, Arizona

USGS Publications Warehouse

Magirl, Christopher S.; Shoemaker, Craig; Webb, Robert H.; Schaffner, Mike; Griffiths, Peter G.; Pytlak, Erik

2007-01-01

Ample geologic evidence indicates early Holocene and Pleistocene debris flows from the south side of the Santa Catalina Mountains north of Tucson, Arizona, but few records document historical events. On July 31, 2006, an unusual set of atmospheric conditions aligned to produce record floods and an unprecedented number of debris flows in the Santa Catalinas. During the week prior to the event, an upper-level area of low pressure centered near Albuquerque, New Mexico generated widespread heavy rainfall in southern Arizona. After midnight on July 31, a strong complex of thunderstorms developed over central Arizona in a deformation zone that formed on the back side of the upper-level low. High atmospheric moisture (2.00' of precipitable water) coupled with cooling aloft spawned a mesoscale thunderstorm complex that moved southeast into the Tucson basin. A 15-20 knot low-level southwesterly wind developed with a significant upslope component over the south face of the Santa Catalina Mountains advecting moist and unstable air into the merging storms. National Weather Service radar indicated that a swath of 3-6' of rainfall occurred over the lower and middle elevations of the southern Santa Catalina Mountains. This intense rain falling on saturated soil triggered over 250 hillslope failures and debris flows throughout the mountain range. Sabino Canyon, a heavily used recreation area administered by the U.S. Forest Service, was the epicenter of mass wasting, where at least 18 debris flows removed structures, destroyed the roadway in multiple locations, and closed public access for months. The debris flows were followed by streamflow floods which eclipsed the record discharge in the 75-year gaging record of Sabino Creek. In five canyons adjacent to Sabino Canyon, debris flows approached or excited the mountain front, compromising floow conveyance structures and flooding some homes.

Ensuring very shallow-water sediment properties: case study from Capo Granitola harbour, Sicily (Italy)

NASA Astrophysics Data System (ADS)

Punzo, Michele; Cavuoto, Giuseppe; Tarallo, Daniela; Di Fiore, Vincenzo

2017-09-01

We present high-resolution Vp models of the Capo Granitola harbor, Sicily (Italy) obtained by first arrival traveltime tomography. Seismic data were collected along four hydrophone arrays on the sea-bottom and via a Watergun as seismic source, in order to plan dredging operations in the harbor. Using a hydrophone spacing of 2.5 m and shot spacing of 5 m, very high resolution quality data were recorded. Seismic tomography expands existing knowledge of the harbour subsoil with a penetration of about 20 m, illuminating the Lower Pleistocene bedrock (Marsala calcarenites) that corresponds to high-Vp regions (Vp > 4.5 km/s). Low Vp (1.8-4.5 km/s) deposits belonging to terraced calcarenites (Upper Pleistocene in age) are also well imaged; they are about 8 m thick and lie below loose sand deposits (Vp = 1.5 km/s). The substratum has an articulated morphology; Vp images unravel small steps in the basement probably related to structural discontinuities (e.g., faults). Processing data with 3D techniques enables images of the structure and the thickness of the lithotypes to be reconstructed, thus leading to large-scale, realistic estimates of the total quantity of material to be excavated or dredged. Tomographic profiles permit clear discrimination of the soft sediment above the basement and thus allow the determination of the total volume of sediment above the seismic bedrock, estimated at about 265,000 m3.

On the long-lasting sequences of coral reef terraces from SE Sulawesi (Indonesia): Distribution, formation, and global significance

NASA Astrophysics Data System (ADS)

Pedoja, Kevin; Husson, Laurent; Bezos, Antoine; Pastier, Anne-Morwenn; Imran, Andy Muhammad; Arias-Ruiz, Camilo; Sarr, Anta-Clarisse; Elliot, Mary; Pons-Branchu, Edwige; Nexer, Maëlle; Regard, Vincent; Hafidz, Abdul; Robert, Xavier; Benoit, Laurent; Delcaillau, Bernard; Authemayou, Christine; Dumoulin, Caroline; Choblet, Gaël

2018-05-01

Many islands of the eastern Indonesian Archipelago exhibit Late Cenozoic sequences of coral reef terraces. In SE Sulawesi, on the Tukang Besi and Buton archipelagos, we identified 23 islands bearing such sequences. Remote sensing imagery and field mapping combined to U/Th and 14C dating enable to establish a chronologic framework of the reef terrace sequences from Wangi-Wangi, Buton as well as on the neighbouring, smaller islands of Ular, Siumpu and Kadatua. We identified the terraces from the last interglacial maximum (MIS 5e) at elevations lower than 20 m except on W Kadatua where it is raised at 34 ± 5 m. Such elevations yield low to moderate Upper Pleistocene uplift rates (<0.3 mm yr-1). On SE Buton Island, a sequence culminates at 650 m and includes at least 40 undated strandlines. Next to this exceptional sequence, on the Sampolawa Peninsula, 18 strandlines culminate at 430 m. Dated samples at the base of this sequence (<40 m) yield mean Middle Pleistocene uplift rates of 0.14 ± 0.09 mm yr-1. Extrapolation of these uplift rates compared to the geological setting suggests that the sequences of the Sampolawa Peninsula provide a record of sea-level high-stands for the last 3.8 ± 0.6 Ma. The sequences on SE Buton Island therefore constitute the best preserved long-lasting geomorphic record of Plio-Quaternary sea-level stands worldwide.

High-precision 14C and 40Ar/39Ar dating of the Campanian Ignimbrite (Y-5) reconciles the time-scales of climatic-cultural processes at 40 ka

NASA Astrophysics Data System (ADS)

Giacco, Biagio; Hajdas, Irka; Isaia, Roberto; Deino, Alan; Nomade, Sebastien

2017-04-01

The Campanian Ignimbrite (CI) super-eruption ( 40 ka, Southern Italy) is the largest known volcanic event of Mediterranean area. The CI tephra is widely dispersed through western Eurasia and occurs in close stratigraphic association with significant Late Pleistocene paleoclimatic and Paleolithic cultural events. This makes the CI tephra one of the most important tool for investigating several scientific issues ranging from volcanology, paleoclimatology to archaeology. Yet despite concerted attempts, the absolute age of the CI eruption is not well constrained. Here we present the first direct radiocarbon age for the CI obtained using accepted modern practices, from multiple 14C analyses of an exceptional large charred tree branch embedded in the lithified Yellow Tuff facies of the CI pyroclastic flow deposits, as well as new high-precision 40Ar/39Ar dating for the CI. These data substantially improve upon previous age determinations and permit fuller exploitation of the chronological potential of the CI tephra marker. Specifically, the results of our study are twofold: they provide (i) a robust pair of 14C and 40Ar/39Ar ages for refining both the radiocarbon calibration curve and the Late Pleistocene time-scale in the narrow, but significant time-span across CI event and (ii) compelling chronological evidence for the significance of the combined influence of the CI eruption and Heinrich Event 4 on European climate and potentially evolutionary processes of the Early Upper Palaeolithic.

Magnetic Properties of Bermuda Rise Sediments Controlled by Glacial Cycles During the Late Pleistocene

NASA Astrophysics Data System (ADS)

Roud, S.

2015-12-01

Sediments from ODP site 1063 (Bermuda Rise, North Atlantic) contain a high-resolution record of geomagnetic field behavior during the Brunhes Chron. We present rock magnetic data of the upper 160 mcd (<900 ka) from hole 1063D that show magnetic properties vary in concert with glacial cycles. Magnetite appears to be the main magnetic carrier in the carbonate-dominated interglacial horizons, yet exhibits contrasting grain size distributions depending on the redox state of the horizons. Higher contributions of single domain magnetite exist above the present day sulfate reduction zone (ca. 44 mcd) with relatively higher multidomain magnetite components below that likely arise from the partial dissolution of SD magnetite in the deeper, anoxic horizons. Glacial horizons on the other hand, characterized by enhanced terrigenous deposition, show no evidence for diagenetic dissolution but do indicate the presence of authigenic greigite close to glacial maxima (acquisition of gyro-remanence, strong magnetostatic interactions and SD properties). Glacial horizons contain hematite (maxima in HIRM and S-Ratio consistent with a reddish hue) and exhibit higher ARM anisotropy and pronounced sedimentary fabrics. We infer that post depositional processes affected the magnetic grain size and mineralogy of Bermuda rise sediments deposited during the late Pleistocene. Hematite concentration is interpreted to reflect primary terrigenous input that is likely derived from the Canadian Maritime Provinces. A close correlation between HIRM and magnetic foliation suggests that changes in sediment composition (terrigenous vs. marine biogenic) were accompanied by changes in the depositional processes at the site.

Quaternary radiolarian biostratigraphy in the subarctic northeastern Pacific (IODP Expedition 341 Site U1417) and synchroneity of bioevents across the North Pacific

NASA Astrophysics Data System (ADS)

Matsuzaki, Kenji M.; Suzuki, Noritoshi

2018-01-01

Expedition 341 of the Integrated Ocean Drilling Program (IODP) retrieved sediment cores spanning the time interval between the Pleistocene and Miocene from the southern Gulf of Alaska. Onboard Pleistocene radiolarian biostratigraphy is hereby refined by increasing the sampling resolution. The 178 core samples from the upper 190 m CCSF-B (Composite Core Depth Scale F-B) of Site U1417 contained faunal elements similar to the northwestern Pacific; for example, the three biozones in the northwestern Pacific (i.e., Eucyrtidium matuyamai, Stylatractus universus and Botryostrobus aquilonaris) were also recognized in the Gulf of Alaska, spanning 1.80-1.13 Ma, 1.13-0.45 Ma, and the last 0.45 Myr, respectively. Based on the age model that we used in this study and the shipboard paleomagnetic reversal events, the first occurrences (FOs) of Amphimelissa setosa and Schizodiscus japonicus in the northeastern Pacific were preliminarily determined to be 1.48 and 1.30 Ma, respectively. The last occurrence (LO) of Eucyrtidium matuyamai and the FO of Lychnocanoma sakaii, both well-established bioevents in the northwestern Pacific, were dated at 0.80 and 1.13 Ma, respectively. The LO of E. matuyamai is a synchronous event at 1.05 ± 0.1 Ma in the North Pacific, while the FOs of A. setosa and S. japonicus at 1.48 and 1.30 Ma, respectively, are significantly older than what has been found elsewhere.

Pleistocene paleo-groundwater as a pristine fresh water resource in southern Germany--evidence from stable and radiogenic isotopes.

PubMed

van Geldern, Robert; Baier, Alfons; Subert, Hannah L; Kowol, Sigrid; Balk, Laura; Barth, Johannes A C

2014-10-15

Shallow groundwater aquifers are often influenced by anthropogenic contaminants or increased nutrient levels. In contrast, deeper aquifers hold potentially pristine paleo-waters that are not influenced by modern recharge. They thus represent important water resources, but their recharge history is often unknown. In this study groundwater from two aquifers in southern Germany were analyzed for their hydrogen and oxygen stable isotope compositions. One sampling campaign targeted the upper aquifer that is actively recharged by modern precipitation, whereas the second campaign sampled the confined, deep Benkersandstein aquifer. The groundwater samples from both aquifers were compared to the local meteoric water line to investigate sources and conditions of groundwater recharge. In addition, the deep groundwater was dated by tritium and radiocarbon analyses. Stable and radiogenic isotope data indicate that the deep-aquifer groundwater was not part of the hydrological water cycle in the recent human history. The results show that the groundwater is older than ~20,000 years and most likely originates from isotopically depleted melt waters of the Pleistocene ice age. Today, the use of this aquifer is strictly regulated to preserve the pristine water. Clear identification of such non-renewable paleo-waters by means of isotope geochemistry will help local water authorities to enact and justify measures for conservation of these valuable resources for future generations in the context of a sustainable water management. Copyright © 2014 Elsevier B.V. All rights reserved.

TERRESTRIAL EFFECTS OF NEARBY SUPERNOVAE IN THE EARLY PLEISTOCENE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, B. C.; Engler, E. E.; Kachelrieß, M.

Recent results have strongly confirmed that multiple supernovae happened at distances of ∼100 pc, consisting of two main events: one at 1.7–3.2 million years ago, and the other at 6.5–8.7 million years ago. These events are said to be responsible for excavating the Local Bubble in the interstellar medium and depositing {sup 60}Fe on Earth and the Moon. Other events are indicated by effects in the local cosmic ray (CR) spectrum. Given this updated and refined picture, we ask whether such supernovae are expected to have had substantial effects on the terrestrial atmosphere and biota. In a first look atmore » the most probable cases, combining photon and CR effects, we find that a supernova at 100 pc can have only a small effect on terrestrial organisms from visible light and that chemical changes such as ozone depletion are weak. However, tropospheric ionization right down to the ground, due to the penetration of ≥TeV CRs, will increase by nearly an order of magnitude for thousands of years, and irradiation by muons on the ground and in the upper ocean will increase twentyfold, which will approximately triple the overall radiation load on terrestrial organisms. Such irradiation has been linked to possible changes in climate and increased cancer and mutation rates. This may be related to a minor mass extinction around the Pliocene-Pleistocene boundary, and further research on the effects is needed.« less

Terrestrial Effects of Nearby Supernovae in the Early Pleistocene

NASA Astrophysics Data System (ADS)

Thomas, B. C.; Engler, E. E.; Kachelrieß, M.; Melott, A. L.; Overholt, A. C.; Semikoz, D. V.

2016-07-01

Recent results have strongly confirmed that multiple supernovae happened at distances of ˜100 pc, consisting of two main events: one at 1.7-3.2 million years ago, and the other at 6.5-8.7 million years ago. These events are said to be responsible for excavating the Local Bubble in the interstellar medium and depositing 60Fe on Earth and the Moon. Other events are indicated by effects in the local cosmic ray (CR) spectrum. Given this updated and refined picture, we ask whether such supernovae are expected to have had substantial effects on the terrestrial atmosphere and biota. In a first look at the most probable cases, combining photon and CR effects, we find that a supernova at 100 pc can have only a small effect on terrestrial organisms from visible light and that chemical changes such as ozone depletion are weak. However, tropospheric ionization right down to the ground, due to the penetration of ≥TeV CRs, will increase by nearly an order of magnitude for thousands of years, and irradiation by muons on the ground and in the upper ocean will increase twentyfold, which will approximately triple the overall radiation load on terrestrial organisms. Such irradiation has been linked to possible changes in climate and increased cancer and mutation rates. This may be related to a minor mass extinction around the Pliocene-Pleistocene boundary, and further research on the effects is needed.

Quaternary stratigraphy and tectonics, and late prehistoric agriculture of the Safford Basin (Gila and San Simon river valleys), Graham County, Arizona

USGS Publications Warehouse

Houser, Brenda B.; Pearthree, Phillip A.; Homburg, Jeffry A.; Thrasher, Lawrence C.

2004-01-01

This guidebook accompanied the 46th annual meeting of the Rocky Mountain Cell of the Friends of the Pleistocene (FOP) and the 2002 Fall Field Trip of the Arizona Geological Society. The meeting and field trip were held in the Safford Basin, southeastern Arizona. The Friends of the Pleistocene is an informal gathering of Quaternary geologists, geomorphologists, and pedologists who meet annually for a field conference. The first part of the guidebook consists of road logs with descriptions of stops covering the three days of the field trip. An overview of the geology of the Safford Basin is given in Stop 1-1. The second part of the guidebook consists of four short papers that discuss adjacent areas or that expand upon the road log descriptions of the field trip stops. The first paper by Reid and Buffler is a summary of upper Cenozoic depositional facies in the Duncan Basin, the first basin to the east of the Safford Basin. The next three papers expand upon (1) the soil study of the gridded field agricultural complex (Stop 2-3, Homburg and Sandor), (2) the vertebrate fossils of the San Simon Valley in the southeastern part of the Safford Basin (Stop 3-1, Thrasher), and (3) paleoIndian irrigation systems and settlements in Lefthand Canyon at the foot of the Pinaleno Mountains (Stop 3-2, Neely and Homburg).

Sudbury Breccia and suevite as glacial indicators transported 800 km to Kentland Astrobleme, Indiana

NASA Technical Reports Server (NTRS)

Mchone, John F.; Dietz, Robert S.; Peredery, Walter V.

1992-01-01

A glacial erratic whose place of origin is known by direct comparison with bedrock is known as an indicator. In 1971, while visiting the known astrobleme at Kentland, Indiana, Peredery recognized and sampled in the overlying glacial drift deposits a distinctive boulder of Sudbury suevite (black member, Onaping Formation) that normally occurs within the Sudbury Basin as an impact fall-back or wash-in deposit. The rock was sampled (but later mislaid) from a farmer's cairn next to a cleared field. Informal reports of this discovery prompted the other authors to recently reconnoiter the Kentland locality in an attempt to relocate the original boulder. Several breccia blocks were sampled but laboratory examination proved most of these probably to be diamictites from the Precambrian Gowganda Formation, which outcrops extensively in the southern Ontario. However, one sample was confirmed as typical Sudbury Breccia, which outcrops in the country rock surrounding the Sudbury Basin. Thus two glacial indicators were transported by Pleistocene continental glaciers about 820 km over a tightly proscribed path and, curiously, from one astrobleme to another. Brecciated boulders in the Illinois/Indiana till plain are usually ascribed to the Gowganda or Mississagi formations in Ontario. But impact-generated rocks need not be confused. The carbonaceous matrix of the suevite, for example, was sufficiently distinctive to assign it to the upper portion of the black Onaping. The unique and restricted source area of these indicators provide an accurate and reliable control for estimating Pleistocene ice movement.

Soanian lithic occurrences and raw material exploitation in the Siwalik Frontal Zone, northern India: a geoarchaeological perspective.

PubMed

Chauhan, Parth R

2008-05-01

In the Himalayan foothills of northern India, evidence of widespread hominin occupation since at least the late Middle Pleistocene has been known since the early 20th century and indicates varied patterns of land-use and intraregional mobility. This lithic evidence primarily belongs to the Soanian industry, representing some of the highest concentrations of Paleolithic assemblages in the Old World based exclusively on pebble and cobble clasts. This body of evidence also signifies interregional dispersal from peninsular India or northern Pakistan, leading to environmental preferences that spread quickly through hominin populations in the region within a relatively short timespan. While rich in its technological repertoire, the Soanian industry is poorly- understood regarding site selection and raw material exploitation over time. Recent efforts demonstrate that Soanian sites on Siwalik frontal slopes between two major rivers vary considerably in their artifact quantities regardless of abundant raw material sources found across the landscape. Most of the assemblages suggest raw material transport distances of three kilometers or less from the localized sources. Geoarchaeological investigations at the richest known Soanian site, Toka, reveal dynamic evidence of pre- and postdepositional site formation including the exploitation of quartzite pebbles and cobbles by Pleistocene hominins from terrace and streambed contexts within a 1 km2 radius. Some field observations also disprove claims made by previous workers, of artifacts eroding out of late Pliocene exposures of the Upper Siwalik Tatrot Formation around Toka.

Late Pleistocene and Holocene vegetation and climate changes in the Lake Baikal region

NASA Astrophysics Data System (ADS)

Demske, D.; Heumann, G.; Granoszewski, W.; Mamakowa, K.; Piotrowska, N.; Bluszcz, A.; Goslar, T.

2003-04-01

Palynological high-resolution records from Lake Baikal sediments document strong vegetational changes during the transitions from an open landscape to Late Glacial shrublands and Holocene forests. For three core sites, investigated within EU-Project CONTINENT, sporomorph concentrates were used for AMS 14C dating of environmental changes. The pollen record from the northern lake site, located in vicinity to the Barguzin Mountains, shows pronounced maxima of Salix and Picea corresponding to late Pleistocene warming. A peak maximum in Alnus fruticosa during the Younger Dryas cooling coincided with low abundance of green algae in the lake and a decline in Picea trees. Fern-rich forests with Picea, Larix and Betula developed during early Holocene. With an abrupt expansion of Pteridium ferns Abies appeared in the northeastern Baikal region, reflecting optimum conditions for dark taiga. Among pines Pinus sibirica prevailed prior to the spread of P. sylvestris. Expansion of pines points to a distinct decrease in precipitation. A palynological sequence from the same site reflects the vegetation development during the last interglacial, with differences indicated by higher abundance of Abies. The upper part of the interglacial record comprises the transition to stadial conditions. Further pollen spectra are probably equivalent to first interstadials of the early glacial period (Zyryansk). Comparison with southern sites, in vicinity to the Selenga Delta and the Khamar-Daban Mountains, reveals that regional and temporal differentiation of Holocene vegetation development and climate conditions was closely related to the distribution of mountain ranges.

Comparison of Handaxes from Bose Basin (China) and the Western Acheulean Indicates Convergence of Form, Not Cognitive Differences

PubMed Central

Wang, Wei; Lycett, Stephen J.; von Cramon-Taubadel, Noreen; Jin, Jennie J. H.; Bae, Christopher J.

2012-01-01

Alleged differences between Palaeolithic assemblages from eastern Asia and the west have been the focus of controversial discussion for over half a century, most famously in terms of the so-called ‘Movius Line’. Recent discussion has centered on issues of comparability between handaxes from eastern Asian and ‘Acheulean’ examples from western portions of the Old World. Here, we present a multivariate morphometric analysis in order to more fully document how Mid-Pleistocene (i.e. ∼803 Kyr) handaxes from Bose Basin, China compare to examples from the west, as well as with additional (Mode 1) cores from across the Old World. Results show that handaxes from both the western Old World and Bose are significantly different from the Mode 1 cores, suggesting a gross comparability with regard to functionally-related form. Results also demonstrate overlap between the ranges of shape variation in Acheulean handaxes and those from Bose, demonstrating that neither raw material nor cognitive factors were an absolute impediment to Bose hominins in making comparable handaxe forms to their hominin kin west of the Movius Line. However, the shapes of western handaxes are different from the Bose examples to a statistically significant degree. Moreover, the handaxe assemblages from the western Old World are all more similar to each other than any individual assemblage is to the Bose handaxes. Variation in handaxe form is also comparatively high for the Bose material, consistent with suggestions that they represent an emergent, convergent instance of handaxe technology authored by Pleistocene hominins with cognitive capacities directly comparable to those of ‘Acheulean’ hominins. PMID:22536441

Geomorphology and habitat diversity in the Pantanal.

PubMed

Mercante, M A; Rodrigues, S C; Ross, J L S

2011-04-01

The present study deals with the inter-relations in the relief which forms the Bacia do Alto Rio Paraguay (BAP) in mid-west Brazil. The overall aim is to discuss the relationship between relief forms and the biodiversity of the Pantanal. The BAP is a natural environmental system with contrasts in two of the compartments on which it is formed: the plateau, the most elevated compartment, highly transformed by human activities, and the plain which forms the Pantanal, which is more preserved and less transformed in relation to productive activities. The analysis was performed based on publications with a geomorphologic focus, examining the different relief units of the BAP and the dynamics of the revealing processes of landscape change which the Pantanal has undergone since the end of the Pleistocene.

The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia

PubMed Central

Duarte, Cidália; Maurício, João; Pettitt, Paul B.; Souto, Pedro; Trinkaus, Erik; van der Plicht, Hans; Zilhão, João

1999-01-01

The discovery of an early Upper Paleolithic human burial at the Abrigo do Lagar Velho, Portugal, has provided evidence of early modern humans from southern Iberia. The remains, the largely complete skeleton of a ≈4-year-old child buried with pierced shell and red ochre, is dated to ca. 24,500 years B.P. The cranium, mandible, dentition, and postcrania present a mosaic of European early modern human and Neandertal features. The temporal bone has an intermediate-sized juxtamastoid eminence. The mandibular mentum osseum and the dental size and proportions, supported by mandibular ramal features, radial tuberosity orientation, and diaphyseal curvature, as well as the pubic proportions align the skeleton with early modern humans. Body proportions, reflected in femorotibial lengths and diaphyseal robusticity plus tibial condylar displacement, as well as mandibular symphyseal retreat and thoracohumeral muscle insertions, align the skeleton with the Neandertals. This morphological mosaic indicates admixture between regional Neandertals and early modern humans dispersing into southern Iberia. It establishes the complexities of the Late Pleistocene emergence of modern humans and refutes strict replacement models of modern human origins. PMID:10377462

A Pleistocene coastal alluvial fan complex produced by Middle Pleistocene glacio-fluvial processes

NASA Astrophysics Data System (ADS)

Adamson, Kathryn; Woodward, Jamie; Hughes, Philip; Giglio, Federico; Del Bianco, Fabrizio

2014-05-01

A coarse-grained alluvial fan sequence at Lipci, Kotor Bay, in western Montenegro, provides a sedimentary record of meltwater streams draining from the Orjen Massif (1,894 m a.s.l.) to the coastal zone. At Lipci sedimentary evidence and U-series ages have been used alongside offshore bathymetric imagery and seismic profiles to establish the size of the fan and constrain the nature and timing of its formation. Establishing the depositional history of such coastal fans is important for our understanding of cold stage sediment flux from glaciated uplands to the offshore zone, and for exploring the impact of sea level change on fan reworking. There is evidence of at least four phases of Pleistocene glaciation on the Orjen massif, which have been U-series dated and correlated to MIS 12, MIS 6, MIS 5d-2 and the Younger Dryas. A series of meltwater channels delivered large volumes of coarse- and fine-grained limestone sediment from the glaciated uplands into the Bay of Kotor. At the southern margin of the Orjen massif, a series of large (>700 m long) alluvial fans has developed. Some of these extend offshore for up to 600 m. Lipci fan lies downstream of end moraines in the valley immediately above, which were formed by an extensive outlet glacier of the Orjen ice cap during MIS 12. The terrestrial deposits are part of the fan apex (50 m a.s.l.) that lies at the foot of a steep bedrock channel, but the majority of the fan is now more than 25 m below sea level. The terrestrial fan sediments are strongly cemented by multiple generations of calcite precipitates: the oldest U-series ages are infinite indicating that the fan is >350 ka in age. These ages are in agreement with alluvial sedimentary evidence and U-series ages from other fluvial units on Mount Orjen. The terrestrial portion of the Lipci fan surface contains several channels. These are well preserved due to cementation with calcium carbonate. Submarine imagery indicates that the now submerged portion of the fan also contains deeply incised (up to 10 m) channels which are similar in morphology to those exposed onshore. It is likely that strong cementation of the fan sediments, and associated channel forms, has protected them from coastal erosion during several regression-transgression cycles. These records provide important opportunities to correlate the Pleistocene terrestrial glacial and fluvial records with the marine archive.

The Role of Neotectonics in Landscape Formation in What Is Now the Divnogorie Nature Park (Southern East European Plain)

NASA Astrophysics Data System (ADS)

Romanovskaya, M. A.; Bessudnov, A. N.; Kuznetsova, T. V.

2015-12-01

The Divnogorie Nature Park is in the basin of the middle Don River. Tectonically, it sits on the Ostrogozhskoye Neotectonic Uplift, a recent extension of the northern wing of the Voronezh Anteclise of the Russian Platform. The neotectonic uplift amplitude of this structure is estimated at more than 200 m. A structural geomorphological study of the area has shown that the Ostrogozhskoye Uplift is an actively growing structure. This is clearly demonstrated by the following: dramatic changes in the flow direction of the rivers Don and Tikhaya Sosna, forced to bypass the growing upland; instances of damming up, which created numerous oxbow lakes and led to waterlogging in floodplains; increase in the density of the erosion grid on the upland; fall of the groundwater table (Romanovskaya, 2015). Uplifting has intensified erosion and slope wash processes, forming numerous canyon-shaped ravines, very steep slopes (>60º) and interconnected bastion-like relief forms. Superimposed on the geology of the area, neotectonic movements and erosion have led to the formation of a peculiar relief (chalk outliers), microclimate and ecosystem (petrophytic steppe). Surrounded by protections in the form of steep slopes and water courses, this area is a natural fortress which has favored human habitation since the Late Paleolithic Age. In a location in the Tikhaya Sosna river basin, gully erosion has exposed a large accumulation of ancient horse (Equus caballus) bones. Now this location (50.9649ºN, 39.3031ºE) is known as the Upper Paleolithic (13.5-14 kaBP) multi-level archaeological site Divnogorie-9. About 8,000 horse bones and 65 human-made stone artifacts have been discovered here in Late Pleistocene diluvial-alluvial-colluvial deposits (Kuznetsova, 2014). The mass die-off of wild horses and their reburial at the site are most probably the result of landscape and geological impact of massive temporary water flows that will be addressed in some detail in the actual presentation of the study.

Geologic map of the Dillon quadrangle, Summit and Grand Counties, Colorado

USGS Publications Warehouse

Kellogg, Karl S.

2002-01-01

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Dillon quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, 1999), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts through the center of the quadrangle, although is mostly covered by surficial deposits. The oldest rocks in the quadrangle underlie the Williams Fork Mountains and the ridge immediately east of South Fork Middle Fork River, and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, 1987). The oldest exposed sedimentary unit is the Upper Jurassic Morrison Formation, but Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale, underlies the southern part of the quadrangle. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Pliocene, on the west flank of the Williams Fork Mountains, (2) deeply weathered, very coarse gravel deposits underlying a mesa in the southwest part of the quadrangle (the Mesa Cortina subdivision. The gravels are gold bearing and were mined by hydraulic methods in the 1800s), (3) moderately to deeply weathered, widespread, bouldery material that is a combination of till of the Bull Lake glaciation, debris-flow deposits, landslide deposits, and possibly pre-Bull Lake till, (4) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene)glaciations, (5) recent landslide deposits, and (6)extensive colluvial and alluvial deposits.

Geologic map of the Dillon quadrangle, Summit and Grand Counties, Colorado

USGS Publications Warehouse

Kellogg, Karl S.

1997-01-01

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Dillon quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, 1999), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts through the center of the quadrangle, although is mostly covered by surficial deposits. The oldest rocks in the quadrangle underlie the Williams Fork Mountains and the ridge immediately east of South Fork Middle Fork River, and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, 1987). The oldest exposed sedimentary unit is the Upper Jurassic Morrison Formation, but Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale, underlies the southern part of the quadrangle. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Pliocene, on the west flank of the Williams Fork Mountains, (2) deeply weathered, very coarse gravel deposits underlying a mesa in the southwest part of the quadrangle (the Mesa Cortina subdivision. The gravels are gold bearing and were mined by hydraulic methods in the 1800s), (3) moderately to deeply weathered, widespread, bouldery material that is a combination of till of the Bull Lake glaciation, debris-flow deposits, landslide deposits, and possibly pre-Bull Lake till, (4) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene)glaciations, (5) recent landslide deposits, and (6)extensive colluvial and alluvial deposits.

Archaeological support for the three-stage expansion of modern humans across northeastern Eurasia and into the Americas.

PubMed

Hamilton, Marcus J; Buchanan, Briggs

2010-08-30

Understanding the dynamics of the human range expansion across northeastern Eurasia during the late Pleistocene is central to establishing empirical temporal constraints on the colonization of the Americas. Opinions vary widely on how and when the Americas were colonized, with advocates supporting either a pre- or post- last glacial maximum (LGM) colonization, via either a land bridge across Beringia, a sea-faring Pacific Rim coastal route, a trans-Arctic route, or a trans-Atlantic oceanic route. Here we analyze a large sample of radiocarbon dates from the northeast Eurasian Upper Paleolithic to identify the origin of this expansion, and estimate the velocity of colonization wave as it moved across northern Eurasia and into the Americas. We use diffusion models to quantify these dynamics. Our results show the expansion originated in the Altai region of southern Siberia approximately 46kBP , and from there expanded across northern Eurasia at an average velocity of 0.16 km per year. However, the movement of the colonizing wave was not continuous but underwent three distinct phases: 1) an initial expansion from 47-32k calBP; 2) a hiatus from approximately 32-16k calBP, and 3) a second expansion after the LGM approximately 16k calBP. These results provide archaeological support for the recently proposed three-stage model of the colonization of the Americas. Our results falsify the hypothesis of a pre-LGM terrestrial colonization of the Americas and we discuss the importance of these empirical results in the light of alternative models. Our results demonstrate that the radiocarbon record of Upper Paleolithic northeastern Eurasia supports a post-LGM terrestrial colonization of the Americas falsifying the proposed pre-LGM terrestrial colonization of the Americas. We show that this expansion was not a simple process, but proceeded in three phases, consistent with genetic data, largely in response to the variable climatic conditions of late Pleistocene northeast Eurasia. Further, the constraints imposed by the spatiotemporal gradient in the empirical radiocarbon record across this entire region suggests that North America cannot have been colonized much before the existing Clovis radiocarbon record suggests.

A new perspective on the generation of the 2016 M6.7 Kaohsiung earthquake, southwestern Taiwan

NASA Astrophysics Data System (ADS)

Wang, Zhi

2017-04-01

In order to investigate the likely generation mechanism of the 2016 M6.7 Kaohsiung earthquake, a large number of high-quality travel times from P- and S-wave source-receiver pairs are used jointly in this study to invert three-dimensional (3-D) seismic velocity (Vp, Vs) and Poisson's ratio structures at high resolution. We also calculated crack density, saturate fracture, and bulk-sound velocity from our inverted Vp, Vs, and σgodels. In this way, multi-geophysical parameter imaging revealed that the 2016 Kaohsiung earthquake occurred along a distinctive edge portion exhibiting high-to-low variations in these parameters in both horizontal and vertical directions across the hypocenter. We consider that a slow velocity and high-σ body that has high ɛ and somewhat high ζ anomalies above the hypocenter under the Coastal Plain represents fluids contained in the young fold-and-thrust belt associated with the passive Asian continental margin in southwestern Taiwan. Intriguing, a continuous low Vp and Vs zone with high Poisson's ratio, crack density and saturate fracturegnomalies across the Laonung and Chishan faults is also clearly imaged in the northwestern upper crust beneath the Coastal Plain and Western Foothills as far as the southeastern lower crust under the Central Range. We therefore propose that this southeastern extending weakened zone was mainly the result of a fluid intrusion either from the young fold-and-thrust belt the shallow crust or the subducted Eurasian continental (EC) plate in the lower crust and uppermost mantle. We suggest that fluid intrusion into the upper Oligocene to Pleistocene shallow marine and clastic shelf units of the Eurasian continental crust and/or the relatively thin uppermost part of the transitional Pleistocene-Holocene foreland due to the subduction of the EC plate along the deformation front played a key role in earthquake generation in southwestern Taiwan. Such fluid penetration would reduce Vp, and Vs while increasing Poisson's ratio and saturate fracture across the source area, leading to mechanical strength failure of the rock matrix in the relative weakened and brittle seismogenic layer and triggering the 2016 earthquake. PIC

A new perspective on the generation of the 2016 M6.4 Meilung earthquake, southwestern Taiwan

NASA Astrophysics Data System (ADS)

Wang, Z.

2017-12-01

In order to investigate the likely generation mechanism of the 2016 M6.4 Meilung earthquake, a large number of high-quality travel times from P- and S-wave source-receiver pairs are used jointly in this study to invert three-dimensional (3-D) seismic velocity (Vp, Vs) and Poisson's ratio structures at high resolution. We also calculated crack density, saturate fracture, and bulk-sound velocity from our inverted Vp, Vs, and s models. In this way, multi-geophysical parameter imaging revealed that the 2016 Meilung earthquake occurred along a distinctive edge portion exhibiting high-to-low variations in these parameters in both horizontal and vertical directions across the hypocenter. We consider that a slow velocity and high-Poisson ratio body that has high-crack density and somewhat high-saturate fracture anomalies above the hypocenter under the coastal plain represents fluids contained in the young fold-and-thrust belt relative to the passive Asian continental margin in southwestern Taiwan. Intriguing, a continuous low Vp and Vs zone with high Poisson ratio, crack density and saturate fracture anomalies across the Laonung and Chishan faults is also clearly imaged in the northwestern upper crust beneath the coastal plain and western foothills as far as the southeastern lower crust under the central range. We therefore propose that this southeastern extending weakened zone was mainly the result of a fluid intrusion either from the young fold-and-thrust belt associated with the passive Asian continental margin in the shallow crust or the subducted Eurasian continental (EC) plate in the lower crust and uppermost mantle. We suggest that fluid intrusion into the upper Oligocene to Pleistocene shallow marine and clastic shelf units of the Eurasian continental crust and/or the relatively thin uppermost part of the transitional Pleistocene-Holocene foreland due to the subduction of the EC plate along the deformation front played a key role in earthquake generation in southwestern Taiwan. Such fluid penetration would reduce Vp, and Vs while increasing Poisson ratio and saturate fracture across the source area, leading to mechanical strength failure of the rock matrix in the relative weakened and brittle seismogenic layer and triggering the 2016 earthquake.

Microbiology and geochemistry of hydrocarbon-rich sediments erupted from the deep geothermal Lusi site, Indonesia

NASA Astrophysics Data System (ADS)

Krüger, Martin; Straten, Nontje; Mazzini, Adriano; Scheeder, Georg; Blumenberg, Martin

2016-04-01

The Lusi eruption represents one of the largest ongoing sedimentary hosted geothermal systems, which started in 2006 following an earthquake on Java Island. Since then it has been producing hot and hydrocarbon rich mud from a central crater with peaks reaching 180.000 m3 per day. Numerous investigations focused on the study of offshore microbial colonies that commonly thrive at offshore methane and oil seeps and mud volcanoes, however very little has been done for onshore seeping structures. Lusi represents a unique opportunity to complete a comprehensive study of onshore microbial communities fed by the seepage of CH4 as well as of heavier liquid hydrocarbons originating from one or more km below the surface. While the source of the methane at Lusi is clear (Mazzini et al., 2012), the origin of the seeping oil, either form the deep mature Eocene Ngimbang (type II kerogen) or from the less mature Pleistocene Upper Kalibeng Fm. (type III kerogen), is still discussed. In the framework of the Lusi Lab project (ERC grant n° 308126) we analysed an oil film and found that carbon preference indices among n-alkanes, sterane and hopane isomers (C29-steranes: 20S/(20S+20R) and α,β-C32 Hopanes (S/(S+R), respectively) are indicative of a low thermal maturity of the oil source rock (~0.5 to 0.6 % vitrinite reflectance equivalents = early oil window maturity). Furthermore, sterane distributions, the pristane to phytane ratio and a relatively high oleanane index, which is an indication of an angiosperm input, demonstrate a strong terrestrial component in the organic matter. Together, hydrocarbons suggest that the source of the oil film is predominantly terrestrial organic matter. Both, source and maturity estimates from biomarkers, are in favor of a type III organic matter source and are therefore suggestive of a mostly Pleistocene Upper Kalibeng Fm. origin. We also conducted a sampling campaign at the Lusi site collecting samples of fresh mud close to the erupting crater, using a remotely controlled drone as well as older, weathered samples for comparison. In all samples large numbers of active microorganisms were present. Rates for aerobic methane oxidation were high, as was the potential of the microbial communities to degrade hydrocarbons (oils, alkanes, BTEX tested). The data suggests a transition of microbial populations from an anaerobic, hydrocarbon-driven metabolism in fresher samples from center or from small seeps to more generalistic, aerobic microbial communities in older, more consolidated sediments. Ongoing microbial activity in crater sediment samples under high temperatures (80-95C) indicate a deep origin of the involved microorganisms (deep biosphere). First results of molecular analyses of the microbial community compositions confirm the above findings. This study represents an initial step to better understand onshore seepage systems and provides an ideal analogue for comparison with the better investigated offshore structures.

[Relationship between crown form of upper central incisors and papilla filling in Chinese Han-nationality youth].

PubMed

Yang, X; Le, D; Zhang, Y L; Liang, L Z; Yang, G; Hu, W J

2016-10-18

To explore a crown form classification method for upper central incisor which is more objective and scientific than traditional classification method based on the standardized photography technique. To analyze the relationship between crown form of upper central incisors and papilla filling in periodontally healthy Chinese Han-nationality youth. In the study, 180 periodontally healthy Chinese youth ( 75 males, and 105 females ) aged 20-30 (24.3±4.5) years were included. With the standardized upper central incisor photography technique, pictures of 360 upper central incisors were obtained. Each tooth was classified as triangular, ovoid or square by 13 experienced specialist majors in prothodontics independently and the final classification result was decided by most evaluators in order to ensure objectivity. The standardized digital photo was also used to evaluate the gingival papilla filling situation. The papilla filling result was recorded as present or absent according to naked eye observation. The papilla filling rates of different crown forms were analyzed. Statistical analyses were performed with SPSS 19.0. The proportions of triangle, ovoid and square forms of upper central incisor in Chinese Han-nationality youth were 31.4% (113/360), 37.2% (134/360) and 31.4% (113/360 ), respectively, and no statistical difference was found between the males and females. Average κ value between each two evaluators was 0.381. Average κ value was raised up to 0.563 when compared with the final classification result. In the study, 24 upper central incisors without contact were excluded, and the papilla filling rates of triangle, ovoid and square crown were 56.4% (62/110), 69.6% (87/125), 76.2% (77/101) separately. The papilla filling rate of square form was higher (P=0.007). The proportion of clinical crown form of upper central incisor in Chinese Han-nationality youth is obtained. Compared with triangle form, square form is found to favor a gingival papilla that fills the interproximal embrasure space. The consistency of the present classification method for upper central incisor is not satisfying, which indicates that a new classification method, more scientific and objective than the present one, is to be found.