Science.gov

Sample records for southwestern neogene bland

  1. Migration of Neogene marine environments, southwestern Dominican Republic

    SciTech Connect

    McLaughlin, P.P. Jr. ); Sen Gupta, B.K. )

    1991-03-01

    The Azua Basin contains a 4000-m-thick regressive Neogene sedimentary sequence that records the effects of neotectonic activity along the northern bounary of the Caribbean plate. Shifts of benthic foraminiferal depth zone boundaries between stratigraphic sections demonstrate a southeastward migration of paleoenvironments in the Miocene and early Pliocene which suggest that the Hispaniola restraining bend was activated near the beginning of the late Miocene. In the morthwestern part of the Azua basin, the boundary between the middle and upper bathyal biofacies is in the uppermost Miocene Globorotalia humerosa Zone; the bathyal-neritic boundary is near the top of the same zone. In contrast, toward the southeastern (i.e., seaward) end of the basin, the middle bathyal/upper bathyal boundary is just above the base of the lower Pliocene Globorotalia margaritae margaritae Subzone, and the bathyal-neritic transition falls within the upper part of the same zone or in the overlying Globorotalia margaritae evoluta Subzone. The diachroneity of biofacies boundaries spans a time interval of ca. 1 m.y. The foraminiferal trends are corroborated by the disposition of time-transgressive lithofacies.

  2. Structural lineaments and neogene volcanism in southwestern Luzon

    NASA Astrophysics Data System (ADS)

    Wolfe, John A.; Self, Stephen

    The Philippine Islands have at least 15 active composite volcanoes and as many more that are fumarolic or dormant. About 20 calderas of Pleistocene age are known so far. Southwestern Luzon, one of the major volcanic districts of the country, contains three young composite volcanoes, four in a fumarolic stage, and over 200 vents of Pliocene-Pleistocene age within 150 km of Manila. There are three large calderas in this zone with a fourth a short distance south on Mindoro Island, plus four summit calderas. One of the most striking features is the Bataan Lineament, a chain of 27 volcanic vents, only one at present active, which marks the western side of the district. The main segment extends from Naujan caldera in the south (on Mindoro Island) on a strike of N31°W through Batangas Bay caldera, Mataas Na Gulod (a summit caldera), Corregidor Island (a small caldera), to Mount Mariveles and Mount Natib on the Bataan peninsula. With a bend of 30° at Mount Natib, the lineament continues northward for another 100 km, giving a total length of 320 km. Here it includes Mount Pinatubo, which is active, and several other vents. The Bataan Lineament is a volcanic arc, with perhaps some extensional element, above the subduction zone of the Manila Trench, dipping eastward under Luzon. Another major volcanic element is the Verde Island transform, which forms a zone across southwest Luzon, including 10 or more volcanoes. Activity extended from the lower Miocene with periodic eruptions until the late Pleistocene. Two volcanoes may be in a waning (fumarolic) stage and have thermal areas. Near the western end of this lineament, recent rifting may have occurred, and presently it is a zone of intense seismic activity. In the zone between the Bataan and Verde Island lineaments, several major volcanoes have developed including Laguna de Bay and Taal volcano-tectonic depressions. Large volume ignimbrite-forming eruptions may have taken place from Laguna de Bay caldera approximately 1.0 m

  3. The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador: Neogene and Cretaceous-Paleogene Total Petroleum Systems

    USGS Publications Warehouse

    Higley, Debra K.

    2004-01-01

    The Progreso Basin province (6083) in northwestern Peru and southwestern Ecuador consists of the Paleogene Santa Elena block and Peru Bank, and the Neogene Tumbes-Progreso subbasin. The Santa Elena block and Peru Bank are part of the Cretaceous-Paleogene Total Petroleum System (TPS)(608302), which contains the Cretaceous-Paleogene Santa Elena Block Assessment Unit (60830201). The Tumbes- Progreso subbasin includes the Neogene TPS (608301) and associated Neogene Pull-Apart Basin Assessment Unit (60830101). The complex tectonic history of the Progreso Basin province influenced depositional and erosional patterns across the region, and also the location, timing, and types of seals, traps, possible source and reservoir rocks, and hydrocarbon generation and migration. Marine shales that are interbedded with and overlie reservoir intervals are the probable hydrocarbon source rocks. Timing of hydrocarbon generation and migration was probably Miocene and younger, following creation of the Tumbes-Progreso subbasin by movement along the Dolores-Guayaquil megashear. More than 220 million barrels of oil (MMBO) and 255 billion cubic feet of gas (BCFG) have been produced from the Progreso Basin province. The means of estimated recoverable oil, gas, and natural gas liquids (NGL) resources from undiscovered fields in the province are 237 MMBO, 695 BCFG, and 32 MMB NGL, respectively. The means of estimated recoverable oil, gas, and NGL resources from undiscovered onshore fields are 45 MMBO, 113 BCFG, and 5 MMBNGL, and from undiscovered offshore fields are 192 BBO, 582 BCFG, and 27 MMBNGL. These are USGS grown undiscovered resources that were determined by using a minimum field size of 1 million barrels of oil equivalent.

  4. Neogene tectonic evolution of the southwestern Alboran Basin as inferred from seismic data off Morocco

    SciTech Connect

    Chalouan, A.; Saji, R.; Michard, A.; Bally, A.W.

    1997-07-01

    The southwestern part of the western Mediterranean Alboran Basin, including part of the Alboran ridge (Xaouen Bank), was investigated through the analysis of 28 intersecting multichannel seismic lines. The seismic stratigraphy is tied to the Amoco well El-Jebha 1. Five seismic units or subunits are described from the Quaternary to the middle (and lower?) Miocene. The acoustic basement is interpreted to be mainly Paleozoic and Triassic metamorphic rocks of the Alboran Domain nappes, and, in places, middle Miocene-Messinian calc-alkalic volcanics. In the depocenters, the thickness of the sedimentary infill (mostly clays and turbidites) exceeds 9 km. Normal faults of middle Miocene-Tortonian age are broadly parallel to the coast, and dip either seaward or landward. They were mostly inverted during pre- and post-Messinian episodes of compression, which formed a set of en echelon, north-verging faulted folds in the Alboran ridge area, in relation with sinistral movement along the offshore projection of the Jebha fault. After Pliocene subsidence, a final episode of compression reactivated the earlier folds and pushed the Alboran ridge onto the Moroccan slope. The complex structural history suggests many structural and stratigraphic potential hydrocarbon traps. A high-resolution seismic survey could lead to the definition of new exploration plays.

  5. Late Neogene and Early Quaternary Paleoenvironmental and Paleoclimatic Conditions in Southwestern Europe: Isotopic Analyses on Mammalian Taxa

    PubMed Central

    Domingo, Laura; Koch, Paul L.; Hernández Fernández, Manuel; Fox, David L.; Domingo, M. Soledad; Alberdi, María Teresa

    2013-01-01

    Climatic and environmental shifts have had profound impacts on faunal and floral assemblages globally since the end of the Miocene. We explore the regional expression of these fluctuations in southwestern Europe by constructing long-term records (from ∼11.1 to 0.8 Ma, late Miocene–middle Pleistocene) of carbon and oxygen isotope variations in tooth enamel of different large herbivorous mammals from Spain. Isotopic differences among taxa illuminate differences in ecological niches. The δ13C values (relative to VPDB, mean −10.3±1.1‰; range −13.0 to −7.4‰) are consistent with consumption of C3 vegetation; C4 plants did not contribute significantly to the diets of the selected taxa. When averaged by time interval to examine secular trends, δ13C values increase at ∼9.5 Ma (MN9–MN10), probably related to the Middle Vallesian Crisis when there was a replacement of vegetation adapted to more humid conditions by vegetation adapted to drier and more seasonal conditions, and resulting in the disappearance of forested mammalian fauna. The mean δ13C value drops significantly at ∼4.2−3.7 Ma (MN14–MN15) during the Pliocene Warm Period, which brought more humid conditions to Europe, and returns to higher δ13C values from ∼2.6 Ma onwards (MN16), most likely reflecting more arid conditions as a consequence of the onset of the Northern Hemisphere glaciation. The most notable feature in oxygen isotope records (and mean annual temperature reconstructed from these records) is a gradual drop between MN13 and the middle Pleistocene (∼6.3−0.8 Ma) most likely due to cooling associated with Northern Hemisphere glaciation. PMID:23717470

  6. Late neogene and early quaternary paleoenvironmental and paleoclimatic conditions in southwestern Europe: isotopic analyses on mammalian taxa.

    PubMed

    Domingo, Laura; Koch, Paul L; Hernández Fernández, Manuel; Fox, David L; Domingo, M Soledad; Alberdi, María Teresa

    2013-01-01

    Climatic and environmental shifts have had profound impacts on faunal and floral assemblages globally since the end of the Miocene. We explore the regional expression of these fluctuations in southwestern Europe by constructing long-term records (from ~11.1 to 0.8 Ma, late Miocene-middle Pleistocene) of carbon and oxygen isotope variations in tooth enamel of different large herbivorous mammals from Spain. Isotopic differences among taxa illuminate differences in ecological niches. The δ(13)C values (relative to VPDB, mean -10.3 ± 1.1‰; range -13.0 to -7.4‰) are consistent with consumption of C3 vegetation; C4 plants did not contribute significantly to the diets of the selected taxa. When averaged by time interval to examine secular trends, δ(13)C values increase at ~9.5 Ma (MN9-MN10), probably related to the Middle Vallesian Crisis when there was a replacement of vegetation adapted to more humid conditions by vegetation adapted to drier and more seasonal conditions, and resulting in the disappearance of forested mammalian fauna. The mean δ(13)C value drops significantly at ~4.2-3.7 Ma (MN14-MN15) during the Pliocene Warm Period, which brought more humid conditions to Europe, and returns to higher δ(13)C values from ~2.6 Ma onwards (MN16), most likely reflecting more arid conditions as a consequence of the onset of the Northern Hemisphere glaciation. The most notable feature in oxygen isotope records (and mean annual temperature reconstructed from these records) is a gradual drop between MN13 and the middle Pleistocene (~6.3-0.8 Ma) most likely due to cooling associated with Northern Hemisphere glaciation.

  7. Late neogene and early quaternary paleoenvironmental and paleoclimatic conditions in southwestern Europe: isotopic analyses on mammalian taxa.

    PubMed

    Domingo, Laura; Koch, Paul L; Hernández Fernández, Manuel; Fox, David L; Domingo, M Soledad; Alberdi, María Teresa

    2013-01-01

    Climatic and environmental shifts have had profound impacts on faunal and floral assemblages globally since the end of the Miocene. We explore the regional expression of these fluctuations in southwestern Europe by constructing long-term records (from ~11.1 to 0.8 Ma, late Miocene-middle Pleistocene) of carbon and oxygen isotope variations in tooth enamel of different large herbivorous mammals from Spain. Isotopic differences among taxa illuminate differences in ecological niches. The δ(13)C values (relative to VPDB, mean -10.3 ± 1.1‰; range -13.0 to -7.4‰) are consistent with consumption of C3 vegetation; C4 plants did not contribute significantly to the diets of the selected taxa. When averaged by time interval to examine secular trends, δ(13)C values increase at ~9.5 Ma (MN9-MN10), probably related to the Middle Vallesian Crisis when there was a replacement of vegetation adapted to more humid conditions by vegetation adapted to drier and more seasonal conditions, and resulting in the disappearance of forested mammalian fauna. The mean δ(13)C value drops significantly at ~4.2-3.7 Ma (MN14-MN15) during the Pliocene Warm Period, which brought more humid conditions to Europe, and returns to higher δ(13)C values from ~2.6 Ma onwards (MN16), most likely reflecting more arid conditions as a consequence of the onset of the Northern Hemisphere glaciation. The most notable feature in oxygen isotope records (and mean annual temperature reconstructed from these records) is a gradual drop between MN13 and the middle Pleistocene (~6.3-0.8 Ma) most likely due to cooling associated with Northern Hemisphere glaciation. PMID:23717470

  8. Neogene climate change and emergence of C 4 grasses in the Namib, southwestern Africa, as reflected in ratite 13C and 18O

    NASA Astrophysics Data System (ADS)

    Ségalen, Loïc; Renard, Maurice; Lee-Thorp, Julia A.; Emmanuel, Laurent; Le Callonnec, Laurence; de Rafélis, Marc; Senut, Brigitte; Pickford, Martin; Melice, Jean-Luc

    2006-04-01

    Stable light isotopes in ratite eggshells have been shown to be reliable indicators of shifts in climate and environmental conditions in the past. Here, we show that δ18O and δ13C values in fossil and modern ratite eggshells collected in the aeolianite deposits of the southern and central Namib Desert track regional distinctions and global climate shifts throughout the Neogene. δ18O values, although variable, are consistently higher in the central compared to the southern Namib throughout the record. δ18O trends during the Miocene differ for the two regions, but track each other post-Miocene. Throughout the Miocene, δ13C values for ratite eggshells from both the central and southern Namib regions are indistinguishable showing that the flora remained C 3 throughout. The overall negative (- 3‰) shift in mean values for Miocene biostratigraphic zones is consistent with the response of C 3 photosynthesis to pCO 2 shifts from 180 to 320 ppmv as estimated from marine alkenone studies and/or evolution of the δ13C of the atmospheric CO 2. Evidence for C 4 plants occurs post-Miocene, with the development of the southern, winter rainfall and central/northern, summer rainfall zonation apparent today. These data provide independent corroboration that the expansion of C 4-dominated ecosystems after ˜ 7 Ma cannot be attributed to a reduction of pCO 2 below a 500 ppmv threshold, as earlier proposed. Proliferation of C 4 plants in the Namib after ˜ 5 Ma and, elsewhere, may be related rather to energy budgets and rainfall seasonality shifts resulting from large-scale atmospheric and oceanic circulation reorganisation.

  9. Ostracods from the Neogene Solimões Formation (Amazonas, Brazil)

    NASA Astrophysics Data System (ADS)

    Feijó Ramos, Maria Inês

    2006-03-01

    Ostracods from an outcrop of the Solimões Formation (southwestern Amazonas state, Brazil) are studied. One new species ( Cytheridella purperae sp. nov. ) is described, and six species endemic to the Neogene of western Amazonia ( Darwinula fragilis, Cyprideis pebasae, C. graciosa, C. longispina, C. lacrimata, and Cypria aqualica) are reported, together with one unidentified species ( Cytheridella sp.). The fauna suggest a low-energy fluviolacustrine depositional setting, possibly with very low salinity. Using facies and ostracod data, the studied outcrop is compared with other Miocene deposits of western Amazonia.

  10. Diversification and extinction patterns among Neogene perimediterranean mammals.

    PubMed

    Jaeger, J J; Hartenberger, J L

    1989-11-01

    The best mammalian fossil record during the Neogene of Western Europe is that of the rodents, the most successful and diversified mammal order. The study of origination and extinction during the Neogene (24-3 Ma BP) in one of the best-documented areas, Spain and southern France, gives an insight into the dynamics of these communities and indicates the possible nature of the driving forces. Three main periods of time show a high rate of origination: the late Burdigalian (17.5 Ma BP), the early Vallesian (11.5-11 Ma BP) and the early Pliocene (4.2-3.8 Ma BP). Two of these high origination-rate periods are immediately followed by important extinction events during which all cohorts are deeply affected (11.5-11 Ma BP and 4.2-3.8 Ma BP). The most important extinction event seems to occur during the early Vallesian (11.5-11 Ma BP), which probably includes the middle/late Miocene boundary. At the Miocene/Pliocene boundary, and during the early Pliocene, the faunal turnover seems to become faster, inducing a strong decrease of the mean species duration. Whereas the main immigration event, which occurs at 17.5 Ma BP, can be related to other faunal migrations in terms of the closure of the Tethys, as it occurs also in eastern Africa and in southwest Asia, the middle/late Miocene boundary event may have been related to a period of ice growth in the Southern Hemisphere. The extinction event that affects the planktonic foraminifera at 12 Ma BP cannot be chronologically correlated to this southwestern European land-mammal extinction event, because the calibration of the marine fossil record during that time-span has to be precise. Some limited terrestrial faunal exchanges that occur during the Messinian between southwestern Europe and northwestern Africa do not deeply affect the general faunal dynamics. Both allochthonous cohorts of immigrants become rapidly extinct. Several endemic rodent faunas, indicating insular conditions, have been reported from the southern edge of the

  11. Transarterial chemoembolization and bland embolization for hepatocellular carcinoma.

    PubMed

    Tsochatzis, Emmanuel A; Fatourou, Evangelia; O'Beirne, James; Meyer, Tim; Burroughs, Andrew K

    2014-03-28

    Transarterial chemoembolization (TACE) is the first line treatment for patients with intermediate stage hepatocellular carcinoma but is also increasingly being used for patients on the transplant waiting list to prevent further tumor growth. Despite its widespread use, TACE remains an unstandardized procedure, with variation in type and size of embolizing particles, type and dose of chemotherapy and interval between therapies. Existing evidence from randomized controlled trials suggest that bland transarterial embolization (TAE) has the same efficacy with TACE. In the current article, we review the use of TACE and TAE for hepatocellular carcinoma and we focus on the evidence for their use. PMID:24695579

  12. Fossil diatoms and neogene paleolimnology

    USGS Publications Warehouse

    Platt, Bradbury J.

    1988-01-01

    Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the

  13. Bland Embolization of Hepatocellular Carcinoma Using Superabsorbent Polymer Microspheres

    SciTech Connect

    Osuga, Keigo; Hori, Shinichi; Hiraishi, Kumiko; Sugiura, Takashi; Hata, Yasuhiro; Higashihara, Hiroki; Maeda, Noboru; Tomoda, Kaname; Nakamura, Hironobu

    2008-11-15

    The purpose of this study was to investigate the clinical outcomes of bland embolization using superabsorbent polymer microspheres (SAP-TAE) as an initial therapeutic option for previously untreated hepatocellular carcinoma (HCC) ineligible for resection or ablation. Fifty-nine patients with previously untreated HCC unamenable to surgery or ablation underwent bland embolization using 100- to 200-{mu}m reconstituted SAP particles (SAP-TAE) as the initial treatment. SAP-TAE was repeated as needed based on tumor response but was switched to chemoembolization when necessary to control residual or progressive tumor. Early tumor response was assessed by contrast-enhanced CT according to RECIST and EASL criteria 1 month after the initial SAP-TAE. The overall survival was calculated using the Kaplan-Meier method. The overall mean follow-up period was 30.6 months (range, 7-59 months). A total of 121 sessions of SAP-TAE were performed, with 1-5 sessions per patient (mean, 2.1 sessions). The mean period of repeated SAP-TAE was 15.6 months (range, 1-51 months), and it exceeded 1 and 2 years in 32 (54%) and 15 (25%) patients, respectively. Thirteen (22%) patients underwent repeated SAP-TAE alone, and the remaining 46 (78%) patients underwent subsequent chemoembolization. No major complication was observed and postembolization syndrome was minimal after SAP-TAE in all patients. Response rate was 14% and 66% by RECIST and EASL criteria, respectively. Overall survival rates were 100% and 83% at 1 and 2 years, respectively, and median survival time was 30 months. In conclusion, SAP-TAE was a safe and repeatable option as the induction therapy for HCC unamenable to surgery or ablation, despite the high incidence of converting to TACE during the total course.

  14. Neogene crustal extension in Aegean, revisited

    SciTech Connect

    Stiros, S.C. )

    1988-08-01

    The Neogene evolution of the Aegean and adjacent areas has been described as the result of homogeneous, subduction-associated lithosphere stretching by a factor near two, interrupted or not by short regional compressional intervals. However, reconsideration of some of the existing data (structural, volcanological, heat flow) and new or unpublished information from Greece, southern Bulgaria, and Yugoslavia concerning different scales, structural (tectonics of lignite and other basins), morpholtectonic (describing bulges, differential coastal movements, rotations of blocks around vertical axes, etc.), some seismic lines offshore, and aeromagnetic data suggest the following. (1) The patterns of Neogene volcanism, heat flow, and vertical motions are inconsistent with the idea of homogeneous stretching. (2) There is no evidence of features that should have accommodated the postulated level of regional extension. (3) The evolution of most Neogene basins, compressional features, and bulges in normal faulting environments most likely does not reflect cycles of regional extension-compression but of transtension-transpression associated with Mesozoic and still active shear zones and deeper processes. These data suggest that for the Aegean the uniform extension model is unsatisfactory in both large and local scale; small amounts of probably secondary extension are likely; and processes other than subduction must be anticipated.

  15. Evolution of Neogene Dynamic Topography in Madagascar

    NASA Astrophysics Data System (ADS)

    Paul, J. D.; Roberts, G.; White, N. J.

    2012-12-01

    Madagascar is located on the fringes of the African superswell. Its position and the existence of a +30 mGal long wavelength free-air gravity anomaly suggest that its present-day topography is maintained by convective circulation of the sub-lithospheric mantle. Residual depth anomalies of oceanic crust encompassing the island imply that Madagascar straddles a dynamic topographic gradient. In June-July 2012, we examined geologic evidence for Neogene uplift around the Malagasy coastline. Uplifted coral reef deposits, fossil beach rock, and terraces demonstrate that the northern and southern coasts are probably being uplifted at a rate of ~0.2 mm/yr. Rates of uplift clearly vary around the coastline. Inland, extensive peneplains occur at elevations of 1 - 2 km. These peneplains are underlain by 10 - 20 m thick laterite deposits, and there is abundant evidence for rapid erosion (e.g. lavaka). Basaltic volcanism also occurred during Neogene times. These field observations can be combined with an analysis of drainage networks to determine the spatial and temporal pattern of convectively driven uplift. ~100 longitudinal river profiles were extracted from a digital elevation model of Madagascar. An inverse model is then used to minimize the misfit between observed and calculated river profiles as a function of uplift rate history. During inversion, the residual misfit decreases from ~20 to ~4. Our results suggest that youthful and rapid uplift of 1-2 km occurred at rates of 0.2-0.4 mm/yr during the last ˜15 Myr. The algorithm resolves distinct phases of uplift which generate localized swells of high topography and relief (e.g. the Hauts Plateaux). Our field observations and modeling indicate that the evolution of drainage networks may contain useful information about mantle convective processes.

  16. Including the Tukey Mean-Difference (Bland-Altman) Plot in a Statistics Course

    ERIC Educational Resources Information Center

    Kozak, Marcin; Wnuk, Agnieszka

    2014-01-01

    The Tukey mean-difference plot, also called the Bland-Altman plot, is a recognized graphical tool in the exploration of biometrical data. We show that this technique deserves a place on an introductory statistics course by encouraging students to think about the kind of graph they wish to create, rather than just creating the default graph for the…

  17. Pliocene reversal of late Neogene aridification

    PubMed Central

    Sniderman, J. M. Kale; Woodhead, Jon D.; Jordan, Gregory J.; Drysdale, Russell N.; Tyler, Jonathan J.; Porch, Nicholas

    2016-01-01

    The Pliocene epoch (5.3–2.6 Ma) represents the most recent geological interval in which global temperatures were several degrees warmer than today and is therefore considered our best analog for a future anthropogenic greenhouse world. However, our understanding of Pliocene climates is limited by poor age control on existing terrestrial climate archives, especially in the Southern Hemisphere, and by persistent disagreement between paleo-data and models concerning the magnitude of regional warming and/or wetting that occurred in response to increased greenhouse forcing. To address these problems, here we document the evolution of Southern Hemisphere hydroclimate from the latest Miocene to the middle Pliocene using radiometrically-dated fossil pollen records preserved in speleothems from semiarid southern Australia. These data reveal an abrupt onset of warm and wet climates early within the Pliocene, driving complete biome turnover. Pliocene warmth thus clearly represents a discrete interval which reversed a long-term trend of late Neogene cooling and aridification, rather than being simply the most recent period of greater-than-modern warmth within a continuously cooling trajectory. These findings demonstrate the importance of high-resolution chronologies to accompany paleoclimate data and also highlight the question of what initiated the sustained interval of Pliocene warmth. PMID:26858429

  18. Geochemical evolution of Cenozoic-Cretaceous magmatism and its relation to tectonic setting, southwestern Idaho, U.S.A

    NASA Technical Reports Server (NTRS)

    Norman, Marc D.; Leeman, William P.

    1989-01-01

    The relationships between Cretaceous to Neogene magmatism and the tectonic setting of southwestern and central Idaho are evaluated. An overview of the tectonics and geology of the northwestern U.S. is presented. Major element, trace element, and Sr, Pb, and Nd isotopic data for the region are used to place constraints on magma source characteristics, the manner in which the magmatic sources evolved through time, and the nature of interactions among mantle and crustal domains in response to changing tectonic environment.

  19. Bland diet

    MedlinePlus

    ... gassy, such as broccoli, cabbage, cauliflower, cucumber, green peppers, and corn Seedy fruits such as berries or ... sauerkraut, and similar foods Spices, such as hot pepper and garlic Foods with a lot of sugar ...

  20. Mapping potential Blanding's turtle habitat using aerial orthophotographic imagery and object based classification

    NASA Astrophysics Data System (ADS)

    Barker, Rebecca

    Blanding's turtle (Emydoidea blandingii) is a threatened species in southern Quebec that is being inventoried to determine abundance and potential habitat by the Quebec Ministry of Natural Resources and Wildlife. In collaboration with that program and using spring leaf-off aerial orthophotos of Gatineau Park, attributes associated with known habitat criteria were analyzed: wetlands with open water, vegetation mounds for camouflage and thermoregulation, and logs for spring sun-basking. Pixel-based classification to separate wetlands from other land cover types was followed by object-based segmentation and rule-based classification of within--wetland vegetation and logs. Classifications integrated several image characteristics including texture, context, shape, area and spectral attributes. Field data and visual interpretation showed the accuracies of wetland and within wetland habitat feature classifications to be over 82.5%. The wetland classification results were used to develop a ranked potential habitat suitability map for Blanding's turtle that can be employed in conservation planning and management.

  1. The Bland-Altman Method Should Not Be Used in Regression Cross-Validation Studies

    ERIC Educational Resources Information Center

    O'Connor, Daniel P.; Mahar, Matthew T.; Laughlin, Mitzi S.; Jackson, Andrew S.

    2011-01-01

    The purpose of this study was to demonstrate the bias in the Bland-Altman (BA) limits of agreement method when it is used to validate regression models. Data from 1,158 men were used to develop three regression equations to estimate maximum oxygen uptake (R[superscript 2] = 0.40, 0.61, and 0.82, respectively). The equations were evaluated in a…

  2. Neogene Extension and Exhumation in NW Sulawesi

    NASA Astrophysics Data System (ADS)

    Advokaat, E. L.; Hall, R.; White, L. T.; Armstrong, R. A.; Kohn, B. P.; BouDagher-Fadel, M. K.

    2014-12-01

    The unusual K-shaped island of Sulawesi, located in the convergent zone between the Eurasian, Australian and Pacific plates, has traditionally been interpreted as the consequence of collision and accretion. New data challenge this idea and indicate that crustal extension has played an important role in its Neogene development. In the north of the Sulawesi North Arm are Eocene-Lower Miocene basalts intercalated with radiolarian chert and volcaniclastic sediments, which were deformed during collision of the Sula Spur with the North Arm. Undeformed granitoids derived from lower crustal rocks intrude the sequence and preliminary LA-ICP-MS U-Pb zircon ages decrease from 9.44±0.43 Ma in the north to 8.19±0.20 Ma in the south. Structurally beneath all these rocks is the Malino Metamorphic Complex (MMC) which exposes dominantly quartzo-feldspathic muscovite schists to gneisses, with subordinate amphibolites and garnet schists. The MMC is a metamorphic core complex, surrounded by a discontinuous greenschist carapace and shear zones with opposite shear senses on the northern and southern sides of the complex. Metamorphic rocks from the MMC yield SHRIMP U-Pb ages on zircon rims of 15.42±0.62 Ma and 15.36±0.53 Ma. Locally these metamorphic rocks are intruded by undeformed granitoids with SHRIMP U-Pb zircon ages of 4.85 ± 0.07 to 3.78±0.04 Ma. Late stage exhumation accommodated by high angle oblique normal faults is indicated by apatite (U-Th)/He ages between 3.26±0.23 Ma and 1.43±0.24 Ma, at a rate of 0.27 mm/a based on age-elevation plots. Lower Pliocene-Lower Pleistocene syn-extensional shallow marine siliciclastic and carbonate sediments are crosscut by normal faults. The timing of faulting and lack of metamorphic detritus in these young sediments support rapid and recent regional uplift. We interpret two phases of extension in North Sulawesi, one during the Middle Miocene and another during the Late Pliocene-Pleistocene, exhuming the granitic and metamorphic rocks.

  3. Paleogene and Neogene reference sections of Eastern Kamchatka

    NASA Astrophysics Data System (ADS)

    Gladenkov, Yu. B.

    2016-01-01

    The available lithological and paleontological data are used to characterize key Cenozoic marine sections in two lithological-facies zones (Kamchatskii Mys Peninsula and southern Valaginskii Range) of the poorly investigated Eastern Kamchatka lithotectonic zone with their correlation and reconstruction of depositional environments at the ocean-continent transition during the Paleogene and Neogene.

  4. Neogene molluscan stages of the West Coast of North America

    USGS Publications Warehouse

    Marincovich, L.

    1984-01-01

    Neogene marine sediments of the West Coast of North America were deposited in a series of widely spaced basins that extended geographically from the western and northern Gulf of Alaska (60??N) to southern California (33??N). Rich molluscan faunas occur extensively throughout these deposits and form the basis for biostratigraphic schemes that are useful for correlating within and between individual basins. Early biostratigraphic work was concerned with faunas from particular horizons and with the stratigraphic range of diverse taxa, such as Pecten and Turritella, without reference to other fossil groups. Succeeding work increasingly dealt with the relationships of molluscan zones to benthic and, later, planktonic foraminiferal stages. In recent years the age limits of Neogene molluscan stages have become better documented by reference to planktonic microfossils from dated DSDP cores and onshore faunas. Neogene molluscan faunas from California, the Pacific Northwest states (Oregon and Washington), and southern Alaska have been treated separately due to differences in faunal composition and geographic isolation. As a result, a different biostratigraphic sequence has been described for each region. Pacific Northwest stages have been formally named and defined, and their names are also used informally for Alaskan faunas. California Neogene stages were proposed early in this century, are in need of redescription, and their usage is informal. Precise correlations between the three regional sequences have not yet been achieved, due to the low number of co-occurring species and the general lack of planktonic microfossils in these largely shallow-water faunas. The objectives of ongoing research include: fuller documentation of the faunas of California and Pacific Northwest stages; formal description of California stages; improved correlation between regional stage sequences; refinement of age estimates for stage boundaries; and, establishment of Neogene stages for Alaskan

  5. Prospective Randomized Comparison of Chemoembolization with Doxorubicin-Eluting Beads and Bland Embolization with BeadBlock for Hepatocellular Carcinoma

    SciTech Connect

    Malagari, Katerina; Pomoni, Mary; Kelekis, Alexis; Pomoni, Anastasia; Dourakis, Spyros; Spyridopoulos, Themis; Moschouris, Hippokratis; Emmanouil, Emmanouil; Rizos, Spyros; Kelekis, Dimitrios

    2010-06-15

    The purpose of this study was to evaluate the added role of a chemotherapeutic in transarterial chemoembolization (TACE) of intermediate-stage hepatocellular carcinoma (HCC). The issue is of major importance since, as suggested by recent evidence, hypoxia or incomplete devascularization of the tumor is a potent stimulator of angiogenesis, and there are not many papers supplying level one evidence confirming the value of a chemotherapeutic. The hypothesis was that since drug-eluting bead (DEB)-TACE is standardized and reproducible, a comparison with bland TACE can readily reveal the potential value of the chemotherapeutic. Two groups were randomized in this prospective study: group A (n = 41) was treated with doxorubicin DEB-TACE, and group B (n = 43) with bland embolization. Patients were randomized for tumor diameter. Patients were embolized at set time intervals (2 months), with a maximum of three embolizations. Tumor response was evaluated using the EASL criteria and {alpha}-fetoprotein levels. At 6 months a complete response was seen in 11 patients (26.8%) in the DEB-TACE group and in 6 patients (14%) in the bland embolization group; a partial response was achieved in 19 patients (46.3%) and 18 (41.9%) patients in the DEB-TACE and bland embolization groups, respectively. Recurrences at 9 and 12 months were higher for bland embolization (78.3% vs. 45.7%) at 12 months. Time to progression (TTP) was longer for the DEB-TACE group (42.4 {+-} 9.5 and 36.2 {+-} 9.0 weeks), at a statistically significant level (p = 0.008). In conclusion, DEB-TACE presents a better local response, fewer recurrences, and a longer TTP than bland embolization with BeadBlock. However, survival benefit and bland embolization with smaller particles must be addressed in future papers to better assess the clinical value.

  6. Relating annual increments of the endangered Blanding's turtle plastron growth to climate.

    PubMed

    Richard, Monik G; Laroque, Colin P; Herman, Thomas B

    2014-05-01

    This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration.

  7. Relating annual increments of the endangered Blanding's turtle plastron growth to climate

    PubMed Central

    Richard, Monik G; Laroque, Colin P; Herman, Thomas B

    2014-01-01

    This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration. PMID:24963390

  8. Relating annual increments of the endangered Blanding's turtle plastron growth to climate.

    PubMed

    Richard, Monik G; Laroque, Colin P; Herman, Thomas B

    2014-05-01

    This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration. PMID:24963390

  9. Marine intervals in Neogene fluvial deposits of western Amazonia

    NASA Astrophysics Data System (ADS)

    Boonstra, Melanie; Troelstra, Simon; Lammertsma, Emmy; Hoorn, Carina

    2014-05-01

    Amazonia is one of the most species rich areas on Earth, but this high diversity is not homogeneous over the entire region. Highest mammal and tree-alpha diversity is found in the fluvio-lacustrine Pebas system, a Neogene wetland associated with rapid radiation of species. The estuarine to marine origin of various modern Amazonian fish, plants, and invertebrates has been associated with past marine ingressions into this freshwater Pebas system. The exact nature and age of these invasions is, however, debated. Here we present new evidence from fluvial and fluvio-lacustrine deposits of Neogene age in southeast Colombia, that point to periods of widespread marine conditions in western Amazonia. Our evidence is based on an analysis of marine palynomorphs, such as organic linings of foraminifera and dinoflagellate cysts, present in dark sandy clay sediments that outcrop along the Caqueta and Amazon rivers. Characteristically, the foraminiferal linings can be assigned to three benthic morphotypes only, e.g. Ammonia, Elphidium and Trochammina. This low diversity assemblage is associated with estuarine/marginal marine conditions. No distinct marine elements such as shelf or planktonic species were encountered. The observed foraminiferal linings and dinocyst assemblages are typical for a (eutrophic) shallow marine environment, suggesting that the Pebas freshwater wetland system occasionally changed to (marginal) marine. Although some reworked elements are found, a typical Neogene dinocyst taxon is commonly found supporting in situ deposition. Sedimentological features typical for tidal conditions that are reported for sites in Peru and northeastern Brazil likely relate to these marine ingressions. Sea level changes as well as foreland basin development related to Andes formation may have facilitated the entry of marine water during the Neogene.

  10. Contourites and their Neogene Development along the NE Atlantic Margin

    NASA Astrophysics Data System (ADS)

    van Weering, T. C. E.; de Haas, H.; Shannon, P.; Praeg, D.; Stoker, M.; Holmes, R.

    2003-04-01

    During the EU funded STRATAGEM* program a new and unified Neogene stratigraphy of the NE Atlantic Margin from Ireland to north Norway was defined on the basis of analysis of a large suite of single and multi-channel profiles collected over the last decade by the STRATAGEM partners, complemented with partially confidential industry seismic and borehole data. Key reflectors were defined and by means of construction of stratigraphic range charts, constrained and tested by existing borehole and well data. These show that especially in the Rockall Trough and Faeroe Shetland Channel, and to a lesser extent off the Norwegian margin, contourite deposits form an important element of the Neogene succession. Onset of contourite development in the Rockall Trough and Porcupine Basin was in the early Oligocene, forced by rapid differential subsidence and seaward tilting of the basins. The contourites are predominantly developed along the basin margins and show in areas of upslope accretion, migration from the deep basin onto the slope with both onlapping and downlapping reflector terminations. The distribution and characteristics of the Neogene contourite development along the NE Atlantic margin will be defined in detail, in relation to tectonic and oceanographic conditions and their variability. *STRATAGEM www.stratagem-europe.org

  11. Survey and monitoring of species at risk at Camp Blanding Training Site, northeastern Florida

    USGS Publications Warehouse

    Gregory, C.J.; Carthy, R.R.; Pearlstine, L.G.

    2006-01-01

    We studied the presence and distribution of 19 species at risk in northeastern Florida at the Camp Blanding Training Site (CBTS) during 2000-2001, seven years after the first major baseline surveys of CBTS were conducted. Much of the training conducted at CBTS deals with light infantry exercises, but the site is also used for mining, silviculture, hunting, fishing, emergency logistical support, and entertainment purposes. CBTS contains more than 2000 species of plants and animals in 14 natural communities, each impacted to various degrees by past and current land management. Adaptive management plans for species may be ineffective without continual feedback and the flexibility for change. Here we summarize and discuss the results of our surveys, compare these results with those of past surveys, identify differences between the surveys, and discuss the importance of systematic protocols and study design for CBTS environmental managers.

  12. Moving on from bland: the evolution of the law and minimally conscious patients.

    PubMed

    Heywood, Rob

    2014-01-01

    The decision in Bland centred on the withdrawal of artificial nutrition and hydration from a patient in a persistent vegetative state (PVS). Since then, a new medical condition has emerged, known as a minimally conscious state (MCS). In W v M, the Court of Protection was asked to authorise the withdrawal of artificial nutrition and hydration from a patient in a MCS. Baker J refused to grant the declaration. More recently, however, the courts were also asked to rule on the lawfulness of withholding treatment in a similar, albeit factually different, case. In the Court of Appeal decision in Aintree University Hospitals NHS Foundation Trust v David James and Others, Sir Alan Ward, with the agreement of Arden LJ and Laws LJ, granted a declaration that it would be lawful to withhold treatment. The Supreme Court then upheld this ruling, Lady Hale stating that the Court of Appeal reached the right result but for the wrong reasons. This article seeks to critically appraise the evolution of the law in regard to withdrawing treatment from MCS patients. The piece begins by explaining the differences between the two conditions of PVS and MCS and defines the law from the starting point of Bland. From here, the discussion progresses to focus on the challenges that the law has had to face in trying to keep pace with the advancing nature of medical understanding of conditions of the brain and explains how it has responded to these. The narrative then critiques the legal mechanism of best interests as it has been employed in the case law concerning MCS patients to date by analysing the various judicial perspectives on the concept. After addressing both the narrow and wide viewpoints, a conclusion is ventured as to how the balancing of best interests should be approached in respect of future MCS cases. PMID:24618294

  13. Aneurysm of the Left Coronary Artery in Postoperative Bland-White-Garland Syndrome.

    PubMed

    Bravo-Valenzuela, Nathalie Jeanne Magioli; Silva, Guilherme Ricardo Nunes

    2015-01-01

    We report a case of anomalous left coronary artery from the pulmonary artery (ALCAPA) or Bland-White-Garland syndrome, present the challenges of performing a differential diagnosis, and discuss the treatment of the syndrome. Although ALCAPA is a rare congenital heart disease, it is one of the most common causes of myocardial ischemia in childhood and presents a diagnostic challenge. A four-year-old girl was referred to a pediatric cardiologist for evaluation of mitral valve regurgitation murmur and heart failure. The transthoracic echocardiogram demonstrated the left coronary artery (LCA) not arising from the aorta, presence of coronary collateral circulation, and moderate mitral valve regurgitation. ALCAPA was confirmed using angiotomography. The LCA was surgically reimplanted into the aorta. After 3 years of postoperative follow-up, the patient developed an LCA aneurysm. Diagnosis of cardiac ischemia in childhood remains a challenge, and careful evaluation of coronary arteries on the echocardiogram is an important tool. In this report, we present a case of ALCAPA with an uncommon postoperative outcome. PMID:26770839

  14. Domal structure in Devonian rocks of Kimberling basin, Bland County, Virginia

    SciTech Connect

    McDowell, R.C.

    1988-08-01

    The Kimberling basin, which is floored with Middle Devonian clastic rocks, is a topographic and structural low in the Narrows fault block of the southern Appalachian Valley and Ridge province in Bland County, Virginia. The basin is bounded on the northwest and southeast by the southeast-dipping Narrows and Saltville thrust faults, respectively. Two doubly plunging anticlines lie along the strike of the basin. Lower Ordovician rocks are exposed in the Burkes Garden dome to the southwest, and Lower Cambrian rocks are present in the core of the Bane dome to the northeast. Previous workers have postulated continuity between the Burkes Garden and Bane domes through the Kimberling basin, as well as the presence in the basin of an anomalously thick Devonian clastic section, which has been ascribed by some authors to contemporaneous downwarp of a depositional syncline. Recent mapping has shown both of these postulates to be incorrect. The basin contains an anticline-syncline pair that is en echelon with the axes of the Burkes Garden and Bane anticlines and that trends about 20/degree/ more northerly than the regional strike of the bounding thrusts. Rediscovery of small outcrops of Lower and Middle Devonian Huntersville Chert and Rocky Gap Sandstone in the core of the Kimberling basin anticline, which were recorded by M.R. Campbell in 1896 but overlooked by later mappers, shows that the Devonian clastic sequence has a normal thickness and that the Kimberling basin contains a domal structure similar to the Burkes Garden and Bane domes.

  15. Neogene sedimentation on the outer continental margin, southern Bering Sea

    USGS Publications Warehouse

    Vallier, T.L.; Underwood, M.B.; Gardner, J.V.; Barron, J.A.

    1980-01-01

    Neogene sedimentary rocks and sediments from sites on the outer continental margin in the southern Bering Sea and on the Alaska Peninsula are dominated by volcanic components that probably were eroded from an emergent Aleutian Ridge. A mainland continental source is subordinate. Most sediment in the marine environment was transported to the depositional sites by longshore currents, debris flows, and turbidity currents during times when sea level was near the outermost continental shelf. Fluctuations of sea level are ascribed both to worldwide glacio-eustatic effects and to regional vertical tectonics. Large drainage systems, such as the Yukon and Kuskokwim Rivers, had little direct influence on sedimentation along the continental slope and Unmak Plateau in the southern Bering Sea. Sediments from those drainage systems probably were transported to the floor of the Aleutian Basin, to the numerous shelf basins that underlie the outer continental shelf, and to the Arctic Ocean after passing through the Bering Strait. Environments of deposition at the sites along the outer continental margin have not changed significantly since the middle Miocene. The site on the Alaska Peninsula, however, is now emergent following shallow-marine and transitional sedimentation during the Neogene. ?? 1980.

  16. Neogene paleoenvironments and tectonics of the Hongchun Peninsula, southern Taiwan

    SciTech Connect

    Chang, S. . Taiwan Petroleum Exploration Div.); Vondra, C.F. . Geological Atmospheric Sciences)

    1993-03-01

    Recent investigations in the Hongchun Peninsula in southern Taiwan provide new evidence concerning the paleoenvironmental and tectonic interpretation of the structurally complex Neogene sediments exposed there. The deposits of the peninsula have been divided into four distinct fault-bounded sequences each displaying a different lithology and style of structural development. The Mutanchi formation consists of feldspathic quartz arenites derived from a granitic provenance to the north that were deposited in a forearc basin. The lower part of the Mutanchi is dominated by thick proximal turbidities and interbedded highly contorted shales of submarine fan origin. These grade upward into shallow marine feldpathic quartz arenites and shales. The Shiman Formation consists of tuffaceous lithic arenites (proximal turbidities) and diamicites (debris flow deposits) with gravel-sized metamorphic and volcanic clasts in the lower part and interbedded lithic arenites and shales in the upper part. Although of contrasting lithology to the Mutanchi, the lower part of the Shiman Formation was also deposited on a submarine fan in a forearc tectonic setting while the upper part was deposited on a shallow marine shelf. The Kentin Formation is composed entirely of thick light green mudstones with contorted slump structures. Locally it contains very large exotic blocks (olistoliths) of variable lithology and is interpreted to be a melange -- the Kentin Melange. The above four fault-bounded units represent a forearc basin-accretionary wedge complex that developed during the late Neogene as a result of convergent interaction between the South China and Philippine plates.

  17. Strontium isotope geochronology of selected intervals within the Florida Neogene

    SciTech Connect

    Jones, D.S.; Mueller, P.A.; Hodell, D.A.; Stanley, L.A. . Dept. of Geology)

    1993-03-01

    The Neogene stratigraphic record of Florida reveals many richly fossiliferous (both invertebrate and vertebrate), shallow-marine deposits whose ages are poorly constrained, despite over a century of paleontological investigation. Chronostratigraphic analyses are frequently hampered by a general absence of age-diagnostic fossils (micro- or nannofossils in particular), laterally discontinuous sedimentary units, and an overall lack of natural exposure. Consequently, temporal correlations among many of Florida's Neogene units as well as with the global geomagnetic polarity timescale (GPTS) remain tenuous. Strontium isotope ([sup 87]Sr/[sup 86]Sr) geochronology offers considerable potential as an independent method for correlating these deposits with one another as well as with the GPTS. Portions of the Miocene and Pliocene as well as most of the Pleistocene were characterized by rapid increases in the global [sup 87]Sr/[sup 86]Sr of seawater. Marine carbonates formed within these intervals are therefore particularly amenable to investigation by Sr isotope techniques. Ratios ([sup 87]Sr/[sup 86]Sr) from mollusk shells collected throughout Florida within stratigraphic context ranged from 0.70785 which roughly correspond to the interval 30 Ma (late Oligocene) to 1 Ma (late Pleistocene). The data suggest that many accepted correlations based on lithologic and/or faunal similarities within Florida's Miocene and Plio-Pleistocene strata are improbable. While additional sampling is in order, improved correlation between vertebrate and invertebrate biochronologies has already resulted from the stratigraphic based upon this approach.

  18. Neogene Topography And Precipitation Patterns Of The Central Anatolian Plateau

    NASA Astrophysics Data System (ADS)

    Mulch, A.; Mikes, T.; Schemmel, F.; Rojay, B.

    2010-12-01

    Long-term stable isotope records of terrestrial environments represent increasingly important tools for tectonic, paleoaltimetric, and paleoclimatic reconstructions within continental interiors. A rapidly growing number of studies within the Earth’s major mountain ranges demonstrates that the growth of topography and orogenic plateaus profoundly influences local, regional, and hemispheric climate and hence precipitation patterns while regional surface uplift patterns are intimately linked to plate-scale geodynamic processes. In contrast, such records are almost absent for the Near East and the Turkish-Iranian plateau, an important topographic element in the Alpine-Himalayan chain and an area most likely to be strongly affected by future climate change and water scarcity. Our objective is to assess the role of orographic factors that have governed the distribution (and isotopic composition) of precipitation across the central Anatolian plateau (CAP, Turkey) from the Neogene to recent. Such data are fundamental for our understanding of the geodynamic and sedimentary history of orogenic plateaus in general and for the role of surface uplift along the plateau margins in the Pontide and Tauride mountains. We present oxygen, carbon, and hydrogen isotope data from Neogene-to-recent fluvio-lacustrine and pedogenic environments, stream and lake waters of the CAP with the ultimate aim of reconstructing past precipitation changes, plateau aridification and ideally Neogene surface uplift histories. Our approach is to cross-calibrate modern patterns of isotopes (oxygen and hydrogen) in precipitation with pedogenic carbonate oxygen and carbon isotope data across topographic barriers that today strongly control the distribution of rainfall along the plateau margins and within the plateau interior. We then compare these patterns with Miocene-to-Pleistocene lacustrine and pedogenic records to assess a) the role of late Neogene (ca. 8-0 Ma) surface uplift in the Taurus mountains

  19. Seismic fabric and 3-D structure of the southwestern intracontinental Palmyride fold belt, Syria

    SciTech Connect

    Chaimov, T.A.; Barazangi, M. ); Al-Saad, D.; Sawaf, T.; Khaddour, M. )

    1993-12-01

    The Palmyride fold belt, a 400 x 100 km transpressive belt in central Syria that is the northeastern arm of the Syrian arc, is the result of late Mesozoic and Cenozoic inversion of a late Paleozoic and Mesozoic, northeast-trending, linear intracontinental basin located within the northern Arabian platform. The southwestern Palmyrides, near the Dead Sea transform fault system and the Anti-Lebanon mountains, are characterized by short wavelength (5--10 km) en echelon folds separated by small intermontane basins that developed mainly in the Neogene to Holocene. A new three-dimensional data cube, 60 x 70 x 10 km, generated on a Landmark Graphics workstation and based on approximately 700 km of two-dimensional seismic reflection profiles, elucidates the structure of the upper 10 km of the crust in the southwestern Palmyrides. Visualization of the subsurface structure, which is represented by a prominent Upper Cretaceous reflection surface in the data cube, is augmented by topographical and Bouguer gravity data of the same region. Preexisting discontinuities, probable normal fault relicts of the Mesozoic Palmyride rift, likely controlled the development of individual Neogene thrusts. The new subsurface image shows important structural features not identified in outcrop. Short, west-northwest-trending transcurrent (or transfer) faults like the short, en echelon northeast-trending thrust faults and blind thrusts of the Palmyrides. A pervasive regional decollment is not observed, even though Triassic evaporites host local detachments. Unlike topographic relief, which only roughly resembles subsurface structures, the Bouguer gravity signature of the southwestern Palmyrides closely mimics underlying shallow geologic structures both on a large ([approximately]50 km wavelength) and a small ([approximately]5--10 km wavelength) scale. The structural analysis and many other recent studies of the region indicate minor right-lateral shear coupled with compression in the Palmyrides.

  20. Neogene Development of the Terror Rift, western Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Sauli, C.; Sorlien, C. C.; Busetti, M.; De Santis, L.; Wardell, N.; Henrys, S. A.; Geletti, R.; Wilson, T. J.; Luyendyk, B. P.

    2015-12-01

    Terror Rift is a >300 km-long, 50-70 km-wide, 14 km-deep sedimentary basin at the edge of the West Antarctic Rift System, adjacent to the Transantarctic Mountains. It is cut into the broader Victoria Land Basin (VLB). The VLB experienced 100 km of mid-Cenozoic extension associated with larger sea floor spreading farther north. The post-spreading (Neogene) development of Terror Rift is not well understood, in part because of past use of different stratigraphic age models. We use the new Rossmap seismic stratigraphy correlated to Cape Roberts and Andrill cores in the west and to DSDP cores in the distant East. This stratigraphy, and new fault interpretations, was developed using different resolutions of seismic reflection data included those available from the Seismic Data Library System. Depth conversion used a new 3D velocity model. A 29 Ma horizon is as deep as 8 km in the south, and a 19 Ma horizon is >5 km deep there and 4 km-deep 100 km farther north. There is a shallower northern part of Terror Rift misaligned with the southern basin across a 50 km right double bend. It is bounded by steep N-S faults down-dropping towards the basin axis. Between Cape Roberts and Ross Island, the Oligocene section is also progressively-tilted. This Oligocene section is not imaged within northern Terror Rift, but the simplest hypothesis is that some of the Terror Rift-bounding faults were active at least during Oligocene through Quaternary time. Many faults are normal separation, but some are locally vertical or even reverse-separation in the upper couple of km. However, much of the vertical relief of the strata is due to progressive tilting (horizontal axis rotation) and not by shallow faulting. Along the trend of the basin, the relief alternates between tilting and faulting, with a tilting margin facing a faulted margin across the Rift, forming asymmetric basins. Connecting faults across the basin form an accommodation zone similar to other oblique rifts. The Neogene basin is

  1. Southwestern desert resources

    USGS Publications Warehouse

    Halvorson, William L.; van Riper, Charles; Schwalbe, Cecil R.

    2010-01-01

    The southwestern deserts stretch from southeastern California to west Texas and then south to central Mexico. The landscape of this region is known as basin and range topography featuring to "sky islands" of forest rising from the desert lowlands which creates a uniquely diverse ecology. The region is further complicated by an international border, where governments have caused difficulties for many animal populations. This book puts a spotlight on individual research projects which are specific examples of work being done in the area and when they are all brought together, to shed a general light of understanding the biological and cultural resources of this vast region so that those same resources can be managed as effectively and efficiently as possible. The intent is to show that collaborative efforts among federal, state agency, university, and private sector researchers working with land managers, provides better science and better management than when scientists and land managers work independently.

  2. Europe's Neogene and Quaternary lake gastropod diversity - a statistical approach

    NASA Astrophysics Data System (ADS)

    Neubauer, Thomas A.; Georgopoulou, Elisavet; Harzhauser, Mathias; Mandic, Oleg; Kroh, Andreas

    2014-05-01

    During the Neogene Europe's geodynamic history gave rise to several long-lived lakes with conspicuous endemic radiations. However, such lacustrine systems are rare today as well as in the past compared to the enormous numbers of "normal" lakes. Most extant European lakes are mainly results of the Ice Ages and are due to their (geologically) temporary nature largely confined to the Pleistocene-Holocene. As glacial lakes are also geographically restricted to glacial regions (and their catchment areas) their preservation potential is fairly low. Also deposits of streams, springs, and groundwater, which today are inhabited by species-rich gastropod assemblages, are rarely preserved. Thus, the pre-Quaternary lacustrine record is biased towards long-lived systems, such as the Late Miocene Lake Pannon, the Early to Middle Miocene Dinaride Lake System, the Middle Miocene Lake Steinheim and several others. All these systems have been studied for more than 150 years concerning their mollusk inventories and the taxonomic literature is formidable. However, apart from few general overviews precise studies on the γ-diversities of the post-Oligocene European lake systems and the shifting biodiversity in European freshwater systems through space and time are entirely missing. Even for the modern faunas, literature on large-scale freshwater gastropod diversity in extant lakes is scarce and lacks a statistical approach. Our preliminary data suggest fundamental differences between modern and pre-Pleistocene freshwater biogeography in central Europe. A rather homogenous central European Pleistocene and Holocene lake fauna is contrasted by considerable provincialism during the early Middle Miocene. Aside from the ancient Dessaretes lakes of the Balkan Peninsula, Holocene lake faunas are dominated by planorbids and lymnaeids in species numbers. This composition differs considerably from many Miocene and Pliocene lake faunas, which comprise pyrgulid-, hydrobiid-, viviparid-, melanopsid

  3. The North Sakhalin Neogene total petroleum system of eastern Russia

    USGS Publications Warehouse

    Lindquist, S.J.

    2000-01-01

    The North Sakhalin Basin Province of eastern Russia contains one Total Petroleum System (TPS) ? North Sakhalin Neogene ? with more than 6 BBOE known, ultimately recoverable petroleum (61% gas, 36% oil, 3% condensate). Tertiary rocks in the basin were deposited by the prograding paleo-Amur River system. Marine to continental, Middle to Upper Miocene shale to coaly shale source rocks charged marine to continental Middle Miocene to Pliocene sandstone reservoir rocks in Late Miocene to Pliocene time. Fractured, self-sourced, Upper Oligocene to Lower Miocene siliceous shales also produce hydrocarbons. Geologic history is that of a Mesozoic Asian passive continental margin that was transformed into an active accretionary Tertiary margin and Cenozoic fold belt by the collision of India with Eurasia and by the subduction of Pacific Ocean crustal plates under the Asian continent. The area is characterized by extensional, compressional and wrench structural features that comprise most known traps.

  4. Pelagic crinoids (Roveacrinida, Crinoidea) discovered in the Neogene of Poland

    NASA Astrophysics Data System (ADS)

    Gorzelak, Przemysław; Salamon, Mariusz A.; Ferré, Bruno

    2011-10-01

    Until recently, it has been assumed that pelagic crinoids, the roveacrinids (Roveacrinida, Crinoidea), became extinct during the Cretaceous-Paleogene boundary event. Recent finds of well-preserved roveacrinidal remains (brachials and radials) in the Danian (Early Paleogene) of Poland showed that they survived into the earliest Cenozoic. This group was thus characterized as a "dead clade walking". Here, we present fossil evidence that these pelagic crinoids survived in Poland until at least the Middle Miocene (Badenian, ca. 14 Myr ago)—more than 50 Myr after their supposed extinction. These Miocene roveacrinids constitute the first documented evidence of Roveacrinida in strata of Neogene age, thus prolonging the stratigraphic range of pelagic crinoids. This find characterizes the order as a "Lazarus taxon" rather than a "dead clade walking" group.

  5. Neogene biomarker record of vegetation change in eastern Africa

    PubMed Central

    Polissar, Pratigya J.; Jackson, Kevin E.; deMenocal, Peter B.

    2016-01-01

    The evolution of C4 grassland ecosystems in eastern Africa has been intensely studied because of the potential influence of vegetation on mammalian evolution, including that of our own lineage, hominins. Although a handful of sparse vegetation records exists from middle and early Miocene terrestrial fossil sites, there is no comprehensive record of vegetation through the Neogene. Here we present a vegetation record spanning the Neogene and Quaternary Periods that documents the appearance and subsequent expansion of C4 grasslands in eastern Africa. Carbon isotope ratios from terrestrial plant wax biomarkers deposited in marine sediments indicate constant C3 vegetation from ∼24 Ma to 10 Ma, when C4 grasses first appeared. From this time forward, C4 vegetation increases monotonically to present, with a coherent signal between marine core sites located in the Somali Basin and the Red Sea. The response of mammalian herbivores to the appearance of C4 grasses at 10 Ma is immediate, as evidenced from existing records of mammalian diets from isotopic analyses of tooth enamel. The expansion of C4 vegetation in eastern Africa is broadly mirrored by increasing proportions of C4-based foods in hominin diets, beginning at 3.8 Ma in Australopithecus and, slightly later, Kenyanthropus. This continues into the late Pleistocene in Paranthropus, whereas Homo maintains a flexible diet. The biomarker vegetation record suggests the increase in open, C4 grassland ecosystems over the last 10 Ma may have operated as a selection pressure for traits and behaviors in Homo such as bipedalism, flexible diets, and complex social structure. PMID:27274042

  6. Neogene biomarker record of vegetation change in eastern Africa.

    PubMed

    Uno, Kevin T; Polissar, Pratigya J; Jackson, Kevin E; deMenocal, Peter B

    2016-06-01

    The evolution of C4 grassland ecosystems in eastern Africa has been intensely studied because of the potential influence of vegetation on mammalian evolution, including that of our own lineage, hominins. Although a handful of sparse vegetation records exists from middle and early Miocene terrestrial fossil sites, there is no comprehensive record of vegetation through the Neogene. Here we present a vegetation record spanning the Neogene and Quaternary Periods that documents the appearance and subsequent expansion of C4 grasslands in eastern Africa. Carbon isotope ratios from terrestrial plant wax biomarkers deposited in marine sediments indicate constant C3 vegetation from ∼24 Ma to 10 Ma, when C4 grasses first appeared. From this time forward, C4 vegetation increases monotonically to present, with a coherent signal between marine core sites located in the Somali Basin and the Red Sea. The response of mammalian herbivores to the appearance of C4 grasses at 10 Ma is immediate, as evidenced from existing records of mammalian diets from isotopic analyses of tooth enamel. The expansion of C4 vegetation in eastern Africa is broadly mirrored by increasing proportions of C4-based foods in hominin diets, beginning at 3.8 Ma in Australopithecus and, slightly later, Kenyanthropus This continues into the late Pleistocene in Paranthropus, whereas Homo maintains a flexible diet. The biomarker vegetation record suggests the increase in open, C4 grassland ecosystems over the last 10 Ma may have operated as a selection pressure for traits and behaviors in Homo such as bipedalism, flexible diets, and complex social structure. PMID:27274042

  7. Neogene biomarker record of vegetation change in eastern Africa.

    PubMed

    Uno, Kevin T; Polissar, Pratigya J; Jackson, Kevin E; deMenocal, Peter B

    2016-06-01

    The evolution of C4 grassland ecosystems in eastern Africa has been intensely studied because of the potential influence of vegetation on mammalian evolution, including that of our own lineage, hominins. Although a handful of sparse vegetation records exists from middle and early Miocene terrestrial fossil sites, there is no comprehensive record of vegetation through the Neogene. Here we present a vegetation record spanning the Neogene and Quaternary Periods that documents the appearance and subsequent expansion of C4 grasslands in eastern Africa. Carbon isotope ratios from terrestrial plant wax biomarkers deposited in marine sediments indicate constant C3 vegetation from ∼24 Ma to 10 Ma, when C4 grasses first appeared. From this time forward, C4 vegetation increases monotonically to present, with a coherent signal between marine core sites located in the Somali Basin and the Red Sea. The response of mammalian herbivores to the appearance of C4 grasses at 10 Ma is immediate, as evidenced from existing records of mammalian diets from isotopic analyses of tooth enamel. The expansion of C4 vegetation in eastern Africa is broadly mirrored by increasing proportions of C4-based foods in hominin diets, beginning at 3.8 Ma in Australopithecus and, slightly later, Kenyanthropus This continues into the late Pleistocene in Paranthropus, whereas Homo maintains a flexible diet. The biomarker vegetation record suggests the increase in open, C4 grassland ecosystems over the last 10 Ma may have operated as a selection pressure for traits and behaviors in Homo such as bipedalism, flexible diets, and complex social structure.

  8. Desert Voices: Southwestern Children's Literature.

    ERIC Educational Resources Information Center

    Polette, Keith

    1997-01-01

    Examines three books with different ways of writing about the desert. Discusses: "Here Is the Southwestern Desert" by Madeline Dunphy, "The Desert Is My Mother" by Pat Mora, and "The Desert Mermaid" by Alberto Blanco. (PA)

  9. Lithofacies Associations and Depositional Environments of the Neogene Molasse succession, Pishin Belt, northwestern Pakistan

    NASA Astrophysics Data System (ADS)

    Kasi, A.; Kassi, A.; Friis, H.; Umar, M.

    2013-12-01

    The Pishin Belt is a NE-SW trending mixed flysch and molasse basin, situated at the northwestern part of Pakistan, bordered by Afghan Block of the Eurasian Plate in the west and Indian Plate in the east. Western boundary of the belt is marked by the well-known Chaman Transform Fault, whereas the Zhob Valley Thrust and Muslim Bagh-Zhob Ophiolite mark the eastern boundary. The Belt is divisible into six tectono-stratigraphic zones bounded by major thrusts. Muslim Bagh-Zhob Ophiolite is the base and Zone-I of this belt. Zone-II comprises shallow marine and flysch successions of the Eocene Nisai Formation and Oligocene Khojak Formation. The Early to Middle Miocene Dasht Murgha group comprises Zone-III, the Late Miocene-Pliocene Malthanai formation comprises Zone-IV, the Pleistocene Bostan Formation makes Zone-V, and the flat-laying Holocene deposits of the Zhob Valley comprise Zone-VI. The Neogene molasse successions of the Pishin Belt include the Dasht Murgha group, Malthanai formation and Bostan Formation; these are mostly composed of sandstone, claystone and conglomerate lithologies. Sandstones have been classified as lithic arenites and their QFL values suggest quartzolithic composition. Twelve distinct lithofacies have been recognized in the succession and thus grouped into four types of facies associations. Lithofacies include clast-supported massive gravel (Gcm), clast-supported crudely bedded gravel (Gh), cross-stratified conglomerate (Gt and Gp), trough cross-stratified sandstone (St), planar cross-stratified sandstone (Sp), ripple cross-laminated sandstone (Sr), horizontally stratified sandstone (Sh), low-angle cross-stratified sandstone (Sl), massive sandstones (Sm), massive mudstone and siltstone (Fm) and paleosol carbonate (P). The lithofacies associations include channel facies association (CHA), crevasse-splay facies association (CSA), natural-levee facies association (LVA) and floodplain facies association (FPA). The lithofacies associations suggest

  10. Paleohydrology of Southwestern Texas

    NASA Astrophysics Data System (ADS)

    Kochel, R. Craig; Baker, Victor R.; Patton, Peter C.

    1982-08-01

    Current statistical methods may be unable to accurately predict recurrence intervals of rare, large-magnitude floods, especially in semiarid regions having positively skewed annual flood distributions, great hydrologic variability, and widely spaced gaging stations. Current approaches rely on historical data, but catastrophic floods may have recurrence intervals far greater than the length of historical records. In the lower Pecos and Devils Rivers of southwestern Texas, paleoflood discharge and frequency estimates are extended over 10,000 years by the study of slack-water flood sediments. Slack-water deposits are typically fine-grained sand and silt that accumulate during floods in areas where current velocity is reduced, i.e., in back-flooded tributary mouths, channel expansions, downstream from bedrock spurs and/or slump blocks, and in shallow caves along bedrock walls. Radiocarbon dating of organic detritus in slack-water deposits establishes the flood chronology while paleoflood discharges can be estimated by slope-area techniques. Paleoflood information extracted from slack-water sediments can greatly extend flood records. These floods may be weighted like historical data in log Pearson type 3 calculations of flood frequency. Our morphostratigraphic approach combines recorded data with geomorphic evidence to derive estimates of flood frequency. This technique offers an inexpensive and rapid way to assess catastrophic flood risk.

  11. Neogene stratigraphy and Andean geodynamics of southern Ecuador

    NASA Astrophysics Data System (ADS)

    Hungerbühler, Dominik; Steinmann, Michael; Winkler, Wilfried; Seward, Diane; Egüez, Arturo; Peterson, Dawn E.; Helg, Urs; Hammer, Cliff

    2002-01-01

    The present paper reviews Tertiary volcanic and sedimentary formations in the Inter-Andean region of southern Ecuador (between 2°S and 4°20'S) in order to develop a geodynamic model of the region. The formations occur in the southern shallow prolongation of the Inter-Andean Valley between the Cordillera Real to the east, and the Cordillera Occidental and Amotape-Tahuı´n Provinces to the west. One hundred fifty zircon fission-track analyses has established a detailed chronostratigraphy for the sedimentary and volcanic formations and several small intrusions. The Paleogene to early Miocene formations are dominated by intermediate and acidic volcanic and pyroclastic rocks. In addition, relics of Eocene continental sedimentary series have been identified. The Neogene sedimentary series lie unconformably on deformed and eroded metamorphic, sedimentary and volcanic formations. They were deposited in two stages, which are separated by a major unconformity dated at ≈10-9 Ma. (1) During the middle and early late Miocene (≈15-10 Ma) marginal marine deltaic, lagoonal, lacustrine and fluvial environments prevailed, which we group under the heading "Pacific Coastal sequences". They presumably covered a greater surface area in southern Ecuador than their present occurrence in small topographic depressions. We suggest that they were deposited in the shallow marine Cuenca and Loja Embayments. Deposition in a marginal marine environment is also supported by the occurrence of brackish water ostracods and other fauna. (2) Above the regional (angular) unconformity, the coastal facies are overlain by late Miocene (≈9-5 Ma) continental alluvial fan and fluvial facies which are in turn covered by mainly airborne volcanic material. They represent the "Intermontane sequences" of the basins of Cuenca, Girón-Santa Isabel, Nabón, Loja and Malacatos-Vilcabamba. Sedimentologic and stratigraphic results are used to discuss the tectonic setting of Neogene sedimentation in the forearc

  12. Differences in habitat use by blanding's turtles, Emydoidea blandingii, and painted turtles, Chysemys picta, in the Nebraska sandhills

    USGS Publications Warehouse

    Bury, R. Bruce; Germano, David J.

    2003-01-01

    We sampled a variety of wetlands in the Nebraska sandhills at Valentine National Wildlife Refuge. Significantly more individuals of painted turtles (Chrysemys picta) occurred in lakes and open waters than in marshes or small ponds, and the opposite was true for Blanding's turtles (Emydoidea blandingii). Besides this marked difference in habitat use, 46% of the captured E. blandingii in pond/marsh habitat were juveniles, but only 31.6% in lakes and open water. Current information suggests that marshes and small ponds are important habitat for juvenile turtles, especially Emydoidea blandingii.

  13. The Neogene Environment of the Beardmore Glacier, Transantarctic Mountains

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Cantrill, D. J.; Francis, J. E.; Roof, S. R.

    2004-12-01

    Discontinuous sequences of Neogene marine and non-marine glacigenic sequences, including the Meyer Desert Formation (MDF), occur throughout the Transantarctic Mountains. The upper 85m of the MDF, consisting of interbedded diamictites, conglomerates, sandstones and siltstones, outcrops in the Oliver Bluffs on the Beardmore Glacier at 85° 07'S, 166° 35'E. The location is about 170 km south of the confluence of the Beardmore Glacier with the Ross Ice Shelf and about 500 km north of the South Pole The glacial, fluvioglacial and glaciolacustrine facies of the MDF represent a dynamic glacial margin which advanced and retreated on at least four occasions. On at least one occasion, the retreat was sufficiently long for plants and animals to colonize the head of a major fjord which existed in the place of the existing Beardmore Glacier. From the fossils we have identified at least 18 species of plants, 3 species of insects, 2 species of freshwater mollusks, and a species of fish. The plant fossils consist of pollen, seeds, fruits, flowers, leaves, wood, and in situ plants. The plants include a cryptogamic flora of mosses and liverworts, conifers, and angiosperms in the families Gramineae, Cyperaceae, Nothofagaceae, Ranunculaceae, Hippuridaceae, ?Caryophyllaceae, and ?Chenopodiaceae or ?Myrtaceae. The plants grew in a weakly developed soil developed on a complex periglacial environment that included moraines, glacial outwash streams, well-drained gravel ridges, and poorly drained depressions in which peat and marl were being deposited. The fossil assemblage represents a mosaic tundra environment of well- and poorly-drained micro-sites, in which nutrient availability would have been patchily distributed. Antarctica has been essentially in a polar position since the Early Cretaceous and at 85° S receives no sunlight from the middle of March until the end of September. Today, the annual radiation received is about 42% that of Tierra del Fuego at 55° S. During the Neogene

  14. REGIONAL PARADOX FORMATION STRUCTURE AND ISOCHORE MAPS, BLANDING SUB-BASIN, UTAH

    SciTech Connect

    Kevin McClure; Craig D. Morgan; Thomas C. Chidsey Jr.; David E. Eby

    2003-12-01

    Over 400 million barrels (64 million m{sup 3}) of oil have been produced from the shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation in the Paradox Basin, Utah and Colorado. With the exception of the giant Greater Aneth field, the other 100 plus oil fields in the basin typically contain 2 to 10 million barrels (0.3-1.6 million m{sup 3}) of original oil in place. Most of these fields are characterized by high initial production rates followed by a very short productive life (primary), and hence premature abandonment. Only 15 to 25 percent of the original oil in place is recoverable during primary production from conventional vertical wells. An extensive and successful horizontal drilling program has been conducted in the giant Greater Aneth field (figure 1). However, to date, only two horizontal wells have been drilled in small Ismay and Desert Creek fields. The results from these wells were disappointing due to poor understanding of the carbonate facies and diagenetic fabrics that create reservoir heterogeneity. These small fields, and similar fields in the basin, are at high risk of premature abandonment. At least 200 million barrels (31.8 million m{sup 3}) of oil will be left behind in these small fields because current development practices leave compartments of the heterogeneous reservoirs undrained. Through proper geological evaluation of the reservoirs, production may be increased by 20 to 50 percent through the drilling of low-cost single or multilateral horizontal legs from existing vertical development wells. In addition, horizontal drilling from existing wells minimizes surface disturbances and costs for field development, particularly in the environmentally sensitive areas of southeastern Utah and southwestern Colorado.

  15. Paleomagnetic studies on Neogene rocks from southern California

    SciTech Connect

    Luyendyk, B.P.

    1988-03-01

    For the past 13 years, the paleomagnetism of Neogene age volcanic and sedimentary rocks in southern California has been studied. Volcanic rocks studied are mostly early and middle Miocene. Sedimentary rocks studied are mostly middle and late Miocene dolostones from the Monterey Formation. Clockwise declination anomalies are prominent and are interpreted as indicators of clockwise tectonic rotation. West of the San Andreas fault in the western Transverse Ranges and Channel Islands, clockwise rotation began during the middle Miocene, paused in late Miocene, and resumed in the Pliocene. An exception is the San Gabriel Mountain region, which possibly has rotated counterclockwise since late Miocene. East of the San Andreas fault, clockwise rotations took place in the central Mojave Desert during the early Miocene. The Orocopia Mountains region may have rotated clockwise during the middle Miocene. The Eastern Transverse Ranges rotated clockwise mostly during post-Miocene time and some parts of the Mojave Desert rotated counterclockwise. Magnetic reversal stratigraphy has been studied for a few sections in the Monterey Formation. Control is dictated by the abundance of dolostone beds, as other lithologies do not possess a primary remanence. Five sections along the north coast of the Santa Barbara Channel have been correlated to the magnetic polarity time scale by J. S. Hornafius. Study of two thick sections of early Miocene flows from the Soledad basin by R.R. Terres yielded a detailed scheme of secular variation. Elsewhere, flow sequences are too short and discontinuous in time to yield a magnetic reversal stratigraphy.

  16. A Palaeohydrological Shift during Neogene East Antarctic Ice Sheet Retreat

    NASA Astrophysics Data System (ADS)

    Rees-Owen, R. L.; Newton, R.; Ivanovic, R. F.; Francis, J.; Tindall, J. C.; Riding, J. B.

    2015-12-01

    The East Antarctic Ice Sheet is an important driver of global climate, playing a particular role in governing albedo and atmospheric circulation (eg. Singh et al., 2013). Recent evidence from marine sediment and terrestrial glaciovolcanic sequences suggests that the EAIS underwent periodic retreat and collapse in response to warmer climates during the late Neogene (14 to 3 million years ago). Mummified prostrate trees recovered from palaeosols at Oliver Bluffs in the Beardmore Glacier region, Transantarctic Mountains (85° S), represent a rare insight into the terrestrial palaeoclimate during one of these periods of retreat. Prostrate trees are an understudied but useful tool for interrogating endmember (e.g. periglacial) environments at high altitudes and latitudes. We present exciting new palaeoclimate data from the sequence at Oliver Bluffs. δ18O analysis of tree ring cellulose suggests that Antarctic summer palaeoprecipitation was enriched relative to today (-25 to -5‰ for ancient, -35 to -20‰ for modern); consistent with our isotope-enabled general circulation model simulations. The MBT/CBT palaeothermometer gives a summer temperature of 3-6ºC, consistent with other palaeobotanical climate indices. These geological and model data have wide-ranging implications for our understanding of the hydrological cycle during this time period. We present data suggesting that changes in moisture recycling and source region indicate a markedly different hydrological cycle.

  17. Late Neogene changes in diatom sedimentation in the North Pacific

    USGS Publications Warehouse

    Barron, J.A.

    1998-01-01

    During the late Neogene, North Pacific diatom sedimentation underwent major changes in response to high-latitude cooling and changes in surface and deep water circulation. At 9 Ma diatom mass accumulation rates (MARs) increased in the NW Pacific and off northeast Japan, possibly due to shoaling of the Isthmus of Panama, which lead to an enrichment of nutrients in North Pacific deep waters. During the latest Miocene, diatom MARs increased progressively off southern California (6.5 Ma), at high latitudes of the North Pacific (6.2 Ma), and off northeastern Japan (5.5 Ma), presumably in response to high latitude cooling. At about 4.5 Ma diatom sedimentation abruptly increased in the NW Pacific but declined off Japan and California, coincident with the onset of a prolonged period of high-latitude warmth. Enhanced upwelling of nutrient-rich deep waters in the NW Pacific probably stimulated diatom production there. A major step in high latitude cooling at 2.7 Ma caused a reversal of these mid Pliocene diatom sedimentation patterns. Upwelling of deep, nutrient-rich waters waned at higher latitudes, leading to a decline in diatom productivity; while wind-driven, coastal upwelling increased off southern California and stimulated diatom growth.

  18. Neogene biostratigraphy and paleoenvironments of Enewetak Atoll, equatorial Pacific Ocean

    USGS Publications Warehouse

    Cronin, T. M.; Bybell, L.M.; Brouwers, E.M.; Gibson, T.G.; Margerum, R.; Poore, R.Z.

    1991-01-01

    Micropaleontologic analyses of Neogene sediments from Enewetak Atoll, Marshall Islands, provide data on the age of lagoonal deposits, stratigraphic disconformities and the paleoenvironmental and subsidence history of the atoll. Benthic foraminifers, planktic foraminifers, calcareous nannofossils and ostracodes were studied from six boreholes, the deepest penetrating 1605 feet below the lagoon floor into upper Oligocene strata. The Oligocene-Miocene boundary occurs at about 1200 ft below the lagoon floor. The early and middle Miocene is characterized by brief periods of deposition and numerous hiatuses. Ostracodes and benthic foraminifers indicate a shallow-marine reefal environment with occasional brackish water conditions. Upper Miocene and lower Pliocene deposits placed in calcareous nannofossil Zones NN9-15 and in planktic foraminifer Zones N16-19 contain species-rich benthic microfaunas which indicate alternating reefal and brackish water mangrove environments. The upper Pliocene contains at least two major depositional hiatuses that coincide with a major faunal turnover in benthic foraminiferal and ostracode assemblages. The Quaternary is characterized by benthic microfaunas similar to those of modern atoll lagoons and is punctuated by at least 11 disconformities which signify periods of low sea level. Atoll subsidence rates during the last 10 Ma averaged 30 to 40 m/m.y. ?? 1991 Elsevier Science Publishers B.V. All rights reserved.

  19. Late Neogene marine incursions and the ancestral Gulf of California

    USGS Publications Warehouse

    McDougall, K.

    2008-01-01

    The late Neogene section in the Salton Trough, California, and along the lower Colorado River in Arizona is composed of marine units bracketed by nonmarine units. Microfossils from the marine deposits indicate that a marine incursion inundated the Salton Trough during the late Miocene. Water depths increased rapidly in the Miocene and eventually flooded the region now occupied by the Colorado River as far north as Parker, Arizona. Marine conditions were restricted in the Pliocene as the Colorado River filled the Salton Trough with sediments and the Gulf of California assumed its present configuration. Microfossils from the early part of this incursion include a diverse assemblage of benthic foraminifers (Amphistegina gibbosa, Uvigerina peregrina, Cassidulina delicata, and Bolivina interjuncta), planktic foraminifers (Globigerinoides obliquus, G. extremus, and Globigerina nepenthes), and calcareous nannoplankton (Discoaster brouweri, Discoaster aff. Discoaster surculus, Sphenolithus abies, and S. neoabies), whereas microfossils in the final phase contain a less diverse assemblage of benthic foraminifers that are diagnostic of marginal shallow-marine conditions (Ammonia, Elphidium, Bolivina, Cibicides, and Quinqueloculina). Evidence of an earlier middle Miocene marine incursion comes from reworked microfossils found near Split Mountain Gorge in the Fish Creek Gypsum (Sphenolithus moriformis) and near San Gorgonio Pass (Cyclicargolithus floridanus and Sphenolithus heteromorphus and planktic foraminifers). The middle Miocene incursion may also be represented by the older marine sedimentary rocks encountered in the subsurface near Yuma, Arizona, where rare middle Miocene planktic foraminifers are found. ?? 2008 The Geological Society of America.

  20. Himalaya evolution at Paleogene-Neogene boundary unraveled by zircon age spectrum from Arabian Sea Sediments

    NASA Astrophysics Data System (ADS)

    Feng, Han; Lu, Huayu; Zhang, Hanzhi

    2016-04-01

    Although virtually all the intensive orogenic activities of Himalaya occurred in Neogene, the tectonic evolution of this high mountain range in Paleogene is poorly understood. Investigations of tectonic change pattern at Paleogene-Neogene boundary are important to better understand the interaction between mountain building and climate evolution. Here we present new U-Pb ages of zircon grains from Indus Fan sediments to constrain the orogenic history of Himalaya at Paleogene-Neogene boundary. 11 samples between late Oligocene and early Miocene from ODP 117 cores are dated by the zircon U-Pb technique. We calculate relative contributions of potential sources by counting zircon grains for each sample, and the quantized results indicate Himalaya contributed sediments to the coring site, and an extremely high input from Great and Tethyan Himalaya during late Oligocene-early Miocene. Four samples in Pleistocene are also dated for comparison, which indicates that high proportion of Lesser Himalaya has contributed to the sediment in Pleistocene. Our results suggest that the high contribution of Great and Tethyan Himalaya at Paleogene-Neogene boundary might correlate with the beginning of activity of MCT and extension of STD with leucogranite intrusion along Himalaya, which give rise to the extensive Great Himalaya exhumation. Our study demonstrates that zircon U-Pb dating technique is a good tool to reconstruct erosional history of mountain building on a tectonic timescale. Key words: ODP, Himalaya, Indus Fan, zircon U-Pb dating, Paleogene-Neogene boundary

  1. Reef productivity and preservation during the Late Neogene

    NASA Astrophysics Data System (ADS)

    Husson, Laurent; Pastier, Anne-Morwenn; Schmitt, Anais; Sarr, Anta-Clarisse; Elliot, Mary; Pedoja, Kevin; Bezos, Antoine

    2016-04-01

    During the glacial-interglacials cycles that prevailed during Plio-Pleistocence times, the pace of sea level oscillations exerts a major control on coral reef growth and expansion. We designed a numerical model to quantify reef productivity and carbonate preservation that accounts for sea level oscillations, reef growth, erosion and subsequent geomorphological carving. We carried out a parametric study of a variety of processes (reef growth, erosion, local slope, uplift and subsidence, relative sea level, etc) towards a probabilistic analysis of reef productivity and carbonate production. We further test the effect of the frequency and amplitude of sea level oscillations using sea level curves derived from both the 18O isotope record of past sea level change and synthetic sinusoidal sea level curves. Over a typical climate cycle, our model simulations confirm that the rate of sea level change is the primary controlling factor of reef production, as it modifies the productivity by several orders of magnitude. Most importantly, reef productivity increases during periods of sea level rise, and decreases during sea level stands, while conversely, the morphology records the opposite in a misleading fashion: Reef terraces expand during sea level stands due to the joint effects of erosion and patient reef growth at a stationary level until the accommodation space is filled up. On the long-term, over the Plio-Pleistocene period, vertical ground motion also significantly alters the production: moderate uplift or subsidence can boost reef productivity up to tenfold with respect to a stationary coastline. Last, the amplitude and frequency of the sea level oscillations (typically 40 kyrs vs. 100 kyrs periods) moderately impact reef productivity. These results can be ultimately converted into estimates of carbonate production and carbon sequestration during the Late Neogene, provided relative sea level is documented in the tectonically agitated intertropical zone.

  2. Upper Neogene stratigraphy and tectonics of Death Valley - A review

    USGS Publications Warehouse

    Knott, J.R.; Sarna-Wojcicki, A. M.; Machette, M.N.; Klinger, R.E.

    2005-01-01

    New tephrochronologic, soil-stratigraphic and radiometric-dating studies over the last 10 years have generated a robust numerical stratigraphy for Upper Neogene sedimentary deposits throughout Death Valley. Critical to this improved stratigraphy are correlated or radiometrically-dated tephra beds and tuffs that range in age from > 3.58 Ma to < 1.1 ka. These tephra beds and tuffs establish relations among the Upper Pliocene to Middle Pleistocene sedimentary deposits at Furnace Creek basin, Nova basin, Ubehebe-Lake Rogers basin, Copper Canyon, Artists Drive, Kit Fox Hills, and Confidence Hills. New geologic formations have been described in the Confidence Hills and at Mormon Point. This new geochronology also establishes maximum and minimum ages for Quaternary alluvial fans and Lake Manly deposits. Facies associated with the tephra beds show that ???3.3 Ma the Furnace Creek basin was a northwest-southeast-trending lake flanked by alluvial fans. This paleolake extended from the Furnace Creek to Ubehebe. Based on the new stratigraphy, the Death Valley fault system can be divided into four main fault zones: the dextral, Quaternary-age Northern Death Valley fault zone; the dextral, pre-Quaternary Furnace Creek fault zone; the oblique-normal Black Mountains fault zone; and the dextral Southern Death Valley fault zone. Post -3.3 Ma geometric, structural, and kinematic changes in the Black Mountains and Towne Pass fault zones led to the break up of Furnace Creek basin and uplift of the Copper Canyon and Nova basins. Internal kinematics of northern Death Valley are interpreted as either rotation of blocks or normal slip along the northeast-southwest-trending Towne Pass and Tin Mountain fault zones within the Eastern California shear zone. ?? 2005 Elsevier B.V. All rights reserved.

  3. The changing course of the Orinoco River during the neogene

    SciTech Connect

    Diaz de Gamero, M.L. )

    1993-02-01

    Recent studies have revealed that the varied fresh-water vertebrate fossil fauna of the Urumaco Formation in northwestern Falcon, of Late Miocene age, belongs biogeographically to the Orinoco River system. This makes possible to chart the changing course of the Orinoco River through the Neogene. The Misoa delta of Lake Maracaibo, of middle Eocene age, was probably constructed by a proto-Orinoco river that ran in a south-north direction, draining the Central Cordillera of Colombia and the Guayana Highlands. The late Eocene uplifting of western Venezuela changed the paleogeographic setting, with no evidence of delta-building during the Oligocene. In the earliest Miocene, the Falcon Basin was the site of marine shale sedimentation. In the second half of the Early Miocene, a deltaic sequence was initiated in northwestern Falcon that continued, except for a transgressive episode, until the end of the Middle Miocene, depositing a total thickness of over 2.5 km. The Urumaco overlies this sequence and its vertebrate fauna indicates that the river that built the previous delta was the proto-Orinoco. The initial uplifting of the northern part of the Andes and the western edge of the Caribbean Mountains can thus be dated to occur at the end of the Middle Miocene, causing the distal course of the river to move to a west-east direction. The sedimentary record of the Orinoco River delta appears in the Maturin Basin of eastern Venezuela at the end of the Miocene, and is especially evident in Trinidad and the Columbus Basin during the Pliocene and Pleistocene.

  4. Neogene rhyolites of the northern Jemez volcanic field, New Mexico

    SciTech Connect

    Loeffler, B.M.; Vaniman, D.T.; Baldridge, W.S.; Shafiqullah, M.

    1988-06-10

    Volcanic centers previously mapped as the 20 Ma El Rechuelos Rhyolite in the northern Jemez volcanic field, New Mexico, include three distinct episodes of rhyolitic volcanism. An early (7.5 Ma) extrusive dome of flow-banded biotite rhyolite and an intermediate (5.8 Ma) rhyolite, possibly a volcanic neck, correspond in age to rhyolites of the Keres Group in the southern Jemez volcanic field. Three other extrusive domes of aphyric, pumiceous rhyolite and obsidian comprise a late volcanic episode, dated at 2.0 Ma. We retain the name El Rechuelos Rhyolite only for these late centers. Another center, farther north than the others but previously mapped with the El Rechuelos Rhyolite, is a dacite pumice ring whose age (5.2 Ma), petrography, major- and trace-element chemistry, and Sr initial ratio all suggest it should be included with rocks of the Tschicoma Formation. Nd and Sr isotopic ratios of the Neogene rhyolites of the northern Jemez volcanic field suggest that these rhyolites were not produced by partial melting of either upper or lower crust. Rather, they may have been generated from a mantle-derived mafic magma, such as the nearby Lobato Basalt, by fractional crystallization with concomitant assimilation of small amounts (<6%) of lower crust. If the El Rechuelos is derived from a lower crust magma chamber, as seems likely, then it is not related to the bandelier magma system, even though it is part of a continuum of rhyolite volcanism ranging from 3.6 Ma to 130,000 years ago that includes the Bandelier and precursor rhyolitic units. copyright American Geophysical Union 1988

  5. Sequence stratigraphic framework of Neogene strata in offshore Nigeria

    SciTech Connect

    Pacht, J.A.; Bowen, B.E.; Hall, D.J.

    1996-08-01

    The western portion of the Nigerian continental margin (Dahomey Basin) exhibits stable to moderately unstable progradation. Systems tracts are similar to those described by Vail for stable progradational margins. In contrast, strata off the central and eastern portions of the Nigerian coast (Niger Delta Complex) exhibit highly unstable progradation, and systems tracts are similar to those in Neogene strata of the offshore Gulf of Mexico. Lowstand basin floor fans in both areas are defined by a well-developed upper reflection. This reflection downlaps along the sequence boundary or abuts against the downthrown side of a growth fault surface. Most lower lowstand (slope fan) strata exhibit discontinuous to semi-continuous subparallel reflections. However, this systems tract also contains channel complexes characterized by chaotic bedding with small bright spots and less common large channels, which exhibit concave-upward reflections. In the western portion of the study area, lower lowstand deposits commonly pinch out on the slope. Deposition occurred largely from point sources. In contrast, contemporaneous shallow-water facies are developed in lower lowstand systems tracts in the Niger Delta Complex. Deposition occurred along a line source. Large amplitude anomalies in the upper lowstand (prograding wedge) suggest well-developed sheet sands occur in shallow-water and deep-water in the Niger Delta complex. However, in the Dahomey Basin there is little evidence of deep-water sands in this interval. The transgressive and highstand systems tracts are usually very thin in outer shelf to basin floor strata in both areas. Both the Dahomey Basin and Niger Delta Complex exhibit different stratigraphic geometries, and therefore, require different exploration strategies.

  6. Drought in Southwestern United States

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The southwestern United States pined for water in late March and early April 2007. This image is based on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite from March 22 through April 6, 2007, and it shows the Normalized Difference Vegetation Index, or NDVI, for the period. In this NDVI color scale, green indicates areas of healthier-than-usual vegetation, and only small patches of green appear in this image, near the California-Nevada border and in Utah. Larger areas of below-normal vegetation are more common, especially throughout California. Pale yellow indicates areas with generally average vegetation. Gray areas appear where no data were available, likely due to persistent clouds or snow cover. According to the April 10, 2007, update from the U.S. Drought Monitor, most of the southwestern United Sates, including Utah, Nevada, California, and Arizona, experienced moderate to extreme drought. The hardest hit areas were southeastern California and southwestern Arizona. Writing for the Drought Monitor, David Miskus of the Joint Agricultural Weather Facility reported that March 2007 had been unusually dry for the southwestern United States. While California's and Utah's reservoir storage was only slightly below normal, reservoir storage was well below normal for New Mexico and Arizona. In early April, an international research team published an online paper in Science noting that droughts could become more common for the southwestern United States and northern Mexico, as these areas were already showing signs of drying. Relying on the same computer models used in the Intergovernmental Panel on Climate Change (IPCC) report released in early 2007, the researchers who published in Science concluded that global warming could make droughts more common, not just in the American Southwest, but also in semiarid regions of southern Europe, Mediterranean northern Africa, and the Middle East.

  7. Reconstructing the cosmogenic 21Ne inventory of Neogene sedimentary sequences

    NASA Astrophysics Data System (ADS)

    Stuart, Finlay; Sinclair, Hugh; McCann, Louise

    2016-04-01

    Ne is ubiquitous. The data require minimum average pebble transport times of 150 kyr. A similar distribution of cosmogenic Ne concentrations is present in quartzite pebbles from gravels from the Pliocene Broadwater Formation and Miocene Ogallala Formation gravels indicates that the rates of transport and pebble recycling on flood plain have not changed over the Neogene. [1] Margerison et al. (2005) Earth Planet. Sci. Lett. 230, 163-175. [2] Codilean et al. (2008) Geology 36, 159-162.

  8. Andean uplift and Neogene climate change in the Atacama Desert

    NASA Astrophysics Data System (ADS)

    Rech, J. A.; Currie, B. S.; Jordan, T. E.

    2006-12-01

    Today the Andean Cordillera and Altiplano provide a major obstacle to atmospheric circulation over South America. The Altiplano Plateau prevents moist air masses from the Amazon Basin from reaching the Atacama Desert, causing the Atacama to be one of the driest places on Earth. Although Neogene sedimentary records from the western flank of the Andes should record the dramatic shift to hyperaridity that resulted from the growth of the Altiplano Plateau, the climatic implications of many sedimentary sequences have been difficult to decipher. The causes of the difficulties are complex, such as the relative influences of tectonics and active volcanism versus climate, and the roles of local as well as regional precipitation on groundwater and on the deposition of paludal sediments in basin centers. Over the last few years our research group has focused on using paleosols and the isotopic composition of palustrine carbonates in the Calama Basin (22°S) to try to identify a local precipitation signal and determine the onset of extreme hyperaridity as a consequence of the growth of the Altiplano. We have determined the soil morphological characteristics, salt chemistry, and mass independent fractionation anomalies (Δ17O values) in dated paleosols to reconstruct a Middle Miocene climatic transition from semi-aridity to extreme hyperaridity in the Atacama Desert. Paleosols along the southeastern margin of the Calama Basin change from calcic Vertisols with root traces, slickensides, and gleyed horizons to an extremely mature salic Gypsisol with pedogenic nitrate. We interpret this transition, which occurred between 19 and 13 Ma, to represent a change in precipitation from >200 mm/yr to <20mm/yr. The isotopic composition of palustrine carbonates in the Calama Basin also show a marked change during this time period. δ13C values of palustrine carbonates increase from -7 to +7? VPDB and δ18O values increases from -7 to +1? VPDB over the late to Middle Miocene time. This major

  9. Neodymium isotopes and the Neogene evolution of Arctic intermediate water

    NASA Astrophysics Data System (ADS)

    Haley, B. A.; Frank, M.; Spielhagen, R.

    2006-12-01

    flow into the Arctic, as seen in a return towards more negative Nd isotopic values. The Quaternary record is argued to reflect stronger glacial brine formation on the Artic shelves under the larger ice sheets, with concomitant restriction of N. Atlantic-sourced intermediate water. These interpretations of the Nd and Arctic ocean intermediate water variability will be assessed in terms of climate change on both the Neogene and glacial-interglacial time scales.

  10. How to regress and predict in a Bland-Altman plot? Review and contribution based on tolerance intervals and correlated-errors-in-variables models.

    PubMed

    Francq, Bernard G; Govaerts, Bernadette

    2016-06-30

    Two main methodologies for assessing equivalence in method-comparison studies are presented separately in the literature. The first one is the well-known and widely applied Bland-Altman approach with its agreement intervals, where two methods are considered interchangeable if their differences are not clinically significant. The second approach is based on errors-in-variables regression in a classical (X,Y) plot and focuses on confidence intervals, whereby two methods are considered equivalent when providing similar measures notwithstanding the random measurement errors. This paper reconciles these two methodologies and shows their similarities and differences using both real data and simulations. A new consistent correlated-errors-in-variables regression is introduced as the errors are shown to be correlated in the Bland-Altman plot. Indeed, the coverage probabilities collapse and the biases soar when this correlation is ignored. Novel tolerance intervals are compared with agreement intervals with or without replicated data, and novel predictive intervals are introduced to predict a single measure in an (X,Y) plot or in a Bland-Atman plot with excellent coverage probabilities. We conclude that the (correlated)-errors-in-variables regressions should not be avoided in method comparison studies, although the Bland-Altman approach is usually applied to avert their complexity. We argue that tolerance or predictive intervals are better alternatives than agreement intervals, and we provide guidelines for practitioners regarding method comparison studies. Copyright © 2016 John Wiley & Sons, Ltd.

  11. North Pacific region in the Paleogene and Neogene as an example of a semiclosed marine system

    NASA Astrophysics Data System (ADS)

    Gladenkov, Yu. B.

    2015-07-01

    Scenarios of different geological events in the Paleogene and Neogene evolution of the North Pacific ecosystem are considered with definition of five large stages in its development. The formation of biotic communities of large semiclosed systems in paratropical and boreal paleoenvironmemts, rates of their evolution, and influence of migration on their development are reconstructed.

  12. Integrated multidisciplinary biostratigraphic and paleoecologic study of southern California Neogene coastal sections

    SciTech Connect

    Blake, G.H.; Arends, R.G.; Filewicz, M.V.; Thornton, M.L.C.; Vork, D.R.

    1988-03-01

    This integrated biostratigraphic and paleoecologic study of several Neogene sections of coastal southern California is based on the use of diatoms, calcareous nannofossils, palynology, and benthic foraminifera. The study included the Naples Bluff, Topanga Canyon, and Newport Bay sections, and DSDP Site 468.

  13. Structuring and evolution of Neogene transcurrent basins in the Tellian foreland domain, north-eastern Tunisia

    NASA Astrophysics Data System (ADS)

    Melki, Fetheddine; Zouaghi, Taher; Harrab, Salah; Sainz, Antonio Casas; Bédir, Mourad; Zargouni, Fouad

    2011-07-01

    The Neogene sedimentary basins (Serravallian to Quaternary) of the Tellian tectonic foreland in north-eastern Tunisia formed within the overall NE-SW sinistral strike-slip tectonic framework of the Ras El Korane-Thibar and El Alia-Teboursouk fault systems. From stratigraphic logs, structural cross sections and interpretation of 2D seismic lines and boreholes, the pre-Neogene basement can be interpreted to be structured according to Eocene (NW-SE) compressional and Oligocene extensional phases. This basement comprises structural highs (anticlines and horsts) and subsiding areas (synclines, half-grabens and grabens) formed during the Neogene. The subsiding areas are delineated by faults striking N030E, N-S and N140E, defining (i) narrow, strongly subsiding synclines, (ii) lozenge-shaped basins and (iii) trapezoidal basins. The architecture of their fill results from the sedimentary balance between tectonics and eustatism. Halokinesis and clay diapirism (driven by Triassic and Neogene evaporites and clays) also played an important role in basin evolution, contributing to the formation of domes and diapirs along active faults.

  14. Southwestern Power Administration Update, October- December 2004

    SciTech Connect

    2004-12-01

    On October 29, 2004, Southwestern and Southwest Power Pool, Inc. (SPP) reached agreement on interim arrangements to be implemented after the October 31, 2004, expiration of the membership agreement between the two parties. According to Jim McDonald, Director of Southwestern’s Division of Customer Service, the interim agreement forged between Southwestern and SPP seeks to minimize impacts to SPP as well as to Southwestern and its customers while Southwestern and SPP work on a seams/coordination agreement to succeed the expired membership agreement.

  15. Lithosphere-scale thrusting in the western US Cordillera as constrained by Sr and Nd isotopic transitions in Neogene volcanic rocks

    SciTech Connect

    Leeman, W.P.; Oldow, J.S. ); Hart, W.K. )

    1992-01-01

    The western Idaho suture zone juxtaposes continental and oceanic terranes with distinctive Sr and Nd isotopic signatures across a sharp isotopic transition coincident with the Mesozoic {sup 87}Sr/{sup 86}Sr = 0.706 line (MSL). Late Cretaceous to Eocene granitic plutons that define the MSL are allochthonous and were transported eastward by {approximately}150 km during late Mesozoic to Tertiary (ca. 100-55 Ma) thrusting. Sr and Nd isotopic compositions of Neogene rhyolites and basalts from southwestern Idaho, southeastern Oregon, and northern Nevada define isotopic transitions coincident with the MSL; there are continental affinities east of long 116{degree}30minutesW and oceanic affinities west of 119W. Between these longitudes, intermediate isotopic compositions imply derivation of magmas from both continental and oceanic mantle (basalts) and crustal (rhyolites) sources. It is inferred that the basal decollement of the Mesozoic and Tertiary contractional orogen dips westward below depths of segregation of basaltic magmas, and that oceanic lithospheric mantle was thrust eastward over a shelf of old, isotopically evolved continental lithospheric mantle that now protrudes {approximately}150 km west of the MSL.

  16. 8. VIEW OF EL PASO AND SOUTHWESTERN RAILROAD BRIDGE, PIER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF EL PASO AND SOUTHWESTERN RAILROAD BRIDGE, PIER BETWEEN EAST APPROACH AND RAILROAD, LOOKING NORTH. - El Paso & Southwestern Railroad Rio Grande Bridge, Spanning Rio Grande at Southwestern Railroad, El Paso, El Paso County, TX

  17. 7. VIEW OF EL PASO AND SOUTHWESTERN RAILROAD BRIDGE, PIER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW OF EL PASO AND SOUTHWESTERN RAILROAD BRIDGE, PIER BETWEEN HIGHWAY AND RAILROAD, LOOKING NORTH. - El Paso & Southwestern Railroad Rio Grande Bridge, Spanning Rio Grande at Southwestern Railroad, El Paso, El Paso County, TX

  18. 4. GENERAL VIEW OF EL PASO AND SOUTHWESTERN RAILROAD BRIDGE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. GENERAL VIEW OF EL PASO AND SOUTHWESTERN RAILROAD BRIDGE, RAILROAD SPAN, LOOKING NORTH. - El Paso & Southwestern Railroad Rio Grande Bridge, Spanning Rio Grande at Southwestern Railroad, El Paso, El Paso County, TX

  19. Magnetostratigraphy of the Neogene sediments of SW Uruguay

    NASA Astrophysics Data System (ADS)

    Sanchez Bettucci, L.; Orgeira, M. J.; Sanchez, G.; Bertoni-Machado, C.; Farina, R.

    2007-05-01

    Preliminary results on the magnetostratigraphy of three Neogene formations from SW Uruguay are presented: Camacho, Raigón and Libertad, and a relative age from the record of reversions in the Earth's magnetic field polarity is proposed. The sediments outcrop in the SW region of Uruguay,and have been received attention due to their fossil contents. The oldest is the late Miocene-Pliocene Camacho Fm, of Huayquerian to Montehermosan affinities. A Pliocene-early Pleistocene age has been assigned to Raigón Fm, of Chapadmalalan affinities. The overlying Libertad Fm has been considered early-middle Pleistocene in age, and to have Marplatan-Ensenadan affinities. The lithology of this facies of Camacho Fm is identified by the presence of fine to very fine sandstones and is composed of silty-sandy and bioturbed silty deposits. The marine facies of this formation is rich in fossil content, as several invertebrate and vertebrate taxa are found. The upper Raigón Fm is formed by sandstones of varied grain size and includes lenses and levels of claystones and conglomerates. It shows the sedimentological features of a deep, pebble-rich braided fluvial system. The 383 vertebrate specimens found in the sandy facies and studied in a taphonomically-oriented study belong to 19 genera and 13 higher taxa. The bones are disarticulated, with smooth fractures and little weathered or abraded, which is congruent with a short time of contact, as observed in strong and sudden flows. The elements belong to the three Voorhies groups and fractured specimens are found along with well preserved materials, implying different taphonomical histories and reworking. The consequent inferred time averaging urges caution at using these remains for defining precise ages. The Libertad Fm, top of the sequence, is conformed by greenish clays, clayey fine sandstones, medium sized sandstones and conglomeratic levels, corresponding to deposits of continental origin under a semiarid climate, which allowed the

  20. Neogene transtensional brittle tectonics in the Lepontine D

    NASA Astrophysics Data System (ADS)

    Allanic, C.; Sue, C.; Champagnac, J.-D.

    2009-04-01

    -parallel extensional phase, at least in the Lepontine Dome. We propose a kinematic model for the Central Alps in which the emplacement of the Lepontine Dome is driven by a pull-apart-like process controlled by the counterclockwise rotation of the Apulian indenter. This model refers to the paleostress field we documented and to kinetics of the main faults bounding the dome. Associated to these processes, lateral escape linked to the Apulia indentation/rotation would have enhanced the global extensional scheme of the Lepontine Dome. REFERENCES Allanic, C., et al. (2006), A paleo-seismogenic Lepontine dome? New insights from pseudotachylytes-generating faults, Geochimica et Cosmochimica Acta, Vol. 70 (18), Suppl. 1, p9 Goldschmidt conf. Melbourne. Bistacchi, A., and Massironi M. (2000), Post-nappe brittle tectonics and kinematic evolution of the north-western Alps: an integrated approach, Tectonophysics, 327, 267-292. Champagnac, J. D., Sue, C., Delacou, B., Burkhard, M. (2006), Miocene orogen-parallel extension in the inner Western Alps revealed by dynamical fault analyses, Tectonics, 25, 1-26. Ciancaleoni, L., and Marquer D. (2008), Late Oligocene to early Miocene lateral extrusion at the eastern borders of the Lepontine dome of the Central Alps (Bergell and Insubric areas, Eastern Central Alps), Tectonics, 27, TC4008, doi:10.1029/2007TC002196, 2008. Grosjean, G., Sue, C., Burkhard, M. (2004), Late Neogene brittle extension in the vicinity of the Simplon fault zone, central Alps, Switzerland., Eclogae Geologicae Helvetiae, 97, 33-46.

  1. Digital Database of Selected Aggregate and Related Resources in Ada, Boise, Canyon, Elmore, Gem, and Owyhee Counties, Southwestern Idaho

    USGS Publications Warehouse

    Moyle, Phillip R.; Wallis, John C.; Bliss, James D.; Bolm, Karen D.

    2004-01-01

    The U.S. Geological Survey (USGS) compiled a database of aggregate sites and geotechnical sample data for six counties - Ada, Boise, Canyon, Elmore, Gem, and Owyhee - in southwest Idaho as part of a series of studies in support of the Bureau of Land Management (BLM) planning process. Emphasis is placed on sand and gravel sites in deposits of the Boise River, Snake River, and other fluvial systems and in Neogene lacustrine deposits. Data were collected primarily from unpublished Idaho Transportation Department (ITD) records and BLM site descriptions, published Army Corps of Engineers (ACE) records, and USGS sampling data. The results of this study provides important information needed by land-use planners and resource managers, particularly in the BLM, to anticipate and plan for demand and development of sand and gravel and other mineral material resources on public lands in response to the urban growth in southwestern Idaho.

  2. Temporary left ventricular assistance for extreme postoperative heart failure in two infants with Bland-White-Garland syndrome

    PubMed Central

    Pawlak, Szymon; Grzybowski, Adam; Śliwka, Joanna; Rycaj, Jarosław; Obersztyn-Zawiślan, Anna; Wierzyk, Arkadiusz; Przybylski, Roman

    2016-01-01

    Anomalous origin of the left coronary artery from the pulmonary artery (Bland-White-Garland syndrome – BWG) is a serious congenital cardiac anomaly leading to myocardial ischemia with severe heart failure. Immediate surgical correction is the treatment of choice, and the risk of postoperative complications depends on the degree of myocardial injury. The authors present two cases of infants with BWG, in whom long-term (175 and 26 days) left ventricular assistance with a Berlin Heart device was used, resulting in successful weaning from the support and subsequent hospital discharge. Because of serious hemorrhagic complications and their neurological consequences observed in the first patient, the anticoagulation protocol was modified in the second patient, providing more stable support and allowing the device to be removed after a shorter period of time. The Berlin Heart left ventricular assist device may be treated not only as a bridge for transplantation but also, considering the shortage of donors in this age group, as a bridge to recovery. PMID:27785147

  3. As Old as the Hills: Montane Scorpions in Southwestern North America Reveal Ancient Associations between Biotic Diversification and Landscape History

    PubMed Central

    Bryson, Robert W.; Riddle, Brett R.; Graham, Matthew R.; Smith, Brian Tilston; Prendini, Lorenzo

    2013-01-01

    Background The age of lineages has become a fundamental datum in studies exploring the interaction between geological transformation and biotic diversification. However, phylogeographical studies are often biased towards lineages that are younger than the geological features of the landscapes they inhabit. A temporally deeper historical biogeography framework may be required to address episodes of biotic diversification associated with geologically older landscape changes. Signatures of such associations may be retained in the genomes of ecologically specialized (stenotopic) taxa with limited vagility. In the study presented here, genetic data from montane scorpions in the Vaejovis vorhiesi group, restricted to humid rocky habitats in mountains across southwestern North America, were used to explore the relationship between scorpion diversification and regional geological history. Results Strong phylogeographical signal was evident within the vorhiesi group, with 27 geographically cohesive lineages inferred from a mitochondrial phylogeny. A time-calibrated multilocus species tree revealed a pattern of Miocene and Pliocene (the Neogene period) lineage diversification. An estimated 21 out of 26 cladogenetic events probably occurred prior to the onset of the Pleistocene, 2.6 million years ago. The best-fit density-dependent model suggested diversification rate in the vorhiesi group gradually decreased through time. Conclusions Scorpions of the vorhiesi group have had a long history in the highlands of southwestern North America. Diversification among these stenotopic scorpions appears to have occurred almost entirely within the Neogene period, and is temporally consistent with the dynamic geological history of the Basin and Range, and Colorado Plateau physiographical provinces. The persistence of separate lineages at small spatial scales suggests that a combination of ecological stenotopy and limited vagility may make these scorpions particularly valuable indicators

  4. Cenozoic geodynamic evolution of the western Mediterranean domain: A view from the Neogene peri-Tyrrhenian basins

    SciTech Connect

    Roure, F.; Montadert, L.; Mueller, C.

    1988-08-01

    Biostratigraphic and structural studies of synorogenic Neogene deposits in the southern Apennines, Calabria, and Cicily are compared to similar data from Sardinia and the Tyrrhenian Sea to trace the geodynamic evolution of the western Mediterranean domain.

  5. Midterm results of left coronary artery reimplantation through the transverse sinus of the pericardium in adult Bland-White-Garland syndrome.

    PubMed

    Kataoka, Go; Nakano, Kiyoharu; Asano, Ryota; Sato, Atsuhiko; Kodera, Kojiro; Tatsuishi, Wataru; Sudo, Shinji

    2015-12-01

    The anomalous origin of the left coronary artery from the pulmonary artery - known as Bland-White-Garland syndrome - is a rare congenital malformation that affects 1 in 300,000 live births. Most patients die in infancy without any surgical treatment. Some patients who survive past childhood often have varying symptoms such as myocardial ischemia, impaired left ventricular function, mitral regurgitation, and progressive heart failure, depending on the development collateral circulation. In the present report, we describe a procedure wherein the left coronary artery ostium was translocated through the transverse sinus of the pericardium in a 43-year-old mother with Bland-White-Garland syndrome and concomitant mitral regurgitation and report on the associated midterm results. PMID:26943392

  6. Dart-stepped leaders observed in rocket-triggered lightning at Camp Blanding, Florida, in 2003-2005

    NASA Astrophysics Data System (ADS)

    Olsen, R. C.; Jordan, D. M.; Rakov, V. A.; Jerauld, J.; Uman, M. A.; Rambo, K. J.

    2006-12-01

    In this paper, we examine linear streak film camera records of four negative lightning flashes obtained at Camp Blanding, Florida, in 2003-2005. All four flashes were triggered with the classical rocket-and-wire technique. The distance from the camera to the lightning termination point ranged from 480 m to 710 m. In each event, one or more strokes were observed to be initiated by dart-stepped leaders. For two of the events, data from an array of photodiodes arranged to observe the lightning channel at eight different heights were also recorded. A total of six dart-stepped leaders were observed, with each leader's average downward (1-dimensional) speed ranging from 1.2 x 106 to 6.6 x 106 m s-1. The average step length per leader ranged from 5.6 to 9.9 m, and the average time interval between steps ranged from 1.1 to 5.0 μs. The interstep intervals and overall speeds are similar to the results reported by Idone (2000), but average step lengths are somewhat shorter. Measurement of the speed of leader step formation was not possible as this process was faster than could be resolved with the streak film. Luminosity pulses resulting from individual steps appeared to travel up the channel at speeds similar to (and possibly higher than) those of the following return stroke, in support of photoelectric observations reported by Wang et al. (1999). The luminosity profile of individual leader steps was observed to have an abrupt reduction at the height of the bottom of the previous leader step in most cases.

  7. Effect of oceanographic and depositional events on Neogene benthic foraminiferal biostratigraphy of California

    SciTech Connect

    Blake, G.H.

    1986-05-01

    The relationships between Neogene environmental events and associated faunal distributional patterns of continental margin benthic foraminiferal faunas are affected or controlled by both local and regional events. These events are related to the complex evolution of the oceanic environment and the California continental margin. Evidence from Deep Sea Drilling Project sites drilled in the Pacific Ocean indicates that major changes in the oceanic environment have produced major faunal turnovers, migrations, and reorganizations of deep-sea benthic foraminiferal assemblages during the Neogene. DSDP Sites 467, 468, and 469, and the Naples Bluff section of southern California, the distributional patterns of continental margin benthic foraminiferal assemblages are strongly related to Neogene climatic-oceanic events. The faunal changes and responses described from the continental margin assemblages are similar in composition and timing to changes documented in the deep sea. The response of the benthic foraminiferal faunas is almost simultaneous across the continental margin in regard to the regional oceanic-climatic events. Several of these events were associated with changes in surface productivity and expansion of the oxygen minima. Local events involved the change in sedimentation and tectonic activity. The oceanic reorganization that occurred 15-13 Ma is responsible for a major change in the faunal patterns across the continental margin. Early Neogene faunas (the Saucesian, Relizian, and Luisian assemblages) were replaced by the Mohnian assemblage. The climatic-oceanic event at 9 to 8 Ma involved an increase in Antarctic glaciation and a resultant increase in upwelling and surface productivity. The associated faunal changes consist of a shift in the character of the Mohnian assemblage. At approximately 5.2 Ma, the Repettian assemblage increased considerably probably in relation to the Messinian event.

  8. Sr-isotope chronostratigraphy of Paleogene-Neogene marine deposits: Austral Basin, southern Patagonia (Argentina)

    NASA Astrophysics Data System (ADS)

    Parras, Ana; Dix, George R.; Griffin, Miguel

    2012-08-01

    The Paleogene to Neogene San Julián and Monte León formations underlie the central and eastern parts of the Austral Basin (Patagonia, Argentina), and represent coastal plain to shallow shelf systems within a retroarc foreland basin east of the Andes. The formations are characterized by prominent occurrences of thin (<1 m) densely compacted fossil concentrations, including the large oyster Crassostrea? hatcheri. Formation ages have been problematic given macrofaunal provincialism effectively precluding precise extrabasinal correlations. A Sr-isotope chronostratigraphy based on fossil shell calcite from oysters, pectinids and brachiopods is presented for a regional NE-SW-oriented transect extending ˜200 km along strike of the Austral Basin. The Paleogene-Neogene boundary (˜23 Ma) may occur within the uppermost San Julián Formation (22.68 Ma, with a range between 22.22 and 23.22 Ma), coincident with a prominent glauconitic interval, or in a meteorically altered erosional paleosurface that caps this formation and may correlate with an eustatic sea level fall coincident with the global boundary. The younger Monte León Formation is entirely of early Neogene (Aquitanian to early Burdigalian) age, with ages of 22.12 Ma (21.68-22.58) at the base to 17.91 Ma (17.51-18.29) at the top. The proposed new chronostratigraphic framework forms a foundation for future differentiation of local, regional, and global sedimentary patterns in the Austral Basin during the Paleogene/Neogene transition; in particular, with contemporaneous basins and tectonic blocks across the southern polar region, such as in Australia, New Zealand, and Antarctica.

  9. Southwestern Power Administration annual site environmental report CY 1997

    SciTech Connect

    1998-11-01

    This report provides a synopsis of Southwestern Power Administration`s (Southwestern`s) effectiveness in managing its operations in an environmentally responsible manner. In CY 1997, the Office of Environmental, Safety, and Health was reorganized and incorporated into the Division of Acquisition and Property. The Division of Acquisition, Property, and Environmental Management maintains responsibility for development, oversight, and implementation of environmental programs. Senior Management at Southwestern has taken actions to increase environmental awareness throughout the organization. During CY 1997, (Southwestern) was not involved in any known programs or activities that had adverse impacts on the environment. The 1997 Environmental Appraisal, a portion of Southwestern`s Self-Assessment and Appraisal Program, indicated approximately 90% compliance with Southwestern`s written environmental programs. Southwestern continued to function throughout CY 1997 in an operations and maintenance posture with minor substation projects.

  10. A Factorial Description of Diversity Variations of the Neogene Planktonic Foraminiferal Lineages and its Paleoceanographic Implication

    NASA Astrophysics Data System (ADS)

    Wei, K.

    2005-12-01

    The species diversities of the 24 planktonic foraminiferal lineages established by Kennett and Srinivasan (1983) were analyzed with a Q-mode factor analysis. The analysis led to recognition of three diversity associations, named as Early, Middle and Late Associations. The three associations are considered to be three idealized - end members - peaked at Early Miocene, Middle Miocene and Pliocene, respectively. Trajectory of factor loadings of the three associations through the Neogene indicates that major changes in faunal composition took place during 18-15 Ma (Upper N6 - N9), 13-10 Ma (N12-N15), and 7-4 Ma (N17-N19). The times of these three major faunal changes are consistent with the intervals of high species turnover in Neogene planktonic foraminifera documented by Wei and Kennett (1986). Based upon each lineage's contribution (factor score) to the three associations, the 24 lineages can be grouped into five faunas: evergreen fauna, early fauna, middle fauna, and late fauna, and miscellaneous fauna. Those in the evergreen fauna play major roles in at least two diversity associations whereas the miscellaneous fauna comprises lineages of low diversities. Lineages in the early, middle and late fauna all enjoyed high speciation rates during the early Miocene, but exhibited different diversification rates afterwards, and therefore assumed successive dominance through the Neogene. The morphological traits and ecological strategies of the various lineages in these five faunas may reveal clues for understanding the modulation of paleoceanographic conditions on planktonic foraminiferal evolution.

  11. Neogene Sequence Along the Eskişehir Fault Zone (EFZ), NW Turkey

    NASA Astrophysics Data System (ADS)

    Apaydın Poşluk, Elif; Koral, Hayrettin

    2015-04-01

    This study aims to explore the stratigraphy and structural features of Neogene units located in the Bozüyük (Bilecik) and Oklubalı (Eskişehir) area in southern Marmara, which lies on the collision zone between the Sakarya and Tauride-Anatolide blocks. Pre-Mesozoic marbles, schists and granodiorites, Mesozoic marbles, schists, ophiolitic units and limestones are basement rocks. Cover units include Neogene age formations. From the bottom to top, they are named the Porsuk Formation and the Akpınar Limestone, the İnönü Volcanics and the Ilıca Formation. Paleontological data which could yield a geological age have not been observed in fluvial sediments of the Porsuk Formation and lacustrine deposits of the Akpınar Limestone. The 40K/40Ar dating analyses on trachy-andesite of the overlying İnönü Volcanics have yielded middle Miocene ages (15.0-15.5 Ma), suggesting the underlying sedimentary units namely the Porsuk Formation and the Akpınar Limestone to be lower-middle Miocene in age. Fossils have been discovered in the lacustrine limestone of the Ilıca Formation in Oklubalı (İnönü-Eskişehir) village, and the age is determined to be lower Pliocene. The Eskişehir Fault Zone (EFZ) transects the Neogene formations and Quaternary sediments along an E-W'ly orientation. The Ormangüzle, Bozalan, Kandilli and İnönü Faults are segments observed from the west to east inside the Eskişehir Fault Zone. Some of these faults have NW-SE and others WNW-ESE orientations. The faults in NW-SE directions were effective for the formation of the Neogene sequence based on NE, SE and SW-oriented paleo-flow orientations and abrupt facies changes. The faults with WNW-ESE orientations, as noted in the Çukurhisar earthquake of February 2, 1956 (M=6.4), still keep their seismic activity and have a potential of producing earthquakes. Keywords: Neogene sediments, 40K/40Ar dating, the Eskişehir Fault Zone, active fault, Çukurhisar earthquake

  12. Southwestern Power Administration Annual Report 2010

    SciTech Connect

    2012-09-01

    Dear Secretary Chu: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2010. In FY 2010, Southwestern delivered nearly 7.6 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Texas, and Oklahoma, generating $189 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  13. Southwestern Power Administration Annual Report 2012

    SciTech Connect

    2013-09-01

    Dear Secretary Moniz: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2012. In FY 2012, Southwestern delivered over 4.1 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas, generating $195 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  14. Southwestern Power Administration Annual Report 2011

    SciTech Connect

    2013-04-01

    Dear Secretary Chu: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2011. In FY 2011, Southwestern delivered over 4.1 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas, generating $167 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  15. Neogene stratigraphy, foraminifera, diatoms, and depositional history of Maria Madre Island, Mexico: Evidence of early Neogene marine conditions in the southern Gulf of California

    USGS Publications Warehouse

    McCloy, C.; Ingle, J.C.; Barron, J.A.

    1988-01-01

    Foraminifera and diatoms have been analyzed from an upper Miocene through Pleistocene(?) sequence of marine sediments exposed on Maria Madre Island, largest of the Tre??s Marias Islands off the Pacific coast of Mexico. The Neogene stratigraphic sequence exposed on Maria Madre Island includes a mid-Miocene(?) non-marine and/or shallow marine sandstone unconformably overlain by a lower upper Miocene to uppermost Miocene upper to middle bathyal laminated and massive diatomite, mudstone, and siltstone unit. This unit is unconformably overlain by lower Pliocene middle to lower bathyal sandstones and siltstones which, in turn, are unconformably overlain by upper Pliocene through Pleistocene(?) upper bathyal to upper middle bathyal foraminiferal limestones and siltstones. These beds are unconformably capped by Pleistocene terrace deposits. Basement rocks on the island include Cretaceous granite and granodiorite, and Tertiary(?) andesites and rhyolites. The upper Miocene diatomaceous unit contains a low diversity foraminiferal fauna dominated by species of Bolivina indicating low oxygen conditions in the proto-Gulf Maria Madre basin. The diatomaceous unit grades into a mudstone that contains a latest Miocene upper to middle bathyal biofacies characterized by Baggina californica and Uvigerina hootsi along with displaced neritic taxa. An angular unconformity separates the upper Miocene middle bathyal sediments from overlying lower Pliocene siltstones and mudstones that contain a middle to lower bathyal biofacies and abundant planktonic species including Neogloboquadrina acostaensis and Pulleniatina primalis indicating an early Pliocene age. Significantly, this Pliocene unit contains common occurrences of benthic species restricted to Miocene sediments in California including Bulimina uvigerinaformis. Pliocene to Pleistocene(?) foraminiferal limestones and siltstones characterize submarine bank accumulations formed during uplift of the Tre??s Marias Island area, and include

  16. Acoustic Velocity Of The Sediments Offshore Southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Tsai, C.; Liu, C.; Huang, P.

    2004-12-01

    Along the Manila Trench south of 21øXN, deep-sea sediments are being underthrusted beneath the Taiwan accretionary prism which is composed of the Kaoping Slope and Hengchun Ridge. Offshore southwestern Taiwan, foreland sediments and Late Miocene strata of the Tainan Basin are being accreted onto the fold-and thrust belt of the syn-collision accretionary wedge of the Kaoping Slope. The Kaoping Slope consists of thick Neogene to Recent siliciclastics deformed by fold-and-thrust structures and mud diapers. These Pliocene-Quaternary sediments deposited in the Kaoping Shelf and upper slope area are considered to be paleo-channel deposits confined by NNE-SSW trend mud diapiric structure. Seismic P-wave velocities of the sediment deposited in the Kaoping Shelf and Kaoping Slope area are derived from mutichannel seismic reflection data and wide-angle reflection and refraction profiles collected by sonobuoys. Sediment velocity structures constrained from mutichannel seismic reflection data using velocity spectrum analysis method and that derived from sonobuoy data using tau-sum inversion method are compared, and they both provide consistent velocity structures. Seismic velocities were analyzed along the seismic profile from the surface to maximum depths of about 2.0 km below the seafloor. Our model features a sediment layer1 with 400 ms in thickness and a sediment layer2 with 600 ms in thickness. For the shelf sediments, we observe a linear interval velocity trend of V=1.53+1.91T in layer1, and V=1.86+0.87T in layer2, where T is the one way travel time within the layer. For the slop sediment, the trend of V=1.47+1.93T in layer1, and V=1.70+1.55T in layer2. The layer1¡¦s velocities gradients are similar between the shelf (1.91 km/sec2) and the slope(1.93 km/sec2). It means layer1 distributes over the slope and shelf widely. The result of the sediment velocity gradients in this area are in good agreement with that reported for the south Atlantic continental margins.

  17. Quaternary deposits in southwestern Afghanistan

    USGS Publications Warehouse

    Smith, G.I.

    1974-01-01

    Geologic evidence in the closed Seistan Basin of southwestern Afghanistan and adjacent parts of Iran and Pakistan indicates that a lake as much as 65,000 sq km in size occupied this closed depression during Pleistocene time. The deposits consist mostly of lacustrine silt and clay and have a maximum observed thickness of about 250 m. A layer of alluvial gravels overlies the sequence. The deposits are probably early or middle Pleistocene in age; they are old enough to have sustained nearly 300 m of erosion over large areas but are not faulted or detectably folded in the central part of the basin although they are upwarped along the west edge of the basin. Sand dunes cover extensive areas of the basin. Dune orientation shows that the strong surface winds enter the basin blowing toward the south-southeast and then are deflected to the east, apparently as a response to mountains bordering the basin on its south side. The Gawdezereh, a large deflation depression, may be a result of an augmented excavation ability of winds that oc urs where turbulence is created along a zone of deflection. ?? 1974.

  18. The Baja California Borderland and the Neogene Evolution of the Pacific-North American Plate Boundary

    NASA Astrophysics Data System (ADS)

    Fletcher, J. M.; Eakins, B. W.

    2001-12-01

    New observational data on Neogene faulting in the borderland of Baja California places important constraints on tectonic models for the evolution of the Pacific-North American (P-NA) plate boundary and rifting in the Gulf of California. Neogene faults in the borderland range from strike slip to normal slip and accommodate integrated transtension. Most have east-facing escarpments and likely reactivate the former east-dipping accretionary complex. Numerous lines of evidence indicate that Neogene faults are still active and accomplish a significant component ( ~1-5 mm/yr) of Pacific-North American shearing. Quaternary volcanoes are found offshore and along the Pacific coastal margin, Quaternary marine terraces are warped and uplifted as high as 200 masl. Many of the offshore faults have fresh escarpments and cut Holocene sediments. Extensive arrays of Quaternary fault scarps are found throughout the coastal region and in Bahia Magdalena they are clearly associated with major faults that bound recently uplifted islands. A prominent band of seismicity follows the coast and eight earthquakes (Ms>5.0) were teleseismically recorded between 1973 and 1998. This evidence for active shearing indicates that the Baja microplate has not yet been completely transferred to the Pacific plate. The best lithologic correlation that can be used to define the total Neogene slip across the borderland faults is the offset between the Magdalena submarine fan and its Baja source terrane. The distal facies of the fan drilled during DSDP leg 63 is dominated by mudstone and siltstone that contain reworked Paleogene cocoliths derived from strata correlative with the Tepetate formation found throughout the borderland and fine-grained sandstone derived from a source terrane of granitoid basement. The Middle Miocene La Calera formation of the Cabo trough is one of many granitoid-clast syn-rift alluvial deposits that could form the continental counterpart of the submarine fan near the mouth of the

  19. Neogene tectono-stratigraphic events in Gulf of Suez rift area, Egypt

    SciTech Connect

    Evans, A.L.

    1987-05-01

    Micropaleontologic and sedimentologic studies of Miocene outcrop and borehole sections from the flanks and axial trough of the Suez rift have documented five major tectono-stratigraphic events, or hiatuses, during the Neogene. The first Neogene hiatus spans the late(.) Oligocene to earliest Miocene and separates Miocene from pre-Miocene strata throughout the Gulf of Suez. This erosional event resulted from both low global sea levels in the Oligocene and the initiation of Suez rifting. A second hiatus, from 21 to 19(.) Ma, separates the poorly dated shallow marine Nukhul formation from overlying middle Burdigalian and younger (NN3-NN5) upper bathyal shales of the Rudeis Formation. This hiatus resulted from both low early Burdigalian sea levels and increased rift-related tectonism. A third major event occurs within the Rudeis around 16 Ma (N7, NN4). This mid-Clysmic event of Garfunkel and Bartove is characterized by accelerated uplift of the rift margins and subsidence of the axial trough. Local unconformities are seen over paleohighs, while coarse clastics are deposited in more basinal areas in submarine fans and turbidites. A fourth hiatus at 14 to 13 Ma (N10-N11) separates the middle Miocene (N9) Kareem Formation from the overlying Belayim Formation evaporites. This hiatus may correlate with the initiation of rifting along the Dead Sea-Aqaba system. The fifth Neogene event is a tectonic pulse in the early (.) Pliocene that further rotated many tilted fault blocks. This event is roughly synchronous with the initiation of Red Sea sea-floor spreading and accelerated sinistral motion along the Dead Sea transform at approx. 5 Ma.

  20. Neogene vegetation and past climate change in the Thakkhola-Mustang Graben (central Nepal).

    NASA Astrophysics Data System (ADS)

    Adhikari, Basanta Raj; Wagreich, Michael; Draxler, Ilse; Paudayal, Khum N.

    2010-05-01

    The Thakkhola-Mustang Graben, which reflects Neogene extensional tectonics in the Tibetan Plateau and Himalaya, lies north of the Dhaulagiri-Annapurna ranges and south of the Yarlung-Tsangpo Suture Zone. The basement of Thakkhola-Mustang Graben is made up of Tibetan-Tethyan sedimentary rocks of Paleozoic and Mesozoic ages, which are unconformably overlain by continental debris (more than 850 m) of Neogene to Quaternary age. Stratigraphically, the Thakkhola-Mustang Graben sediments have been divided into five formations namely the Tetang Formation, the Thakkhola Formation, the Sammargaon Formation, the Marpha Formation and the Kaligandaki Formation. Different approaches have been made to study the Neogene sediments in this graben. In this study, we mainly focused on sedimentological and palynological studies of the Thakkhola-Mustang Graben, which provides a basis for discussing the paleo-environmental evolution of the southern continental margin of the Tibetan Plateau towards the end of the Miocene. Field mapping, profile logging, stable carbon and oxygen isotope analysis, and palynological studies were carried out to understand the depositional environment and the paleoclimate. The methodology developed by Zetter (1989) was followed for the pollen extraction. Pollen samples were processed in the laboratory and were studied under the light microscope (LM), which were later transferred to the scanning electron microscope (SEM). A variety of sedimentary environments are recognized including alluvial fan, lacustrine, braided river and glacio-fluvial. Neogene sediments are composed of braided fluvial deposits with lacustrine deposits in different level of the succession. Most of the pollens were found in the lacustrine layers of the Tetang and Thakkhola formations. Pollen analysis shows that the sediments contain dominant alpine trees like Abies, Pinus, Keteleeria, Picea Tsuga and Quercus with some steppe elements like Artemisia, Compositae, Chenopodiaceae, Plantago and

  1. Paleoceanographic model of neogene phosphorite deposition, u.s. Atlantic continental margin.

    PubMed

    Riggs, S R

    1984-01-13

    The Neogene stratigraphic section of the southeastern U.S. continental shelf-coastal plain system is characterized by (i) a series of major regional phosphogenic episodes; (ii) a strong spatial relationship between the structural or topographic framework and phosphate deposition; and (iii) distinct cyclical and regional patterns of deposition of the terrigenous, carbonate, and phosphate lithofacies. The complex depositional patterns are explained by a paleoceanographic model based upon the interaction of glacial eustatic sea-level fluctuations, associated changes in climate, and the dynamics of the Gulf Stream in response to the bathymetric configurations of the continental margin during the past 20 million years.

  2. Northeastern Exterior, Northwestern Exterior, & Southwestern Exterior Elevations, Northeastern Interior, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Northeastern Exterior, Northwestern Exterior, & Southwestern Exterior Elevations, Northeastern Interior, Southeastern Interior, & Southwestern Interior Elevations, Floor Plan, and Eastern Corner Detail - Manatoc Reservation, Vale Edge Adirondack, 1075 Truxell Road, Peninsula, Summit County, OH

  3. Cenozoic kinematic evolution of southwestern Central Iran: Strain partitioning and accommodation of Arabia-Eurasia convergence

    NASA Astrophysics Data System (ADS)

    Kargaranbafghi, Fariba; Neubauer, Franz; Genser, Johann

    2011-04-01

    The Yazd block of southwestern Central Iran is located in the back of the Zagros fold-thrust belt and monitors accommodation of Cenozoic shortening within the Arabia-Eurasia collision zone. The Saghand area within the Yazd block exposes a basin-and-range type morphology, which results from NE respectively E-W direction of shortening and a major tectonic change in structural trends within the southwestern Central Iranian block. The NNE-structural trend of various lithotectonic units including the Eocene Chapedony metamorphic core complex in the north is parallel to prominent Cenozoic NNE-trending Chapedony and Posht-e-Badam strike-slip faults. In the south the NNW-trending Anar, Kharanagh-Zarrin, Behabad and Kuhbanan faults are parallel to the Zagros fold-thrust belt and represent dextral strike-slip respectively NE-directed thrust faults, the thrust component representing a back-thrust component to the Zagros fold-thrust belt. Results of interpretation of satellite images, and structural and geomorphic field observations show a distributed deformation pattern covering a wide domain within southwestern Central Iran. Morphotectonic features like linear mountain ranges and intervening basins (kavirs) are interpreted to result from Neogene to Recent crustal-scale folding with uplifting mountain ranges and subsiding basins. Active thrust faults and evidence for block tilting are common on the eastern side of mountain blocks. Five distinct regional deformation phases respectively paleostress tensor groups have been recognized in the Central Iran from the major structures and through using paleostress inversion techniques for fault slip data. The first phase occurred in the Late Paleocene to Oligocene and is characterized by a subvertical σ1 and ca. N-S oriented σ3, which indicate N-S extension associated with late stages of normal faulting possibly due to post-orogenic collapse during exhumation of the Chapedony metamorphic complex. The second phase occurred from Late

  4. Eocene ostracoda from Oshosun formation Southwestern Nigeria

    NASA Astrophysics Data System (ADS)

    Okosun, E. A.

    A biostratigraphic study of the phosphate-bearing Oshosun Formation in southwestern Nigeria (eastern Dahomey Embayment) gave ostracos which are diagnostic for the Eocene. The ostracod assemblage contains the early to middle Eocene zonal index Costa dahomeyi. The majority of the species are common to the phosphatic sequence in the western Dahomey Embayment. This paleontologic evidence, and the association of clay and shale with the phosphate occurrences in different parts of the basin, suggest that the phosphatic beds were deposited in the Dahomey Embayment under similar paleoenvironmental conditions. Phosphatic sedimentation in southwestern Nigeria is inferred to have occurred during an early to early middle Eocene minor marine transgression.

  5. 25 CFR 38.15 - Southwestern Indian Polytechnic Institute.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Southwestern Indian Polytechnic Institute. 38.15 Section 38.15 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION EDUCATION PERSONNEL § 38.15 Southwestern Indian Polytechnic Institute. (a) The Southwestern Indian Polytechnic Institute...

  6. 25 CFR 38.15 - Southwestern Indian Polytechnic Institute.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 1 2011-04-01 2011-04-01 false Southwestern Indian Polytechnic Institute. 38.15 Section 38.15 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION EDUCATION PERSONNEL § 38.15 Southwestern Indian Polytechnic Institute. (a) The Southwestern Indian Polytechnic Institute...

  7. Stratigraphic record of the Yellowstone hotspot track, Neogene Sixmile Creek Formation grabens, southwest Montana

    NASA Astrophysics Data System (ADS)

    Sears, James W.; Hendrix, Marc S.; Thomas, Robert C.; Fritz, William J.

    2009-11-01

    The Sixmile Creek Formation fills deep grabens in southwest Montana and preserves a stratigraphic record of the evolution of the Yellowstone hotspot track from ~ 17 Ma to ~ 2 Ma. The Ruby, Beaverhead, Big Hole, Deer Lodge, Medicine Lodge-Grasshopper, Three Forks, Canyon Ferry, Jefferson, Melrose, Wise River, and Paradise grabens were active during outbreak of the hotspot. They appear to be parts of a radial system of extensional structures that may have formed on a broad dome that was centered on the hotspot outbreak area in southwest Idaho and southeast Oregon. Early in the evolution of the grabens, massive debris flows surged down Paleogene paleovalleys from uplifted and tilted horst blocks and accumulated in the grabens. The grabens captured runoff from the hotspot dome with thick deposits of river gravel that appear to have been derived, in part, from east-central Idaho. As the hotspot track propagated along the eastern Snake River Plain, silicic ash fell into the graben drainage basins and was reworked into thick fluvial beds along graben axes. The grabens were cross-cut by northwest-trending late Neogene grabens that propagated on the flanks of silicic volcanic centers along the hotspot track. The late Neogene grabens diverted the Middle Miocene drainage patterns in southwest Montana.

  8. A Neogene calcareous nannofossil biozonation scheme for the deep offshore Niger Delta

    NASA Astrophysics Data System (ADS)

    Fadiya, Lawrence Suyi; Salami, Babajide Moshood

    2015-12-01

    A detailed calcareous nannofossil analysis was carried out on the deep-water offshore Niger Delta strata penetrated by eight wells in order to erect a basin-wide Neogene biozonation scheme for the region. Four of the wells penetrated Miocene to Early Pliocene strata while the others drilled through Miocene sediments. The recorded rich and diversified nannofossil suites enabled the subdivision of the Neogene sequences into 13 zones [NN1 (CN1a) - Early Miocene to NN13 (CN10c) - Early Pliocene] and 15 subzones. Five (NN1, NN2, NN4, NN5 and NN11) zones are divided into subzones based on First and Last occurrences plus relative abundance of marker species. Dearth of nannofossils in the Middle Miocene NN5-NN8 zones precludes a refined zonation construction for the interval. Several new criteria are suggested for delineating new and previously erected zones. The resulting refined scheme offers an improved stratigraphic framework for correlation of thin reservoir units within and across Niger Delta fields.

  9. Tectonic Evolution of the Çayirhan Neogene Basin (Ankara), Central Turkey

    NASA Astrophysics Data System (ADS)

    Behzad, Bezhan; Koral, Hayrettin; İşb&idot; l, Duygu; Karaaǧa; ç, Serdal

    2016-04-01

    Çayırhan (Ankara) is located at crossroads of the Western Anatolian extensional region, analogous to the Basin and Range Province, and suture zone of the Neotethys-Ocean, which is locus of the North Anatolian Transform since the Late Miocene. To the north of Çayırhan (Ankara), a Neogene sedimentary basin comprises Lower-Middle Miocene and Upper Miocene age formations, characterized by swamp, fluvial and lacustrine settings respectively. This sequence is folded and transected by neotectonic faults. The Sekli thrust fault is older than the Lower-Middle Miocene age formations. The Davutoǧlan fault is younger than the Lower-Middle Miocene formations and is contemporaneous to the Upper Miocene formation. The Çatalkaya fault is younger than the Upper Miocene formation. The sedimentary and tectonic features provide information on mode, timing and evolution of this Neogene age sedimentary basin in Central Turkey. It is concluded that the region underwent a period of uplift and erosion under the influence of contractional tectonics prior to the Early-Middle Miocene, before becoming a semi-closed basin under influence of transtensional tectonics during the Early-Middle Miocene and under influence of predominantly extensional tectonics during the post-Late Miocene times. Keywords: Tectonics, Extension, Transtension, Stratigraphy, Neotectonic features.

  10. High-resolution sedimentological and subsidence analysis of the Late Neogene, Pannonian Basin, Hungary

    USGS Publications Warehouse

    Juhasz, E.; Muller, P.; Toth-Makk, A.; Hamor, T.; Farkas-Bulla, J.; Suto-Szentai, M.; Phillips, R.L.; Ricketts, B.

    1996-01-01

    Detailed sedimentological and paleontological analyses were carried out on more than 13,000 m of core from ten boreholes in the Late Neogene sediments of the Pannonian Basin, Hungary. These data provide the basis for determining the character of high-order depositional cycles and their stacking patterns. In the Late Neogene sediments of the Pannonian Basin there are two third-order sequences: the Late Miocene and the Pliocene ones. The Miocene sequence shows a regressive, upward-coarsening trend. There are four distinguishable sedimentary units in this sequence: the basal transgressive, the lower aggradational, the progradational and the upper aggradational units. The Pliocene sequence is also of aggradational character. The progradation does not coincide in time in the wells within the basin. The character of the relative water-level curves is similar throughout the basin but shows only very faint similarity to the sea-level curve. Therefore, it is unlikely that eustasy played any significant role in the pattern of basin filling. Rather, the dominant controls were the rapidly changing basin subsidence and high sedimentation rates, together with possible climatic factors.

  11. Neogene folding and faulting in southern Monterey Bay, Central California, USA

    USGS Publications Warehouse

    Gardner-Taggart, J. M.; Greene, H. Gary; Ledbetter, M.T.

    1993-01-01

    The goal of this study was to determine the Neogene structural history of southern Monterey Bay by mapping and correlating the shallow tectonic structures with previously identified deeper occurring structures. Side scan sonographs and Uniboom seismic reflection profiles collected in the region suggest that deformation associated with both compressional and transcurrent movement is occurring. Strike-slip movement between the North American and Pacific plates started as subduction ceased 21 Ma, creating the San Andreas fault system. Clockwise rotation of the Pacific plate occurred between 3.4 and 3.9 Ma causing orthogonal convergence between the two plates. This plate rotation is responsible for compressional Neogene structures along the central California coast. Structures exhibit transpressional tectonic characteristics such as thrust faulting, reverse faulting and asymmetrical folding. Folding and faulting are confined to middle Miocene and younger strata. Shallow Mesozoic granitic basement rocks either crop out or lie near the surface in most of the region and form a possible de??collement along which the Miocene Monterey Formation has decoupled and been folded. Over 50% of the shallow faults strike normal (NE-SW) to the previously identified faults. Wrench fault tectonics complicated by compression, gradual uplift of the basement rocks, and a change in plate convergence direction are responsible for the observed structures in southern Monterey Bay. ?? 1993.

  12. Diatom biostratigraphy of chert intervals in Santa Maria and other Neogene basins, California

    SciTech Connect

    White, L.D.

    1988-03-01

    Chert is a common component of the Monterey Formation in many outer Neogene basins. Successful recovery of diatoms from dolomite beds and concretions, which are sufficiently abundant in chert-bearing sections, makes diatom biostratigraphic analyses possible in several poorly chronicled Neogene basins. At Ano Nuevo in the Outer Santa Cruz basin, where the section consists mainly of porcelanite and chert, diatom biostratigraphy yields an age duration from 14.7-13.4 Ma. Precise age control allows analysis of cyclical aspects of chert and dolomite to be carried out on the section. Frequency estimates of silica-carbonate cycles at Ano Nuevo suggest that the cycles may be related to early middle Miocene paleo-oceanographic events. In the Santa Maria basin, where black quartz cherts are widespread, diatom biostratigraphy has been successfully applied on the Mussel Rock, Lions Head, and Shell Beach sections. Preliminary data suggest black chert intervals are strongly age controlled and are possibly related to Miocene cooling events that affected the Santa Maria basin. Ongoing studies of the diatom biostratigraphy of dolomites promise improved age control in the Santa Maria basin. This will not only aid in paleo-oceanographic interpretations, but will also improve constraints on tectonic and depositional aspects of the basin.

  13. Variations in the strontium isotopic composition of seawater during the Neogene

    SciTech Connect

    Hodell, D.A.; Mueller, P.A.; Garrido, J.R. )

    1991-01-01

    The authors report 261 strontium isotopic analyses of well-preserved planktonic foraminifers from three Deep Sea Drilling Project Sites (519, 588, and 607). These samples cover the period from 24 Ma to present with an average of approximately one sample per 100 ka. The combination of high sample density and uniformity of analytical procedures has produced a well-defined record of changes in the {sup 87}Sr/{sup 86}Sr of seawater during the Neogene. The record can be viewed as a series of essentially linear segments with slopes ranging from as high as 6{times}10{sup {minus}5}/m.y. to as low as 0/m.y. The times associated with major inflections in the curve do not appear to correspond to simple geologic phenomena such as eustatic cycles, but are probably controlled by a combination of tectonic and climatic factors that influenced the abundance and isotopic composition of terrestrial strontium input to the oceans. The strontium isotopic data are consistent with a progressive increase in the chemical weathering rates of the continents during the Neogene, probably related to repeated glaciations, increased exposure of continents by lowered sea level, and increased continental relief resulting from high rates of tectonic uplift.

  14. The Neogene equatorial Pacific: A view from 2009 IODP drilling on Expedition 320/321. (Invited)

    NASA Astrophysics Data System (ADS)

    Lyle, M. W.; Shackford, J.; Holbourn, A. E.; Tian, J.; Raffi, I.; Pälike, H.; Nishi, H.

    2013-12-01

    The equatorial Pacific responds strongly to global climate and is a source of ENSO, the largest global decadal climate oscillation. Equatorial Pacific circulation and upwelling result from global atmospheric circulation patterns so it is unsurprising that oceanographic changes in the equatorial Pacific reverberate globally. IODP expedition 320/321 (Pacific Equatorial Age Transect) drilled 8 sites to reconstruct a 50-million-year record of ocean change for the equatorial Pacific. The resulting record, when spliced together, will resolve orbital variations through most of the Cenozoic. All sedimentary sequences have now been scanned by XRF, so that biogeochemical changes through the Cenozoic can be studied. Here we report data from IODP Sites U1335, U1336, U1337, and U1338, the Neogene part of the PEAT megasplice. Sediments of the Neogene equatorial Pacific are primarily biogenic carbonates, with about 15% biogenic silica tests and 5% assorted other components, including clays. Typically, highest sediment deposition occurs when plate tectonic movement carries a drill site underneath the equatorial zone, indicating that equatorial upwelling and high productivity have been consistent features of the Neogene equatorial Pacific. Sedimentation rates become significantly slower and dissolution of both biogenic carbonates and silica are more pronounced when sites are beyond 3° in latitude away from the equator, as biogenic sediment production drops but dissolution does not. The differences between equatorial and off-equator sites allow assessment of productivity vs dissolution as drivers of the sediment record. Carbonate dissolution can also be assessed by a ratio of XRF-estimated carbonate to dissolution resistant biogenic residue, like barite. There is a common stratigraphy of carbonate variation in the Neogene equatorial Pacific, as proposed by earlier work from DSDP Leg 85 and ODP Leg 138. The new Exp 320/321 drilling extends the high-resolution record from ~0-5 Ma

  15. The Neogene Ogallala Formation in Southwestern Kansas and Northeastern New Mexico: Preliminary Magnetostratigraphic Analyses for the High Plains-Ogallala Drilling Program

    NASA Astrophysics Data System (ADS)

    Zeigler, K. E.; Petronis, M. S.; Smith, J. J.; Ludvigson, G. A.; Doveton, J.

    2012-12-01

    A better understanding of the Ogallala Formation is critical in terms of refining groundwater flow models and management policies for communities relying on aquifers in heterolithic sequences around the globe. The High Plains aquifer remains under increasing stress with the growth of both urban and agricultural areas and therefore, developing the best groundwater management policies will depend on the most accurate characterization of the aquifer, the aquifer materials and their stratigraphic and geochronologic framework. Although mammalian faunal assemblages and volcanic ash bed tephrochronology provide a basic geochronologic framework for the Ogallala Formation, better precision in terms of correlation is needed in order to understand formative processes and depositional histories for the primary water-bearing units in the High Plains aquifer and confining strata. The High Plains-Ogallala Drilling Program (HPODP) was developed to advance understanding of sedimentary facies, stratigraphic framework, and chronostratigraphy of the Ogallala Formation and overlying units that comprise the central High Plains aquifer. The drilling program began in the early summer of 2011 in Haskell Co., western Kansas. By early fall 2011; the drill crew was at 92 m with about 32 m to go until they expect to hit bedrock. The final 32 meters of core was extracted during the summer 2012. Here we report the preliminary magnetostratigraphic and rock magnetic data from the first section of core. We scanned the entire 92 meters of core using an ASC Core Analysis System with a Bartington Instruments MS2C magnetic susceptibility coil allowing for bulk susceptibility measurements to be obtained along the length of the core. In addition, we collected 40 sub samples for paleomagnetic and rock magnetic. Bulk susceptibility data reveal depth dependent changes in rock magnetic properties that we interpret to reflect either climatic driven variations impacting the depositional system or a change in provenance of the sediments. Bulk susceptibility of the sediments decreases by an order of magnitude from the surface to the base of the measured core suggesting a change in detrital magnetic influx. Curie point estimates indicate that the dominant magnetic mineral in all samples is cubic, titanomagnetite phase of variable composition; whether a systemic change with depth exist is as of yet to be revealed. Preliminary paleomagnetic data are encouraging with many sub samples yielding a single component magnetization that decays near univectorally to the origin during both alternating field and thermal demagnetization.

  16. Media Makes the Message at Southwestern Life

    ERIC Educational Resources Information Center

    Brosseau, Beth

    1974-01-01

    The new J. Carlton Smith Educational Center, training center of Southwestern Life Insurance Company, Dallas, Texas, utilizes a 3,600 square feet facility and employs a wide range of methods to make life underwriting training fast and interesting. Multimedia instruction is the key to their effective educational programs. (MW)

  17. Fossil proxies of near-shore sea surface temperatures and seasonality from the late Neogene Antarctic shelf.

    PubMed

    Clark, Nicola A; Williams, Mark; Hill, Daniel J; Quilty, Patrick G; Smellie, John L; Zalasiewicz, Jan; Leng, Melanie J; Ellis, Michael A

    2013-08-01

    We evaluate the available palaeontological and geochemical proxy data from bivalves, bryozoans, silicoflagellates, diatoms and cetaceans for sea surface temperature (SST) regimes around the nearshore Antarctic coast during the late Neogene. These fossils can be found in a number of shallow marine sedimentary settings from three regions of the Antarctic continent, the northern Antarctic Peninsula, the Prydz Bay region and the western Ross Sea. Many of the proxies suggest maximum spring-summer SSTs that are warmer than present by up to 5 °C, which would result in reduced seasonal sea ice. The evidence suggests that the summers on the Antarctic shelf during the late Neogene experienced most of the warming, while winter SSTs were little changed from present. Feedbacks from changes in summer sea ice cover may have driven much of the late Neogene ocean warming seen in stratigraphic records. Synthesized late Neogene and earliest Quaternary Antarctic shelf proxy data are compared to the multi-model SST estimates of the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Despite the fragmentary geographical and temporal context for the SST data, comparisons between the SST warming in each of the three regions represented in the marine palaeontological record of the Antarctic shelf and the PlioMIP climate simulations show a good concordance.

  18. The geochemical signature of Neogene Eastern Mediterranean sediment: evidence for temporal and spatial variations in provenance

    NASA Astrophysics Data System (ADS)

    Klaver, Martijn; Vroon, Pieter; Wijbrans, Jan

    2014-05-01

    Subducted sediment is one of the main geochemical components in arc magmas. Although an east-west gradient in Eastern Mediterranean Sea (EMS) sediment composition has been evoked to explain the along-arc geochemical variations in Aegean arc magmas [1], solid evidence for E-W changes in EMS sediment composition is lacking. The EMS sediment dataset is limited to Holocene samples, while the sediment currently underneath the volcanic arc has an age of at least 6 Ma. In order to characterise EMS sediment, we have used a combination of thermogravimetric and geochemical analyses of 45 Neogene DSDP and ODP drill core samples. Thermogravimetric dissociation curves provide a rapid way to determine carbonate-content and relative abundance of clay mineral groups in mixed sediment samples. Clear clay mineral distribution patterns are observed in the EMS: smectite is dominant in Nile sediment, aeolian dust consist mainly of kaolinite while illite is present in coarser (shelf) sediment. Four distinct provenance areas can be recognised on the basis of radiogenic isotope and trace element ratios of the EMS sediment samples. In line with previous studies [e.g. 2], we conclude that Sahara dust and Nile sediment are main constituents of EMS sediment. However, we recognize two additional source areas. Sediment derived from Cyprus and/or SW Turkey, characterised by high Ni/Nb ratios, is an important component in Quaternary EMS sediment. Sediment from the Aegean region has an arc signature (e.g. high La/Nb) and is distinguishable only in the Hellenic Trench. During the Neogene, an increase in aeolian dust input to the EMS is observed, which is consistent with the progressive aridification of the Sahara region. The geochemical characterisation of Neogene EMS sediment and the recognition of distinct provenance areas can be used to assess the contribution of subducted sediment to magmas in the Aeolian and Aegean volcanic arcs. In addition, it allows further high-resolution investigation of

  19. The radiologist's tragedy, or Bland-White-Garland syndrome (BWGS). On the 80th anniversary of the first clinical description of ALCAPA (anomalous left coronary artery from the pulmonary artery)

    PubMed Central

    Kusa, Jacek

    2014-01-01

    In 1933, three doctors from the Massachusetts General Hospital in Boston, Paul Dudley White, William Franklin Bland, and Joseph Garland, described a case of an anomalous origin of the left coronary artery arising from the pulmonary artery (ALCAPA) in a three-month-old boy. The infant died following two weeks of hospitalization. The child's father was Dr. Aubrey Hampton, a radiologist and colleague of White, Bland, and Garland. The paper presents a perspective view on the occasion of the 80th anniversary of the first clinical description of ALCAPA. PMID:26336427

  20. Late Cenozoic Colorado River Incision and Implications for Neogene Uplift of the Colorado Rockies

    NASA Astrophysics Data System (ADS)

    Aslan, A.; Karlstrom, K. E.; Kirby, E.; Heizler, M. T.

    2012-12-01

    Basalt flows and volcanic ashes serve as a datum for calculating post-10 Ma river incision rates in western Colorado. The main picture that emerges from the data is one of regional variability of incision rates, which we hypothesize to reflect differential uplift of the Colorado Rockies during the Neogene. Maximum rates (90-180 m/Ma) and magnitudes (750-1500 m) of river incision are recorded between Grand Mesa and Glenwood Canyon, and in the Flat Tops. Minimum rates (<30 m/Ma) and magnitudes (<250 m) of river incision are associated post-Laramide normal faults within the Browns Park-Sand Wash basin in northwestern Colorado and in Middle Park of north-central Colorado. Differential uplift of the Colorado Rockies during the late Cenozoic can be inferred by comparing incision rates and magnitudes at locations upstream and downstream of knickzones. Along the Colorado River, post-10 Ma incision rates and magnitudes incision remain fairly constant (rates >100 m/Ma; magnitudes >1000 m) from Grand Mesa upstream to Gore Canyon, and then decrease markedly in Middle Park (rates <10 m/Ma; magnitudes <100 m) across the Gore Canyon knickzone. Normal-faulting of ca. 10 Ma deposits in Middle Park shows that incision rate variations partly reflect late Cenozoic faulting. Along the Yampa River, post-10 Ma incision rates and magnitudes are low (rates 15-27 m/Ma; magnitudes < 230 m) immediately upstream of Yampa Canyon, and then increase significantly (rates 96-132 m/Ma; magnitudes ~1250 m) upstream near the headwaters. We interpret this upstream increase in river incision rate and magnitude to reflect Neogene uplift of the Yampa River headwaters relative to its lower reaches. Lastly, differential late Cenozoic uplift of the Colorado Rockies is suggested by differences in the timing of regional exhumation and river incision within different drainage basins. Colorado River incision and regional exhumation occurred between 9.8 and 7.8 Ma. In contrast, Yampa River incision began between

  1. A Neogene structural dome in the Klamath Mountains, California and Oregon

    NASA Astrophysics Data System (ADS)

    Mortimer, N.; Coleman, R. G.

    1985-04-01

    Regional structural doming of Neogene age has affected rocks of the Klamath and Cascade mountains near the California-Oregon border. Evidence for this is seen in (1) subannular outcrop patterns of pre-Cretaceous lithotectonic units, (2) a crude pattern of radially oriented high-angle faults, (3) tilted Jurassic plutons, (4) tilted Cretaceous to Miocene strata, and (5) various geomorphological features. The age of doming is constrained by a major middle Miocene to earliest Pliocene angular unconformity within the Cascade Mountains and uplifted upper Miocene marine beds on the western edge of the Klamath Mountains. Uplift and doming may be the result of shortening in the Cascade fore-arc region or, more speculatively, the recent accretion of subducted material to the North American plate beneath the Klamath Mountains. *Present addresses: Mortimer, Department of Geological Sciences, University of British Columbia, Vancouver, British Columbia V6T 2B4, Canada; Coleman, U.S. Geological Survey, Menlo Park, California 94025

  2. Biodiversity and paleobiogeography of the European freshwater Neogene: trends, hotspots and faunal turnovers

    NASA Astrophysics Data System (ADS)

    Neubauer, Thomas A.; Harzhauser, Mathias; Georgopoulou, Elisavet; Andreas, Kroh; Mandic, Oleg

    2015-04-01

    We present an outline of a paleobiogeographic framework for the European fresh- and brackish-water systems during the Neogene. Data basis is a presence-absence matrix of lacustrine gastropods from over 2,700 localities. Cluster analyses were separately carried out on the datasets of the four time slices Early Miocene, Middle Miocene, Late Miocene, and Pliocene. Based on the results of the cluster analyses, the degree of endemicity, and geographical coherence, we classified the lake systems of the four time intervals into biogeographic units. The increasing degree of provincialism throughout the Neogene supported more detailed breakdowns in younger intervals. This pattern reflects the ongoing continentalization of Europe linked to the Alpidic Orogenesis. Additionally, the retreat of the Paratethys Sea and its isolation from the Mediterranean promoted the evolution of endemic faunas in surrounding lacustrine systems. Direct descendants such as long-lived Lake Pannon, Lake Dacia or Lake Slavonia persisted over several millions of years and promoted the evolution of highly diverse and endemic faunas. Because of their extensive duration they crucially influenced family-level composition, differences of the relative species richnesses per biogeographic unit, and rising rate of endemicity. We show that the biogeographic classification as well as the existence of biodiversity hotspots are tightly linked to the formation and evolution of long-lived lacustrine environments and thus to Europe's geodynamic history. Heat maps are provided to visualize the shifting distributions of hotspots through time. The only physiographic factor that can be shown to be correlated with species richness is the size of a lake. Other factors such as latitude, longitude or temporal duration show weak relationships. Correlation of biodiversity trends to climatic parameters such as temperature and precipitation are feasible only for selected periods. Climate is considered to have only minor

  3. Neogene rotations in the Northeastern Tibetan Plateau: a synthesis of paleomagnetic studies

    NASA Astrophysics Data System (ADS)

    Yan, M.; Fang, X.; Song, C.; Zhang, W.

    2013-12-01

    Paleomagnetism can quantitative determine tectonic rotations around a vertical axis and test geodynamic models concerning the kinematics of the India-Asia collision. However, so far paleomagnetic studies in the northeastern (NE) Tibetan Plateau are still difficult to relate tectonic rotations to regional geodynamics, due to poor age control and some discordant paleomagnetic results on the studied rocks. Recent three magnetostratigraphic based rotation studies around the NE Tibetan Plateau have successfully revealed rotation variations through time, all indicating the existences of multiple rotation patterns during the late Neogene. Given recent large numbers of magnetostratigraphic studies and the possible existence of multiple changes in the sense and magnitude of rotations, the averaging of which possibly have resulted in the discordant paleomagnetic rotations, to better understand the Neogene rotations of the NE Tibetan Plateau, we report here new rotation studies through synthesizing available well dated magnetostratigraphic results of the region. A total of eight basin magnetostratigraphic results are utilized. These are the Kunlun, Qaidam, Jiuquan, Chaka, Guide, Linxia, Tianshui and Liupanshan basins. The analyses of paleomagnetic declination variations through time of these basins indicate that significant rotations have occurred around the NE Tibetan Plateau: although rotations close to the major faults are complicated, (1) within the NE Tibetan Plateau, it indicates an overall pattern of insignificant rotations before 11 Ma, significant clockwise rotations since ~11-8 Ma, with accelerated rotations or switch of rotation patterns since ~5-3 Ma; and the magnitude of clockwise rotations decreases from the west (Qaidam and Guide Basins) of ~30 degree to the east (Linxia and Tianshui Basins) of ~10 degree; (2) outside of the plateau, it in general shows a trend of clockwise rotations before 11 Ma, and significant counterclockwise rotations after that.

  4. The Influence of North Atlantic Valves and Gateways on Neogene Climate Change

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    2015-12-01

    Our current proxies for pCO2 suggest Neogene levels were relatively constant (~300 ± 100 ppm) except for the middle Miocene Climatic Optimum with estimates approaching 400 ± 100 ppm. Yet, the East Antarctic Ice Sheet became a polar ice sheet and permanent feature on Earth while large-scale Northern Hemisphere ice sheets waxed and waned with scant differences in pCO2. Three possibilities to explain these observations are: 1) our pCO2 proxies are incorrect; 2) Earth's climate is far more sensitive than our current model simulations suggest; or 3) tectonic differences overprinted accepted climate sensitivity to pCO2. Two marine gateways that influenced Neogene deep-water circulation are the Greenland-Scotland Ridge and the Central American Isthmus (CAI). Driven by mantle plume variations under Iceland, the GSR acted as a regulator of Northern Component Water (NCW, analogous to NADW) by controlling access to the dense polar waters to the north. During the latest Miocene and early Pliocene, mean depths along the GSR and NCW production were at their greatest. By the late Pliocene (~3 Ma), mantle plume activity increased and NCW production waned. Most researchers have focused on surface water changes (e.g., salinity) in relating closure of the CAI to Pliocene climate change. However, I propose that its primary influence came with the elimination of low-latitude, deep-water connection between the Atlantic and Pacific. Combined with vigorous NCW production, closure of the CAI re-distributed nutrients between the oceans. Carbon isotope and Cd/Ca profiles indicate that "modern" basin-to-basin differences started during the latest Miocene and were fully developed in the Pliocene. The South Atlantic path for NCW also delivered heat to the Southern Ocean, facilitating sea ice changes, as indicated by biosiliceous patterns. These tectonic boundary changes and their affects on surface and deep water circulation contributed to the Pliocene pause in global cooling that began in

  5. A closer look at the Neogene erosion and accumulation rate increase

    NASA Astrophysics Data System (ADS)

    Willenbring, J.; von Blanckenburg, F.

    2008-12-01

    Glacial erosion and Quaternary cold-stage warm-stage climate cycling have been cited as mechanisms to explain observations of increased Neogene marine sedimentation rates. Quantification of long-term glacial erosion rates from cosmogenic radionuclides from large areas mostly covered by cold-based ice during the Quaternary show very low erosion rates over several glacial cycles. In addition, isotope ratio proxies of dissolved metals in seawater, measured in chemical ocean sediments, lack clear evidence for an increase in terrigenous denudation. In particular, the stable isotope 9Be, derived from continental erosion, shows no change in its ratio to meteoric cosmogenic nuclide 10Be, derived from rain over the past 10 My. Radiogenic Pb and Nd isotopes, mainly show a change in the style of denudation from more chemical to more physical processes in the Quaternary. These data are at odds with a suggested increase in marine sedimentation rates during the late Cenozoic. In order to resolve this contradiction we have scrutinized these sedimentation rate calculations from ocean cores to identify whether they might show only apparent increases in the Neogene sections. Potential explanations are that in some cases, measured sediment thicknesses for different time intervals lack corrections for sediment compaction. Compaction of the lower portions of the cores drastically increases the apparent thickness of the more recent (Quaternary) sediment. In addition, sedimentation rates often only appear higher for recent sections in cores due to an artifact of an averaging timescale that decreases up-core. Such an averaging time scale decrease arises from better chronological resolution in recent times (Sadler et al., 1999). Cannibalization of older sediment might add to this effect. Together, these data question a clear, global-scale Quaternary climate-erosion connection that would be unique in Earth's history.

  6. Neogene tectonic and crustal elements in the eastern part of the NORCAL transect

    SciTech Connect

    Grose, T.L.T. . Dept of Geology and Geological Engineering); Saucedo, G.J. . Div. of Mines and Geology); Wagner, D.L. . Div. of Mines and Geology)

    1993-04-01

    Distinctive first-order Neogene tectonic provinces defined geologically in the shallow crust may also be expressed geophysically in the deep crust. They include (1) N end of Sierra Nevada block, (2) SE end of Cascade Range, (3) S margin of Modoc Plateau, and (4) W margin of Basin and Range province. Prominent second-order tectonic features include the Honey Lake depression and the Walker Lane Belt which together compose a transitional NW-trending boundary between the Sierra-Cascade arc and the Basin and Range-Modoc back arc. A less obvious more complex zone of Neogene crustal contrast between areas to N and to S passes generally EW through the Susanville area. The Susanville zone internally includes (1) the northern fault margin of the Honey Lake depression, (2) the region's greatest volcanic center (Skedaddle Mts.), (3) a well-defined westward-evolving line of volcanoes, and (4) several active geothermal systems. South of the Susanville zone (1) faults dip E and blocks tilt W, (2) Walker Lane fault zone tends N60W, (3) hornblende-rich volcanics prevail and (4) Sierran granitic rocks crop out widely. North of the Susanville zone (1) faults dip W and blocks tilt E, (2) Walker Lane trends N35W, (3) olivine-rich volcanics prevail, and (4) Cascade-Modoc volcanic rocks are ubiquitous. The Susanville zone, the S end of active Cascade volcanism, the Battle Creek fault, the Klamath-Sierra gap, the N end of the Great Valley, the Mendocino triple junction, and other features define an EW zone of crustal contrast through the NORCAL transect.

  7. Marine environmental changes at the Brazilian equatorial margin related to Amazon River evolution during the Neogene

    NASA Astrophysics Data System (ADS)

    Lammertsma, Emmy; Troelstra, Simon; Sangiorgi, Francesca; Chemale, Farid, Jr.; do Carmo, Dermeval A.; D'Avila, Roberto; Soares, Emilson; Hoorn, Carina

    2014-05-01

    Today, the nutrient-rich Amazon River outflow causes massive algal blooms in the western equatorial Atlantic Ocean, forming a considerable carbon sink as well as a primary food source in the otherwise oligotrophic surface water. However, the history of this high-productivity system is largely unknown, although a strong relation to the evolution of the Amazon River can be expected. The Amazon submarine fan provides direct evidence for the development of a transcontinental river system, of which the base of the primarily Andean-sourced siliciclastic deposits is dated as late Miocene. Ditch cuttings from Amazon Fan exploration 'Well 2' were made available by Petrobras for microfossil and lithological research. 'Well 2' is located on the uppermost fan at a water depth of 750 meters. Organic-walled dinoflagellate cyst and foraminifer assemblages were studied to reconstruct Neogene marine environmental changes in relation to the Amazon River development. Planktonic foraminifera are present throughout the studied section and largely confirm the already available biostratigraphic age determination based on nannofossils. Benthic foraminifer assemblages indicate that the paleo-water depth has not substantially deviated from current conditions. The ecological affinities of most observed dinocyst taxa are well known, which allows us to reconstruct changes in paleo-productivity based on the assemblages. Mineral composition suggests that local river systems already drained into the Amazon basin before the onset of the transcontinental system, but environmental conditions remained oligotrophic at this time. Decreased abundances of both dinocysts and planktonic foraminifera during the Pleistocene are related to highest sedimentation rates (dilution effect). Overall, a complex interplay of orogenesis, climatic and sea level variations during the Neogene are responsible for the fluvially-induced changes in the marine environment at the Atlantic margin.

  8. Neogene currents and the monsoon in the Indian Ocean: The Maldives carbonate platform

    NASA Astrophysics Data System (ADS)

    Betzler, C.; Luedmann, T.; Huebscher, C. P.

    2012-12-01

    Seismic and hydroacoustic data from the Maldives in the Indian Ocean show that the Neogene of this carbonate platform image larges drift deposits. The stacking pattern of Lower to Middle Miocene depositional sequences, with an evolution of a ramp geometry to a flat-topped platform, reflects variations of accommodation, which here are proposed to be primarily governed by fluctuations of relative sea level. Easterly currents during this stage of bank growth controlled an asymmetric East-directed progradation of the bank edge. During the late Middle Miocene this system was replaced by a twofold configuration of bank development. Bank growth continued synchronously with partial bank demise and associated sediment-drift deposition. This turnover is attributed to the onset and/or intensification of the Indian monsoon and related upwelling and occurrence of currents, locally changing environmental conditions and impinging upon the carbonate system. Mega spill over lobes, shaped by reversing currents, formed as large-scale prograding complexes, which have previously been interpreted as deposits formed during a forced regression. Findings are not only expected to be applicable to other examples of Tertiary platforms in the Indo-Pacific region but also to other carbonate platforms in the geological record. Onset, type and variations of drift deposits in the platform edifice further provide not only a new and valuable proxy for the reconstruction of the oceanic currents around the Maldives during the Neogene but also for the development of the associated large-scale oceanographic current system with a world-wide impact. Additionally, the sedimentary record of the drift deposits may represent an excellent archive of the Indian monsoon history.

  9. Southwestern Power Administration Annual Report 2008

    SciTech Connect

    2010-12-01

    Dear Secretary Chu, I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2008. In FY 2008, Southwestern delivered over 7.3 billion kilowatt-hours of energy to its wholesale customers – nearly 31% more than average due to numerous record rainfall amounts in the southwest region. These record amounts produced revenues which exceeded the average annual revenue requirement by nearly $20 million and resulted in over $200 million in economic benefits to the region. Yet even as Southwestern exceeded its goals of marketing and delivering Federal hydroelectric power to our customers, we stayed focused on safety, security, and reliability. For example, we maintained our nearly 1,400 miles of high-voltage transmission lines, substations, and communications sites while achieving a Recordable Accident Frequency Rate of 0.0, a record that reflects Southwestern’s safety achievement of no recordable injuries for every 200,000 hours worked. We kept our rights-of-way secure from vegetation and other obstacles, work that not only supports our mission but also promotes reliability of the regional and National grid. We exceeded all North American Electric Reliability Corporation (NERC) Control Performance Standards (CPS- 1 and CPS-2), and maintained regulation and reserve obligations and reactive reserve margins to ensure the reliability of the bulk electric system, even during extended periods of restricted hydro operations due to unusually high project inflows. Finally, we continued our partnerships with the Department of Energy, the U.S. Army Corps of Engineers, our customers, and other Federal power stakeholders, partnerships that are vital to our continued success in marketing and delivering carbon-free, renewable, and domestically produced energy to our customers and to the Nation. Sincerely, Jon Worthington Administrator

  10. Southwestern Power Administration Annual Report 2007

    SciTech Connect

    2008-01-01

    “Renewable energy” isn’t just a catchphrase at Southwestern Power Administration (Southwestern). It describes the hydroelectric energy we market, and the energy that Southwestern’s employees bring to work every day, constantly challenging themselves to become more eff ective and effi cient in providing aff ordable, environmentally clean power to the American people. As Southwestern’s new Administrator, I have had the opportunity to view our operations from a fresh perspective, and I’m proud to share with you how a focus on continual improvement has been evident in accomplishments throughout the agency during fi scal year (FY) 2007. When the North American Electric Reliability Corporation (NERC) implemented new reliability standards, we met applicable implementation dates and exceeded NERC’s control performance standards throughout the year. When tasked with reducing the agency’s carbon footprint, we found ways to achieve an 8.7% reduction in energy intensity from last year without impacting our operational capabilities. And when faced with record-breaking infl ows into the reservoir projects from which we market power, we capitalized on the opportunity to provide customers with signifi cant quantities of supplemental energy. Our supplemental sales this year not only saved customers over $122 million, but increased Southwestern’s revenues -- a huge win-win for Southwestern’s ratepayers and the Nation’s taxpayers alike. Southwestern is proud of its role in protecting National and economic security by contributing to the diverse supply of domestically produced energy, operating and maintaining a safe and reliable transmission system, and ensuring good stewardship of our Nation’s water resources and environment. In FY 2007, Southwestern continued to repay all power costs to the American taxpayers by marketing and delivering approximately 5.6 billion kilowatthours of hydropower at cost-based rates to customers in our six-state region. This energy

  11. Neogene vegetation development in the Amazon Basin: evidence from marine well-2, Foz do Amazonas (Brazil)

    NASA Astrophysics Data System (ADS)

    Bogota-Angel, Raul; Chemale Junior, Farid; Davila, Roberto; Soares, Emilson; Pinto, Ricardo; Do Carmo, Dermeval; Hoorn, Carina

    2014-05-01

    Origen and development of the highly diverse Amazon tropical forest has mostly been inferred from continental sites. However, sediment records in the marine Foz do Amazonas Basin can provide important information to better understand the influence of the Andes uplift and climate change on its plant biomes evolution since the Neogene. Sediment analyses of samples from BP-Petrobras well 1 and 2, drilled in the Amazon Fan, allowed to infer the onset of the transcontinental Amazon river and the fan phase during the middle to late Miocene (c. 10.5 Ma). As part of the CLIMAMAZON research programme we performed pollen analysis on the 10.5 to 0.4 Ma time interval. 76 ditch cutting samples of the upper 4165 m sediments of well 2 permitted us to infer changes in floral composition in the Amazon Basin. The palynological spectra across this interval (nannofossil based age model) include pollen, fern spores, dinocysts and foram lignings. When possible pollen and fern spores were grouped in four vegetation types: estuarine, tropical, mountain forest and high mountain open treeless vegetation. Pollen is generally corroded and reflects the effects of sediment transportation while reworked material is also common. Good pollen producers such as Poaceae, Asteraceae and Cyperaceae are common and reflect indistinctive vegetation types particularly those associated to riverine systems. Rhizophora/Zonocostites spp. indicate "close-distance" mangrove development. Tropical forest biomes are represented by pollen that resemble Moraceae-Urticaceae, Melastomataceae-Combretaceae, Sapotaceae, Alchornea, Euphorbiaceae, Rubiaceae, Bignoniaceae, Mauritia and Arecaceae. Myrica, and particularly sporadic occurrences of fossil fern spores like Lophosoria, and Cyathea suggest the development of a moist Andean forest in areas above 1000 m. First indicators of high altitudes appear in the last part of late Miocene with taxa associated to current Valeriana and particularly Polylepis, a neotropical taxon

  12. Sediment supply from the Betic-Rif orogen to basins through Neogene

    NASA Astrophysics Data System (ADS)

    Iribarren, L.; Vergés, J.; Fernàndez, M.

    2009-09-01

    We present a quantification of total and partial (divided by time slices) sedimentary volumes in the Neogene basins of the Betic-Rif orogen. These basins include the Alboran Sea, the intramontane basins, the Guadalquivir and Rharb foreland basins and the Atlantic Margin of the Gibraltar Arc. The total volume of Neogene sediments deposited in these basins is ~ 209,000 km 3 and is equally distributed between the internal (Alboran Basin and intramontane basins) and the external basins (foreland basins and Atlantic Margin). The largest volumes are recorded by the Alboran Basin (89,600 km 3) and the Atlantic Margin (81,600 km 3). The Guadalquivir and Rharb basins amount 14,000 km 3 and 14,550 km 3, respectively whereas the intramontane basins record 9235 km 3. Calculated mean sediment accumulation rates for the early-middle Miocene show an outstanding asymmetry between the Alboran basin (0.24 mm/yr) and the foreland basins (0.06-0.07 mm/yr) and the Atlantic Margin (0.03 mm/yr). During the late Miocene, sedimentation rates range between 0.17 and 0.18 mm/yr recorded in the Alboran Basin and 0.04 mm/yr in the intramontane basins. In the Pliocene-Quaternary, the highest sedimentation rates are recorded in the Atlantic Margin reaching 0.22 mm/yr. Sedimentary contribution shows similar values for the inner and outer basins with a generalized increase from late Miocene to present (from 3500 to 6500 km 3/My). Interestingly, the Alboran Basin records the maximum sedimentary contribution during the late Miocene (5500 km 3/My), whereas the Atlantic Margin does during the Pliocene-Quaternary (6600 km 3/My). The spatial and time variability of the sediment supply from the Betic-Rif orogen to basins is closely related to the morphotectonic evolution of the region. The high sedimentation rates obtained in the Alboran Basin during the early-middle Miocene are related to active extensional tectonics, which produced narrow and deep basins in its western domain. The highest sedimentary

  13. Cryptic diversity of African tigerfish (genus Hydrocynus) reveals palaeogeographic signatures of linked neogene geotectonic events.

    PubMed

    Goodier, Sarah A M; Cotterill, Fenton P D; O'Ryan, Colleen; Skelton, Paul H; de Wit, Maarten J

    2011-01-01

    modified Africa's Neogene drainage. Haplotypes shared amongst extant Hydrocynus populations across northern Africa testify to recent dispersals that were facilitated by late Neogene connections across the Nilo-Sahelian drainage. These events in tigerfish evolution concur broadly with available geological evidence and reveal prominent control by the African Rift System, evident in the formative events archived in phylogeographic records of tigerfish. PMID:22194910

  14. Interpreting the Calcium Isotopic Composition of Seawater Through the Neogene and Quaternary

    NASA Astrophysics Data System (ADS)

    de La Rocha, C. L.; Sime, N. G.; Tipper, E. T.; Tripati, A.; Galy, A.; Bickle, M. J.

    2006-12-01

    It has been proposed that the calcium isotopic composition (δ^{44/42}Ca) of marine biogenic carbonates can be used to reconstruct past changes in the Ca2+ content of the ocean, lending insight into in weathering fluxes of Ca to the oceans and atmospheric concentrations of CO2. Here we present a 20 million year record of the δ^{44/42}Ca of planktonic foraminifera from ODP site 925, in the Atlantic Ocean (Ceara Rise), and make a critical analysis of Ca isotope-based reconstructions of the Ca cycle. The Ceara Rise record, whose δ^{44/42}Ca averages +0.37 ± 0.05 (1σ S.D.) and ranges from +0.21 ‰ to +0.52 ‰, is a good match to previously published Neogene Ca isotope records based on foraminifera, but differs from the record based on bulk carbonates which has values that are as much as 0.25 ‰ lower. Bulk carbonate and planktonic foraminfera from core tops differ only by 0.06 ± 0.06 ‰ (n =5), leaving room for additional factors than potentially differing fractionation factors for the production of calcite by foraminifera and coccolithophorids to cause discrepancy between bulk carbonate and foraminiferan values back through time. Modeling the global Ca cycle from downcore variations in δ^{44/42}Ca by assuming fixed values for the isotopic composition of weathering inputs (δ^{44/42}Caw) and for isotope fractionation associated with the production of carbonate sediments (Δsed) results in large variations in the mass of Ca2+ in the oceans during the Neogene. This suggests that δ^{44/42}Caw and Δsed instead fluctuate over time. Ca isotope fractionation during weathering processes, such as has been recently documented, could easily result in variations in δ^{44/42}Caw of a few tenths of permil associated with shifts in climate on land. Likewise the differing degree of isotope fractionation associated with aragonite versus calcite formation could drive shifts in Δsed of several tenths of permil with changes in the Mg/Ca of seawater or the relative importance

  15. Neogene Palynology of the Snake River Plain: Climate Change and Volcanic Effects.

    NASA Astrophysics Data System (ADS)

    Davis, O. K.; Ellis, B.; Link, P.; Wood, S.; Shervais, J. W.

    2006-12-01

    Preliminary palynological analyses of lake sediment and inter-flow samples reveal environmental and vegetation changes in response to climatic and volcanic events over the late Neogene. On the evolutionary timescale, sagebrush steppe has expanded and coniferous and deciduous forests have declined. In part this trend has followed the cooling and drying of the late Neogene, but volcanic impact may also be recorded in the effects of long-term subsidence and in periodic deposition of volcanic tephra. The most detailed palynological record yet published for the region (Thompson, 1992) records increasing pine and juniper percentages and decreasing sagebrush and Sarcobatus percentages spanning the Pliocene Glenns Ferry Formation and Pleistocene Bruneau Formation. Palynology of a well in Lake Idaho sediments (Canyon County, Davis, this abstract) shows the same decline of sagebrush and Sarcobatus, but records decreasing juniper percentages during the Pliocene. These Lake Idaho records are spanned by the palynology of the Great Salt Lake (Davis, 2002), which records a modern pollen flora from the late Miocene onward. Salt sage and sagebrush steppe developed progressively from the late Miocene through the Holocene, with peaks in sagebrush pollen percentages during the Mio- Pliocene transition and the late Pleistocene. The Great Salt Lake and Glenns Ferry records both include low percentages of the pollen of deciduous forest taxa such as oak and elm throughout the Pliocene and sporadically into the Pleistocene. Recent studies of soils associated with volcanic tephra reveal a Pliocene upland with abundant grass and high percentages of the pollen and spores of aquatic vegetation: a landscape with drainages choked by ash falls. Palynology above the Fossil Gulch Ash (Hagerman Valley) contains abundant charcoal and high percentages of the pollen of mountain conifers, suggesting devastation of the local vegetation and erosion into Lake Idaho from the surrounding mountains

  16. Late Neogene sedimentary facies and sequences in the Pannonian Basin, Hungary

    USGS Publications Warehouse

    Juhasz, E.; Phillips, L.; Muller, P.; Ricketts, B.; Toth-Makk, A.; Lantos, M.; Kovacs, L.O.

    1999-01-01

    This paper is part of the special publication No.156, The Mediterranean basins: Tertiary extension within the Alpine Orogen. (eds B.Durand, L. Jolivet, F.Horvath and M.Seranne). Detailed sedimentological, facies and numerical cycle analysis, combined with magnetostratigraphy, have been made in a number of boreholes in the Pannonian Basin, in order to study the causes of relative water-level changes and the history of the basin subsidence. Subsidence and infilling of the Pannonian Basin, which was an isolated lake at that time occurred mainly during the Late Miocene and Pliocene. The subsidence history was remarkably different in the individual sub-basins: early thermal subsidence was interrupted in the southern part of the basin, while high sedimentation rate and continuous subsidence was detected in the northeastern sub-basin. Three regional unconformities were detected in the Late Neogene Pannonian Basin fill, which represent 0.5 and 7.5 Ma time spans corresponding to single and composite unconformities. Consequently two main sequences build up the Late Neogene Pannonian Basin fill: a Late Miocene and a Pliocene one. Within the Late Miocene sequence there are smaller sedimentary cycles most probably corresponding to climatically driven relative lake-level changes in the Milankovitch frequency band. Considering the periods, the estimated values for precession and eccentricity in this study (19 and 370 ka) are close to the usually cited ones. In the case of obliquity the calculated period (71 ka) slightly deviates from the generally accepted number. Based on the relative amplitudes of oscillations, precession (sixth order) and obliquity (fifth order) cycles had the most significant impact on the sedimentation. Eccentricity caused cycles (fourth order) are poorly detectable in the sediments. The longer term (third order) cycles had very slight influence on the sedimentation pattern. Progradation, recorded in the Late Miocene sequence, correlates poorly in time

  17. Cryptic Diversity of African Tigerfish (Genus Hydrocynus) Reveals Palaeogeographic Signatures of Linked Neogene Geotectonic Events

    PubMed Central

    Goodier, Sarah A. M.; Cotterill, Fenton P. D.; O'Ryan, Colleen; Skelton, Paul H.; de Wit, Maarten J.

    2011-01-01

    events modified Africa's Neogene drainage. Haplotypes shared amongst extant Hydrocynus populations across northern Africa testify to recent dispersals that were facilitated by late Neogene connections across the Nilo-Sahelian drainage. These events in tigerfish evolution concur broadly with available geological evidence and reveal prominent control by the African Rift System, evident in the formative events archived in phylogeographic records of tigerfish. PMID:22194910

  18. Ground Level Observations of a Possible Downward-Beamed TGF during a Rocket-Triggered Lightning Flash at Camp Blanding, Florida in August 2014

    NASA Astrophysics Data System (ADS)

    Bozarth, A.; Dwyer, J. R.; Cramer, E. S.; Rassoul, H.; Uman, M. A.; Jordan, D.; Grove, J. E.

    2015-12-01

    Ground level high-energy observations of an August 2014 rocket-triggered lightning event at the International Center for Lightning Research and Testing (ICLRT) in Camp Blanding, Florida show a 180 µs burst of multiple-MeV photons during the latter part of the Upward Positive Leader (UPL) phase of an altitude-triggered lightning flash, following the first, truncated return stroke. The timing and waveform profile being atypical from x-ray emissions from lightning leaders, our observations suggest the occurrence of a downward beamed terrestrial gamma ray flash (TGF). Instrumentation operating during this event include a set of 16 NaI(TI)/PMT detectors plus 7 1-m2 plastic scintillation detectors spread across the 1 km2 facility, with 38 additional Na(TI)/PMT detectors located inside the 1"-thick Pb-shielded x-ray camera and an x-ray spectrometer. Comparing the location and energy data from these detectors to Monte Carlo simulations of TGFs from the REAM code developed by Dwyer [2003], our analysis investigates possible TGF production regions and determines the likelihood of the observed high-energy emissions being produced by a TGF inside the thunderstorm.

  19. Survival and physiological responses of hatchling blanding's turtles (Emydoidea blandingii) to submergence in normoxic and hypoxic water under simulated winter conditions.

    PubMed

    Dinkelacker, Stephen A; Costanzo, Jon P; Iverson, John B; Lee, Richard E

    2005-01-01

    Overwintering habits of hatchling Blanding's turtles (Emydoidea blandingii) are unknown. To determine whether these turtles are able to survive winter in aquatic habitats, we submerged hatchlings in normoxic (155 mmHg Po2) and hypoxic (6 mmHg Po2) water at 4 degrees C, recording survival times and measuring changes in key physiological variables. For comparison, we simultaneously studied hatchling softshell (Apalone spinifera) and snapping (Chelydra serpentina) turtles, which are known to overwinter in aquatic habitats. In normoxic water, C. serpentina and A. spinifera survived to the termination of the experiment (76 and 77 d, respectively). Approximately one-third of the E. blandingii died during 75 d of normoxic submergence, but the cause of mortality was unclear. In hypoxic water, average survival times were 6 d for A. spinifera, 13 d for E. blandingii, and 19 d for C. serpentina. Mortality during hypoxic submergence was probably caused by metabolic acidosis, which resulted from accumulated lactate. Unlike the case with adult turtles, our hatchlings did not increase plasma calcium and magnesium, nor did they sequester lactate within the shell. Our results suggest that hatchling E. blandingii are not particularly well suited to hibernation in hypoxic aquatic habitats. PMID:15887082

  20. Late Neogene oroclinal bending in the central Taurides: A record of terminal eastward subduction in southern Turkey?

    NASA Astrophysics Data System (ADS)

    Koç, Ayten; van Hinsbergen, Douwe J. J.; Kaymakci, Nuretdin; Langereis, Cornelis G.

    2016-01-01

    The Tauride fold-thrusts belt formed during ∼S-N convergence between Africa and Eurasia since Cretaceous time. The western end of the central Taurides strike NW-SE, highly obliquely to the overall convergence direction, and connect to the NE-SW Beydağları-Lycian Nappe flank of the western Taurides, forming the so-called 'Isparta Angle'. In Neogene time, the western and central Taurides and the inner part of the Isparta Angle became overlain by Neogene sedimentary basins including Manavgat, Köprüçay and Aksu, characterized by marine clastics and carbonates. The eastern limb of the Isparta Angle experienced multidirectional Miocene to Present extension, whereas E-W shortening affected the marine sedimentary basins in the heart of the Isparta Angle. To quantitatively reconstruct the Neogene kinematic evolution of the Taurides, towards restoring the subduction system accommodating Africa-Eurasia convergence, we paleomagnetically assess if and when vertical axis rotations affected the Manavgat, Köprüçay, and Aksu basins in Early Miocene to Pliocene times. We show that the northern Köprüçay Basin rotated ∼20-30° clockwise, the Manavgat Basin underwent ∼25-35° counterclockwise rotation, and the Aksu Basin underwent no rotation since the Early-Middle Miocene. It was previously shown that the Beydağları region underwent a post-Middle Miocene ∼20° counterclockwise rotation. These results show that the prominent oroclinal salient geometry of the western Taurides thus acquired, at least in part, since Miocene times, that the Köprüçay Basin rotated relative to the Aksu Basin along the Aksu thrust, and that the Beydağları platform rotated relative to the Aksu Basin along the Bucak thrust, which must have both been active until Late Neogene time. This synchronous E-W shortening in the heart of the Isparta Angle, and multidirectional extension in its eastern limb may be explained by relative westward retreat of an eastward dipping subducting Antalya

  1. The rare Chrysopidae (Neuroptera) of southwestern Europe

    NASA Astrophysics Data System (ADS)

    Canard, Michel; Letardi, Agostino; Thierry, Dominique

    2007-05-01

    Quantitative surveys of the chrysopid fauna from southwestern Europe, namely the Iberian and Italian peninsulas, France south of 46° N, and the west-Mediterranean Islands, were analysed. A total of 56 species of Chrysopidae were reported, of which three species were abundant. These, Chrysoperla carnea (Stephens, 1836) sensu lato, Dichochrysa prasina (Burmeister, 1839) and D. flavifrons (Brauer, 1850), comprised a large percentage of the specimens. For the rarer species, comments are made on their distributions, the enhanced geographic range of exotic ones, and on levels of endemism and stenotopy.

  2. The instrumental climate history of southwestern Colorado

    SciTech Connect

    Doesken, N.J.; McKee, T.B.

    1995-09-01

    Instrumental observations of the climate of southwestern Colorado date back to about 1880. Climatic conditions since the late 19th century will be described with emphasis on temperatures, temperature ranges and observed precipitation. Typical seasonal patterns of temperature and precipitation will be shown, and variations and apparent trends over time will be discussed. Drought characteristics will be described based on a standardized precipitation index developed for Colorado. Finally, brief comments on the challenge of collecting accurate and consistent long-term data will be given.

  3. Monitoring Fires in Southwestern Amazonia Rain Forests

    NASA Astrophysics Data System (ADS)

    Brown, I. Foster; Schroeder, Wilfrid; Setzer, Alberto; de Los Rios Maldonado, Monica; Pantoja, Nara; Duarte, Alejandro; Marengo, Jose

    2006-06-01

    From mid-July to mid-October 2005, an environmental disaster unfolded in the trinational region of Madre de Dios, Peru; Acre, Brazil; and Pando, Bolivia (the MAP region), in southwestern Amazonia. A prolonged dry season and human-initiated fires resulted in smoke pollution affecting more than 400,000 persons, fire damage to over 300,000 hectares of rain forest, and over US$50 million of direct economic losses. Indicators suggest that anomalous drought conditions could occur again this year.

  4. Paleomagnetic investigation of late Neogene vertical axis rotation and remagnetization in central coastal California

    NASA Astrophysics Data System (ADS)

    Horns, Daniel M.; Verosub, Kenneth L.

    1995-03-01

    Outcrops of shallow marine sedimentary rocks of the Neogene Purisima Formation and Santa Cruz Mudstone occur throughout the Santa Cruz Mountains and along the coast of Santa Cruz and San Mateo counties in California. Within the Santa Cruz Mountains, the Purisima Formation has been extensively folded and offset by reverse faults. Along the coast, the Purisima Formation and Santa Cruz Mudstone are only gently folded although the Purisima Formation is cut by the San Gregorio Fault Zone. Previous paleomagnetic studies have shown that vertical axis rotation has occurred within some parts of the San Gregorio Fault Zone. As part of a kinematic study of the San Gregorio Fault Zone, this paleomagnetic investigation of the Purisima Formation and Santa Cruz Mudstone was conducted to determine the extent of the vertical axis rotation. The characteristic paleomagnetic directions of the Purisima Formation and Santa Cruz Mudstone, which we interpret as the primary directions, indicate that a clockwise vertical axis rotation of 35 deg to 60 deg has occurred throughout the San Gregorio Zone, whereas no rotation has occurred away from the fault zone. This result suggests that vertical axis rotation is fundamentally related to shear across the San Gregorio Fault Zone. Our work also indicates that while the Purisima Formation and Santa Cruz Mudstone along the coast have retained their primary magnetizations, the Purisima Formation within the Santa Cruz Mountains has been remagnetized after folding.

  5. The Central American Seaway and the Late Neogene ocean conveyor belt

    NASA Astrophysics Data System (ADS)

    Schneider, Birgit; Krebs-Kanzow, Uta; Park, Wonsun

    2013-04-01

    'The great ocean conveyor belt' depicts the large scale exchange of water mass properties between today's oceans. Over the past million years the tectonic evolution of ocean passages altered this pan-oceanic communication. The last such tectonic transformation was the closure of the Central American Seaway (CAS) which represented a low latitude gateway between Pacific and Atlantic prior to 4 million years ago. We use a coupled general circulation model and configure the topography for the past. The Central American Seaway modifies the global ocean circulation and the ocean conveyor belt which implies drastic changes in water mass properties and inter basin heat and freshwater transports. Compared to an experiment with modern basin geometry, a 1000-meter deep passage at the location of today's Isthmus of Panama results in a fundamental change in the warm water route of the conveyor belt while the cold path remains qualitatively unchanged. A transport of 10 Sv from Pacific to Atlantic is associated with the meridional transport in the South Atlantic changing from 10Sv northward to 2 Sv southward. Both Indonesian throughflow and export of warm water from the Indian Ocean across 30S are reduced by about 7 Sv. Analysing transports in density classes we are able to propose a sketch of the late Neogene conveyor belt.

  6. Neogene structural characteristics of Louisiana shelf with emphasis on growth-fault interplay with salt tectonics

    SciTech Connect

    Xue, Fangjian, Xi, Jiebo )

    1996-01-01

    Growth faulting and salt tectonics are the most pronounced structural features in the offshore Louisiana. Regional examination of seismic data(4 mile x 4 mile grid) of OCS area Suggests that polyphase halokinesis happened along the whole shelf area during the Neogene sedimentation but with different type of salt movement and faulting in time and space. The sublinear and regularly basinward-dipping lower and middle Miocene faults predominate beneath the present inner shelf region with scarcity of shallow salt features. These fault trends detached on bottom Miocene decollement related ductile shale and salt welds. The shorter and more arcuate-shaped upper Miocene and Pliocene faults complicated by abundant near-surface salt bodies characterize the farther offshore beneath the outer-shelf region. Most of these fault root into or related to salt diapirs, but at the West Cameron and at the South Timberlier, families of growth-faults were developed on the upper Miocene allochthonous salt sheet detachment and played an important role in segmenting salt sheet in this salt raft regime. The more irregularly oriented Pleistocene faults with combination of shallow basinward-dipping and counter-basinward-dipping detachment on top of large and thick upper Pliocene allochthonous salt mass occurred in the present shelf edge and slope region. This study suggest at least three episodes of salt movement occurred at early Miocene, late Miocene-early Pliocene and early Pleistocene and the existence and possible position of large right-slip transfer faults.

  7. Newfoundland Neogene sediment drifts: transition from the Paleogene greenhouse to the modern icehouse

    NASA Astrophysics Data System (ADS)

    Friedrich, O.; Norris, R. D.; Wilson, P. A.; Opdyke, B. N.

    2015-05-01

    This workshop brought together specialists from various fields to develop a drilling proposal to fill the "Oligo-Miocene Gap" that exists in our understanding of the functions of Earth's systems. We propose to establish the first continuous high-deposition record of the Oligo-Miocene through new International Ocean Discovery Program (IODP) drilling in the North Atlantic to allow the development of a continuous Neogene cyclostratigraphy and to enhance our knowledge of Oligo-Miocene ocean-ice-climate dynamics. The workshop was held in Heidelberg from 15 to 17 September 2014 funded by ESF (EARTHTIME EU), NSF, and the ECORD MagellanPlus Workshop Series Program. A total of 24 participants from six different countries (Australia, France, Germany, the Netherlands, United Kingdom, and United States) attended the workshop, including several early career stage researchers. We discussed certain aspects of Cenozoic paleoceanography and paleoclimate and how the gaps in the Oligo-Miocene could be filled using scientific drilling. The ultimate goal of the workshop (to submit a pre-proposal to IODP) was achieved (IODP Proposal 874-pre was submitted 1 October 2014). Our workshop consisted of overview presentations followed by self-selected breakout groups that discussed different topics and produced text and figures for the proposal. Here, we give a short overview of the major topics discussed during the workshop and the scientific goals presented in the resulting IODP pre-proposal.

  8. Plate boundary readjustment in oblique convergence: Example of the Neogene of Hispaniola, Greater Antilles

    NASA Astrophysics Data System (ADS)

    Pubellier, Manuel; Mauffret, Alain; Leroy, Sylvie; Vila, Jean Marie; Amilcar, Helliot

    2000-08-01

    The Haitian fold-and-thrust belt is the major mountain belt of Haiti (western part of Hispaniola, Greater Antilles) and resembles a compressive restraining bend between the two major faults which have driven the opening of the Cayman Basin since the Eocene. During the rifting stage, from the middle to the late Eocene, this area underwent an extensional evolution with fissural volcanic activity along NE-SW tilted blocks. The Haitian fold-and-thrust belt was constructed from the Early Miocene until the Present by stacking sedimentary units into a collisional wedge perpendicular to the tilted blocks, which was propagating to the southwest. During the construction of the wedge, piggyback basins were formed and progressively uplifted. During the late Neogene, convergence is localized in the Cul-de-Sac-Enriquillo trough where the active front proceeds southward onto the Beata ridge. In this area, Miocene to Quaternary wrench structures of the lower plate, like the Southern Peninsula and the Enriquillo-Plantain Garden faults, are reactivated as normal faults, owing to the loading of the fold-and-thrust belt.

  9. Depositional environmental and geologic age of neogene rocks at Cape Aliaksin, Beaver Bay, Alaska Peninsula

    SciTech Connect

    Armentrout, J.M.

    1985-04-01

    Neogene sandstone and conglomerate cropping out along the eastern end of Beaver Bay at Cape Aliaksin have been assigned to the Unga Conglomerate Member of the Bear Lake formation. New data suggest that this correlation may be incorrect. The fossil assemblage includes gastropods, pelecypods, barnacles, and echionoids indicative of a shallow marine, cold-water biofacies. Taxa indicate a strong similarity to the fossil assemblage of the Tachilni Formation and the upper Bear Lake Formation, both assigned to the late Miocene Graysian Molluscan stage, approximately 12 Ma to 3 Ma. Teeth of the desmostylian (sea cows) Desmostylus sp. cf. D. hesperus have been collected from the Cape Aliaksin beds. D. Hesperus is known from North Pacific rocks assigned to the late early to early late Miocene, approximately 18 ma to 10 Ma. The Unga Conglomerate is in part typified by the middle Miocene pelecypod Mytilus gratacapi and an associated fauna unlike that of the Cape Aliaksin beds. It is suggested that the Cape Aliaksin beds are younger than the Unga Conglomerate, and are correlative to the upper Bear Lake Formation and Tachilni Formation rocks of early late Miocene age.

  10. Neogene compressional deformation and possible thrust faulting in southwest Dominican Republic

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Goreau, P.; Dixon, T. H.

    1985-01-01

    Analysis of regional and high resolution remote sensing data coupled with detailed field investigations indicates Neogene compressional deformation in the southwest Dominican Republic. Airborne synthetic aperture radar data and high resolution near infrared photography show folds in Tertiary sediments and possible thrust fault scarps implying NE to SW compression in the region. Large road cuts through the scarps allow study of otherwise poorly accessible, heavily vegetated karst terrain. Deformation increases toward scrap fronts where small bedding-plane thrust faults become more numerous. Analysis of mesoscopic faults with slickensides indicates compression oriented between N to S and E to W. The lowermost scarp has highly sheared fault breccia and undeformed frontal talus breccias implying it is the basal thrust into which the higher thrust faults sole. Thus, the scarps probably formed in a regional NE to SW compressional stress regime and are the toes of thrust sheets. Previous workers have suggested that these scarps are ancient shorelines. However, the gross morphology of the scarps differs substantially from well known erosional terraces on the north coast.

  11. Faunal turnover in Neogene to Recent Caribbean reef corals and region environmental change

    SciTech Connect

    Budd, A.F. . Geology Dept.); Johnson, K.G. . Palaeontology Dept.); Stemann, T.A. . Geologisches Inst.)

    1993-03-01

    Quantitative analyses of species richness and species extinction and origination rates in the Neogene to Recent Caribbean reef coral fauna show that a major episode of turnover occurred during middle to late Pliocene time (4--1 Ma). The data for the authors analyses consist of a new compilation of occurrences of 175 species and 49 genera in reef sequences in the Dominican Republic and Costa Rica and in 21 scattered sites ranging in age from 22 Ma to present. The results show that: (1) during turnover, more than 75% of all species living between 6--4 Ma (n = 82) became extinct; (2) during turnover, extinction and origination rates were equally and simultaneously high, and a relatively constant number of species was maintained in the fauna; (3) the taxonomic composition of Caribbean reefs remained relatively constant before (10--4 Ma) and after (1--0 Ma) turnover. Turnover therefore preceded the high frequency sea level oscillations of late Pleistocene time, and appears related to long-term, unidirectional changes in climate and/or ocean circulation across the Caribbean region in association with closure of the Isthmus of Panama. The observed correspondence between high origination and extinction rates indicates that the same environmental factors may have been associated with increases in both rates, and that local habitat differentiation and fragmentation may have been involved. Stability persisted in the region despite the severe environmental stresses associated with Pleistocene climate change.

  12. Geological Studies in eastern Venezuela and Trinidad from Cretaceous passive margin to Neogene transpressional thrust belt

    SciTech Connect

    Algar, S.T.; Erikson, J.E.; Pindell, J.L. )

    1991-03-01

    Sedimentological and structural analyses of Trinidad's Northern and Central ranges and Venezuela's Serrania del Interior have led to new interpretations of northeastern. South America's tectonic evolution within the Southern Caribbean Plate Boundary Zone. Medial ( ) Jurassic through early Cenozoic passive margin sediments make up the majority of these areas and were deposited somewhat to the WNW (between 80 and 130 km for Northern Range of Trinidad) of their present positions prior to structural shortening. Neogene southeastward displacement of Jurassic-Cretaceous passive slope and rise sediments (Northern Range) drove propagation of thrusts southward into the Serrania and Central ranges. Displacements were driven by migration of the Caribbean Plate relative to South America. Thus, the Serrania and Central ranges are the western hemisphere's only exposed Mesozoic-Cenozoic passive Atlantic margin stratigraphic section. As such, they provide a Cretaceous-Paleogene record of passive margin sedimentation at a thermally subsiding margin where the complicating effects of tectonism are absent. This makes these sections especially suited for studies of eustatic sea level behavior. Preliminary assessments are shown which suggest that sea level changes for Cretaceous to Paleogene time are not as pronounced as the frequent large and rapid sea level falls and rises that are promoted by some.

  13. Accretion in the wake of terrane collision: The Neogene accretionary wedge off Kenai Peninsula, Alaska

    USGS Publications Warehouse

    Fruehn, J.; Von Huene, R.; Fisher, M.A.

    1999-01-01

    Subduction accretion and repeated terrane collision shaped the Alaskan convergent margin. The Yakutat Terrane is currently colliding with the continental margin below the central Gulf of Alaska. During the Neogene the terrane's western part was subducted after which a sediment wedge accreted along the northeast Aleutian Trench. This wedge incorporates sediment eroded from the continental margin and marine sediments carried into the subduction zone on the Pacific plate. Prestack depth migration was performed on six seismic reflection lines to resolve the structure within this accretionary wedge and its backstop. The lateral extent of the structures is constrained by high-resolution swath bathymetry and seismic lines collected along strike. Accretionary structure consists of variably sized thrust slices that were deformed against a backstop during frontal accretion and underplating. Toward the northeast the lower slope steepens, the wedge narrows, and the accreted volume decreases notwith-standing a doubling of sediments thickness in the trench. In the northeasternmost transect, near the area where the terrane's trailing edge subducts, no frontal accretion is observed and the slope is eroded. The structures imaged along the seismic lines discussed here most likely result from progressive evolution from erosion to accretion, as the trailing edge of the Yakutat Terrane is subducting.

  14. Neogene marine isotopic evolution and the erosion of Lesser Himalayan strata: Implications for Cenozoic tectonic history

    NASA Astrophysics Data System (ADS)

    Myrow, Paul M.; Hughes, Nigel C.; Derry, Louis A.; Ryan McKenzie, N.; Jiang, Ganqing; Webb, A. Alexander G.; Banerjee, Dhiraj M.; Paulsen, Timothy S.; Singh, Birendra P.

    2015-05-01

    An extensive, northward deepening blanket of Neoproterozoic and Cambrian sedimentary rocks once extended from the Himalayan margin far onto the Indian craton. Cambrian deposits of this "upper Lesser Himalayan" succession, which include deposits of the "outer" Lesser Himalaya tectonic unit, are enriched in radiogenic 187Os. They make up part of a proximal marine facies belt that extends onto the craton and along strike from India to Pakistan. By contrast, age-equivalent facies in the Tethyan Himalaya are more distal in nature. Neoproterozoic to Cambrian strata of the upper Lesser Himalayan succession are now missing in much of the Lesser Himalaya, with their erosion exposing older Precambrian Lesser Himalayan strata. We suggest that exhumation and weathering of the upper Lesser Himalaya and related strata caused dramatic changes in the 187Os/188Os and 87Sr/86Sr Neogene record of seawater starting at ∼ 16 Ma. First-order estimates for the volume of upper Himalayan strata, as well as the volume of all LH rock eroded since this time, and geochemical box modeling, support this idea. Exhumation at 16 Ma is a fundamental event in the evolution of the Himalayan orogeny and the geochemical evolution of the oceans, and will be a critical part of the construction of future models of Himalayan thrust belt evolution.

  15. Migration history of air-breathing fishes reveals Neogene atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Böhme, M.

    2004-05-01

    The migration history of an air-breathing fish group (Channidae; snakehead fishes) is used for reconstructing Neogene Eurasian precipitation and atmospheric circulation patterns. The study shows that snakeheads are sensitive indicators of summer precipitation maxima in subtropical and temperate regions, and are present regularly if the wettest month exceeds 150 mm precipitation and 20 °C mean temperature. The analysis of 515 fossil freshwater fish deposits of the past 50 m.y. from Africa and Eurasia shows two continental-scale migration events from the snakeheads' center of origin in the south Himalayan region, events that can be related to changes in the Northern Hemisphere circulation pattern. The first migration, ca. 17.5 Ma, into western and central Eurasia may have been caused by a northward shift of the Intertropical Convergence Zone that brought western Eurasia under the influence of trade winds that produced a zonal and meridional precipitation gradient in Europe. During the second migration, between 8 and 4 Ma, into Africa and East Asia, snakeheads reached their present-day distribution. This migration could have been related to the intensification of the Asian monsoon that brought summer precipitation to their migratory pathways in East Africa Arabia and East Asia.

  16. Lower crustal zircons reveal Neogene metamorphism beneath the Pannonian Basin (Hungary)

    NASA Astrophysics Data System (ADS)

    Downes, Hilary; Carter, Andrew; Armstrong, Richard; Dobosi, Gabor; Embey-Isztin, Antal

    2015-08-01

    Neogene alkaline intraplate volcanic deposits in the Pannonian Basin (Hungary) contain many lower crustal granulite-facies xenoliths. U-Pb ages have been determined for zircons separated from a metasedimentary xenolith, using LA-ICPMS and SHRIMP techniques. The zircons show typical metamorphic characteristics and are not related to the hostmagmatism. The oldest age recorded is late Devonian, probably related to Variscan basement lithologies. Several grains yield Mesozoic dates for their cores, which may correspond to periods of orogenic activity. Most of the zircons show young ages, with some being Palaeocene-Eocene, but the majority being younger than 30Ma. The youngest zircons are Pliocene (5.1-4.2 Ma) and coincide with the age of eruptions of the host alkali basalts. Such young zircons, so close to the eruption age, are unusual in lower crustal xenoliths, and imply that the heat flow in the base of the Pannonian Basin was sufficiently high to keep many of them close to their blocking temperature. This suggests that metamorphism is continuing in the lower crust of the region at the present day.

  17. Neogene sedimentary evolution of Baja California in relation to regional tectonics

    NASA Astrophysics Data System (ADS)

    Helenes, J.; Carreño, A. L.

    1999-11-01

    During the Neogene, the tectonic and sedimentary evolution of the Baja California Peninsula followed four stages: (1) during the early Miocene (22 Ma), the initiation of transform motion between Pacific and North American plates, caused a rapid subsidence in the Continental Borderland Province and in some adjacent areas.This subsidence coincided in time with with a global rise in sea level. At this time, the eastern and southern parts of the peninsula did not show any evidence of subsidence. (2) During the middle Miocene (12 Ma), normal and strike slip faulting migrated eastward, causing subsidence in the northern part of the Gulf of California, where the oldest Tertiary marine sedimentary rocks were deposited. The areas in central Baja California Sur and the central part of the Gulf itself received abundant volcanic deposits related to continental extension. (3) During the late Miocene (8 Ma), the western margin of the Peninsula changed to a slightly compressive regime, while the northern part of the Gulf contained a marine basin with upper bathyal environments. The central area of the Gulf continued receiving abundant volcanic deposits, while the Los Cabos block received marine sedimentation, correlatable with sedimentary units reported from the continental margins in Nayarit, Jalisco and Michoacán. (4) Beginning in the early Pliocene (5 Ma), the present configuration of the Gulf of California developed through right-lateral strike slip and extension in the Gulf itself. Since Pliocene times, the Gulf presents widespread marine sedimentation with deep basins reaching lower bathyal depths.

  18. Transformational Leadership and Teacher Motivation in Southwestern Arizona High Schools

    ERIC Educational Resources Information Center

    Reynolds, Catherine L.

    2009-01-01

    The purpose of this study was to explore the relationship between transformational leadership and teacher motivation in Southwestern Arizona high schools. Teachers in a school district in Southwestern Arizona comprised of high schools were surveyed using two instruments, Leithwood and Jantzi's (1998) The Leadership and Management of Schools in…

  19. 75 FR 52527 - Southwestern Power Administration; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    .... 714, 73 FR 57515 (Oct. 3, 2008), FERC Stats. & Regs ] 31,276 (2008) (Order No. 714). \\2\\ 18 CFR 35.28... Federal Energy Regulatory Commission Southwestern Power Administration; Notice of Filing August 19, 2010. Take notice that on August 17, 2010, the Department of Energy, Southwestern Power...

  20. 77 FR 5247 - Southwestern Power Administration; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-02

    ... Energy Regulatory Commission Southwestern Power Administration; Notice of Filing Take notice that on... in Rate Order SWPA-63, Southwestern Power Administration Integrated System Rates, Rate Schedule P-11, Wholesale Rates for Hydro Peaking Power, Rate Schedule NFTS-11, Wholesale Rates for Non-Federal...

  1. 77 FR 65679 - Southwestern Power Administration; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-30

    ... Energy Regulatory Commission Southwestern Power Administration; Notice of Filing Take notice that on..., Southwestern Power Administration annual rate for the sale of power and energy from the Willis Project to the Sam Rayburn Municipal Power Agency. Any person desiring to intervene or to protest this filing...

  2. 78 FR 64494 - Southwestern Power Administration; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Southwestern Power Administration; Notice of Filing Take notice that on...), confirmed, approved, and placed in effect on an interim basis in Rate Order SWPA- 66, Southwestern...

  3. 78 FR 64494 - Southwestern Power Administration; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-29

    ... Energy Regulatory Commission Southwestern Power Administration; Notice of Filing Take notice that on...), confirmed, approved, and placed in effect on an interim basis in Rate Order SWPA- 67, Southwestern Power Administration annual rate for the sale of power and energy from the Rayburn Project to the Sam Rayburn...

  4. 77 FR 3766 - Southwestern Gas Storage Technical Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Southwestern Gas Storage Technical Conference Notice of Public Conference On... interested parties to discuss issues related to natural gas storage development in the southwestern...

  5. Tobacco Use Among Southwestern Alaska Native People

    PubMed Central

    Renner, Caroline C.

    2013-01-01

    Introduction: We examined the characteristics, attitudes, beliefs, and exposure to tobacco products in a cohort of rural dwelling Alaska Native (AN) people. Methods: We conducted a study of 400 of AN adult tobacco users and nonusers living in Southwestern Alaska. Questionnaires covered variables such as demographics, tobacco-use history, current tobacco use and dependence scales, general health status, attitudes and beliefs about tobacco, and quitting history. Results: The study population smoked 7.8 cigarettes per day compared with 16.8 on average for the U.S. population: a significant proportion of the population engaged in dual use of cigarettes and smokeless tobacco products. Over one third (40.9%), first tried tobacco at age 11 or younger. The mean measures of tobacco addiction (e.g., Fagerstrom Test for Nicotine Dependence, Severson Scale of Smokeless Tobacco Dependence) scores were lower compared with other U.S. populations. Conclusions: Very high tobacco-use prevalence, dual product use, and early tobacco use are observed in Southwestern AN people. Unexpectedly these did not appear to be correlated with heavier individual tobacco use or higher levels of addiction in this population. PMID:22949573

  6. Uplifted Neogene margin, southernmost Cascadia-Mendocino triple junction region, California

    NASA Astrophysics Data System (ADS)

    Aalto, K. R.; McLaughlin, R. J.; Carver, G. A.; Barron, J. A.; Sliter, W. V.; McDougall, K.

    1995-10-01

    Along a 10-km length of coast north of the Mendocino triple junction, a Neogene accretionary complex has been uplifted ≥2 km and tilted northward in response to the interaction of the southern Juan de Fuca (Gorda) plate with the older North American and Pacific plates. These plate interactions were accompanied by tectonic intercalation of Miocene to Pliocene deposits of the southern Cascadia forearc (Wildcat Group), with penetratively deformed Oligocene to Miocene accretionary prism deposits of the False Cape terrane (new name) and the Cretaceous to Eocene Coastal terrane of the Franciscan Complex. North of Cape Mendocino, more than 2 km of stratigraphic section of the accretionary False Cape terrane crops out at beach level in an east-west trending anticline and recumbent syncline. The folded False Cape rocks are juxtaposed with forearc deposits to the north along the subvertical Russ shear zone. To the south, a second subvertical shear zone truncates the False Cape terrane near the mouth of the Bear River. This North Bear River shear zone interleaves rocks of the False Cape and Coastal terranes with additional Neogene forearc deposits (the Bear River beds). South of the North Bear River shear zone, the Bear River beds crop out for about 5 km in a continuous folded and imbricated section that is again truncated to the south by a third subvertical shear zone. This South Bear River shear zone interleaves rocks of the Coastal terrane, the Bear River beds, and Pliocene to Pleistocene shelf deposits. Folding, tilting, and shear zone development reflect ongoing north-south crustal shortening that has occurred in response to interplate coupling and wedge thickening in the deforming Miocene and younger accretionary complex. The strain recorded in the accreted terranes and in the forearc overlap assemblage reflects a stress regime unlike that in the Cascadia fold-and-thrust belt north of the Eel River syncline. Thus the deformation pattern may be unique to the triple

  7. Neogene Uplift and Exhumation of Plutonic Bodies in the Beni Bou Ifrour Massif (Nador, northeastern Morocco)

    NASA Astrophysics Data System (ADS)

    Lebret, Noëmie; Jolivet, Laurent; Branquet, Yannick; Bourdier, Jean-Louis; Jolivet, Marc; Marcoux, Eric

    2013-04-01

    In Neogene times, the whole Mediterranean Sea was the center of an intense magmatic activity. This post-collisional magmatism produced a large amount of volcanic edifices through the Alpine belts, together with some intrusives. These plutonic bodies can be associated with skarn-type mineralization, well-known in Elba Island or Serifos Island (Cyclades), where they are generally exhumed by detachment faults. In Morocco, the plutons hosted by the Beni Bou Ifrour massif are connected to the biggest skarn-type iron concentrations of the country (production > 60 Mt, reserves ≈ 25 Mt). The purpose of this work is to explain the late uplift of this massif and subsequent exhumation of the intrusives. As a final product of the Africa-Eurasia plate convergence since ca. 70 Ma, the Rif Mountains constitute the westernmost segment of the Mediterranean Alpine belts. In the oriental part of this range, volcanic summits and Paleozoic to Mesozoic massifs outcrop in the surrounding Mio-Pliocene plains. The Beni Bou Ifrour massif, in the Nador province, consists in a dome-shaped folded Mesozoic series (Domerian to Barremian) affected by a slight epizonal regional metamorphism (ca. 14-12 Ma), dislocated by Neogene NE-SW faults and eventually sealed by upper Miocene transgressive sediments. The hosted intrusives (7.58 ± 0.03 Ma; Duggen et al., 2005) are the plutonic equivalents to the potassic calc-alkaline lavas (andesites mainly) from the surrounding "satellite" volcanic massifs. They turn out to stand in higher topographic position than the younger shoshonitic lavas of the neighboring Gourougou stratovolcano (6.12 ± 0.01 Ma; Duggen et al., 2005). Previous studies have attributed this uplift to the action of normal faults (pull-apart basins; Guillemin & Houzay, 1982), thrusting (Kerchaoui, 1985; 1995) or even of a caldeira resurgence (El Bakkali, 1995). To discriminate against those exhumation mechanisms, field work has been performed, coming along with new cross-sections to

  8. Neogene and Quaternary ignimbrites in the area of Arequipa, Southern Peru: Stratigraphical and petrological correlations

    NASA Astrophysics Data System (ADS)

    Lebti, Perrine Paquereau; Thouret, Jean-Claude; Wörner, Gerhard; Fornari, Michel

    2006-06-01

    This study focuses on the correlation of four newly identified rhyolitic ignimbrites located around Arequipa, which were previously described as a single ignimbrite sheet: (1) The Río Chili Ignimbrite (ca. 13.33 Ma) crops out in the Río Chili canyon and consists of a cooling unit of non-welded to partially welded, massive, crystal-rich lapilli tuff. This ignimbrite represents the base of the Neogene ignimbrite succession in the Arequipa area and may be stratigraphically equivalent to the 14-13 Ma Huaylillas Ignimbrites in southern Peru. (2) The second voluminous (˜ 20 km 3) and widespread La Joya Ignimbrite sheet (ca. 4.87 Ma) filled the Arequipa depression. Its probable source is now buried underneath the Chachani volcanic complex. The La Joya Ignimbrite covers both the Arequipa Batholith toward the Río Vitor piedmont and also part of the Altiplano to the East and North of the Chachani complex. (3) The Arequipa Airport Ignimbrite (AAI) sheet (ca. 1.6 Ma, ˜18 km 3), the third and latest infill of the Arequipa basin, consists of a lower white, columnar jointed, massive lapilli tuff, indurated by vapor-phase recrystallization, and is overlain by an upper, pink, lithic-rich, non-welded, massive lapilli-tuff. The source of this ignimbrite is also buried underneath the Chachani complex, as indicated by anisotropy of magnetic susceptibility measurements and component lithology. (4) The Yura non-welded pumice-flow deposits (ca. 1.02 Ma, 1.5 km 3) are restricted to the northern and western flanks of the Chachani complex and may correlate with tuffs of the Capillune Formation on the Altiplano. All ignimbrites are high-K calc-alkaline to alkaline rhyolites, which contain variable amounts of plagioclase, biotite, quartz, sanidine, and Fe-Ti oxides. The modal composition of mineral phases and chemistry of amphiboles and biotites are useful for distinguishing the ignimbrites. Specific geochemical fingerprints, such as Sr, Y, Rb, Ba, Cs, REE, and Sr isotopes were effective

  9. Seismic architecture and morphology of Neogenic sediment waves and drifts, offshore West Africa

    NASA Astrophysics Data System (ADS)

    Baglioni, Luca; Bonamini, Enrico

    2013-04-01

    The three dimension visualisation softwares of seismic data and the recent development of semi-automatic interpretation tools allow to define the 3D morphology of ancient depositional systems at a resolution never achieved before. This study analyses a Neogenic stratigraphic interval in the deep water of the West African margin. The purpose of the work is the understanding of the sedimentary architectures and the link with the genetic depositional processes. The study is mainly based on the interpretation of seismic geometries and amplitude/isochron maps derived from newly-interpreted seismic horizons. The seismic stratigraphy reveals abrupt changes in depositional styles and sedimentary processes. Transitions between Sediment Drifts (SD), Sediment Waves (SWs) and Mass Transport Complexes (MTCs) are here frequently observed, suggesting that cyclically either bottom-current intensity decreased or gravity-flow input overwhelmed the bottom-current signal. The lower studied interval corresponds to a SD sequence, made up of stacked individual packages and having a maximum thickness of 300 ms. The landward drift morphology is characterized by convex-upward, mounded seismic reflections. Each drift onlaps on a seaward-dipping reflection interpreted as paleo-slope. These contouritic deposits are concentrated near the base of slope, and fade out downdip. The drift appears to be grown from the deeper part of the basin and backstepped up the slope. It is inferred that the deposition of the drifts took place under the influence of a marine current, subparallel to the southern margin of West African coast. The backstepping of the onlapping architecture may have resulted from bottom current acceleration across the ramp. The intermediate studied interval represents a transitional sequence in which SW are alternated with MTDs of minor size (up to 60 ms thick). In this transition interval, onlap relationships and thickness variations suggest that gravity flow deposits preferentially

  10. Chemical and Isotope Compositions of Neogene Hippopotamidae Teeth From Lake Albert (Uganda): Implications for Environmental Change

    NASA Astrophysics Data System (ADS)

    Brugmann, G. E.; Brachert, T. C.; Ssemmanda, I.; Mertz, D. F.

    2008-12-01

    The Neogene was a period of long-term global cooling and increasing climatic variability on astronomical time scales. Lake systems strongly depend on rainfall patterns and size or geographical distribution of river networks. To unravel environmental change and watershed dynamics in the western branch of the East African Rift (Lake Albert, Uganda) during the Late Neogene, we use proxy data (trace elements, O, C and Sr isotopes) from Hippopotamidae teeth. Laser ablation ICPMS profiles in enamel measured from the outside rim towards the dentin show an asymmetric trace element distribution in that the concentrations continuously decrease by up to 5 orders of magnitude within a distance of about 1 mm until a minimum is reached (<10 ppb for REE, Y, U). From thereon concentrations stay rather constant or even increase until about 100 μm in front of the dentin where concentrations rise sharply. This concentration minimum represents the least altered part of the enamel and it probably represents a primary biological fingerprint which has the potential to monitor migration pathways and palaeoenvironmental changes. On geological time scales δ13C compositions reflect a transition from pure C3 browsers (-11 per mil PDB) at 5 to 6 Ma towards C4 dominated grazers (0 per mil PDB) at 2.0 to 2.5 Ma. The oxygen stable isotope (δ18O) composition of enamel rises from 26 per mil at 5 to 6 Ma to a maximum of 32 per mil SMOW at 2.3 Ma. Increasing δ18O values suggest enhanced evaporation of the lake due to rising aridity. This is in agreement with a synchronous spread of C4 vegetation in the reach of Hippopotamid populations. The Sr isotopic composition of enamel displays a large variation and 87Sr/86Sr is 0.714 about 5 Ma ago, reaches a maximum of 0.717 at about 2.3 Ma and decreases from there on to about 0.708. Thus, Sr and O isotopic compositions correlate with each other on the geological time scale. This is plausible if the Sr isotopic composition of Hippopotamid enamel dominantly

  11. Neogene exhumation of the Internal Rif units (Northern Morocco) evidenced by low- temperature thermochronology

    NASA Astrophysics Data System (ADS)

    Romagny, Adrien; Munch, Philippe; Corsini, Michel; Azdimoussa, Ali; Arnaud, Nicolas; Monié, Patrick; Bonno, Michael; Vazquez, Mercedes

    2013-04-01

    The Rif Chain (Northern Morocco) belongs, with the Betic Cordillera (Southern Spain) to the westernmost part of the Alpine belt. There, the Beni Bousera peridotite massif is exhumed and corresponds to one of the deepest exhumed lithospheric rocks of the chain. Tectono-metamorphic studies showed that the internal units were subjected to very fast exhumation during the late Oligocene - early Miocene interval in relation with a crustal thinning and the Alboran sea rifting (synthesis in Chalouan et al., 2008). However, no data are available for the subsequent period despite that Neogene uplift sediments are well known in the internal domain since the work of Wildi and Wernli (1977) and predicted during the Messinian by thermomecanical modelling (Duggen et al., 2003). We present here for the first time a low temperature thermochronologic study (apatite (U-Th)/He and fission tracks; AHe and AFT) of these rocks in order to date and quantify the Neogene exhumation history of internal units of the Rif Chain. Most AHe ages are comprised between 14.25 ± 0.21 and 21.32 ± 0.31 Ma however some are younger (e.g. 6.92 ± 0.14 Ma). AHe ages are closed to fission tracks ages, indicating a very rapid cooling. Moreover they do not show any clear age-elevation relationship that is consistent with a very rapid cooling. Youngest ages correspond to apatite with low eU concentration and thus are interpreted in terms of lower closure temperatures. We performed thermal modelling with HeFTy software (Ehlers et al., 2005; Ketcham et al., 2007) on fission tracks lengths and He diffusion data as they provide a statistical but more complete temperature-time history for the samples. We also used available 40Ar/39Ar data on biotite and field data to better constrain thermal modelling. Exhumation occurred in two main steps: i) a very rapid cooling between 22 and 17 Ma until rocks reached the top of the PAZ (80 to 60°C) at a rate of ~70 to 120°C/Ma) and ii) a very slow cooling between 17 and 4 Ma

  12. Analysis of Neogene deformation between Beaver, Utah, and Barstow, California: suggestions for altering the extensional paradigm

    USGS Publications Warehouse

    Anderson, R. Ernest; Beard, L. Sue; Mankinen, Edward A.; Hillhouse, John W.

    2013-01-01

    For more than two decades, the paradigm of large-magnitude (~250 km), northwest-directed (~N70°W) Neogene extensional lengthening between the Colorado Plateau and Sierra Nevada at the approximate latitude of Las Vegas has remained largely unchallenged, as has the notion that the strain integrates with coeval strains in adjacent regions and with plate-boundary strain. The paradigm depends on poorly constrained interconnectedness of extreme-case lengthening estimated at scattered localities within the region. Here we evaluate the soundness of the inferred strain interconnectedness over an area reaching 600 km southwest from Beaver, Utah, to Barstow, California, and conclude that lengthening is overestimated in most areas and, even if the estimates are valid, lengthening is not interconnected in a way that allows for published versions of province-wide summations. We summarize Neogene strike slip in 13 areas distributed from central Utah to Lake Mead. In general, left-sense shear and associated structures define a broad zone of translation approximately parallel to the eastern boundary of the Basin and Range against the Colorado Plateau, a zone we refer to as the Hingeline shear zone. Areas of steep-axis rotation (ranging to 2500 km2) record N-S shortening rather than unevenly distributed lengthening. In most cases, the rotational shortening and extension-parallel folds and thrusts are coupled to, or absorb, strike slip, thus providing valuable insight into how the discontinuous strike-slip faults are simply parts of a broad zone of continuous strain. The discontinuous nature of strike slip and the complex mixture of extensional, contractional, and steep-axis rotational structures in the Hingeline shear zone are similar to those in the Walker Lane belt in the west part of the Basin and Range, and, together, the two record southward displacement of the central and northern Basin and Range relative to the adjacent Colorado Plateau. Understanding this province

  13. Development of the Neogene current system in the Cape Basin as recorded in the seismostratigraphy

    NASA Astrophysics Data System (ADS)

    Weigelt, E.; Uenzelmann-Neben, G.

    2003-04-01

    The sedimentary sequences of the continental margin off southwest Africa have been shaped by different currents. At the surface, the Benguela and Agulhas Currents are active, in greater depths the Antarctic Intermediate Water (AAIW), the North Atlantic Depth Water (NADW) and Antarctic Bottom Water (AABW) take effect. Our aim is to unravel the development and modifications of those current systems. Especially we want to concentrate on the onset of the Benguela Current Upwelling System, which represents one of the largest upwelling regions worldwide and is closely related to the developement of the climate in southern Africa. Significant events as incursions of warm or cold waters, terrigenous input, climate changes and slumpings are recorded in the deposited material. The sedimentary properties are expected to be reflected in the signal structure of the seismic data from this area. In this contribution we will present a seismic stratigraphy for the Neogene sedimentary layers in the entire Cape Basin on the base of results of the ODP Leg 175 Sites 1081-1087 which are correlated with seismic data. With a maximum depth of 610mbsf (Site 1085a) the sites span the time period between Holocene and late Miocene (0-15 Ma). Corelog parameters as for example velocity, density, lithostratigraphy, carbon and carbonate content are linked to the seismic sections via synthetic seismograms. This procedure enables an interpretation of the origin of reflectors and a spatial extrapolation of sites informations. The depositional enviroment in the Cape Basin can be divided roughly into three major areas and is reflected in a change in stratigraphy from north to south: Deposition in the northern regions is influenced by eroded sediments from the Walvis Ridge and by upwelling sediments. Sediments of the middle Cape Basin are dominated by the presumable most productive coastal upwelling cells. The depositions in the southern Cape Basin contain the most imprint of incursions from the south

  14. Neogene and Quaternary history of vegetation, climate, and plant diversity in Amazonia

    NASA Astrophysics Data System (ADS)

    van der Hammen, Thomas; Hooghiemstra, Henry

    2000-04-01

    The neotropical Amazonian and Andean plant diversity developed mainly during the Tertiary. In Amazonia, Miocene floral diversity seems considerably higher than today. During the Neogene, tropical taxa entered newly created montane area, and montane taxa entered the tropical lowlands. The general decrease of temperature during the upper Neogene and especially during the Quaternary glacial periods may have caused considerable extinctions in the lowlands. Representation of pollen of apparently principally montane taxa ( Podocarpus, Hedyosmum) in Miocene, Pliocene, and Quaternary sediments of Amazonia and surroundings, is still difficult to interpret in terms of temperature decrease at low elevation. Changes in precipitation may have profound impact on the composition of vegetation communities; Ilex and Melastomataceae increase significantly in many glacial pollen records. Increase of Weinmannia in Amazonian pollen records seems the best indicator of downward migration of montane vegetation belts. A temperature lowering at sea-level of 4.5 ±1°C during the Last Glacial Maximum (LGM) seems reasonable; it may have caused a downslope migration of some 700 m of the lower montane vegetation belt; lower montane arboreal species may have been able to grow in higher elevation areas (>500 m) of Amazonia, increasing background pollen values of montane taxa in the area. Difference between a cool and wet Middle Pleniglacial (60-28 ka BP), and a cold and dry Upper Pleniglacial (28-14 ka BP; thus including the LGM) is evident in Andean and Amazonian records; statements about environmental conditions of the ice-age Amazon should be specified chronologically. The Middle Pleniglacial is a time of accumulation of fluvial sediments. The Upper Pleniglacial is a time of incision of the rivers in their sediments; sedimentation started again in the Lateglacial (since ca. 13 ka BP) and the Holocene, when lake levels rose again. Based on simplified considerations of precipitation changes and

  15. Southwestern Power Administration site environmental report for calendar year 1993

    SciTech Connect

    Not Available

    1994-06-01

    During CY 93, Southwestern was not involved in any programs that had a direct effect on the environment, involving endangered species, protection of wetlands, or increased electromagnetic radiation. Southwestern continued to function throughout the year in an operations and maintenance posture with minor substation projects. Southwestern received an environmental management audit by the Department of Energy`s Office of Environmental Audit (EH-24), during CY 1992. The purpose of the audit was to give Southwestern, DOE headquarters, and the Secretary an indication of the status of Southwestern management`s effectiveness in discharging its duties in an environmentally responsible manner. The audit identified 17 findings. An action plan was developed and remediation of the findings has been accomplished. Several strengths were identified during the audit with regard to the environmental programs at Southwestern. Most importantly, senior management at Southwestern has taken actions to increase environmental awareness throughout the organization which is evidenced by the creation of the Environmental, Safety, Health, and Security Office.

  16. Magnetostratigraphy of the late Neogene purisima formation, Santa Cruz County, California

    NASA Astrophysics Data System (ADS)

    Madrid, Victor M.; Stuart, Robert M.; Verosub, Kenneth L.

    1986-09-01

    The magnetic polarity zonation of a late Neogene sedimentary sequence in Santa Cruz County, California, has provided a chronologic framework for studies of the sedimentologic and tectonic processes involved in an episode of basin formation in the vicinity of the San Andreas fault system in central coastal California. The zonation is based on the analysis of samples from 79 horizons in a 300 m thick section of the Purisima Formation and a portion of the overlying Aromas Formation. Although rock magnetic studies support the hypothesis that the primary carrier of the remanence is magnetite, many samples contain a secondary overprint which cannot be completely removed by alternating field demagnetization. Nevertheless, systematic analysis of the behavior of the samples during demagnetization has led to an unambiguous determination of the polarity of each horizon and to the development of a magnetic polarity zonation containing thirteen magnetozones. These magnetozones can be correlated to the magnetic polarity time scale using biostratigraphic constraints provided by diatoms in the lower portion of the section and invertebrates and vertebrates in the upper portion. The studied section is found to span the interval from the Epoch 5/Epoch 6 boundary (6.07 Mya) to the Matuyama/Gauss boundary (2.47 Mya) with a hiatus corresponding to the upper part of the Gilbert epoch (4.5 Mya to 3.5 Mya). This hiatus does not coincide with major regressions in the global sea-level curve and is interpreted as a period of tectonic uplift. The compression which generated this uplift was probably caused by interplay between the San Andreas fault east of the study area and the San Gregorio-Hosgri fault west of it.

  17. Stratigraphy of the Neogene Sahabi units in the Sirt Basin, northeast Libya

    NASA Astrophysics Data System (ADS)

    El-Shawaihdi, M. H.; Mozley, P. S.; Boaz, N. T.; Salloum, F.; Pavlakis, P.; Muftah, A.; Triantaphyllou, M.

    2016-06-01

    A revision of the nomenclature of lithostratigraphic units of Neogene strata at As Sahabi, northeast Libya, is presented, based on new fieldwork conducted during 2006-2008. The Sahabi units are correlated across the Ajdabya Sheet (NH 34-6) in northeastern Libya. Major conclusions are: (1) Miocene (Langhian through Messinian) strata are predominantly carbonate and should be referred to as formation "M"; (2) A local unconformity of Miocene (early Messinian) age overlies strata of the formation "M"; (3) This unconformity is overlain by Messinian gypsiferous sand and mud (formerly formation "P" and partially member "T"), which are designated as the "lower member" (gypsiferous) of the Sahabi Formation; (4) The "lower member" is overlain by sand and mud of late Messinian age (formerly partially member "T" and members "U1", "UD", and "U2") in a generally fining-upwards sequence, and are designated as the "upper member" (non-gypsiferous) of the Sahabi Formation; (5) The latest Miocene sand and mud of the "upper member" are capped by an unconformity that is correlated with the regression and desiccation of the Mediterranean Sea during the Messinian Salinity Crisis and with Eosahabi Channel cutting; (6) The unconformity is overlain by Pliocene medium, coarse, and pebbly sands, which are referred to as the Qarat Weddah Formation (formerly Garet Uedda Formation); (7) The Pliocene sands of Qarat Weddah Formation are overlain by carbonate soil (calcrete) of Late Pliocene age, which is referred to as formation "Z" (formerly member "Z"). The major outcome of this study is a revised stratigraphic description and nomenclature of the Sahabi units that helps to provide a formal and unified context for understanding paleontological discoveries in northeastern Libya, which will serve to facilitate a broader correlation of the Sahabi units with their equivalents elsewhere in Africa and in Europe and Asia.

  18. Neogene sinistral transtension along the Hickman fault zone, southeastern Colorado Plateau, New Mexico

    SciTech Connect

    Chamberlin, R.M. )

    1993-04-01

    A north-northeast-trending crustal flaw known as the Hickman fault zone (HFZ) transects the southeastern margin of the Colorado Plateau from Mangas to Grants, New Mexico, a distance of 140 km. Recent reconnaissance mapping of the eastern half of the Quemado 1:100,000 sheet by the author indicates that the southern half of the HFZ is a Neogene oblique-slip zone that displays a normal-sinistral sense of shear. The vertical slip component is 150--200 m and the apparent horizontal component is as much as 120 m. Basaltic debris flows and fluvial deposits of the Miocene Fence Lake Formation are preferentially preserved on the downthrown western side of the HFZ. West of Pietown, Fence Lake strata define an asymmetric synclinal basin. Older northwest-striking Late Oligocene basaltic dikes are locally concealed where they pass under the shallow (200 m) northeast--trending basin. Within the 5-km-wide HFZ, north-trending segments appear to form releasing bends and east-northeast-trending segments appear to form weakly constraining bends, a pattern that implies distributed sinistral shear. Small alluvial basins (incipient half grabens) in the Mangas Mountains are associated with north-striking bends. An east-northeast-trending bend near Pietown is locally defined by an asymmetric anticline; also the Late Oligocene dike trend here bends westerly (counterclockwise) where it crosses the anticlinal axis. Near Hickman (a.k.a. Lehew), the HFZ shows two sinistral offsets of another Late Oligocene dike; cumulative offset is about 120 m.

  19. Paleogene strata of the Eastern Los Angeles basin, California: Paleogeography and constraints on neogene structural evolution

    USGS Publications Warehouse

    McCulloh, T.H.; Beyer, L.A.; Enrico, R.J.

    2000-01-01

    Post-Paleogene dextral slip of 8-9 km is demonstrated for the southeastern part of the Whittier fault zone in the eastern Los Angeles basin area of southern California. A linear axis of greatest thickness for the combined upper Paleocene and lower to lower-middle Eocene clastic formations intersects the fault zone and is offset by it to give the new measure. Fragmentary evidence hints that the Whittier structural zone may have exerted control on bathymetric-topographic relief and sedimentation even in latest Paleocene (ca. 54 Ma). A clear topographic influence was exerted by 20-17 Ma. Strike-slip and present deformational style is younger than ca. 8 Ma. Our Paleogene isopach map extends as far west as long 117??58'W and is a foundation for companion zonal maps of predominant lithology and depositional environments. Integration of new palynological data with published biostratigraphic results and both new and published lithologic and sedimentological interpretations support the zonal maps. Reconstruction of marine-nonmarine facies and fragmented basin margins yields a model for the northeastern corner of a Paleogene coastal basin. Palinspastic adjustment for the Neogene-Quaternary Whittier fault offset and a reasoned westerly extension of the northern edge of the basin model yield a reconstruction of Paleogene paleogeography-paleoceanography. Our reconstruction is based partly on the absence of both Paleocene and Eocene deposits beneath the unconformable base of the middle Miocene Topanga Group in a region nowhere less than 15 km wide between the Raymond-Sierra Madre-Cucamonga fault zone and the northern edge of the Paleocene basin. Thus, Paleogene strata of the Santa Monica Mountains could not have been offset from the northern extension of the Santa Ana Mountains by sinistral slip on those boundary faults. Structural rearrangements needed to accommodate the clockwise rotation of the western Transverse Ranges from the early Miocene starting position are thereby

  20. Dated Plant Phylogenies Resolve Neogene Climate and Landscape Evolution in the Cape Floristic Region

    PubMed Central

    2015-01-01

    In the context of molecularly-dated phylogenies, inferences informed by ancestral habitat reconstruction can yield valuable insights into the origins of biomes, palaeoenvironments and landforms. In this paper, we use dated phylogenies of 12 plant clades from the Cape Floristic Region (CFR) in southern Africa to test hypotheses of Neogene climatic and geomorphic evolution. Our combined dataset for the CFR strengthens and refines previous palaeoenvironmental reconstructions based on a sparse, mostly offshore fossil record. Our reconstructions show remarkable consistency across all 12 clades with regard to both the types of environments identified as ancestral, and the timing of shifts to alternative conditions. They reveal that Early Miocene land surfaces of the CFR were wetter than at present and were dominated by quartzitic substrata. These conditions continue to characterize the higher-elevation settings of the Cape Fold Belt, where they have fostered the persistence of ancient fynbos lineages. The Middle Miocene (13–17 Ma) saw the development of perennial to weakly-seasonal arid conditions, with the strongly seasonal rainfall regime of the west coast arising ~6.5–8 Ma. Although the Late Miocene may have seen some exposure of the underlying shale substrata, the present-day substrate diversity of the CFR lowlands was shaped by Pliocene-Pleistocene events. Particularly important was renewed erosion, following the post-African II uplift episode, and the reworking of sediments on the coastal platform as a consequence of marine transgressions and tectonic uplift. These changes facilitated adaptive radiations in some, but not all, lineages studied. PMID:26422465

  1. Upper Neogene stratigraphy and tectonics of Death Valley — a review

    NASA Astrophysics Data System (ADS)

    Knott, J. R.; Sarna-Wojcicki, A. M.; Machette, M. N.; Klinger, R. E.

    2005-12-01

    New tephrochronologic, soil-stratigraphic and radiometric-dating studies over the last 10 years have generated a robust numerical stratigraphy for Upper Neogene sedimentary deposits throughout Death Valley. Critical to this improved stratigraphy are correlated or radiometrically-dated tephra beds and tuffs that range in age from > 3.58 Ma to < 1.1 ka. These tephra beds and tuffs establish relations among the Upper Pliocene to Middle Pleistocene sedimentary deposits at Furnace Creek basin, Nova basin, Ubehebe-Lake Rogers basin, Copper Canyon, Artists Drive, Kit Fox Hills, and Confidence Hills. New geologic formations have been described in the Confidence Hills and at Mormon Point. This new geochronology also establishes maximum and minimum ages for Quaternary alluvial fans and Lake Manly deposits. Facies associated with the tephra beds show that ˜3.3 Ma the Furnace Creek basin was a northwest-southeast-trending lake flanked by alluvial fans. This paleolake extended from the Furnace Creek to Ubehebe. Based on the new stratigraphy, the Death Valley fault system can be divided into four main fault zones: the dextral, Quaternary-age Northern Death Valley fault zone; the dextral, pre-Quaternary Furnace Creek fault zone; the oblique-normal Black Mountains fault zone; and the dextral Southern Death Valley fault zone. Post - 3.3 Ma geometric, structural, and kinematic changes in the Black Mountains and Towne Pass fault zones led to the break up of Furnace Creek basin and uplift of the Copper Canyon and Nova basins. Internal kinematics of northern Death Valley are interpreted as either rotation of blocks or normal slip along the northeast-southwest-trending Towne Pass and Tin Mountain fault zones within the Eastern California shear zone.

  2. Late Neogene paleoceanography of the Sea of Japan based upon diatoms

    SciTech Connect

    Burkle, L.H. )

    1990-06-01

    The authors identified several time intervals apparent late Neogene stepwise paleoenvironmental change in the southern Sea of Japan. The paleoenvironment of the middle Pliocene and older sediments cannot be characterized because the diatom assemblage is made up of a near monospecific ooze (Coscinodiscus marginatus). The middle Pliocene, prior to 2.4 Ma but after the deposition of the C. marginatus ooze, is characterized by warm water diatoms while the late Pliocene (between approximately 2.4 my and the Pliocene/Pleistocene boundary) is characterized by cool water diatoms belonging to an upwelling assemblage. The Tsushima Strait became emergent at approximately 2.4 Ma owing to sea level drop caused by initiation of continental ice build-up on Greenland and by ongoing tectonic uplift across the southern part of Honshu. Diatoms deposited above the Pliocene/Pleistocene boundary suggest that the Tsushima Strait was again submergent and that a branch of the Kuroshio Current flowed into the Sea of Japan. The early Quaternary is characterized by variable preservation and abundance of diatoms with warm water species predominating. They observed changes in both diatom abundance and preservation in upper Quaternary sediments, probably reflecting changes in productivity induced by major glacial/interglacial oscillations. They found no evidence of the complete isolation of the Sea of Japan from the Pacific but their data do suggest, at least, constriction of the Tsushima Strait during maximum glacial episodes. The late Pliocene-Pleistocene interval is characterized by alternating intervals of laminated/homogenous sediments. There are some 30 laminated intervals within the last 300 kyr suggesting that this signal may be the second harmonic of precession. The laminated layers may reflect salinity changes in the southern Sea of Japan.

  3. Neogene stratigraphy and sedimentology in eastern Azerbaijan: Outcrop observations and subsurface implications

    SciTech Connect

    Ali-zade, A.A.; Guliyev, I.S.; Ateava, E.Z.

    1995-08-01

    The largely Pliocene Productive Series of eastern Azerbaijan contains about 26 billion barrels oil equivalent. It is well exposed in outcrops on the Apsheron Peninsula which a joint team from the GIA and the BP and Statoil Alliance have described. Detailed biostratigraphic and petrographic studies have subsequently been carried out. Productive Series deposition was initiated by a dramatic relative sea-level fall which left the South Caspian an isolated basin fed by deeply incised precursors to the modern Volga, Amu Darya, and Kura rivers. Five facies associations have been recognised within the Productive Series at outcrop, encompassing a range of palaeoenvironments from alluvial braided river sandstones and conglomerates to delta-front siltstones and mudstones. The facies associations suggest a river-dominated, braid delta. Four idealised reservoir models can be recognised: fluvial, delta-plain, proximal delta-front and distal delta-front. Each has distinct grain-size and shale distributions. Studies of nearby oilfields suggest that these models form useful subsurface analogues. Flow simulation models suggest that each reservoir type has dramatically different performance. Productive Series sediments are typically loosely cemented and smectite rich, which may result in clay swelling and sand control problems. Localised reduction in reservoir quality is caused by fault-associated calcite cements. Proximal facies of the upper Productive Series contain porosity occluding gypsum cements. Palynology and nannopalaeontology have been applied to the Neogene sediments of Azerbaijan for almost the first time, and have given encouraging results, at least in terms of a broad biozonation. Micropaleontological analyses have also provided useful palaeoenvironmental data.

  4. Neogene paleoelevation of intermontane basins in a narrow, compressional mountain range, southern Central Andes of Argentina

    NASA Astrophysics Data System (ADS)

    Hoke, Gregory D.; Giambiagi, Laura B.; Garzione, Carmala N.; Mahoney, J. Brian; Strecker, Manfred R.

    2014-11-01

    The topographic growth of mountain ranges at convergent margins results from the complex interaction between the motion of lithospheric plates, crustal shortening, rock uplift and exhumation. Constraints on the timing and magnitude of elevation change gleaned from isotopic archives preserved in sedimentary sequences provide insight into how these processes interact over different timescales to create topography and potentially decipher the impact of topography on atmospheric circulation and superposed exhumation. This study uses stable isotope data from pedogenic carbonates collected from seven different stratigraphic sections spanning different tectonic and topographic positions in the range today, to examine the middle to late Miocene history of elevation change in the central Andes thrust belt, which is located immediately to the south of the Altiplano-Puna Plateau, the world's second largest orogenic plateau. Paleoelevations are calculated using previously published local isotope-elevation gradients observed in modern rainfall and carbonate-formation temperatures determined from clumped isotope studies in modern soils. Calculated Neogene basin paleoelevations are between 1 km and 1.9 km for basins that today are located between 1500 and 3400 m elevation. Considering the modern elevation and δ18O values of precipitation at the sampling sites, three of the intermontane basins experienced surface uplift between the end of deposition during the late Miocene and present. The timing of elevation change cannot be linked to any documented episodes of large-magnitude crustal shortening. Paradoxically, the maximum inferred surface uplift in the core of the range is greatest where the crust is thinnest. The spatial pattern of surface uplift is best explained by eastward migration of a crustal root via ductile deformation in the lower crust and is not related to flat-slab subduction.

  5. Dated Plant Phylogenies Resolve Neogene Climate and Landscape Evolution in the Cape Floristic Region.

    PubMed

    Hoffmann, Vera; Verboom, G Anthony; Cotterill, Fenton P D

    2015-01-01

    In the context of molecularly-dated phylogenies, inferences informed by ancestral habitat reconstruction can yield valuable insights into the origins of biomes, palaeoenvironments and landforms. In this paper, we use dated phylogenies of 12 plant clades from the Cape Floristic Region (CFR) in southern Africa to test hypotheses of Neogene climatic and geomorphic evolution. Our combined dataset for the CFR strengthens and refines previous palaeoenvironmental reconstructions based on a sparse, mostly offshore fossil record. Our reconstructions show remarkable consistency across all 12 clades with regard to both the types of environments identified as ancestral, and the timing of shifts to alternative conditions. They reveal that Early Miocene land surfaces of the CFR were wetter than at present and were dominated by quartzitic substrata. These conditions continue to characterize the higher-elevation settings of the Cape Fold Belt, where they have fostered the persistence of ancient fynbos lineages. The Middle Miocene (13-17 Ma) saw the development of perennial to weakly-seasonal arid conditions, with the strongly seasonal rainfall regime of the west coast arising ~6.5-8 Ma. Although the Late Miocene may have seen some exposure of the underlying shale substrata, the present-day substrate diversity of the CFR lowlands was shaped by Pliocene-Pleistocene events. Particularly important was renewed erosion, following the post-African II uplift episode, and the reworking of sediments on the coastal platform as a consequence of marine transgressions and tectonic uplift. These changes facilitated adaptive radiations in some, but not all, lineages studied. PMID:26422465

  6. Dated Plant Phylogenies Resolve Neogene Climate and Landscape Evolution in the Cape Floristic Region.

    PubMed

    Hoffmann, Vera; Verboom, G Anthony; Cotterill, Fenton P D

    2015-01-01

    In the context of molecularly-dated phylogenies, inferences informed by ancestral habitat reconstruction can yield valuable insights into the origins of biomes, palaeoenvironments and landforms. In this paper, we use dated phylogenies of 12 plant clades from the Cape Floristic Region (CFR) in southern Africa to test hypotheses of Neogene climatic and geomorphic evolution. Our combined dataset for the CFR strengthens and refines previous palaeoenvironmental reconstructions based on a sparse, mostly offshore fossil record. Our reconstructions show remarkable consistency across all 12 clades with regard to both the types of environments identified as ancestral, and the timing of shifts to alternative conditions. They reveal that Early Miocene land surfaces of the CFR were wetter than at present and were dominated by quartzitic substrata. These conditions continue to characterize the higher-elevation settings of the Cape Fold Belt, where they have fostered the persistence of ancient fynbos lineages. The Middle Miocene (13-17 Ma) saw the development of perennial to weakly-seasonal arid conditions, with the strongly seasonal rainfall regime of the west coast arising ~6.5-8 Ma. Although the Late Miocene may have seen some exposure of the underlying shale substrata, the present-day substrate diversity of the CFR lowlands was shaped by Pliocene-Pleistocene events. Particularly important was renewed erosion, following the post-African II uplift episode, and the reworking of sediments on the coastal platform as a consequence of marine transgressions and tectonic uplift. These changes facilitated adaptive radiations in some, but not all, lineages studied.

  7. The Neogene monsoon and oceanic currents in the Indian Ocean: The Maldives archipelago.

    NASA Astrophysics Data System (ADS)

    Betzler, C.; Hübscher, C.; Lüdmann, T.; Reijmer, J.; Eberli, G.; Kroon, D.; Droxler, A.; Tiwari, M.; Gischler, E.

    2012-04-01

    New seismic data from the Maldives show that the Neogene of the Maldives carbonate edifice image large drift deposits. The stacking pattern of depositional sequences through the Lower to Middle Miocene traces variations of accommodation space, which are proposed to be primarily governed by fluctuations of relative sea level. During the late Middle Miocene, this system was replaced by a twofold configuration of bank development. Bank growth continued synchronously with partial bank drowning and associated deposition of giant sediment-drifts. Drowned banks show shapes attesting the occurrence of strong surface currents. Therefore, this turnover is attributed to the onset and/or intensification of oceanic currents and related upwelling. Drift sediments, characterized by offlapping geometries, formed as large-scale prograding complexes. Findings are not only expected to be applicable to other examples of Tertiary platforms in the Indo-Pacific region but also to other carbonate platforms in the geological record. Onset, type and variations of drift deposits in the platform edifice further provide not only a new and valuable proxy for the reconstruction of the oceanic currents around the Maldives but also for the development of the associated large-scale oceanographic current system with a world-wide impact. Additionally, the sedimentary record of the drift deposits may represent an excellent archive of the Indian monsoon history. The overall aim of an IODP drilling campaign thus would be to place the Maldives current system into the larger scale development of the global oceanographic current system by integrating results from other ODP and IODP expeditions like the south Atlantic or the Mediterranean outflow expedition.

  8. Compositional Variations of Paleogene and Neogene Tephra From the Northern Izu-Bonin-Mariana Arc

    NASA Astrophysics Data System (ADS)

    Tepley, F. J., III; Barth, A. P.; Brandl, P. A.; Hickey-Vargas, R.; Jiang, F.; Kanayama, K.; Kusano, Y.; Li, H.; Marsaglia, K. M.; McCarthy, A.; Meffre, S.; Savov, I. P.; Yogodzinski, G. M.

    2014-12-01

    A primary objective of IODP Expedition 351 was to evaluate arc initiation processes of the Izu-Bonin-Mariana (IBM) volcanic arc and its compositional evolution through time. To this end, a single thick section of sediment overlying oceanic crust was cored in the Amami Sankaku Basin where a complete sediment record of arc inception and evolution is preserved. This sediment record includes ash and pyroclasts, deposited in fore-arc, arc, and back-arc settings, likely associated with both the ~49-25 Ma emergent IBM volcanic arc and the evolving Ryukyu-Kyushu volcanic arc. Our goal was to assess the major element evolution of the nascent and evolving IBM system using the temporally constrained record of the early and developing system. In all, more than 100 ash and tuff layers, and pyroclastic fragments were selected from temporally resolved portions of the core, and from representative fractions of the overall core ("core catcher"). The samples were prepared to determine major and minor element compositions via electron microprobe analyses. This ash and pyroclast record will allow us to 1) resolve the Paleogene evolutionary history of the northern IBM arc in greater detail; 2) determine compositional variations of this portion of the IBM arc through time; 3) compare the acquired data to an extensive whole rock and tephra dataset from other segments of the IBM arc; 4) test hypotheses of northern IBM arc evolution and the involvement of different source reservoirs; and 5) mark important stratigraphic markers associated with the Neogene volcanic history of the adjacent evolving Ryukyu-Kyushu arc.

  9. Gastropoda-Bivalvia Fauna And Neogene-Quaternary Stratigraphy of the Southwest of Dardanelles (Çanakkale-NWAnatolia)

    NASA Astrophysics Data System (ADS)

    Kapan, Sevinç; Kabasakal, Sinem

    2016-04-01

    Gastropoda-Bivalvia Fauna And Neogene-Quaternary Stratigraphy of the Southwest of Dardanelles (Çanakkale-NWAnatolia) Sevinç KAPAN, Sinem KABASAKAL, Çanakkale Onsekiz Mart University, Engineering Faculty, Geological Engineering Department sevinckapan_yesilyurt@hotmail.com In this study, paleontology and stratigraphy of Neogene and Quaternary units around south of the Dardanelles have been examined using Gastropoda and Bivalvia fauna. In the investigation area, the base of the sediments that belongs to Neogene, consist of the volcanics which are formed with basalts, andesites and tuff. Neogene begins unconformity with basal conglomerate which are formed with basalt and tuff gravels. The measurable thickness of the Neogene sediments is approximately 200meters in total. First fossiliferius level which consist of Lymnocardium (Euxinicardium) nobile Sabba has showed similarities with the Pontian (Late Miocene) fauna of the Eastern Paratethys. The existence of Melanopsis and Psidium species indicate that the basin has been brackish water feeding by fresh water in the Early Pliocene. Theodoxus fluviatilis (Linne), Theodoxus (Calvertia) aff. imbricata Brusina, Theodoxus (Calvertia) licherdopoli scriptus (Stefanescu), Viviparus mammatus (Stefanescu), Valvata (Valavata) sulekiana Brusina, Valvata (Cincinna) crusitensis Fontannes, Hydrobia cf grandis Cobalcescu, Hydrobia ventrosa Monfort, Melanopsis (Melanopsis) cf. bergeroni Stefanescu, , Melanopsis (Melanopsis) sandbergeri rumana Tournouer, Melanopsis (Canthidomus) hybostoma anili Taner, Melanopsis (Canthidomus) hybostoma amaradica Fontannes, Melanopsis (Canthidomus) lanceolata Neumayr, Amphimelania fossariformis (Tournouer), Melanoides tuberculata monolithica (Bukowski), Radix (Radix) peregra (Müller), Planorbarius thiollierei (Michaud), Potamida (Potamida) craiovensis craiovensis (Tournouer), Potamida (Potamida) berbestiensis (Fontannes), Unio pristinus davilai Porumbaru, Unio subexquisitus Jatzko, Anadonta zmaji

  10. Neogene basins of the northern Rio Grande rift: Partitioning and asymmetry inherited from Laramide and older uplifts

    USGS Publications Warehouse

    Kellogg, K.S.

    1999-01-01

    Three asymmetric Neogene basins in the northern Rio Grande rift of New Mexico and Colorado - the San Luis basin, the upper Arkansas River graben, and the Blue River graben - are tilted toward large flanking normal faults and lie astride the similarly asymmetric Late Cretaceous-early Tertiary (Laramide) San Juan-San Luis, Sawatch, and Front Range-Gore Range uplifts, respectively. The steep, thrust-faulted side of each uplift is on the same side as the down-rotated side of each of the Neogene basins. In addition, the direction of stratal tilt changes northward across the Villa Grove accommodation zone from east in the San Luis basin to west in the upper Arkansas River graben. This accommodation zone coincides approximately with the northward change from the east-directed San Juan-San Luis uplift to the west-directed Sawatch uplift. These observations, supported by seismic-reflection studies across the San Luis basin and studies of several other superimposed pairs of rift basins and Laramide uplifts, suggest that the basin-bounding normal faults are listric and merge at depth with the older thrusts, which are also listric and root into the crust at about 15-16 km. The Blue River graben is complicated by lack of basin fill and a thrust history along the west side of the Gore Range that is at least as old as late Paleozoic. Nonetheless, the Neogene valley is demonstrably tilted west and lies astride an overall west-directed thrust system, similar to other thrust-and-basin relationships in the northern Rio Grande rift.

  11. Sequence stratigraphy and systems tract analysis of the Neogene-Quaternary continental margin off the Zambezi delta, Mozambique

    SciTech Connect

    Kolla, V. ); Macurda, D.B. Jr. ); Nelson, H.R. Jr. )

    1991-03-01

    During the Neogene and Quaternary, the Zambezi River built a broad delta-platform from 75 to over 100 km into the Indian Ocean. A regional seismic grid shows numerous discontinuities in the delta platform, slope, and deeper basinal areas. Based on downward shifts of reflection terminations and onlaps at or below shelf edge, more than 25 sequences have been identified. Within the gross Neogene package, the basal section is characterized by aggradation, followed by rapid and significant (oblique) progradation, which is then followed by numerous aggradational-progradation and progradation packages in the upper, younger sections. From recognition of aggradation-progradation patterns and from well information, it appears that the first, significant, and rapid progradation occurred since mid-Miocene. The earliest of the Neogene sequence appears thicker towards south and thinner towards north, opposite of the younger sequences. The number of sequences, their modes of stacking, and thickness distributions reflect relative sea-level changes and the points of sediment input as the Zambezi River shifted in position from south to north in time. The Zambezi passive continental margin, located in the Indian Ocean basin, is a stable platform as opposed to the unstable continental margins off the Mississippi, McKenzie, and Niger deltas and is far from the stable margins that were the basis of the Haq et al. cycle-chart (1987). Thus the Zambezi continental margin provides an independent test case for verification of eustatic cycles and for the evaluation of allogenic (eustatic) versus autogenic (subsidence and delta switching) effects on depositional systems and systems tracts.

  12. Late Neogene-Recent uplift of the Cabo de Gata volcanic province, Almerı´a, SE Spain

    NASA Astrophysics Data System (ADS)

    Martín, José M.; Braga, Juan C.; Betzler, Christian

    2003-02-01

    Cabo de Gata is a Miocene volcanic province in the Betic Cordillera in southeastern Spain. The distribution of coastal deposits in the successive marine sedimentary units overlying the last volcanic episode (about 7.5 Ma old) has been used to reconstruct the post-volcanic palaeogeographic evolution of the region during the Late Neogene. The current elevation of well-dated shoreline marker rocks has been used to estimate uplift amount and rates. Since the late Tortonian, a N45°E-aligned (the strike of the Carboneras fault system) topographic relief was emergent in the Cabo de Gata region. The extension and height of this island increased throughout the late Neogene. Smaller, independent islands were emergent and finally became connected to the main island during the Messinian. The Carboneras and Agua Amarga Pliocene sub-basins were the last two marine basins prior to the final emergence of the region. Since the last volcanic eruption (ca. 7.5 Ma), maximum uplift of sedimentary rocks in Cabo de Gata has taken place on the western margin of the N45°E-aligned palaeorelief. The altitude of the shoreline marker rocks in the successive sedimentary units decreases eastwards to the present-day coast and northwards of the Rambla del Plomo. Uplift rates since deposition remain nearly constant for the successive Messinian rocks and decrease slightly for the lower Pliocene outcrops. Most of the uplift took place before the Pliocene while the main island enlarged. Uplift amounts and rates since deposition of the upper Neogene sedimentary units in the Cabo de Gata area are similar to the ones estimated for laterally equivalent units in the eastern Betic basins (approximately 50 m/Ma). Despite its volcanic nature and the occurrence of the Carboneras fault system, the Cabo de Gata probably became elevated as a consequence of regional uplift in connection with the rest of the Betic Cordillera.

  13. Environmental Assessment for power marketing policy for Southwestern Power Administration

    SciTech Connect

    Not Available

    1993-12-01

    Southwestern Power Administration (Southwestern) needs to renew expiring power sales contracts with new term (10 year) sales contracts. The existing contracts have been in place for several years and many will expire over the next ten years. Southwestern completed an Environmental Assessment on the existing power allocation in June, 1979 (a copy of the EA is attached), and there are no proposed additions of any major new generation resources, service to discrete major new loads, or major changes in operating parameters, beyond those included in the existing power allocation. Impacts from a no action plan, proposed alternative, and market power for less than 10 years are described.

  14. New allocyclic dimensions in a prograding carbonate bank: Evidence for eustatic, tectonic, and paleoceanographic control (late Neogene, Bahamas)

    USGS Publications Warehouse

    Lidz, B.H.; McNeill, D.F.

    1997-01-01

    The deep-sea record, examined recently for the first time in a shallow-depocenter setting, has unveiled remarkable evidence for new sedimentary components and allocyclic complexity in a large, well-studied carbonate bank, the western Great Bahama Bank. The evidence is a composite foraminiferal signature - Paleocene to early Miocene (allogenic or reworked) and late Miocene to late Pliocene (host) planktic taxa, and redeposited middle Miocene shallow benthic faunas. Ages of the oldest and youngest planktic groups range from ??? 66 to ??? 2 Ma. The reworked and redeposited taxa are a proxy for significant sediment components that otherwise have no lithofacies or seismic resolution. The composite signature, reinforced by a distinctive distribution of the reworked and redeposited faunas, documents a much more complex late Neogene depositional system than previously known. The system is more than progradational. The source sequences that supplied the constituent bank-margin grains formed at different water depths and over hundreds of kilometers and tens of millions of years apart. New evidence from the literature and from data obtained during Ocean Drilling Program (OOP) Leg 166 in the Santaren Channel (Bahamas) support early interpretations based on the composite fossil record and provide valuable new dimensions to regional allocyclicity. The middle Miocene taxa were confined to the lower part of the section by the latest Miocene-earliest Pliocene(?) lowstand of sea level. An orderly occurrence of the allogenic taxa is unique to the global reworked geologic record and appears to have been controlled by a combination of Paleogene-early Neogene tectonics at the source, eustatic changes, and late Neogene current activity at the source and across the bank. The allogenic taxa expand the spatial and temporal range of information in the northern Bahamas by nearly an order of magnitude. In essence, some of the major processes active in the region during ??? 64 m.y. of the

  15. Late Neogene geohistory analysis of the Humboldt basin and its relationship to convergence of the Juan de Fuca plate

    USGS Publications Warehouse

    McCrory, P.A.

    1989-01-01

    Geohistory analysis of Neogene Humboldt basin strata provides important constraints for hypotheses of the tectonic evolution of the southern Cascadia subduction margin, leading up to the arrival of the Mendocino triple junction. This analysis suggests that the tectonic evolution of the Humboldt basin area was dominated by coupling between the downgoing Juan de Fuca plate and the continental margin. This coupling is reflected in the timing of major hiatuses within the basin sedimentary sequence and margin uplift and subsidence which occur during periods of tectonic plate adjustment. -from Author

  16. Evolution of a trench-slope basin within the Cascadia subduction margin: the Neogene Humboldt Basin, California

    USGS Publications Warehouse

    McCrory, P.A.

    1995-01-01

    The Neogene Humboldt (Eel River) Basin is located along the north-eastern margin of the Pacific Ocean within the Cascadia subduction zone. This sedimentary basin originated near the base of the accretionary prism in post-Eocene time. Subduction processes since that time have elevated strata in the south-eastern portion of the basin above sea level. High-resolution chronostratigraphic data from the onshore portion of the Humboldt Basin enable correlation of time-equivalent lithofacies across the palaeomargin, reconstruction of slope-basin evolution, and preliminary delineation of climatic and tectonic influence on lithological variation. -from Author

  17. Neogene uplift of the eastern Betic Cordillera (Spain) : new constraints from low-temperature thermochronology and stream profile analysis

    NASA Astrophysics Data System (ADS)

    Janowski, Marianne; Loget, Nicolas; Gautheron, Cécile; Meyer, Bertrand; Van Den Driessche, Jean; Babault, Julien

    2015-04-01

    The Betic Cordillera (south Spain), forms the western european ending of the peri-Mediterranean alpine belts. In the eastern Betics, uplift of the cordillera and the peripheral neogene marine basins results from recent tectonic processes (shortening linked to Africa-Eurasia convergence, dynamic topography associated with Alboran slab evolution). These processes are connected to the Alboran domain tectonic inversion subsequent to the Miocene thinning stage and exhumation of metamorphic domes. These metamorphic domes now correspond to the highest topographies in the area (e.g. Sierra Nevada, Sierra de Gador) surrounded by the neogene basins. Based on a geomorphological study of the eastern Betics, and a LT thermochronology analysis focused on the Sierra de Gador, our aim is to bring new constraints on the late-neogene topography evolution. Apatite (U-Th)/He analysis was performed on samples from the Alpujarride Complex of the Sierra de Gador and reveals an AHe cooling age of ~ 9 Ma. Thermal modeling of the Alpujarride Complex, based on the new AHe and published data (AFT, ZFT and Ar/Ar on muscovite), was performed using QTQt software. The thermal model shows a very fast cooling of ~ 120°C/Ma between 20 and 16 Ma associated with Miocene thinning, then a brutal stop in the cooling path between 16 and 10 Ma when the temperature remains approximately at 65°C and may be linked to a peneplanation event. Low-relief surfaces (detected by relief spatial analysis and field mapping) preserved at the summit of the Sierra de Gador could be related to this event. Surfacing is constrained by uncomfortably late-tortonian inner platform deposits on the top of the Sierra de Gador. Post-Tortonian non-resetting indicates (i) the thickness of these platform deposits has not been significant, and (ii) tortonian tectonic inversion of the domain is not expressed in the exhumation signal. On the other hand, we performed a stream profile analysis to investigate large scale neogene uplift

  18. The ecology of extinction: molluscan feeding and faunal turnover in the Caribbean Neogene.

    PubMed

    Todd, J A; Jackson, J B C; Johnson, K G; Fortunato, H M; Heitz, A; Alvarez, M; Jung, P

    2002-03-22

    Molluscan faunal turnover in the Plio-Pleistocene of the tropical western Atlantic has been attributed to drops in temperature or primary productivity, but these competing hypotheses have not been assessed ecologically. To test these alternatives, we compiled data on changing molluscan life habits and trophic composition over 12 million years derived from 463 newly made collections from the southwestern Caribbean. Shelf ecosystems have altered markedly in trophic structure since the Late Pliocene. Predatory gastropods and suspension-feeding bivalves declined significantly in abundance, but not in diversity, and reef-dwellers became common. By contrast, all other ecological life habits remained remarkably stable. Food-web changes strongly support the hypothesis that declining regional nutrient supply had an increasing impact on regional macroecology, culminating in a faunal turnover.

  19. Integrated magnetobiostratigraphy at the Oligocene/Miocene transition in the southwestern Atlantic Ocean (DSDP Leg 72, Hole 516F)

    NASA Astrophysics Data System (ADS)

    Gennari, Rocco; Persico, Davide; Florindo, Fabio; Turco, Elena; Villa, Giuliana

    2014-05-01

    , Paleoceanography, 15, 486-496. Plancq, J., Grossi, V., Henderiks, J., Simon, L. and Mattioli E., 2012. Alkenone producers during late Oligocene-early Miocene revisited, Paleoceanography, 27, PA1202. Pujol, C. and Duprat, J., 1983. Quaternary planktonic foraminifers of the southwestern Atlantic (Rio Grande Rise) Deep Sea Drilling Project Leg 72. In: Barker, P.F., Carlson, R.L., Johnson, D.A., et al. (Eds.), Initial Reports of the Deep Sea Drilling Project, 72, 601-615. Spezzaferri, S., 1994. Planktonic foraminifers biostratigraphy of the Oligocene and lower Miocene in the oceanic record. An overview. Palaeontographia Italica 81, 1-187. Steininger, F.F., Aubry, M.P., Berggren, W.A., Biolzi, M., Borsetti, A.M., Cartlidge, J., Cati, F., Corfield, R., Gelati, R., Iaccarino, S., Napoleone, C., Ottner, F., Rogl, R., Spezzaferri, S., Tateo, F., Villa, G. and Zevenboom, D. 1997. The Global Stratotype Section and Point (GSSP) for the base of the Neogene. Episodes vol. 20, 23-28.

  20. 7. DETAIL VIEW OF SOUTHWESTERN CORNER OF BRIDGE AND FOUNDATION, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. DETAIL VIEW OF SOUTHWESTERN CORNER OF BRIDGE AND FOUNDATION, SHOWING TRACES OF CONCRETE POURING DURING CONSTRUCTION AND EMBEDDED IRON HARDWARE ON OUTER FACE OF PARAPET. FACING NORTHEAST - Brevard Bridge, Spanning Westland Run at Ullom Road, Export, Washington County, PA

  1. Sphere-Enhanced Microwave Ablation (sMWA) Versus Bland Microwave Ablation (bMWA): Technical Parameters, Specific CT 3D Rendering and Histopathology

    SciTech Connect

    Gockner, T. L.; Zelzer, S.; Mokry, T. Gnutzmann, D. Bellemann, N.; Mogler, C.; Beierfuß, A. Köllensperger, E. Germann, G.; Radeleff, B. A. Stampfl, U. Kauczor, H. U.; Pereira, P. L.; Sommer, C. M.

    2015-04-15

    PurposeThis study was designed to compare technical parameters during ablation as well as CT 3D rendering and histopathology of the ablation zone between sphere-enhanced microwave ablation (sMWA) and bland microwave ablation (bMWA).MethodsIn six sheep-livers, 18 microwave ablations were performed with identical system presets (power output: 80 W, ablation time: 120 s). In three sheep, transarterial embolisation (TAE) was performed immediately before microwave ablation using spheres (diameter: 40 ± 10 μm) (sMWA). In the other three sheep, microwave ablation was performed without spheres embolisation (bMWA). Contrast-enhanced CT, sacrifice, and liver harvest followed immediately after microwave ablation. Study goals included technical parameters during ablation (resulting power output, ablation time), geometry of the ablation zone applying specific CT 3D rendering with a software prototype (short axis of the ablation zone, volume of the largest aligned ablation sphere within the ablation zone), and histopathology (hematoxylin-eosin, Masson Goldner and TUNEL).ResultsResulting power output/ablation times were 78.7 ± 1.0 W/120 ± 0.0 s for bMWA and 78.4 ± 1.0 W/120 ± 0.0 s for sMWA (n.s., respectively). Short axis/volume were 23.7 ± 3.7 mm/7.0 ± 2.4 cm{sup 3} for bMWA and 29.1 ± 3.4 mm/11.5 ± 3.9 cm{sup 3} for sMWA (P < 0.01, respectively). Histopathology confirmed the signs of coagulation necrosis as well as early and irreversible cell death for bMWA and sMWA. For sMWA, spheres were detected within, at the rim, and outside of the ablation zone without conspicuous features.ConclusionsSpecific CT 3D rendering identifies a larger ablation zone for sMWA compared with bMWA. The histopathological signs and the detectable amount of cell death are comparable for both groups. When comparing sMWA with bMWA, TAE has no effect on the technical parameters during ablation.

  2. A new Munidopsis species (Galatheoidea, Munidopsidae) from the Southwestern Atlantic.

    PubMed

    Cardoso, Irene A; Serejo, Cristiana S; Rodrigues, Celso

    2014-01-01

    Six Munidopsis species are recorded to the Southwestern Atlantic: M. barbarae; M. erinacea; M. nitida; M. sigsbei; M. riveroi and M. transtridens. Herein a new Munidopsis species from Southwestern Atlantic is described: Munidopsis trindadensis sp.nov., was sampled off Trindade Island (Espírito Santo, Brazil) at 360 m depth and differs from all six species previously recorded in this region by the telson with seven plates.

  3. Palaeogeographic, climatic and tectonic change in southeastern Australia: the Late Neogene evolution of the Murray Basin

    NASA Astrophysics Data System (ADS)

    McLaren, Sandra; Wallace, Malcolm W.; Gallagher, Stephen J.; Miranda, John A.; Holdgate, Guy R.; Gow, Laura J.; Snowball, Ian; Sandgren, Per

    2011-05-01

    The Murray Basin is a low-lying but extensive intracratonic depocentre in southeastern Australia, preserving an extraordinary record of Late Neogene sedimentation. New stratigraphic and sedimentologic data allow the long-term evolution of the basin to be re-evaluated and suggest a significant role for: (1) tectonism in controlling basin evolution, and (2) progressive and step-wise climatic change beginning in the early Pleistocene. Tectonic change is associated with regional uplift, occurring at approximately the same rate from the early Pliocene until the present day, and possibly associated with changing mantle circulation patterns or plate boundary processes. This uplift led to the defeat and re-routing of the Murray River, Australia's major continental drainage system. Key to our interpretation is recognition of timing relationships between four prominent palaeogeographic features - the Loxton-Parilla Sands strandplain, the Gambier coastal plain, palaeo megalake Bungunnia and the Kanawinka Escarpment. Geomorphic and stratigraphic evidence suggest that during the Early Pliocene the ancestral Murray River was located in western Victoria, flowing south along the Douglas Depression. Relatively small amounts of regional uplift (<200 m) defeated this drainage system, dramatically changing the palaeogeography of southeastern Australia and forming Plio-Pleistocene megalake Bungunnia. At its maximum extent Lake Bungunnia covered more than 50,000 km 2, making it one of the largest known palaeo- or modern-lakes in an intracontinental setting. Magnetostratigraphic constraints suggest lake formation c. 2.4 Ma. The formation of Lake Bungunnia influenced the Pliocene coastal dynamics, depriving the coastline of a sediment source and changing the coastal system from a prograding strandline system to an erosional one. Erosion during this period formed the Kanawinka Escarpment, a palaeo sea-cliff and one of the most prominent and laterally extensive geomorphic features in

  4. Miocene Evaporites in the Intermountain Tuzluca -Iǧdir Neogene Basin, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Ayyıldız, T.; Varol, B.; Sözeri, K.; Karakaş, Z.

    2012-04-01

    The study area, which continues into Armenia south of Yerevan as Aras/Araxes or Hoktemberian Basin, is located within the Eastern Turkish High Plateau lying east of the intersection point of the North and East Anatolian faults at Karlıova, where folds, thrust and strike-slip faults, and large-scale extensional fractures related to a shortening regime have been developing as a result of continent-continent collision during the Neotectonic episode. Simultaneously with the shortening phase, structural basins developed such as intermountane. Detailed mapping of the Neogene deposits (Early Oligocene - Middle to early Late Miocene) in the eastern part of this basin studied allowed the recognition of four successive sedimentary units composed of fluvial, fluvio-deltaic, lake and saline pan. The depositional units were ended by intensive volcanic activity started in the Late Miocene epoch. Pre-evaporitic stage, some levels with siliciclastic and carbonate might be important for petroleum potential, which consists of bituminous mudstone (TOC: % 0.67 - 6.14; Tmax: 422 - 4620C; HI: 37-54). Evaporites are mainly represented by bedded/banded halite that were formed as four separate layers (10-40 m thick) intersected by red siliciclastic deposits with single selenitic gypsum and cubic halite crystals. Bedded gypsum was formed as marginal evaporites, laterally interfingering with the halite layers. On the other hand, it was precipitated as final evaporite deposits on the top of the halite-dominated succession, indicating upward increasing value of SO4 to Cl, probably resulted from a climatic changing leading to transition from saline pan to sulphate lake. As based on the different kinds of precipitation, the evaporite succession includes following 1) evaporitic red mudstone inner-sabkha mud flats; 2) bedded/banded halite and mudstone with organic matter in inner-sabkha salt pan; 3) interdigitated gypsum in marginal sabkha; 4) sealed gypsum in sulphate lake / floodwater sabkha

  5. Seismic Evidence for Neogene and Active Shortening Offshore Lebanon (SHALIMAR Cruise)

    NASA Astrophysics Data System (ADS)

    Carton, H.; Singh, S. C.; Tapponnier, P.; Elias, A.; Briais, A.; Sursock, A.; Jomaa, R.; King, G. C.; Daeron, M.; Jacques, E.; Barrier, L.

    2007-12-01

    Lebanon is located on a 160 km long transpressional bend of the left-lateral Levant (Dead Sea) Fault. The main objective of the SHALIMAR (2003) marine survey was to characterize and map active deformation offshore Lebanon using a range of geophysical techniques, particularly seismic reflection profiling. The cruise results clearly establish the presence of submarine thrust faults - likely the source of one of the most devastating submarine historical earthquakes that happened along the Levantine shores - and clarify the structure of this part of the Levant margin. A submarine fold-belt, bounded by thrusts and lateral ramps and extending in places to at least 30 km from the shoreline, is interpreted as the foreland thrust system of the actively growing Mount Lebanon range. There is no large fault extending into the Levant Basin towards Cyprus, which indicates that thrusting only absorbs local transpression resulting from the Lebanese restraining bend. Both the Miocene and Plio-Quaternary sedimentary sequences are affected by shortening, with landward-dipping blind thrusts and associated growth strata. The presence of the Messinian evaporites creates complex deformation patterns, including normal faults due both to folding accommodation and gravity spreading, all well imaged in the seismic reflection profiles. Because the evaporite layer acts as a decollement level, deformation extends farther out seawards through a series of thrust imbricates or duplexes. Shortening is strongest between Beyrut and Batroun and decreases towards the south between Saida and Tyre. North of Tripoli, the passive margin is not affected by Neogene deformation, and is well preserved. We propose that, since the Miocene, the northward propagating Levant Fault interacted with margin structures inherited from the Mesozoic rifting phase, and was deviated away from the more rigid oceanic crust flooring the Levant basin, a process which led to the formation of the Lebanese restraining bend, and

  6. Seismic Evidence for Neogene and Active Shortening Offshore Lebanon (SHALIMAR Cruise)

    NASA Astrophysics Data System (ADS)

    Carton, H.; Singh, S. C.; Tapponnier, P.; Elias, A.; Briais, A.; Sursock, A.; Jomaa, R.; King, G. C.; Daeron, M.; Jacques, E.; Barrier, L.

    2004-12-01

    Lebanon is located on a 160 km long transpressional bend of the left-lateral Levant (Dead Sea) Fault. The main objective of the SHALIMAR (2003) marine survey was to characterize and map active deformation offshore Lebanon using a range of geophysical techniques, particularly seismic reflection profiling. The cruise results clearly establish the presence of submarine thrust faults - likely the source of one of the most devastating submarine historical earthquakes that happened along the Levantine shores - and clarify the structure of this part of the Levant margin. A submarine fold-belt, bounded by thrusts and lateral ramps and extending in places to at least 30 km from the shoreline, is interpreted as the foreland thrust system of the actively growing Mount Lebanon range. There is no large fault extending into the Levant Basin towards Cyprus, which indicates that thrusting only absorbs local transpression resulting from the Lebanese restraining bend. Both the Miocene and Plio-Quaternary sedimentary sequences are affected by shortening, with landward-dipping blind thrusts and associated growth strata. The presence of the Messinian evaporites creates complex deformation patterns, including normal faults due both to folding accommodation and gravity spreading, all well imaged in the seismic reflection profiles. Because the evaporite layer acts as a decollement level, deformation extends farther out seawards through a series of thrust imbricates or duplexes. Shortening is strongest between Beyrut and Batroun and decreases towards the south between Saida and Tyre. North of Tripoli, the passive margin is not affected by Neogene deformation, and is well preserved. We propose that, since the Miocene, the northward propagating Levant Fault interacted with margin structures inherited from the Mesozoic rifting phase, and was deviated away from the more rigid oceanic crust flooring the Levant basin, a process which led to the formation of the Lebanese restraining bend, and

  7. Seismic evidence for Neogene and active shortening offshore of Lebanon (Shalimar cruise)

    NASA Astrophysics Data System (ADS)

    Carton, H.; Singh, S. C.; Tapponnier, P.; Elias, A.; Briais, A.; Sursock, A.; Jomaa, R.; King, G. C. P.; DaëRon, M.; Jacques, E.; Barrier, L.

    2009-07-01

    Lebanon, located on a 160-km-long transpressional bend of the left-lateral Levant (Dead Sea) fault system (LFS), has been the site of infrequent but large earthquakes, including one submarine, tsunamigenic event. The main objective of the Shalimar marine survey was to characterize and map active deformation offshore of Lebanon using a range of geophysical techniques, particularly seismic reflection profiling. The cruise results clearly establish the presence of young submarine thrust faults and folds and clarify the structure of this part of the Levant margin. A submarine fold belt, bounded by thrusts and lateral ramps and extending up to 30 km from the shoreline, is interpreted as the foreland thrust system of the actively growing Mount Lebanon range. There is no large fault extending into the Levant basin toward Cyprus, which indicates that thrusting only absorbs local transpression resulting from the Lebanese restraining bend. Both the Miocene and Plio-Quaternary sedimentary sequences are affected by shortening, with landward dipping blind thrusts and associated growth strata. The presence of the Messinian evaporites creates complex deformation patterns, including normal faults due both to folding accommodation and to gravity spreading, all well imaged in the seismic reflection profiles. Because the evaporite layer acts as a décollement level, shortening extends farther out seaward through a series of thrust imbricates or duplexes. The strongest shortening, observed between Beirut and Batroun, decreases toward the south between Saida and Tyre. North of Tripoli, the passive margin is not affected by Neogene deformation and is well preserved. We propose that since the Miocene, the northward propagating LFS interacted with margin structures inherited from the Mesozoic rifting phase and was deviated along the more rigid oceanic crust flooring the Levant basin, a process which led to the formation of the Lebanese restraining bend of the LFS and consequently to the

  8. High Resolution Quaternary and Neogene Reconstructions of the Southwest Indian Ridge and Rifting in Eastern Africa

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Merkuryev, S. A.; Calais, E.; Sauter, D.

    2014-12-01

    The Southwest Indian Ridge (SWIR) south of Africa is a critical link in plate circuits between the Atlantic and Indian Ocean basins and between the Nubia and Somalia plates. Detailed reconstructions of its seafloor spreading history are challenging due to the low fidelity of its magnetic anomalies, which were mostly created at slow to ultraslow spreading rates, and gaps in data coverage for some areas of the ridge. Here, we describe the first high-resolution analysis of Quaternary/Neogene SWIR plate kinematics based on nearly 5000 identifications that we made of magnetic reversals C1n (0.78 Ma) to C6no (19.7 Ma) and ~6000 crossings of 21 fracture zones and transform faults that offset the ridge. We also outline the implications for estimates of motion between the Nubia and Somalia plates since 20 Ma across rifts in eastern Africa. Searches for the Nubia-Lwandle and Lwandle-Somalia plate boundaries north of the SWIR with our new data corroborate previous evidence for respective locations near the Andrew Bain transform fault at ~30°E and at ~50°E. Inversions of the abundant new data to find best-fitting rotations at ~1 Myr intervals since 20 Ma reveal a previously unknown, ~20% deceleration of seafloor spreading rates at 7.2±1 Ma everywhere along the SWIR. Motion since 7 Ma has remained remarkably steady and agrees within uncertainties with GPS estimates that are based on more than 100 continuous GPS sites on the Nubia, Somalia, and Antarctic plates. The consistency of the geodetic and geologic estimates validates both and also supports evidence we will describe for anomalously wide outward displacement west of ~30E. Nubia-Somalia rotations determined from our new model indicate that the two plates have undergone steady relative motion since at least 19 Ma. Our new rotation for C5n.2 predicts ~70% less opening across the East Africa rift since 11 Ma than the most recently published kinematic estimate, in better accord with at least one geologically

  9. Heterogeneous sources of marlstone in a piggy-back basin: the Neogene Lopare basin in Dinarides

    NASA Astrophysics Data System (ADS)

    Grba, Nenad; Neubauer, Franz; Šajnović, Aleksandra; Jovančićević, Branimir

    2014-05-01

    The chemical composition of marlstones is commonly not used to investigate to provenance of the sedimentary basin fill because of variable dilution by authigenic carbonate and the assumed uniformity of the clay fraction. Here, we report geochemical compositions of marlstone from the Neogene Lopare basin in Internal Dinarides, which have an unusual chemical composition reflecting at least two different sources. The Lopare basin formed as a piggy-back basin on top of the growing Dinaric orogenic wedge. Much of its Miocene evolution, this basin represented a partly hypersaline lake in a warm climate likely formed during the Miocene Climatic Optimum during Early Miocene. Several lithofacies of marlstone reflect basin center deposits and the chemical composition could be considered as well mixed from external siliciclastic input (clay fraction) and internal carbonate precipitation. Sandstone layers are very thin and are not considered here. A total of 46 samples from two boreholes POT-3 (depth to 344 m) and POT-1 (depth to 193 m) were selected for geochemical investigation. The contents of major, minor and trace including rare earth elements were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The qualitative composition of the mineral part was determined by means of X-ray diffractometry. The main chemical features of the Lopare basin marlstone are variable but high contents of most metals like Fe (5.36 ± 1.05 wt%), Cr (215 ± 34 ppm), Ni (183 ± 36 ppm), Pb (173 ± 43 ppm), but also of some alkalies like Li (340 ± 123 ppm). Particularly the heavy metal contents like Cr, Ni, Fe are much higher than for average continental mudstones (e.g., Taylor and McLennan, 1985). These contrasting compositions may result from two geochemically different sources: (1) Ophiolites (oceanic source) occurring in the neighborhood are responsible for high Cr, Ni, Fe contents, while (2) the increased alkali contents (e.g., Li; continental source) likely

  10. Emergence of the Namib Desert During the Neogene, and Correlations With Global Palaeoclimate Changes

    NASA Astrophysics Data System (ADS)

    Segalen, L.; Renard, M.; Lee-Thorp, J. A.; Senut, B.; Pickford, M.

    2004-12-01

    The Namib is one of the oldest known desert systems, hence its formation and maintenance are of considerable regional and global importance. Fluctuations in Atlantic climate and oceanic circulation patterns directly affect the ecology of the Namibian desert, and the entire South African west coast area, on a variety of timescales. The discovery of mammalian fossils and ratite eggshells has provided a biochronology, while the ratite eggshells have allowed stable oxygen and carbon isotope studies of this material to pinpoint the plant dietary base of these birds and to provide clues about changing environments through time. The results of the existing multidisciplinary study provide a sequence showing that during the lower Miocene, prior to 17 Ma, (fluviatile environments, terraces of the Proto-Orange river) a tropical/subtropical climate existed. The onset of aridification is correlated with appearance of the first aeolianites in the basal middle Miocene period. In the Southern Namib, cross-stratification in aeolianites represent the lower slipface of crescent dunes. The predominant northeast-northwest azimuths of the cross-bedded strata indicate deposition under a prevailing southerly wind regime. This regime remained in place throughout the Neogene. The aeolianites of the Northern Namib present different lithologies from those in the south: sand sheet deposits rich in cemented roots (stabilization phase of the arid system), cross-stratification of complex dunes and deflation surfaces related to water flowing from nearby inselbergs. The azimuths of these cross-bedded strata indicate deposition under westerly/southerly winds and also easterly and northeasterly winds during the Late Miocene (at present the bergwinds produce similar conditions). Isotopic data from the ratite eggshells shows advance of C4 grasses in this region at the end of the Miocene, and emergent differences in the plant cover of the southern versus northern sectors. Eggshell carbon isotope

  11. The Sense of Magma Flow in Neogene Dike Intrusions from East Iceland (Invited)

    NASA Astrophysics Data System (ADS)

    Riishuus, M. S.; Eriksson, P. I.; Elming, S.

    2013-12-01

    Neogene dike intrusions in east Iceland have been subjected to field studies and magnetic fabric analyses. We examine the applicability of the AMS (anisotropy of magnetic susceptibility) method to define fossil magma flow directions, and test models for propagation of magma during dike emplacement. The Streitishvarf composite dike with basalt margins and a quartz-porphyry core extends for ~15 km along strike (NNE-SSW) and displays indisputable field evidence, in the form of parabolic shaped flow banding, of a lateral magma flow component directed from north to south. AMS and rock magnetic studies have been made on conjugate margins from three outcrops of the quartz-porphyry along the length of the dike. The magnetic fabric is interpreted according to the imbrication model, using the minor susceptibility axis as shear plane indicator. The absolute directions given by the minor susceptibility axis are quantified using vector algebra. The fossil magma is interpreted to flow from north to south, with an upward inclination between 30° and 64° (95% confidence ellipse of 3°-9°), in support of the field observations. Our preferred emplacement model for the Streitishvarf dike involves rupture of stagnant felsic magma by a hotter basaltic dike, mobilizing the felsic magma to propagate south within the insulated pathway established by the dolerite dike. With confirmation that the AMS method can produce reliable directional data tested against independent field observations, we examine the fossil magma flow in a suite of basaltic dikes for which field evidence of magma flow directions is typically scarce. Regional dikes extending north of the Álftafjördur central volcano form an elongated swarm, ~5 km in width and up to 40 km in length. Samples were collected from 24 dikes at varying lateral distance from the central volcano. Contemporaneous shear resolved on the dike walls may modify a pure flow-induced fabric and such shear regimes are therefore retracted. The magma

  12. Chemical and isotopic characteristics of hot springs along the along the Neogene Malawi rift.

    NASA Astrophysics Data System (ADS)

    Atekwana, E. A.; Tsokonombwe, G. W.; Elsenbeck, J.; Wanless, V. D.; Atekwana, E. A.

    2015-12-01

    We measured the concentrations of major ions and dissolved inorganic carbon (DIC) and the stable isotopes of carbon (δ13CDIC), hydrogen (δD) and oxygen (δ18O) of hot springs along the Neogene Malawi rift. We compared the results with those of streams and a cold spring. We aimed to assess the hot springs for evidence of addition of mantle mass, specifically water and carbon and (2) determine the processes that control the chemical and isotopic evolution of the hot springs. Understanding the source(s) of heat for the springs and if the chemical and isotopic characteristics show evidence of mantle processes is an important goal of the Project for Rift Initiation, Development and Evolution (PRIDE). The temperature of the hot springs ranged from 35 to 80 ºC. High temperature anomalies are observed between latitudes 10 to 11, 12 to 13 and 15 to 16 degrees south along the rift axis. The δD and δ18O for the cold spring, hot springs and streams had a similar range, were positively correlated and lie on the trend of the local meteoric water line. We suggest negligible contribution of water from a connate or magmatic source and limited oxygen exchange from water-rock interaction or CO2 exchange from deep sedimentary carbonates. The DIC concentrations of the hot springs are higher (5 to 61 mg C/L) than those of streams (2 to 28 mg C/L) indicating addition of carbon to the DIC pool during the circulation of some springs. The range in the δ13CDIC of the hot springs (-17 to -8‰) is broader and lower compared to streams (-12 to -5‰) due to addition of carbon with a δ13CDIC of -15‰ to the spring water during circulation. Our results indicate that (1) the source of water for the hot springs is meteoric, (2) the hot springs have not experienced extensive water-rock interaction due to fast circulation suggesting highly permeable fault zones, (3) the source of carbon in the DIC of the hot springs is mostly CO2(g) from the soil zone and (4) the springs are heated by normal

  13. Wrench tectonics control on Neogene-Quaternary sedimentation along the Mid-Hungarian Mobile Belt

    NASA Astrophysics Data System (ADS)

    Pogacsas, Gyorgy; Juhász, Györgyi; Mádl-Szőnyi, Judit; Simon, Szilvia; Lukács, Szilveszter; Csizmeg, János

    2010-05-01

    The Neogene Pannonian basin is underlain by a large orogenic collage which is built up by several tectonostratigraphic terrains. The basement of the Pannonian Basin became imbricate nappes during the Cretaceous Alpine collision. Nappes of Late Cretaceous in age have been proven below the Great Hungarian Plain (Grow et al 1994). The boundary of the two main terrains, the northwestern ALCAPA (Alpine-Carpathian-Pannonian) and the southeastern TISZA, is the Mid-Hungarian Mobile Belt. It is the most significant neotectonic zone of the Pannonian Basin. The structural analysis of the middle section of the Mid-Hungarian Mobile Belt was carried out on a 120km x 50km area, between the Danube and the Tisza river, on the basis of interpretation of seismic data. The structural analysis of the Neogene-Quaternary sediments was supported by sequence stratigraphic interpretation of seismic, well log and core-sample data. Regional seismic profiles were both oriented in the dip direction, which highlights sediment supply routes into the basin, and strike-oriented. The studied segment of the Mid-Hungarian Mobile Belt consists of several long (some ten kilometres long) strike slip fault zones. The offset lengths of the individual strike slipe faults varies between a few and a dozens of kilometres. Activity along the Mid-Hungarian Mobile Belt can be characterised by four periods, the size and shape of facies zones of each development period were controlled by tectonics: 1. During the early Miocene, the ALPACA moved eastward, bounded by sinistral strike-slipe system along its northern side and dextral strike-slipe fault system along its contact with the Southern Alps and the TISZA terrain. The largest movement took part during the Ottnangian-Karpatian (19-16.5 Ma). The TISZA unit moved northeastward over the remnant Carpathian Flysch Basin (Nemcok et al 2006). These terrains movements resulted in right lateral, convergent wide wrench along the Mid-Hungarian Mobile Belt. The ALPACA

  14. Neogene deformation of thrust-top Rzeszów Basin (Outer Carpathians, Poland)

    NASA Astrophysics Data System (ADS)

    Uroda, Joanna

    2015-04-01

    The Rzeszów Basin is a 220 km2 basin located in the frontal part of Polish Outer Carpathians fold-and-thrust belt. Its sedimentary succession consist of ca. 600 m- thick Miocene evaporates, litoral and marine sediments. This basin developed between Babica-Kąkolówka anticline and frontal thrust of Carpathian Orogen. Rzeszów thrust-top basin is a part of Carpathian foreland basin system- wedge-top depozone. The sediments of wedge -top depozone were syntectonic deformed, what is valuable tool to understand kinematic history of the orogen. Analysis of field and 3D seismic reflection data showed the internal structure of the basin. Seismic data reveal the presence of fault-bend-folds in the basement of Rzeszów basin. The architecture of the basin - the presence of fault-releated folds - suggest that the sediments were deformed in last compressing phase of Carpathian Orogen deformation. Evolution of Rzeszów Basin is compared with Bonini et.al. (1999) model of thrust-top basin whose development is controlled by the kinematics of two competing thrust anticlines. Analysis of seismic and well data in Rzeszów basin suggest that growth sediments are thicker in south part of the basin. During the thrusting the passive rotation of the internal thrust had taken place, what influence the basin fill architecture and depocentre migration opposite to thrust propagation. Acknowledgments This study was supported by grant No 2012/07/N/ST10/03221 of the Polish National Centre of Science "Tectonic activity of the Skole Nappe based on analysis of changes in the vertical profile and depocentre migration of Neogene sediments in Rzeszów-Strzyżów area (Outer Carpathians)". Seismic data by courtesy of the Polish Gas and Oil Company. References Bonini M., Moratti G., Sani F., 1999, Evolution and depocentre migration in thrust-top basins: inferences from the Messinian Velona Basin (Northern Apennines, Italy), Tectonophysics 304, 95-108.

  15. Neogene History of Antarctic Sea-ice and Development of the Sea-ice Diatom Community

    NASA Astrophysics Data System (ADS)

    Harwood, D. M.; Bohaty, S. M.; Whitehead, J. M.

    2002-12-01

    Sea-ice plays an important role in the modern Antarctic climate system and in this region's linkage to lower latitude regions. Today, the seasonal sea-ice cover decouples oceanic heat transfer to the atmosphere, which amplifies winter's low temperatures and shifts sources of moisture far to the north. The sea-ice zone is an important site for biological productivity and bottom water formation, through cooling and brine exclusion. The absence of the sea-ice during past and future periods of elevated temperatures would significantly impact the biology, oceanography, glaciology and meteorology of the Antarctic region. A unique diatom assemblage is adapted to life in and around the sea-ice, and serves as an increasingly useful proxy to mark the presence, extent and duration of sea-ice cover. This assemblage dominates Antarctic shelf sediments today and back through most of the Quaternary. The oldest fossil diatom flora with a similar composition and structure to that of the modern sea-ice community was identified in a late Miocene mudstone erratic MB-244C in coastal moraine from McMurdo Sound. This assemblage did not persist through to the present day, and it is absent, or significantly reduced, in numerous marine diatom-bearing strata of late Miocene, Pliocene and Quaternary age, including the upper Miocene McLeod Beds of the Battye Glacier Formation, Prince Charles Mountains, the lower Pliocene Sorsdal Formation in the Vestfold Hills, the Pliocene sediments from the DVDP and CIROS drillcores, and the lower Quaternary carbonate unit in the Cape Roberts Project drillcore CRP-1. The sea-ice diatom community likely persisted in low numbers in interior fjords and basins, adjacent to glacier margins during these times. The history of sea-ice development and fluctuation during the Neogene appears to be complex, with substantial variability in sea-ice cover. Core records are currently insufficient to document the details of this history, and variation in the diatom

  16. Neogene kinematic history of Nazca-Antarctic-Phoenix slab windows beneath Patagonia and the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Breitsprecher, Katrin; Thorkelson, Derek J.

    2009-01-01

    The Patagonian slab window is a subsurface tectonic feature resulting from subduction of the Nazca-Antarctic spreading-ridge system (Chile Rise) beneath southern South America. The geometry of the slab window had not been rigorously defined, in part because of the complex nature of the history of ridge subduction in the southeast Pacific region, which includes four interrelated spreading-ridge systems since 20 Ma: first, the Nazca-Phoenix ridge beneath South America, then simultaneous subduction of the Nazca-Antarctic and the northern Phoenix-Antarctic spreading-ridge systems beneath South America, and the southern Phoenix-Antarctic spreading-ridge system beneath Antarctica. Spreading-ridge paleo-geographies and rotation poles for all relevant plate pairs (Nazca, Phoenix, Antarctic, South America) are available from 20 Ma onward, and form the mathematical basis of our kinematic reconstruction of the geometry of the Patagonia and Antarctic slab windows through Neogene time. At approximately 18 Ma, the Nazca-Phoenix-Antarctic oceanic (ridge-ridge-ridge) triple junction enters the South American trench; we recognize this condition as an unstable quadruple junction. Heat flow at this junction and for some distance beneath the forearc would be considerably higher than is generally recognized in cases of ridge subduction. From 16 Ma onward, the geometry of the Patagonia slab window developed from the subduction of the trailing arms of the former oceanic triple junction. The majority of the slab window's areal extent and geometry is controlled by the highly oblique (near-parallel) subduction angle of the Nazca-Antarctic ridge system, and by the high contrast in relative convergence rates between these two plates relative to South America. The very slow convergence rate of the Antarctic slab is manifested by the shallow levels achieved by the slab edge (< 45 km); thus no point on the Antarctic slab is sufficiently deep to generate "normal" mantle-derived arc-type magmas

  17. Early Neogene unroofing of the Sierra Nevada de Santa Marta along the Bucaramanga -Santa Marta Fault

    NASA Astrophysics Data System (ADS)

    Piraquive Bermúdez, Alejandro; Pinzón, Edna; Bernet, Matthias; Kammer, Andreas; Von Quadt, Albrecht; Sarmiento, Gustavo

    2016-04-01

    Plate interaction between Caribbean and Nazca plates with Southamerica gave rise to an intricate pattern of tectonic blocks in the Northandean realm. Among these microblocks the Sierra Nevada de Santa Marta (SNSM) represents a fault-bounded triangular massif composed of a representative crustal section of the Northandean margin, in which a Precambrian to Late Paleozoic metamorphic belt is overlain by a Triassic to Jurassic magmatic arc and collateral volcanic suites. Its western border fault belongs to the composite Bucaramanga - Santa Marta fault with a combined left lateral-normal displacement. SE of Santa Marta it exposes remnants of an Oligocene marginal basin, which attests to a first Cenoizoic activation of this crustal-scale lineament. The basin fill consists of a sequence of coarse-grained cobble-pebble conglomerates > 1000 m thick that unconformably overlay the Triassic-Jurassic magmatic arc. Its lower sequence is composed of interbedded siltstones; topwards the sequence becomes dominated by coarser fractions. These sedimentary sequences yields valuable information about exhumation and coeval sedimentation processes that affected the massif's western border since the Upper Eocene. In order to analyse uplifting processes associated with tectonics during early Neogene we performed detrital zircon U-Pb geochronology, detrital thermochronology of zircon and apatites coupled with the description of a stratigraphic section and its facies composition. We compared samples from the Aracataca basin with analog sequences found at an equivalent basin at the Oca Fault at the northern margin of the SNSM. Our results show that sediments of both basins were sourced from Precambrian gneisses, along with Mesozoic acid to intermediate plutons; sedimentation started in the Upper Eocene-Oligocene according to palynomorphs, subsequently in the Upper Oligocene a completion of Jurassic to Cretaceous sources was followed by an increase of Precambrian input that became the dominant

  18. Neogene extension and volcanism in the Kunlun fault zone Northern Tibet

    NASA Astrophysics Data System (ADS)

    Jolivet, M.; Brunel, M.; Seward, D.; Malavieille, J.; Roger, F.; Leyreloup, A.; Arnaud, N.

    2003-04-01

    basin. Yin A., Kapp P.A., Murphy M.A., Manning C.E., Harrison T.M., Grove M., Lin D., Xi-Guang D., Cun-Ming W., 1999, Significant late Neogene east-west extension in northern Tibet. Geology, Vol.27, N°9, pp. 787-790. Kidd W.S.F., and Molnar P., 1988, Quaternary and active faulting observed on the 1985 Academia Sinica Royal Society Geotraverse of Tibet. Phil. Trans. R. Soc. Lond., Vol. A 327, pp. 337-363.

  19. Preliminary stratigraphic and paleomagnetic results from Neogene basins across the Anatolian Plateau (Turkey).

    NASA Astrophysics Data System (ADS)

    Lucifora, Stella; Cifelli, Francesca; Mazzini, Ilaria; Cosentino, Domenico; Mattei, Massimo; Cipollari, Paola; Gliozzi, Elsa; Palolo Cavinato, Gian

    2010-05-01

    An integrated paleomagnetic and stratigraphic study on Neogene basins across the Anatolian Plateau was carried out. This study is developed within the VAMP (Vertical Anatolian Movement Project), an interdisciplinary project aimed to the recent tectonic evolution of the central Anatolian Plateau. The studied areas are located in southern Turkey (Adana, Mut and Ermenek basins) and in northern Turkey (Kazan, Çankiri, Kastamonu, Boyabat and Sinop basins). For paleomagnetic analyses we sampled 1062 standard cylindrical samples from 13 stratigraphic sections, and 746 samples for paleontological analysis were taken from the same sections. AMS (Anisotropy of Magnetic Susceptibility), magnetic mineralogy and paleomagnetic polarity data are presented together with the results of the integrated stratigraphic analyses. In the Southern Turkey basins preliminary results show the diffuse presence of authigenic iron sulphides, together with magnetite, as main magnetic carriers. In these sections the iron-sulphides Characteristic Natural Magnetization (ChRM) component is characterized by inconsistent polarity record, suggesting that iron-sulphides have a late diagenetic origin. Conversely, magnetite bearing sediments show more reliable results in term of magnetic polarity interpretations. Preliminary stratigraphic and paleomagnetic results from the southern margin of the plateau allow us both to refine the stratigraphy for the late Miocene of the Adana Basin and to better constrain the age of the youngest marine deposits of the Mut and Ermenek basins. In the late Miocene of the Adana Basin evidence of the Messinian salinity crisis led to a new stratigraphic framework specially for the Messinian-Pliocene interval. Thick fluvial conglomerates from the uppermost Messinian deposits of the Adana Basin, which could be linked to the activation of the southern margin of the plateau, allow us to constrain at about 5.4 Ma the uplift of the central Anatolian Plateau. On the other hand, the

  20. Detailed record of the Neogene Sr isotopic evolution of seawater from DSDP Site 590B. [Deep Sea Drilling Project

    SciTech Connect

    DePaolo, D.J.

    1986-02-01

    A detailed study of strontium isotope variations in Neogene marine carbonate sediments from Deep Sea Drilling Project Site 590B, using techniques that allow the /sup 87/Sr//sup 86/Sr ratio to be determined to better than +/- 0.000 01, gives a high-resolution record of the Sr isotopic evolution of seawater. The data show that the rate of change of the marine /sup 87/Sr//sup 86/Sr ratio has varied significantly even on time scales as short as 1 m.y. Periods of particularly rapid growth appear to follow major marine regressions and probably reflect an increase in the delivery of radiogenic Sr from the continents coupled with a decreased submarine carbonate dissolution rate (greater carbonate compensation depth). Periods of relatively slowly changing /sup 97/Sr//sup 86/Sr follow major marine transgressions. On the basis of correlations with the marine oxygen isotope record and the times of major continental glacier growth, it is inferred that the effects of sea-level variations are modified by climatic factors that affect the intensity of continental weathering and runoff. The effects of sea-floor generation rate variations are not discernible for the Neogene. The maximum attainable stratigraphic resolution using Sr isotopes is between 0.1 and 2 m.y. for this time period. 24 references.

  1. Genesis of economic relevant fresh groundwater resources in Pleistocene/ Neogene aquifers in Nam Dinh (Red River Delta, Vietnam).

    NASA Astrophysics Data System (ADS)

    Wagner, F.; Ludwig, R. R.; Noell, U.; Hoang, H. V.; Pham, N. Q.; Larsen, F.; Lindenmaier, F.

    2012-04-01

    In the Southern Red River Delta (Nam Dinh Province, Vietnam), a local lens of low saline pore water of high quality has been identified in unconsolidated Pleistocene and Neogene aquifers, which are regionally known to contain brackish and saline pore waters. Since the 1990ies, ongoing overexploitation of the fresh groundwater results in decreasing GW heads up to 0.6 m/a and the development of a regional abstraction cone. The presented study focuses on distribution and genesis of fresh and saline pore waters and reflects the results in frame of the regional hydrogeological context. Observations of the geological structure and groundwater dynamics combined with hydrochemical and isotopic studies suggest adjacent Triassic hard rock aquifers as the major source for fresh Pleistocene and Neogene groundwater. Salinization status in the economically most relevant Pleistocene aquifer has been studied based on archive and new hydrochemical and geophysical data. Own hydrochemical field studies as well as laboratory measurements of the specific resistivity of dry sediment samples allow the translation of induction logging data from existing monitoring wells into vertical pore water salinity profiles. This approach suggests the regional occurrence of saline pore water in shallow Holocene sediments in the working area, as confirmed by pore water studies in Hoan et al. (2010). Interpretation of induction logging and stable isotope data suggest vertical diffusion of saline pore water in shallow Holocene sediments as a source for high saline pore water in deeper aquifers. Analytical diffusion modeling for a period of 3000 years confirms that vertical diffusion of Holocene paleo-sea water can explain saline pore water in Pleistocene and Neogene aquifers in a stagnant environment. The constant influx of fresh groundwater from adjacent Triassic hard rocks results in flushing of the primary Pleistocene and Neogene pore water and inhibits the infiltration of saline water from marine

  2. Crustal structure of southwestern Saudi Arabia

    USGS Publications Warehouse

    Gettings, M.E.; Blank, H.R.; Mooney, W.D.; Healy, J.H.

    1983-01-01

    The southwestern Arabian Shield is composed of uplifted Proterozoic metamorphic and plutonic rocks. The Shield is bordered on the southwest by Cenozoic sedimentary and igneous rocks of the Red Sea paar and on the east by the Arabian Platform, an area of basin sedimentation throughout Phanerozoic time. The Shield appears to have been formed by successive episodes of island arc volcanism and sea-floor spreading, followed by several cycles of compressive tectonism and metamorphism. An interpretation and synthesis of a deep-refraction seismic profile from the Riyadh area to the Farasan Islands, and regional gravity, aeromagnetic, heat flow, and surface geologic data have yielded a self-consistent regional-scale model of the crust and upper mantle for this area. The model consists of two 20 km-thick layers of crust with an average compressional wave velocity in the upper crust of about 6.3 km/s and an average velocity in the lower. crust of about 7.0 km/s. This crust thins abruptly to less than 20 km near the southwestern end of the profile where Precambrian outcrops abut the Cenozoic rocks and to 8 km beneath the Farasan Islands. The data over the coastal plain and Red Sea shelf areas are fit satisfactorily by an oceanic crustal model. A major lateral velocity inhomogeneity in the crust is inferred about 25 km northeast of Sabhah and is supported by surface geologic evidence. The major velocity discontinuities occur at about the same depth across the entire Shield and are interpreted to indicate horizontal metamorphic stratification of the Precambrian crust. Several lateral inhomogenities in both the upper and lower .crust of the . Shield are interpreted, to indicate bulk compositional variations. The subcrustal portion of the model is composed of a hot, low-density lithosphere beneath the Red Sea which is systematically cooler and denser to the northeast. This model provides a mechanism which explains the observed topographic uplift, regional gravity pattern, heat

  3. Neogene Gas Total Petroleum System -- Neogene Nonassociated Gas Assessment Unit of the San Joaquin Basin Province: Chapter 22 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

    USGS Publications Warehouse

    Hosford Scheirer, Allegra; Magoon, Leslie B.

    2009-01-01

    The Neogene Nonassociated Gas Assessment Unit (AU) of the Neogene Total Petroleum System consists of nonassociated gas accumulations in Pliocene marine and brackish-water sandstone located in the south and central San Joaquin Basin Province (Rudkin, 1968). Traps consist mainly of stratigraphic lenses in low-relief, elongate domes that trend northwest-southeast. Reservoir rocks typically occur as sands that pinch out at shallow depths (1,000 to 7,500 feet) within the Etchegoin and San Joaquin Formations. Map boundaries of the assessment unit are shown in figures 22.1 and 22.2; this assessment unit replaces the Pliocene Nonassociated Gas play 1001 (shown by purple line in fig. 22.1) considered by the U.S. Geological Survey (USGS) in its 1995 National Assessment (Beyer, 1996). The AU is drawn to include all existing fields containing nonassociated gas accumulations in the Pliocene to Pleistocene section, as was done in the 1995 assessment, but it was greatly expanded to include adjacent areas believed to contain similar source and reservoir rock relationships. Stratigraphically, the AU extends from the topographic surface to the base of the Etchegoin Formation (figs. 22.3 and 22.4). The boundaries of the AU explicitly exclude gas accumulations in Neogene rocks on the severely deformed west side of the basin and gas accumulations in underlying Miocene rocks; these resources, which primarily consist of a mixture of mostly thermogenic and some biogenic gas, are included in two other assessment units. Lillis and others (this volume, chapter 10) discuss the geochemical characteristics of biogenic gas in the San Joaquin Basin Province. Primary fields in the assessment unit are defined as those containing hydrocarbon resources greater than the USGS minimum threshold for assessment—3 billion cubic feet (BCF) of gas; secondary fields contain smaller volumes of gas but constitute a significant show of hydrocarbons. Although 12 fields meet the 3 BCF criterion for inclusion in

  4. Southwestern Pine Forests Likely to Disappear

    SciTech Connect

    McDowell, Nathan

    2015-12-21

    A new study, led by Los Alamos National Laboratory's Nathan McDowell, suggests that widespread loss of a major forest type, the pine-juniper woodlands of the Southwestern U.S., could be wiped out by the end of this century due to climate change, and that conifers throughout much of the Northern Hemisphere may be on a similar trajectory. New results, reported in the journal Nature Climate Change, suggest that global models may underestimate predictions of forest death. McDowell and his large international team strove to provide the missing pieces of understanding tree death at three levels: plant, regional and global. The team rigorously developed and evaluated multiple process-based and empirical models against experimental results, and then compared these models to results from global vegetation models to examine independent simulations. They discovered that the global models simulated mortality throughout the Northern Hemisphere that was of similar magnitude, but much broader spatial scale, as the evaluated ecosystem models predicted for in the Southwest.

  5. Southwestern Pine Forests Likely to Disappear

    ScienceCinema

    McDowell, Nathan

    2016-07-12

    A new study, led by Los Alamos National Laboratory's Nathan McDowell, suggests that widespread loss of a major forest type, the pine-juniper woodlands of the Southwestern U.S., could be wiped out by the end of this century due to climate change, and that conifers throughout much of the Northern Hemisphere may be on a similar trajectory. New results, reported in the journal Nature Climate Change, suggest that global models may underestimate predictions of forest death. McDowell and his large international team strove to provide the missing pieces of understanding tree death at three levels: plant, regional and global. The team rigorously developed and evaluated multiple process-based and empirical models against experimental results, and then compared these models to results from global vegetation models to examine independent simulations. They discovered that the global models simulated mortality throughout the Northern Hemisphere that was of similar magnitude, but much broader spatial scale, as the evaluated ecosystem models predicted for in the Southwest.

  6. Early Cambrian hydrocarbon potential in Southwestern Ohio

    SciTech Connect

    Sfara, R.M.; Benjamin, H.R.; Wolfe, P.J.

    1995-09-01

    A sedimentary basin, inferred to be of Early Cambrian age, has been recently identified in southwestern Ohio. A well drilled into this basin in 1926 penetrated 404 m of sedimentary rocks below the Middle Cambrian Mount Simon Sandstone. This is the only well in Ohio to have penetrated limestone below the Mt. Simon Sandstone. Since 1992 Wright State University has gathered about 35 km of seismic data in this area. The seismic data suggest that these strata dip south into a large basin. The seismic character of the limestone interval at the well extends to a thickness of at least 1000 m. In addition, material underlying the limestone has reflection characteristics similar to the Late Proterozoic Middle Run Sandstone that exists about 40 km to the southwest. The surface on which Mount Simon Sandstone was deposited appears to be a mature karst surface and there was a natural gas show at this horizon. An oil show existed in an 8 m thick arkose within the limestone. All of the limestone encountered in the well was rich in organic material. Since there were gas and oil shows in the old well and the material appears younger than the Middle Run Sandstone, we feel this basin has hydrocarbon production potential.

  7. Paleocene sequence stratigraphy of southwestern Alabama

    SciTech Connect

    Mancini, E.A.; Tew, B.H.

    1988-09-01

    In southwestern Alabama, the Paleocene consists of about 1300 ft (396 m) of marginal marine and marine terrigenous and carbonate sediments. Based on regional stratigraphic, sedimentologic, and paleontologic data, up to seven unconformity-bounded depositional sequences resulting from relative changes in coastal onlap during the Paleocene are recognized in these strata. These sequences are, in ascending order, the TP1.1a, comprised of the Pine Barren Member of the Clayton Formation; the TP1.1b, comprised of the Turritella rock beds of the Pine Barren and the McBryde Limestone Member of the Clayton Formation, and the clays and marls of the lower member of the Porters Creek Formation; the TP1.2, comprised of the cross-bedded sands of the lower member and the Matthews Landing Marl Member of the Porters Creek Formation, and Oak Hill Member of the Naheola Formation; the TP1.3, comprised of the Coal Bluff Marl Member of the Naheola Formation; the TP2.1, comprised of the Gravel Creek Sand, Ostrea thirsae beds, and Grampian Hills Members of the Nanafalia Formation, and the lower beds of the Tuscahoma Sand; the TP2.2, comprised of the Greggs Landing Marl Member and the middle beds of the Tuscahoma Sand; and the TP2.3, comprised of the Bells Landing Marl Member and the upper beds of the Tuscahoma Sand.

  8. Southwestern USA Drought over Multiple Millennia

    NASA Astrophysics Data System (ADS)

    Salzer, M. W.; Kipfmueller, K. F.

    2014-12-01

    Severe to extreme drought conditions currently exist across much of the American West. There is increasing concern that climate change may be worsening droughts in the West and particularly the Southwest. Thus, it is important to understand the role of natural variability and to place current conditions in a long-term context. We present a tree-ring derived reconstruction of regional-scale precipitation for the Southwestern USA over several millennia. A network of 48 tree-ring chronologies from California, Nevada, Utah, Arizona, New Mexico, and Colorado was used. All of the chronologies are at least 1,000 years long. The network was subjected to data reduction through PCA and a "nested" multiple linear regression reconstruction approach. The regression model was able to capture 72% of the variance in September-August precipitation over the last 1,000 years and 53% of the variance over the first millennium of the Common Era. Variance captured and spatial coverage further declined back in time as the shorter chronologies dropped out of the model, eventually reaching 24% of variance captured at 3250 BC. Results show regional droughts on decadal- to multi-decadal scales have been prominent and persistent phenomena in the region over the last several millennia. Anthropogenic warming is likely to exacerbate the effects of future droughts on human and other biotic populations.

  9. Neogene exhumation in the eastern Alaska Range and its relationship to splay fault activity in the Denali fault system

    NASA Astrophysics Data System (ADS)

    Waldien, T.; Roeske, S.; Benowitz, J.; Allen, W. K.; Ridgway, K.

    2015-12-01

    Dextral oblique convergence in the Denali fault system results from subduction zone strain in the Alaska syntaxis that is partitioned into the upper plate. This convergence is accommodated by dextral-reverse oblique slip on segments of the main strand of the Denali fault in the center of the Alaska Range and by splay faults north and south of the Denali fault at the margins of the Alaska Range. Low-temp. thermochronometry applied to basement rocks bounded by faults within the Denali fault system aids stratigraphic data to determine the timing and locations of exhumation in the Alaska Range, which augment regional seismicity studies aimed at resolving modern fault activity in the Denali fault system. The McCallum Creek and Broxson Gulch faults are north-dipping faults that splay southward from the Denali fault near the Delta River and mark the southern margin of the eastern Alaska Range. Apatite fission track thermochronometry on rocks north of the McCallum Creek fault shows rapid cooling in the hanging wall coeval with basin development in the footwall initiating at the Miocene-Pliocene boundary. Apatite fission track and apatite (U-Th)/He ages from plutonic rocks in the hanging wall of the Broxson Gulch fault, west of the McCallum Creek fault, show final cooling in the Miocene, slightly younger than hanging wall cooling associated with the Susitna Glacier thrust further to the west. Neogene low-temp. cooling ages in the hanging walls of the Susitna Glacier thrust, Broxson Gulch, and McCallum Creek faults suggest that these structures have been accommodating convergence in the Denali fault system throughout the Neogene. More recent cooling in the hanging wall of the McCallum Creek compared to the Susitna Glacier thrust suggests that this fault-related exhumation has migrated eastward throughout the Neogene. Convergence on these splay faults south of the Denali fault results in internal contraction of the crust south of the Denali fault, implying that the Southern

  10. Making Earth's earliest continental crust - an analogue from voluminous Neogene silicic volcanism in NE-Iceland

    NASA Astrophysics Data System (ADS)

    Berg, Sylvia E.; Troll, Valentin R.; Burchardt, Steffi; Riishuus, Morten S.; Deegan, Frances M.; Harris, Chris; Whitehouse, Martin J.; Gústafsson, Ludvik E.

    2014-05-01

    Borgarfjörður Eystri in NE-Iceland represents the second-most voluminous exposure of silicic eruptive rocks in Iceland and is a superb example of bimodal volcanism (Bunsen-Daly gap), which represents a long-standing controversy that touches on the problem of crustal growth in early Earth. The silicic rocks in NE-Iceland approach 25 % of the exposed rock mass in the region (Gústafsson et al., 1989), thus they significantly exceed the usual ≤ 12 % in Iceland as a whole (e.g. Walker, 1966; Jonasson, 2007). The origin, significance, and duration of the voluminous (> 300 km3) and dominantly explosive silicic activity in Borgarfjörður Eystri is not yet constrained (c.f. Gústafsson, 1992), leaving us unclear as to what causes silicic volcanism in otherwise basaltic provinces. Here we report SIMS zircon U-Pb ages and δ18O values from the region, which record the commencement of silicic igneous activity with rhyolite lavas at 13.5 to 12.8 Ma, closely followed by large caldera-forming ignimbrite eruptions from the Breiðavik and Dyrfjöll central volcanoes (12.4 Ma). Silicic activity ended abruptly with dacite lava at 12.1 Ma, defining a ≤ 1 Myr long window of silicic volcanism. Magma δ18O values estimated from zircon range from 3.1 to 5.5 (± 0.3; n = 170) and indicate up to 45 % assimilation of a low-δ18O component (e.g. typically δ18O = 0 ‰, Bindeman et al., 2012). A Neogene rift relocation (Martin et al., 2011) or the birth of an off-rift zone to the east of the mature rift associated with a thermal/chemical pulse in the Iceland plume (Óskarsson & Riishuus, 2013), likely brought mantle-derived magma into contact with fertile hydrothermally-altered basaltic crust. The resulting interaction triggered large-scale crustal melting and generated mixed-origin silicic melts. Such rapid formation of silicic magmas from sustained basaltic volcanism may serve as an analogue for generating continental crust in a subduction-free early Earth (e.g. ≥ 3 Ga, Kamber et

  11. Response of the European Vegetation to the Global Climatic Changes during the Neogene

    NASA Astrophysics Data System (ADS)

    Popescu, S.; Jimenez-Moreno, G.; Suc, J.; Rabineau, M.

    2009-12-01

    The beginning of the Neogene coincides with a transient cooler climate event (Mi-1) as response to the intermittent expansion on the EAIS. The Miocene is characterized by warm and humid climate that implied the development of forest environments in Europe. The vegetation was composed mainly by tropical, subtropical and warm-temperate plants, which attempted the maximum of diversity during the Miocene Climate Optimum event (17-15 Ma). Reconstruction of climatic parameters, applied to our pollen records, indicates for the NE Spain, for the Early Miocene a MAT~19°C, a MTW~24.5°C, a MTC~7.5 °C, and MAP = 900 - 1700 mm. Several cooling events (Mi-1 to Mi-7) are responsible for a progressive impoverishment in tropical and subtropical plants, which will be replaced by warm-temperate ones. The most important, Monterey Cooling Event induce the decrease of MAT about 2-4°C implying the disappearance of the Avicennia mangrove from the NW Mediterranean coastline. Warm climate characterized the Serravallian and Tortonian. Paleoclimatic reconstruction for the Late Miocene indicates a MAT=15-24°C, with a strong seasonality correlated with high precipitation values (1100 -1550 mm) in N.Europe and respectively low seasonality and precipitation values (320-680 mm) in SW Europe and N Africa. The West Antarctic glaciations at 6 Ma, probably caused the disappearance of the Avicennia mangrove from S. Mediterranean coastlines. During the Early Pliocene, the climate was relatively warmer with MAT higher of about 1-5°C than today.Increase in humidity characterize the Central and Eastern Europe (MAP higher of about 400 -1000 mm than today), that promoted the development of forest vegetation in this area. The pollen floras from the European Early Pliocene allow a refined geographic specification of the different kinds of reconstructed vegetation. The Late Pliocene is still too much poorly-documented and needs more attention as it represents the key-moment of the progressive transition

  12. Bilharziasis survey in south-western Asia*

    PubMed Central

    Abdel Azim, M.; Gismann, Anne

    1956-01-01

    This paper describes a limited survey of bilharziasis and its vectors carried out during 1950 and 1951 in some countries of south-western Asia. Lack of time and of full facilities prevented the survey from being as comprehensive and systematic as would have been wished, but enough data were obtained to provide a general estimate of the situation. Information already available from the literature was supplemented by collecting unpublished records, questioning the inhabitants, examining random samples of stools and urine, and investigating rivers, wells, and springs. Bilharziasis haematobia is already heavily endemic in the irrigated areas of Iraq and is also present, in comparatively smaller foci, in northern Syria, Israel, and Sa'udi Arabia. In the opinion of the senior author (M. A. A.), the envisaged extension of irrigation is likely to create a serious health problem in Mesopotamia and to introduce the disease into the Jordan region unless the spread of the molluscan vector, Bulinus sp., is checked. Intensification of infection and further spread are possible in Israel and in the Syrian Jezire, while the remainder of Syria and Lebanon are not considered to be endangered. Bilharziasis mansoni is widespread in the fertile areas of Sa'udi Arabia and also occurs in one minor focus in Israel. The industrialization of Sa'udi Arabia which is planned to exploit its oil resources, with its inevitable concentration of population, equally presents a danger in the intensification of bilharziasis. It is considered that, unless prompt measures are undertaken to break the link between the agricultural and industrial expansion and the spread of the disease, the debilitation of large groups of the population and the economic loss which may well result over most of the inhabited parts of the area discussed will be significant. ImagesFIG. 1 PMID:13342925

  13. The occurrence and fission-track ages of late neogene and quaternary volcanic sediments, Siwalik group, Northern Pakistan

    USGS Publications Warehouse

    Johnson, G.D.; Zeitler, P.; Naeser, C.W.; Johnson, N.M.; Summers, D.M.; Frost, C.D.; Opdyke, N.D.; Tahirkheli, R.A.K.

    1982-01-01

    Volcanic sediments, now mostly bentonites and bentonitic mudstones, occur throughout the Late Neogene and Quaternary Siwalik Group of northern Pakistan. A number of these deposits have been dated by the fission-track method, utilizing zircon phenocrysts from these deposits, and provide the chronometric constraints upon which a paleomagnetic stratigraphy is developed for the Siwalik Group. Notable in the occurrence of these altered tuff horizons is an apparent mode in their stratigraphic development from approximately 3.0 to 1.5 m.y. B.P. which coincides with the period of activity of the Dacht-e-Nawar volcanic complex of east-central Afghanistan. Fission-track ages of certain tuffs for critical areas of northern Pakistan are reported herein. ?? 1982.

  14. K-Ar ages confirm Pliocene age for oldest Neogene marine strata near Loreto, Baja California Sur, Mexico

    SciTech Connect

    McLean, H.

    1987-05-01

    Beds of pumiceous tuff interbedded with mollusk-rich sedimentary rocks provide new age constraints on the timing of the late Neogene subsidence and marine transgression a few kilometers north of Loreto, Baja California Sur, Mexico. The lower part of the Neogene section consists of approximately 1500 m of early to middle Miocene nonmarine volcanic-derived sandstone, breccia, and porphyritic andesite and dacite lavas, called the Comondu Formation or Comondu Group by previous workers. The Miocene rocks are unconformably overlain by nearly 1000 m of predominantly marine sandstone, siltstone, conglomerate, coquina, and tuff of Pliocene age. This 1000-m section grades upward from unfossiliferous fanglomerate, sandstone, and pelitic red beds that are interpreted to be nonmarine into mollusk-rich marine strata; this sequence indicates that marine transgression occurred within the Pliocene section. Plagioclase and hornblende from three pumiceous tuff beds stratigraphically located near the base, middle, and top of the marine section yield K-Ar ages of 3.2, 1.9, and 1.8 Ma, respectively; these ages are similar to Pliocene ages indicated by reconnaissance studies of ostracods, diatoms, and foraminifers. The diatoms indicate open-ocean waters and the foraminifers indicate outer shelf depth. Ostracods, oysters, pectens, and other fossil bivalves seem to indicate a shallow-water embayment. Lateral distribution of nonmarine and marine facies suggests a paleoenvironment in which alluvial fans fed coarse debris into a series of coastal fan deltas. The Pliocene basin may have been a largely landlocked embayment similar to the modern Bahia Concepcion, located 70 km north of Loreto. Marine and volcanic rocks are assumed to be associated with the opening of the Gulf of California. If this assumption is correct, the beds near Loreto suggest that the opening occurred during the Pliocene.

  15. Role of Neogene Exhumation and Sedimentation on Critical-Wedge Kinematics in the Zagros Orogenic Belt, Northeastern Iraq, Kurdistan

    NASA Astrophysics Data System (ADS)

    Koshnaw, R. I.; Horton, B. K.; Stockli, D. F.; Barber, D. E.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The Zagros orogenic belt and foreland basin formed during the Cenozoic Arabia-Eurasia collision, but the precise histories of shortening and sediment accumulation remain ambiguous, especially at the NW extent of the fold-thrust belt in Iraqi Kurdistan. This region is characterized by well-preserved successions of Cenozoic clastic foreland-basin fill and deformed Paleozoic-Mesozoic hinterland bedrock. The study area provides an excellent opportunity to investigate the linkage between orogenic wedge behavior and surface processes of erosion and deposition. The aim of this research is to test whether the Zagros orogenic wedge advanced steadily under critical to supercritical wedge conditions involving in-sequence thrusting with minimal erosion or propagated intermittently under subcritical condition involving out-of-sequence deformation with intense erosion. These endmember modes of mountain building can be assessed by integrating geo/thermochronologic and basin analyses techniques, including apatite (U-Th)/He thermochronology, detrital zircon U-Pb geochronology, stratigraphic synthesis, and seismic interpretations. Preliminary apatite (U-Th)/He data indicate activation of the Main Zagros Fault (MZF) at ~10 Ma with frontal thrusts initiating at ~8 Ma. However, thermochronometric results from the intervening Mountain Front Flexure (MFF), located between the MZF and the frontal thrusts, suggest rapid exhumation at ~6 Ma. These results suggest that the MFF, represented by the thrust-cored Qaradagh anticline, represents a major episode of out-of-sequence deformation. Detrital zircon U-Pb analyses from the Neogene foreland-basin deposits show continuous sediment derivation from sources to the NNE in Iraq and western Iran, suggesting that out-of-sequence thrusting did not significantly alter sedimentary provenance. Rather, intense hinterland erosion and recycling of older foreland-basin fill dominated sediment delivery to the basin. The irregular distribution of

  16. 78 FR 46332 - Golden Spread Electric Cooperative, Inc. v. Southwestern Public Service Company; Notice of Complaint

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-31

    ... Energy Regulatory Commission Golden Spread Electric Cooperative, Inc. v. Southwestern Public Service.... (Golden Spread or Complainant) filed a formal complaint against Southwestern Public Service Company (SPS... Energy Open Access Tariff applicable to pricing of transmission service over the facilities of...

  17. Seven Global Goals. 2013 annual report, Southwestern Power Administration

    SciTech Connect

    none,

    2014-09-01

    For over 70 years, Southwestern has marketed and delivered reliable, renewable, and affordable hydropower, partnering with Federal power stakeholders and others in the industry to make sure the lights stay on. This kind of effective, efficient, and cost conscious operation is made possible only by hard work and dedication. Southwestern employees work individually and as a team to meet seven comprehensive agency goals that touch on all aspects of the agency’s operations. Dubbed the “Seven Global Goals” by Administrator Chris Turner, these objectives identify specific, measurable targets that support Southwestern’s mission and reinforce its responsibilities toward its customers and the Nation.

  18. 40 CFR 81.125 - Southwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Southwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.125 Southwestern Oklahoma Intrastate Air Quality Control Region. The Southwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  19. 40 CFR 81.125 - Southwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Southwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.125 Southwestern Oklahoma Intrastate Air Quality Control Region. The Southwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  20. 40 CFR 81.125 - Southwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false Southwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.125 Southwestern Oklahoma Intrastate Air Quality Control Region. The Southwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  1. 40 CFR 81.125 - Southwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Southwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.125 Southwestern Oklahoma Intrastate Air Quality Control Region. The Southwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  2. 40 CFR 81.125 - Southwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Southwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.125 Southwestern Oklahoma Intrastate Air Quality Control Region. The Southwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  3. 75 FR 70616 - Prevailing Rate Systems; Redefinition of the Madison, WI, and Southwestern Wisconsin Appropriated...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ... areas. The proposed rule would redefine Adams and Waushara Counties, WI, from the Southwestern Wisconsin... would redefine Adams and Waushara Counties, WI, from the Southwestern Wisconsin wage area to the Madison... industrial establishments. Adams County is currently defined to the Southwestern Wisconsin area...

  4. 40 CFR 81.241 - Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Southwestern Mountains-Augustine... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.241 Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region. The Southwestern Mountains-Augustine Plains Intrastate...

  5. 40 CFR 81.241 - Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Southwestern Mountains-Augustine... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.241 Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region. The Southwestern Mountains-Augustine Plains Intrastate...

  6. 40 CFR 81.241 - Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Southwestern Mountains-Augustine... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.241 Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region. The Southwestern Mountains-Augustine Plains Intrastate...

  7. 40 CFR 81.241 - Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false Southwestern Mountains-Augustine... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.241 Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region. The Southwestern Mountains-Augustine Plains Intrastate...

  8. 40 CFR 81.241 - Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Southwestern Mountains-Augustine... PLANNING PURPOSES Designation of Air Quality Control Regions § 81.241 Southwestern Mountains-Augustine Plains Intrastate Air Quality Control Region. The Southwestern Mountains-Augustine Plains Intrastate...

  9. The energy behind the power. Southwestern Power Administration 1994 annual report

    SciTech Connect

    1994-12-31

    This is the Southwestern Power Administration 1994 annual report. The topics of the report include a letter to the secretary; an overview including the mission statement, a description of the Southwestern Federal Power System, financial statement, performance measurements, national performance review; year in review, summary of results, financial and statistical data and the Southwestern Power Administration Organization.

  10. Hydrogeology of the Markagunt Plateau, Southwestern Utah

    USGS Publications Warehouse

    Spangler, Lawrence E.

    2010-01-01

    The Markagunt Plateau, in southwestern Utah, lies at an altitude of about 9,500 feet and is capped primarily by Quaternary-age basalt that overlies Eocene-age freshwater limestone of the Claron Formation. Over large parts of the Markagunt Plateau, dissolution of the Claron limestone and subsequent collapse of the overlying basalt have produced a terrain characterized by sinkholes as much as 1,000 feet across and 100 feet deep. Numerous large springs discharge from the basalt and underlying limestone on the plateau, including Mammoth Spring, one of the largest springs in Utah, with a discharge that can exceed 300 cubic feet per second. Discharge from Mammoth Spring is from the Claron Formation; however, recharge to the spring largely takes place by both focused and diffuse infiltration through the basalt that caps the limestone. Results of dye tracing to Mammoth Spring indicate that recharge originates largely southwest of the spring outside of the Mammoth Creek watershed, as well as from losing reaches along Mammoth Creek. Maximum groundwater travel time to the spring from dye-tracer tests during the snowmelt runoff period was about 1 week. Specific conductance and water temperature data from the spring show an inverse relation to discharge during snowmelt runoff and rainfall events, also indicating short groundwater residence times. Results of major-ion analyses for samples collected from Mammoth and other springs on the plateau indicate calcium-bicarbonate type water containing low (less than 200 mg/L) dissolved-solids concentrations. Investigations in the Navajo Lake area along the southern margin of the plateau have shown that water losing to sinkholes bifurcates and discharges to both Cascade and Duck Creek Springs, which subsequently flow into the Virgin and Sevier River basins, respectively. Groundwater travel times to these springs, on the basis of dye tracing, were about 8.5 and 53 hours, respectively. Similarly, groundwater travel time from Duck Creek

  11. Listenership of Radio Agricultural Broadcasts in Southwestern Nigeria

    ERIC Educational Resources Information Center

    Emmanuel, Adekoya Adegbenga; Olabode, Badiru Idris

    2012-01-01

    Agricultural broadcasts on radio play a major role in agricultural extension and rural development in Nigeria due to the low ratio of extension agents in relation to the farming population. The broadcasts have been on air for some time and therefore there is a need to investigate their acceptance among the rural dwellers in Southwestern Nigeria.…

  12. Wildlife Reservoir for Hepatitis E Virus, Southwestern France

    PubMed Central

    Lhomme, Sebastien; Top, Sokunthea; Bertagnoli, Stephane; Dubois, Martine; Guerin, Jean-Luc

    2015-01-01

    Pigs are a reservoir for hepatitis E virus (HEV). To determine the relative contribution of game to the risk for human HEV infection in southwestern France, we tested wildlife samples. HEV RNA was in 3.3% of wildlife livers, indicating that in this region, eating game meat is as risky as eating pork. PMID:26079541

  13. Guanophilic fungi in three caves of southwestern Puerto Rico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fifty species of guanophilic (bat guano-loving) fungi were isolated from field-collected samples within three caves in south-western Puerto Rico; most were mitosporic fungi (23 species). The caves studied were Cueva La Tuna (Cabo Rojo), Cueva de Malano (Sistema de Los Chorros, San Germán), and Cuev...

  14. SOUTHWESTERN CORNER OF SECTION 1, WITH (L TO R) BIVOUAC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SOUTHWESTERN CORNER OF SECTION 1, WITH (L TO R) BIVOUAC OF THE DEAD TABLET, INVERTED CANNON AND UNION WOMAN’S RELIEF CORPS #44 MONUMENT IN FOREGROUND. VIEW TO NORTHEAST. - Crown Hill Cemetery, Crown Hill National Cemetery, 700 West Thirty-eighth Street, Indianapolis, Marion County, IN

  15. Native American Student Resiliency within Southwestern Tribal Colleges

    ERIC Educational Resources Information Center

    Peralez, Elizabeth

    2014-01-01

    The purpose of this study was to explore the degree to which Native American culture impacts the resiliency of Native American students earning degrees at three tribal colleges in the southwestern part of the United States. This study was a qualitative case study that was based on the following research question: "How does Native American…

  16. Paleozoic vertical movements in Um Bogma area, southwestern Sinai

    SciTech Connect

    Beyth, M.

    1981-01-01

    The Wadi Khaboba-Gebel Nukhul high, in the Um Bogma area of southwestern Sinai, underwent a small-scale uplift-subsidence cycle during the Paleozoic. The trend of this structure is close to and almost parallel with the Suez rift, indicating that the young rift is related to older structures.

  17. Sphaeroma terebrans: A Threat to the Mangroves of Southwestern Florida.

    PubMed

    Rehm, A; Humm, H J

    1973-10-12

    Sphaeroma terebrans, a wood-boring isopod, is destroying the prop roots of red mangroves along the southwestern coast of Florida to such an extent that the Ten Thousand Islands and mangrove fringes of the mainland are steadily shrinking. Mangroves of the Florida Keys apparently are free of this wood borer.

  18. 2014 annual site environmental report, Southwestern Power Administration

    SciTech Connect

    none,

    2014-12-31

    Southwestern Power Administration’s Annual Site Environmental Report (ASER) serves as the chief reporting mechanism for site environmental performance information within the Department of Energy and as a valuable resource for shared and collaborative environmental protection and performance information to Agency stakeholders and members of the public living near Southwestern Power Administration’s (Southwestern) facilities and transmission line rights-of-ways. This ASER meets the requirements of Department of Energy (DOE) Order 231.B. Southwestern’s key environmental involvement includes an emphasis on the protection of ecological resources which is effectively accomplished through environmental program elements such as protecting water resources, generation of clean hydropower energy, oil spill prevention practices, elimination of green-house gas emissions, and comprehensive project reviews to ensure the protection of living organisms, migratory birds, Federally threatened or endangered species, and historic or cultural resources. Southwestern continues to actively minimize effects to natural resources and strive for continual improvement in the area of environmental compliance and sustainability while achieving the agency mission to market and deliver Federal hydroelectric power.

  19. Southwestern Power Administration Annual Report 2004-2006

    SciTech Connect

    2006-01-01

    Confidence Commitment Cooperation These are words that spring to mind regarding Southwestern Power Administration’s performance during fiscal years (FY) 2004-2006 By offering innovative, customer-oriented service, working to improve system reliability and efficiency, and partnering with customers and other Federal power stakeholders, Southwestern has certainly exhibited all three of these qualities during these challenging yet productive years In fact, our cooperative working relationships were critical to our success during the severe and widespread drought conditions which prevailed throughout Southwestern’s marketing area for much of 2005-2006 When we proposed a temporary energy deferral program, our customers came on board by voluntarily taking less Federal hydropower than they were entitled to, enabling us to preserve system storage and fulfill our contract obligations during the crucial summer months of 2006 The U S Army Corps of Engineers (Corps) also helped improve our drought situation by allowing Southwestern more operational flexibility on a regional level Despite the challenges this critical drought period presented, Southwestern remained committed to fulfilling our mission and strategic goals From FY 2004 through FY 2006, we marketed and delivered all available Federal hydropower while meeting and even exceeding the reliability standards of the North American Electric Reliability Corporation (NERC) Our Power Operations Training Center in Springfield, Missouri, was cited as an “Example of Excellence” during a NERC readiness audit in October 2006; and as we have every year since NERC began measuring, Southwestern far exceeded the accepted NERC compliance ratings for power system operations reliability Our commitment to excellence and accountability has kept our repayment goals on target as well Revenues were sufficient to repay all annual expenses and the required principal investment in the Federal hydropower facilities Furthermore, the original

  20. New stratigraphic, chronologic, and magnetic fabric constraints for Neogene and Quaternary ignimbrites in the Central Andes (South Peru)

    NASA Astrophysics Data System (ADS)

    De La Rupelle, A.; Thouret, J. C.; Cubukcu, H. E.; Jicha, B.; Bréard, E.; Gerbe, M.-C.; Le Pennec, J.-L.; Diot, H.; Boivin, P.

    2012-04-01

    Central Andean deformation history in southern Peru is recorded in Neogene volcanic units of Ocoña and Cotahuasi canyons that cut across the western Cordillera. Acceleration (<25 Ma) of uplift in the region is reflected in the Neogene epiclastic deposits with interspersed and subsequent rhyolitic ignimbrites between 24.6 and 1.37 Ma. Large-volume (>100 km3) Nazca (c.24.6 Ma), Alpabamba (19.4-18.0 Ma), and Huaylillas (14.25-12.7 Ma) ignimbrite sheets preceded the canyon incision, whereas sheets of smaller volume (<50 km3), Caraveli (9.5-8.9 Ma), Lower (5.13-3.6 Ma) and Upper Sencca (c.2 Ma) and Las Lomas (c.1.56-1.37 Ma), were deposited during canyon incision and are interspersed with Lower and Upper Barroso lava flows. The Alpabamba compound ignimbrite sheets comprise a vitrophyre at the base, grading into a strongly welded, eutaxitic, crystal-rich facies overlain by a thick, multi-bedded ash-flow tuff and a lithic-rich, indurated flow unit. The Huaylillas ignimbrite sheet comprises a strongly welded, crystal-rich, lithic-poor, columnar lithofacies, with devitrified pumice. The Caraveli ignimbrite sheet has a jointed vitrophyre overlain by a welded, blocky, crystal-rich flow unit. A vacuolar, saccharolytic unit forms the top of the sequence. The Lower Sencca ignimbrite sheet comprises of a basal vitrophyre and a slightly welded, fibrous pumice-rich flow unit, which grades into a welded, vapor-phase unit that contains more crystals than pumice and lithics. The Upper Sencca ignimbrite sheet consists of a black vitrophyre, grading into a strongly welded, crystal-rich, eutaxitic cooling unit. The latter is capped by a slightly welded unit, and an indurated pumice-rich, crystal-poor vapour-phase facies. Quaternary valley-fill termed Las Lomas consists of unwelded, crystal-poor pumice-flow deposits. Eighteen new 40Ar/39Ar analyses have been carried out on feldspar/glass separates from pumice and lavas. Results for the Caraveli ignimbrite (9.35±0.06 Ma), Upper Barroso

  1. Neogene tectonics and modern geodynamics and seismicity of Pannonia north-eastern remote area (Ukrainian Transcarpathian yield)

    NASA Astrophysics Data System (ADS)

    Lozynak, Petro; Nazarevych, Andriy; Nazarevych, Lesya

    2010-05-01

    Pannonia north-eastern remote area (Ukrainian Transcarpathian yield) joins to East (Ukrainian) Carpathians and their geodynamic mode is interdependent from the alpine stage until now. Due to the detailed study in the last few years of structures of surface of basement and sedimentary layers of the Transcarpathian yield of postalpine ages (neogene - from early Miocene to Sarmatian and farther) (see Lozynak at al., 2002-2007) we have the possibility to trace the Neogene's tectonics of the region and its connection with modern geodynamics and seismicity of Ukrainian Transcarpathians and adjoining territories of Slovakia, Hungary and Romania. These data indicate that active orogenic processes (dominance of compression caused by a plate-tectonic processes) in this region to beginning of early miocene made off and began the process of formation of the Transcarpathian yield in his modern view (due to an output on the first plan of the plum-tectonic processes caused by Pannonian asthenolite?) (see Nazarevych A. and Nazarevych L., 2000-2007). The process of formation (origin) of yield (and the proper accumulation of sedimentary layers) began in his east part (in the area of border with Romania (Siget - Solotvyno)) at the beginning of early Miocene (about 23 million years ago), continue in north-western direction (in the rear of modern Carpathians) to the border with Slovakia at first as a narrow (10-15 km) bar (roughly during 2-4 million years) and then broadened (during next 2-3 million years) in north-eastern - south-west direction on all modern territory of the Transcarpathian yield. In future (in Sarmatian epoch, approximately from 12-14 to 10-11 million years ago) east part of yield (so-called Solotvyno depression) transgress to the mode of compression and raising with ending of intensive sedimentation, and in western part (so-called Tchop-Mukatcheve depression) the process of sagging was farther displaced westward and at present he is concentrated (by geodesic and

  2. IODP Expedition 354 to the Bengal Fan: a Neogene record of Himalayan erosion. Implications on the carbon cycle

    NASA Astrophysics Data System (ADS)

    France-Lanord, Christian; Spiess, Volkard; Galy, Albert; Galy, Valier; Huyghe, Pascale; Klaus, Adam; IODP Expedition 354 Scientists

    2016-04-01

    Bengal Fan Expedition 354 drilled an E-W transect in the middle fan at 8°N to investigate interactions between the growth of the Himalaya, the development of the Indian monsoon, and processes affecting the carbon cycle. A comprehensive record of turbiditic deposition between the Late Oligocene and Holocene was drilled over a seven sites E-W transect at 8°N. Shipboard results reveal that the chemical and mineralogical compositions of turbiditic sediments cored across the transect are relatively stable throughout the Neogene. By comparison to modern river sediment compositions (Lupker et al. ref), they reveal a weak intensity of chemical weathering without marked variation through time. Clay assemblages are dominated by illite and chlorite with minor proportions of newly formed clays. This differs from the distal fan record (Leg 116) where the Late Miocene and Pliocene turbidites show high weathering signatures and smectite rich clay assemblage. This difference im plies that the distal fan record does not reflect to an evolution of the source erosion. Rather it is controlled by a change in sediment transport within the fan. Shipboard estimates of organic carbon loading and behaviour resemble observations made in the modern Ganga-Brahmaputra river sediments, suggesting efficient terrestrial organic carbon burial in the Bengal Fan [1]. Preliminary observations support the idea that Himalayan erosion has consumed atmospheric CO2 through the burial of organic carbon, more than by silicate weathering. The main evolution observed in Expedition 354 record is the content of detrital carbonate that is persistent through the Neogene but appears to show a consistent decreasing trend from 8-10% during the Miocene to 3-6% during the Pleistocene and Pliocene. Also, a prominent feature of Miocene silt and sand beds is the higher abundance of plant fragments compared to younger sediments. Together these observations reveal changes in the sediment sources and erosion conditions of

  3. Variations in terrigenous matter transport evaluated by plant terpenoid analysis in the Neogene eastern equatorial Pacific sediment

    NASA Astrophysics Data System (ADS)

    Nakamura, H.; Sawada, K.; Yamamoto, S.; Kobayashi, M.

    2012-12-01

    We analyze land plant biomarkers in sediments recovered during the IODP Expeditions 320/321, the Pacific Equatorial Age Transect (PEAT), to reconstruct variations in terrestrial input in the eastern equatorial Pacific Ocean, as well as to evaluate transport systems of terrigenous matter from land to ocean. We used the Neogene sediments (23-0.23 Ma) recovered from site U1337. We could identify cadalene (sesquiterpenoid), as well as series of aromatic abietane type diterpenoids (e.g. retene) from most samples. These terpenoids are derived from biomolecules that constitute plant resin and supportive tissues. Plant-derived compounds in deep-sea sediments are considered that initially transported via fluvial process, followed by redistribution by gravity flow to the deeper part. Although, the typical pelagic setting of site U1337, even far from land across the mid-ocean-ridge, exclude such pathway. Therefore, the variations in mass accumulation rate (MAR) of plant terpenoids in this site depend eolian transportation and can be used as an indicator of change in atmospheric circulation. The increasing spikes in MAR of plant terpenoids were observed in the horizons of 16 Ma, 14 Ma, 12 Ma, 10 Ma, 9 - 8 Ma, 7 Ma and 2.5 - 1Ma. It is found that some of the spikes, 14 Ma, 7 Ma, 2.5 - 1 Ma correspond to the East Antarctica Ice Sheet event (EAIS), the Biogenic bloom event, and the Northern Hemisphere Glaciation (NHG), respectively. Furthermore, the degree of aromatization in diterpenoids, which represented by retene to the sum of abietane type diterpenoids, tends to increase concurrently with the MAR of total plant terpenoids. The aromatization of plant terpenoids take place under thermal maturation after deposition as well as in earlier processes such as biomass burning. In the U1337 sediments, the degree of aromatization of diterpenoids was uncorrelated with the age or depositional depth, suggesting its variations retain potential for paleoclimatic application. For example

  4. Cosmogenic nuclide concentrations in Neogene rivers of the Great Plains reveal the evolution of fluvial storage and recycling

    NASA Astrophysics Data System (ADS)

    Sinclair, Hugh; Stuart, Fin; McCann, Louise; Tao, Zui

    2016-04-01

    The measurement of the duration of near surface residence of sediment grains from the stratigraphic record has the potential to quantitatively reconstruct processes such as stratal condensation, sediment recycling and the exposure histories of unconformities. Geomorphological measurements of dates and rates of surfaces and erosion respectively has enabled significant advances in understanding, however, the radiogenic half life of typical cosmogenic nuclides such as 10Be and 26Al means they are not suitable for the stratigraphic record. Instead, we have applied the stable cosmogenic nuclide of 21Ne to quartz-rich sediment to quantify the routing history of the river systems that have drained the southern Rockies of Wyoming and Colorado during Neogene times. The Neogene sediments of Nebraska record fluvial systems of the Great Plains that flow from the Rockies towards the east and into the Mississippi catchment. This succession is <300 m thick, and records successive episodes of fluvial incision and aggradation associated with regional tilting from 6 to 4 Ma and periods of climate change. As part of an evaluation of the application of 21Ne to the stratigraphic record, we sampled quartzite pebbles from an Upper Miocene, Pliocene and modern river channel of the North Platte approximately 400 km from their mountainous source. The quartzite is derived from a single exposure of the Medicine Bow quartzites in Wyoming, therefore all three intervals recorded the same travel distance from source. Additionally, we know the erosion rate of the Medicine Bow quartzites from detrital 10Be analyses, and we also sampled shielded bedrock samples from the quartzite to evaluate for any non-cosmogenic 21Ne. This means that the concentrations of 21Ne in detrital pebbles >400 km from their source could be corrected for both inherited non-cosmogenic and erosion induced accumulation at source. Therefore, any additional amounts of 21Ne must record storage and exposure during transport down

  5. Late Neogene sedimentation at ODP Site 1171 (Leg 189), South Tasman Rise: history of paleoproductivity and ice rafting.

    NASA Astrophysics Data System (ADS)

    Diester-Haass, L.

    2002-12-01

    The late Neogene (11.3-1 Ma) sediments at Site 1171 reflect changing paleoproductivity, radiolarian opal preservation as well as coarse glauconite and clastic material input as shown by an analysis of the coarse fraction and stable isotopes. A hiatus spans the 8.7-5.23 Ma interval. Accumulation rates fluctuate between 0.5 and 4.5 cm/ky. The following results have been obtained: 1. A coarsening of the sand (increase in >250 μm sized fraction and related reduction in fine sand) since 5.23 Ma is not due to winnowing after the time of non-deposition, but to improved carbonate preservation. 2. Up to 1000 μm sized glauconite, quartz grains and rock debris present in nearly all samples are attributed to delivery from melting icebergs (IRD). Major periods of IRD delivery are at 10.5-10.7, 9.2-10.2 and 3.2 Ma. 3. Two measures of paleoproductivity, which were thought to be interdependent so far, proved to be independent. Whereas the paleoproductivity data in gC/cm2*ky derived from benthic foraminiferal numbers as well as Uvigerina numbers, fish debris concentration and carbonate dissolution show a coherent picture with higher productivity prior to 9 Ma ( paleo-export- productivity values of 25-75 gC/cm2*ky) than after the hiatus ( values of 8-45 gC/cm2*ky), the data derived from radiolarian and sponge skeletons show minima during times of highest paleoproductivity as derived from benthic foraminifers. Abundance of radiolarian skeletons is interpreted in terms of preservation conditions related mainly to production, location of the site relative to the polar front and water temperature. The observed anticorrelation of radiolaria and IRD leads to the assumption that radiolaria are better preserved during cool periods, whereas during warmer intervals radiolarian opal is more or less completely dissolved and IRD supply is enhanced perhaps because of more rapidly moving glaciers or preferential melting over Site 1171 or less sea-ice that impedes iceberg dispersal or increased

  6. Moderation of Neogene Deep-Water Overflow at the Greenland-Scotland Ridge by the Icelandic Plume

    NASA Astrophysics Data System (ADS)

    Henstock, T.; White, N. J.; Jones, S. M.; Murton, B. J.; Maclennan, J.

    2010-12-01

    A global analysis of Neogene δ13C records shows that overflow of Northern Component Water (NCW), the ancient precursor of North Atlantic Deep Water, varies with time. It is generally accepted that the Icelandic plume, which has dominated the tectonic evolution of the North Atlantic Realm since its inception ˜60 million years ago, has played a key role in moderating deep-water overflow. The V-shaped ridges, which straddle the mid-oceanic ridge system on either side of Iceland, are an important window into transient convective circulation associated with this plume. Knowledge of the evolving pattern of convective circulation can be used to constrain vertical displacement of the Greenland-Scotland Ridge through time. Although some progress has been made in refining the variation of NCW with time, any link between overflow and convective circulation has relied upon vintage seismic reflection profiles acquired in the 1960s. In order to construct a more accurate chronology of plume activity through time, we have acquired a set of regional seismic reflection profiles along flowlines which traverse the Iceland and Irminger basins between 60° and 62° N. We used a single generator-injector airgun operating at 3,000 p.s.i. and a 2 km streamer with a group spacing of 12.5 m with an average fold of 20. The porcessed seismic images are excellent. The sediment-basement interface can be accurately mapped and fine details of the sedimentary cover are resolved. We have identified a series of V-shaped ridges and erected a chronology of plume activity on an astronomical timescale. This chronology correlates with the Neogene history of deep-water overflow and confirms that convective circulation of the mantle has played a significant role in moderating deep-water overflow. Our seismic profiles also cross the major contourites of the North Atlantic Ocean, notably the Gardar, Bjorn and Eirik Drifts. Excellent images of their detailed internal stratigraphy demonstrate that distinct

  7. Late Neogene kinematics of intra-arc oblique shear zones: The Petilia-Rizzuto Fault Zone (Calabrian Arc, Central Mediterranean)

    NASA Astrophysics Data System (ADS)

    van Dijk, J. P.

    1994-10-01

    The kinematics of intra-arc shear zones play a key role in the secondary shaping of orogenic arcs such as the Calabrian Arc (central Mediterranean). Comparison of the Neogene structural development of the Petilia-Rizzuto Fault Zone and the basement structure of the bordering Sila massif reveals that the fault zone is the surface expression of a deep NW-SE trending sinistral crustal oblique shear zone. This shear zone continues over a length of more than 130 km across the northern segment of the Calabrian Arc and shows a post-Eocene sinistral displacement of about 50 km. The late Neogene forearc basin development and syndepositional tectonics along the fault zone are reconstructed in great detail by analyzing the middle Miocene-Recent tectonic sequence stratigraphy. A strike-slip cycle can be recognized whereby the subsequent activity of Riedel shears, tensional faults, and P shears, positive flower structures and principle displacement wrench faults, can accurately be traced in time. Observed phenomena are discussed in terms of the activity of a conjugate system of oblique thrust zones within the growing accretionary complex. The evolution of special types of thrust belt basins is illustrated. These include oblique thin-skinned pull-apart basins, oblique rhomboidal "harmonica" basins, and "detached slab" basins (new terms introduced here), evolving one into the other. A new feature illustrated is the recurrent basin inversion which generated passive roof duplexes through back-shear motion and out-of-sequence thrusting along the wedge. The fault patterns and the style of inversion tectonics imply an E-W directed axis of effective compressive stress in this part of the arc. This resulted from an interaction of (1) local E-W directed compression related to a differential displacement of two parallel segments of the arc (generated by the migration to the southeast of the Calabrian Arc and opening of the Tyrrhenian backarc basin); (2) alternating NW-SE directed

  8. Mapping Neogene and Quaternary sedimentary deposits in northeastern Brazil by integrating geophysics, remote sensing and geological field data

    NASA Astrophysics Data System (ADS)

    Andrades-Filho, Clódis de Oliveira; Rossetti, Dilce de Fátima; Bezerra, Francisco Hilario Rego; Medeiros, Walter Eugênio; Valeriano, Márcio de Morisson; Cremon, Édipo Henrique; Oliveira, Roberto Gusmão de

    2014-12-01

    Neogene and late Quaternary sedimentary deposits corresponding respectively to the Barreiras Formation and Post-Barreiras Sediments are abundant along the Brazilian coast. Such deposits are valuable for reconstructing sea level fluctuations and recording tectonic reactivation along the passive margin of South America. Despite this relevance, much effort remains to be invested in discriminating these units in their various areas of occurrence. The main objective of this work is to develop and test a new methodology for semi-automated mapping of Neogene and late Quaternary sedimentary deposits in northeastern Brazil integrating geophysical and remote sensing data. The central onshore Paraíba Basin was selected due to the recent availability of a detailed map based on the integration of surface and subsurface geological data. We used airborne gamma-ray spectrometry (i.e., potassium-K and thorium-Th concentration) and morphometric data (i.e., relief-dissection, slope and elevation) extracted from the digital elevation model (DEM) generated by the Shuttle Radar Topography Mission (SRTM). The procedures included: (a) data integration using geographic information systems (GIS); (b) exploratory statistical analyses, including the definition of parameters and thresholds for class discrimination for a set of sample plots; and (c) development and application of a decision-tree classification. Data validation was based on: (i) statistical analysis of geochemical and airborne gamma-ray spectrometry data consisting of K and Th concentrations; and (ii) map validation with the support of a confusion matrix, overall accuracy, as well as quantity disagreement and allocation disagreement for accuracy assessment based on field points. The concentration of K successfully separated the sedimentary units of the basin from Precambrian basement rocks. The relief-dissection morphometric variable allowed the discrimination between the Barreiras Formation and the Post-Barreiras Sediments. In

  9. Groundwater Modeling of Playa-Focused Recharge at the Southwestern Edge of the High Plains Aquifer in West Texas

    NASA Astrophysics Data System (ADS)

    Blainey, J.; Pickens, J. F.; grisak, G. E.; Holt, R. M.; Sigda, J.; Cook, S.; Hughes, E.

    2011-12-01

    Ongoing hydrogeologic investigations at a licensed low-level radioactive waste disposal site in Andrews County, Texas include monitoring of a groundwater system in Ogallala (Neogene), Antlers (Cretaceous), and Gatuna (Neogene/Quaternary) Formation sediments on the southwestern edge of the Southern High Plains physiographic province. The disposal site is underlain by unsaturated sands and gravels of these laterally contiguous sediments, informally termed the OAG. North of the site these sediments develop into the continuously saturated High Plains or Ogallala aquifer. Episodes of focused recharge to the OAG sediments have been observed during the last 9 years of groundwater level monitoring near small playas and topographic depressions that collect water after large precipitation events. During smaller precipitation events water is stored in the unsaturated zone and evapotranspired, predominately by mesquite, creosote and grasses. The climate is semi-arid with average evaporation rates far exceeding the estimated average annual precipitation of 15-16 inches/year. Monitoring at more than 250 wells in the OAG and environmental tracer studies confirm a conceptual model of playa-focused natural recharge to the groundwater system with little or no recharge occurring in inter-playa areas. The thickness of the OAG saturated sediments in the vicinity of the disposal sites ranges from 3 feet to 10 feet, with areas of discontinuous saturation away from areas of focused recharge. Environmental tracer studies show the groundwater in the OAG is poorly mixed and disconnected from regional groundwater flow further to the northeast. The disposal facilities are located over a structural high on the erosional surface of the Dockum Group, which immediately underlies the OAG sediments. This feature, referred to as the red bed ridge, is roughly coincident with the topographic divide between the High Plains and the Pecos Valley physiographic provinces and serves as a divide for

  10. Lucky guess or knowledge: a cross-sectional study using the Bland and Altman analysis to compare confidence-based testing of pharmacological knowledge in 3rd and 5th year medical students.

    PubMed

    Kampmeyer, Daniela; Matthes, Jan; Herzig, Stefan

    2015-05-01

    Multiple-choice-questions are common in medical examinations, but guessing biases assessment results. Confidence-based-testing (CBT) integrates indicated confidence levels. It has been suggested that correctness of and confidence in an answer together indicate knowledge levels thus determining the quality of a resulting decision. We used a CBT approach to investigate whether decision quality improves during undergraduate medical education. 3rd- and 5th-year students attended formative multiple-choice exams on pharmacological issues. Students were asked to indicate their confidence in a given answer. Correctness of answers was scored binary (1-correct; 0-wrong) and confidence levels were transformed to an ordinal scale (guess: 0; rather unsure: 0.33; rather sure: 0.66; very sure: 1). 5th-year students gave more correct answers (73 ± 16 vs. 49 ± 13 %, p < 0.05) and were on average more confident regarding the correctness of their answers (0.61 ± 0.18 vs. 0.46 ± 0.13, p < 0.05). Correlation of these parameters was stronger for 5th-year students (r = 0.81 vs. r = 0.52), but agreement of confidence and correctness ('centration') was lower. By combining the Bland-and-Altman approach with categories of decision-quality we found that 5th-year students were more likely to be 'well-informed' (41 vs. 5 %), while more 3rd-students were 'uninformed' (24 vs. 76 %). Despite a good correlation of exam results and confidence in given answers increased knowledge might be accompanied by a more critical view at the own abilities. Combining the statistical Bland-and-Altman analysis with a theoretical approach to decision-quality, more advanced students are expected to apply correct beliefs, while their younger fellows are rather at risk to hesitate or to act amiss.

  11. Southwestern Power Administration Combined Financial Statements, 2006-2009

    SciTech Connect

    2009-09-01

    We have audited the accompanying combined balance sheets of the Southwestern Federal Power System (SWFPS), as of September 30, 2009, 2008, 2007, and 2006, and the related combined statements of revenues and expenses, changes in capitalization, and cash flows for the years then ended. As described in note 1(a), the combined financial statement presentation includes the hydroelectric generation functions of another Federal agency (hereinafter referred to as the generating agency), for which Southwestern Power Administration (Southwestern) markets and transmits power. These combined financial statements are the responsibility of the management of Southwestern and the generating agency. Our responsibility is to express an opinion on these combined financial statements based on our audits. We conducted our audits in accordance with auditing standards generally accepted in the United States of America. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the combined financial statements are free of material misstatement. An audit includes consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of Southwestern and the generating agency’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the combined financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall combined financial statement presentation. We believe that our audits provide a reasonable basis for our opinion. In our opinion, the combined financial statements referred to above present fairly, in all material respects, the respective financial position of the Southwestern Federal Power

  12. Late Neogene geohistory analysis of the Humboldt Basin and its relationship to convergence of the Juan de Fuca Plate

    NASA Astrophysics Data System (ADS)

    McCrory, Patricia A.

    1989-03-01

    Geohistory analysis of Neogene Humboldt basin strata provides important constraints for hypotheses of the tectonic evolution of the southern Cascadia subduction margin, leading up to the arrival of the Mendocino triple junction. This analysis suggests that the tectonic evolution of the Humboldt basin area was dominated by coupling between the downgoing Juan de Fuca plate and the continental margin. This coupling is reflected in the timing of major hiatuses within the basin sedimentary sequence and margin uplift and subsidence which occur during periods of tectonic plate adjustment. Stratigraphic evidence indicates that Humboldt basin originated at the base of the continental slope in early Miocene time. Syndepositional uplift of basin strata began in the late Pliocene and was both thermal isostatic and tectonic in origin. Isostatic uplift was a function of an increasingly more buoyant slab being subducted, whereas tectonic uplift was due to imbricated thrusting of the accretionary complex and underplating of offscraped sediment during subduction. A component of margin uplift is postulated to have been caused by a change in the rate of convergence between the Juan de Fuca and North American plates. Coeval with late Pliocene uplift documented onshore was a sharp decrease in covergence rate ˜3 Ma. A reduction in rate of tectonic uplift, observed in the Eel River section, in early Pleistocene time was coeval with a marked increase in relative motion parallel to the continental margin. This localized subsidence may have been caused by syndepositional folding.

  13. Terrestrial biome distribution in the Late Neogene inferred from a black carbon record in the northeastern equatorial Pacific.

    PubMed

    Kim, Donghyun; Lee, Yong Il; Hyeong, Kiseong; Yoo, Chan Min

    2016-01-01

    The appearance and expansion of C4 plants in the Late Cenozoic was a dramatic example of terrestrial ecological change. The fire hypothesis, which suggests fire as a major cause of C4 grassland is gaining support, yet a more detailed relationship between fire and vegetation-type change remains unresolved. We report the content and stable carbon isotope record of black carbon (BC) in a sediment core retrieved from the northeastern equatorial Pacific that covers the past 14.3 million years. The content record of BC suggests the development process of a flammable ecosystem. The stable carbon isotope record of BC reveals the existence of the Late Miocene C4 expansion, the 'C4 maximum period of burned biomass' during the Pliocene to Early Pleistocene, and the collapse of the C4 in the Late Pleistocene. Records showing the initial expansion of C4 plants after large fire support the role of fire as a destructive agent of C3-dominated forest, yet the weak relationships between fire and vegetation after initial expansion suggest that environmental advantages for C4 plants were necessary to maintain the development of C4 plants during the late Neogene. Among the various environmental factors, aridity is likely most influential in C4 expansion. PMID:27604853

  14. Superposed local and regional paleostresses: fault-slip analysis of Neogene extensional faulting near coeval caldera complexes, Yucca Flat, Nevada

    USGS Publications Warehouse

    Minor, S.A.

    1995-01-01

    Numerous reduced stress tensors are computed by multiple inversions of 906 temporally and spatially partitioned fault-slip data from the Yucca Flat region in the southwest Nevada volcannic field to constrain the Neogene paleostress and faulting history and to investigate how the regional tectonic stress field was affected by local caldera magmatism. Perturbed, shalalow (<400 m), pre-11 Ma paleostress configurations, determined west and northwest of present (post-11 Ma) Yucca Flat basin, existed during mild extensional faulting and are attributed to superposition of transient caldera-magmatic stresses on the regional stress field. The stress field has rotated as much as 65?? clockwise since 11 Ma during extensional development of Yucca Flat basin, with most of the rotation and extension occurring before about 8.5 Ma. Results suggest that shallow magmatism and caldera development can strongly alter extensional tectonic stress fields, fault patterns, and slip directions in the uppermost crust out to distances of roughly two magma chamber radii away from a magma body. -from Author

  15. Paleomagnetism of the Jianshui basin in Yunnan, SW China, and geomorphological evolution of the Yunnan Plateau since the Neogene

    NASA Astrophysics Data System (ADS)

    Xiong, Jianguo; Li, Youli; Zhong, Yuezhi; Si, Supei; Yao, Yifan

    2016-06-01

    There are still a lot of uncertainty on the process of the Tibetan Plateau uplift and the response of the Yunnan Plateau in the Cenozoic. In order to have a further understanding on the Yunnan Plateau uplift process, we combine the studies on the sedimentary history of the Jianshui basin and other basins and faults in the Yunnan Plateau. We established magnetostratigraphy for the Wanyao (WY) and Qingyunshuiku (QS) fluviolacustrine sections in the northern and middle parts of the Jianshui basin, which indicates eight reverse magnetozones (R1-R8) and seven normal magnetozones (N1-N7), correlating to Chrons C1r.3r through C3n.2r. The strata are constrained to a span from ∼4.77 to ∼1.73 Ma, representing an early Pliocene to early Pleistocene age. The accumulation rate of the WY section has accelerated trend, stopping deposit earlier than the QS section. The stratigraphic characteristics of the two sections and their nearby regions indicate the Shiping-Jianshui (SJ) and Xiaojiang faults have already existed and affected the accumulation of the basin at least since the early Pliocene. According to the history of faults activities and the sedimentary strata of basins, we established the geomorphological evolution process of the Yunnan Plateau since the Neogene.

  16. Terrestrial biome distribution in the Late Neogene inferred from a black carbon record in the northeastern equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Kim, Donghyun; Lee, Yong Il; Hyeong, Kiseong; Yoo, Chan Min

    2016-09-01

    The appearance and expansion of C4 plants in the Late Cenozoic was a dramatic example of terrestrial ecological change. The fire hypothesis, which suggests fire as a major cause of C4 grassland is gaining support, yet a more detailed relationship between fire and vegetation-type change remains unresolved. We report the content and stable carbon isotope record of black carbon (BC) in a sediment core retrieved from the northeastern equatorial Pacific that covers the past 14.3 million years. The content record of BC suggests the development process of a flammable ecosystem. The stable carbon isotope record of BC reveals the existence of the Late Miocene C4 expansion, the ‘C4 maximum period of burned biomass’ during the Pliocene to Early Pleistocene, and the collapse of the C4 in the Late Pleistocene. Records showing the initial expansion of C4 plants after large fire support the role of fire as a destructive agent of C3-dominated forest, yet the weak relationships between fire and vegetation after initial expansion suggest that environmental advantages for C4 plants were necessary to maintain the development of C4 plants during the late Neogene. Among the various environmental factors, aridity is likely most influential in C4 expansion.

  17. Geochemistry of Neogene sedimentary rocks from Borneo Basin, Malaysia: implications on paleo-weathering, provenance and tectonic setting

    NASA Astrophysics Data System (ADS)

    Ramasmay, N.; Roy, P.; MP, J.; Rufino, L.; Franz, L. K.; Viswanathan, P. M.

    2013-05-01

    Multi-element geochemistry and mineralogy are used to characterize the chemical composition, degree of paleo-weathering, provenance and tectonic settingsof the Neogene sedimentary rocks of Borneo Basin from east Malaysia. The sedimentary rocks are classified as extremely weathered sandstones (i.e. wacke, arkose, litharenite, Fe-sandstone and quartz arenite). Higher values of both weathering indices of alteration (i.e. CIA>83 and PIA>89) suggest that the sandstones have undergone extreme chemical weathering. Absence of any feldspar in the mineralogical analysis indicates its degradation during the weathering. Except for the quartz arenite, all other sandstones are characterized by post-depositional K-metasomatism and zircon enrichment through sediment recycling. The geochemical characteristics suggest a mixed-nature provenance for the sandstones with contribution coming from both felsic and mafic igneous rocks. Enriched Cr in quartz arenite and Fe-sandstone are related to contribution from ophiolite or fractionation of Cr-bearing minerals. The inferred tectonic settings are variable and suggest a complex nature of tectonic environment in the basin.

  18. Neogene magnetostratigraphy and rock magnetic study of the Kashi Depression, NW China: Implications to neotectonics in the SW Tianshan Mountains

    NASA Astrophysics Data System (ADS)

    Qiao, Qingqing; Huang, Baochun; Piper, John D. A.; Deng, Tao; Liu, Chengying

    2016-03-01

    The southwest Tianshan Mountains of China are bordered by the Tarim foreland and comprise an actively deforming segment of the India-Asia collisional system. We report a detailed magnetostratigraphic study of the Dashankou section in the Kashi Depression of the Tarim Basin to improve the understanding of the history of sedimentation, denudation, and mountain building in this region. The preferred correlation of the succession with the geomagnetic polarity timescale defines a depositional history between 12.4 and 3.0 Ma with a substantial increase in sedimentation rates identified at ~6.7 Ma corresponding to a pulse of rapid uplift in the southwest Tianshan Mountains. Although climatic changes may have modulated the record during Neogene times, they do not appear to have had an important influence on sediment accumulation rates between 7.0 and 2.6 Ma. Magnetic fabrics identify the influence of a regional stress field imparted by ongoing India-Asia collision in the lower part of the succession contrasting with predominantly sedimentary fabrics in the higher part of the succession. A major clastic influx with a maximum age estimate of ~3.6 Ma comprises the Xiyu conglomerates, and integration with other magnetostratigraphic investigations around the Tianshan demonstrates unambiguously that depositional onset of this coarse clastic episode is diachronous. Hence, the Xiyu Formation cannot be considered as a chronostratigraphic marker related to any specific tectonic or climatic event.

  19. Terrestrial biome distribution in the Late Neogene inferred from a black carbon record in the northeastern equatorial Pacific

    PubMed Central

    Kim, Donghyun; Lee, Yong Il; Hyeong, Kiseong; Yoo, Chan Min

    2016-01-01

    The appearance and expansion of C4 plants in the Late Cenozoic was a dramatic example of terrestrial ecological change. The fire hypothesis, which suggests fire as a major cause of C4 grassland is gaining support, yet a more detailed relationship between fire and vegetation-type change remains unresolved. We report the content and stable carbon isotope record of black carbon (BC) in a sediment core retrieved from the northeastern equatorial Pacific that covers the past 14.3 million years. The content record of BC suggests the development process of a flammable ecosystem. The stable carbon isotope record of BC reveals the existence of the Late Miocene C4 expansion, the ‘C4 maximum period of burned biomass’ during the Pliocene to Early Pleistocene, and the collapse of the C4 in the Late Pleistocene. Records showing the initial expansion of C4 plants after large fire support the role of fire as a destructive agent of C3-dominated forest, yet the weak relationships between fire and vegetation after initial expansion suggest that environmental advantages for C4 plants were necessary to maintain the development of C4 plants during the late Neogene. Among the various environmental factors, aridity is likely most influential in C4 expansion. PMID:27604853

  20. Synchroneity of major Late Neogene sea level fluctuations and paleoceanographically controlled changes as recorded by two carbonate platforms

    NASA Astrophysics Data System (ADS)

    Betzler, Christian; Kroon, Dick; Reijmer, John J. G.

    2000-12-01

    Shallow-water carbonate systems are reliable recorders of sea level fluctuations and changes in ambient seawater conditions. Drilling results from Ocean Drilling Program (ODP) Legs 133 and 166 indicate that the timing of late Neogene sedimentary breaks triggered by sea level lowerings is synchronous in the sedimentary successions of the Queensland Plateau and the Great Bahama Bank. This synchrony indicates that these sea level changes were eustatic in origin. The carbonate platforms were also affected by contemporary, paleoceanographically controlled fluctuations in carbonate production. Paleoceanographic changes are recorded at 10.7, 3.6, and 1.7-2.0 Ma. At the Queensland Plateau, sea surface temperature shifts are documented by shifts from tropical to temperate carbonates (10.7 Ma) and vice versa (3.6 Ma); the modern tropical platform was established at 2.0-1.8 Ma. At Great Bahama Bank, changes were registered in compositional variations of platform-derived sediment, such as major occurrence of peloids (3.6 Ma) and higher rates of neritic carbonate input (1.7 Ma). The synchroneity of these changes attests to the far-field effects of modifications in the oceanographic circulation on shallow-water, low-latitude carbonate production.

  1. Late Miocene breccia of Menorca (Balearic Islands) a basis for the interpretation of a Neogene ramp deposit

    NASA Astrophysics Data System (ADS)

    Obrador, A.; Pomar, L.; Taberner, C.

    1992-08-01

    Neogene (Tortonian) ramp facies associations crop out in the southern sector of Menorca (Balearic island). These are made mainly by sigmoidal and oblique clinoform units comprising rhodoliths, bryozoans, molluscs and foraminifera. These units are interpreted as outer-ramp deposits. A breccia deposit infilling an erosional surface is found at the top of the carbonate ramp sequence. The breccia components (mainly rhodoliths and oolite clasts) may represent erosion of the underlying ramp deposits and inner-ramp counterparts, which do not crop out on the island. The study of components in the breccia deposits confirms the indigenous character of the outer-ramp facies associations, which suggests that the ramp was steepened distally. The breccia deposits correspond laterally to a discontinuity surface locally showing karstic features. Transgressive sediments (including a phosphatic crust) are found above the discontinuity surface. All together these features, and the dolomitisation of the uppermost ramp sediments and breccia deposits, suggest that the breccia originated from erosion of the ramp after a major relative sea-level fall. The breccia and discontinuity surface separate the ramp sequence from an overlying prograding sequence. A correlation of this sequence boundary to other areas in the western Mediterranean is proposed.

  2. Digital geologic map of Lawton quadrangle, southwestern Oklahoma

    USGS Publications Warehouse

    Cederstrand, Joel R.

    1996-01-01

    This data set consists of digital data and accompanying documentation for the surficial geology of the 1:250,000-scale Lawton quadrangle, Oklahoma. The original data are from the Geologic Map, sheet 1 of 4, included in the Oklahoma Geological Survey publication, 'Reconnaissance of the water resources of the Lawton quadrangle, southwestern Oklahoma', Hydrologic Atlas 6, Havens, 1977. The geology was compiled by R.O. Fay, in 1967-68 and J.S. Havens, in 1973.

  3. Uranium-Bearing Carbonaceous Nodules of Southwestern Oklahoma

    USGS Publications Warehouse

    Hill, James Wilcott

    1956-01-01

    Uranium-bearing carbonaceous nodules have been found along the north flank of the Wichita uplift in southwestern Oklahoma. The carbonaceous nodules are black, hard, and predominantly nodular shaped. One specimen, by analyses, was found to contain approximately 42 percent carbon and 3 percent hydrogen. The uranium, vanadium, cobalt, arsenic, nickel, lead and iron contents each range between 1 and 10 percent. It is concluded that the carbonaceous nodules are epigenetic and that the organic and inorganic constituents were derived from, mobile soluttons.

  4. Toxic Trichodesmium bloom occurrence in the southwestern South Atlantic Ocean.

    PubMed

    Sacilotto Detoni, Amália Maria; Costa, Luiza Dy Fonseca; Pacheco, Lucas Abrão; Yunes, João Sarkis

    2016-02-01

    Harmful Trichodesmium blooms have been reported on the continental slope of the southwestern South Atlantic Ocean; we sampled six such blooms. The highest saxitoxin concentration was observed where the number of colonies was proportionally greater relative to the total density of trichomes. Trichodesmium blooms are harmful to shrimp larvae and may lead to plankton community mortality. This study is the first record of neurotoxic blooms in the open waters of the South Atlantic.

  5. A new species of Danothrips from Southwestern China (Thysanoptera: Thripidae).

    PubMed

    Li, Yajin; Xie, Yonghui; Zhang, Hongrui

    2016-01-01

    Danothrips salicis sp. n. is described from young leaves of Salix sp. in Southwestern China. This species is similar to D. moundi, D. theifolii and D. trifasciatus, but can be distinguished by the colour of the fore wing, the median longitudinal split on tergite X of females, and in males by the situation of the median short thorn-like setae on tergite IX. PMID:27615912

  6. Small wind power in the southwestern United States

    NASA Astrophysics Data System (ADS)

    Tennyson, G. P.

    1983-01-01

    The Southwestern Great Plains agricultural production in both vegetable crops and cattle, and the extraction industries in oil and natural gas recovery both feed and power a significant percentage of our nation. Energy costs that are rising faster than the rate of return on the sale of these products are contributing to a serious situation with many farms being abandoned and oil wells being capped. Wind energy, which is abundant in the region, is investigated as a near term applicable alternative energy sources.

  7. Lichens from Simeonof Wilderness, Shumagin Island, Southwestern Alaska

    USGS Publications Warehouse

    Talbot, Stephen S.; Talbot, Sandra L.; Thomson, J.W.; Daniels, F.J.A.; Schofield, W.B.

    2002-01-01

    One hundred eighty-eight taxa of lichens are reported from Simeonof Island in the Shumagin Islands of southwestern Alaska. Wide-ranging arctic-alpine and boreal species dominate the lichens; a coastal element is moderately represented, while amphi-Beringian species form a minor element. The lichen component of Empetrum nigrum dwarf shrub heath, the dominant vegetation type, was analyzed to identify the most frequently occurring lichens within this community.

  8. Extended megadroughts in the southwestern United States during Pleistocene interglacials

    USGS Publications Warehouse

    Fawcett, P.J.; Werne, J.P.; Anderson, R. Scott; Heikoop, J.M.; Brown, E.T.; Berke, M.A.; Smith, S.J.; Goff, F.; Donohoo-Hurley, L.; Cisneros-Dozal, L. M.; Schouten, S.; Damste, J.S.S.; Huang, Y.; Toney, J.; Fessenden, J.; Woldegabriel, G.; Atudorei, V.; Geissman, J.W.; Allen, C.D.

    2011-01-01

    The potential for increased drought frequency and severity linked to anthropogenic climate change in the semi-arid regions of the southwestern United States (US) is a serious concern. Multi-year droughts during the instrumental period and decadal-length droughts of the past two millennia were shorter and climatically different from the future permanent, dust-bowl-like-megadrought conditions, lasting decades to a century, that are predicted as a consequence of warming. So far, it has been unclear whether or not such megadroughts occurred in the southwestern US, and, if so, with what regularity and intensity. Here we show that periods of aridity lasting centuries to millennia occurred in the southwestern US during mid-Pleistocene interglacials. Using molecular palaeotemperature proxies to reconstruct the mean annual temperature (MAT) in mid-Pleistocene lacustrine sediment from the Valles Caldera, New Mexico, we found that the driest conditions occurred during the warmest phases of interglacials, when the MAT was comparable to or higher than the modern MAT. A collapse of drought-tolerant C 4 plant communities during these warm, dry intervals indicates a significant reduction in summer precipitation, possibly in response to a poleward migration of the subtropical dry zone. Three MAT cycles-1/42-C in amplitude occurred within Marine Isotope Stage (MIS) 11 and seem to correspond to the muted precessional cycles within this interglacial. In comparison with MIS 11, MIS 13 experienced higher precessional-cycle amplitudes, larger variations in MAT (4-6??C) and a longer period of extended warmth, suggesting that local insolation variations were important to interglacial climatic variability in the southwestern US. Comparison of the early MIS 11 climate record with the Holocene record shows many similarities and implies that, in the absence of anthropogenic forcing, the region should be entering a cooler and wetter phase. ?? 2011 Macmillan Publishers Limited. All rights

  9. Extended megadroughts in the southwestern United States during Pleistocene interglacials.

    PubMed

    Fawcett, Peter J; Werne, Josef P; Anderson, R Scott; Heikoop, Jeffrey M; Brown, Erik T; Berke, Melissa A; Smith, Susan J; Goff, Fraser; Donohoo-Hurley, Linda; Cisneros-Dozal, Luz M; Schouten, Stefan; Sinninghe Damsté, Jaap S; Huang, Yongsong; Toney, Jaime; Fessenden, Julianna; WoldeGabriel, Giday; Atudorei, Viorel; Geissman, John W; Allen, Craig D

    2011-02-24

    The potential for increased drought frequency and severity linked to anthropogenic climate change in the semi-arid regions of the southwestern United States (US) is a serious concern. Multi-year droughts during the instrumental period and decadal-length droughts of the past two millennia were shorter and climatically different from the future permanent, 'dust-bowl-like' megadrought conditions, lasting decades to a century, that are predicted as a consequence of warming. So far, it has been unclear whether or not such megadroughts occurred in the southwestern US, and, if so, with what regularity and intensity. Here we show that periods of aridity lasting centuries to millennia occurred in the southwestern US during mid-Pleistocene interglacials. Using molecular palaeotemperature proxies to reconstruct the mean annual temperature (MAT) in mid-Pleistocene lacustrine sediment from the Valles Caldera, New Mexico, we found that the driest conditions occurred during the warmest phases of interglacials, when the MAT was comparable to or higher than the modern MAT. A collapse of drought-tolerant C(4) plant communities during these warm, dry intervals indicates a significant reduction in summer precipitation, possibly in response to a poleward migration of the subtropical dry zone. Three MAT cycles ∼2 °C in amplitude occurred within Marine Isotope Stage (MIS) 11 and seem to correspond to the muted precessional cycles within this interglacial. In comparison with MIS 11, MIS 13 experienced higher precessional-cycle amplitudes, larger variations in MAT (4-6 °C) and a longer period of extended warmth, suggesting that local insolation variations were important to interglacial climatic variability in the southwestern US. Comparison of the early MIS 11 climate record with the Holocene record shows many similarities and implies that, in the absence of anthropogenic forcing, the region should be entering a cooler and wetter phase.

  10. Extended megadroughts in the southwestern United States during Pleistocene interglacials.

    PubMed

    Fawcett, Peter J; Werne, Josef P; Anderson, R Scott; Heikoop, Jeffrey M; Brown, Erik T; Berke, Melissa A; Smith, Susan J; Goff, Fraser; Donohoo-Hurley, Linda; Cisneros-Dozal, Luz M; Schouten, Stefan; Sinninghe Damsté, Jaap S; Huang, Yongsong; Toney, Jaime; Fessenden, Julianna; WoldeGabriel, Giday; Atudorei, Viorel; Geissman, John W; Allen, Craig D

    2011-02-24

    The potential for increased drought frequency and severity linked to anthropogenic climate change in the semi-arid regions of the southwestern United States (US) is a serious concern. Multi-year droughts during the instrumental period and decadal-length droughts of the past two millennia were shorter and climatically different from the future permanent, 'dust-bowl-like' megadrought conditions, lasting decades to a century, that are predicted as a consequence of warming. So far, it has been unclear whether or not such megadroughts occurred in the southwestern US, and, if so, with what regularity and intensity. Here we show that periods of aridity lasting centuries to millennia occurred in the southwestern US during mid-Pleistocene interglacials. Using molecular palaeotemperature proxies to reconstruct the mean annual temperature (MAT) in mid-Pleistocene lacustrine sediment from the Valles Caldera, New Mexico, we found that the driest conditions occurred during the warmest phases of interglacials, when the MAT was comparable to or higher than the modern MAT. A collapse of drought-tolerant C(4) plant communities during these warm, dry intervals indicates a significant reduction in summer precipitation, possibly in response to a poleward migration of the subtropical dry zone. Three MAT cycles ∼2 °C in amplitude occurred within Marine Isotope Stage (MIS) 11 and seem to correspond to the muted precessional cycles within this interglacial. In comparison with MIS 11, MIS 13 experienced higher precessional-cycle amplitudes, larger variations in MAT (4-6 °C) and a longer period of extended warmth, suggesting that local insolation variations were important to interglacial climatic variability in the southwestern US. Comparison of the early MIS 11 climate record with the Holocene record shows many similarities and implies that, in the absence of anthropogenic forcing, the region should be entering a cooler and wetter phase. PMID:21350483

  11. Geology, geochronology and tectonic setting of late Cenozoic volcanism along the southwestern Gulf of Mexico: The Eastern Alkaline Province revisited

    NASA Astrophysics Data System (ADS)

    Ferrari, Luca; Tagami, Takahiro; Eguchi, Mugihiko; Orozco-Esquivel, Ma. Teresa; Petrone, Chiara M.; Jacobo-Albarrán, Jorge; López-Martínez, Margarita

    2005-09-01

    A NNW-trending belt of alkaline mafic volcanic fields parallels the Gulf of Mexico from the U.S. border southward to Veracruz state, in eastern Mexico. Previous studies grouped this volcanism into the so-called "Eastern Alkaline Province" (EAP) and suggested that it resulted from Gulf-parallel extensional faulting migrating from north to south from Oligocene to Present. On the basis of new geologic studies, forty-nine unspiked K-Ar and two 40Ar- 39Ar ages, we propose a new geodynamic model for the volcanism along the southwestern Gulf of Mexico. We studied in detail four of the six recognized fields of mafic alkaline volcanism in Veracruz state: 1) The lavas flows of Tlanchinol area (7.3-5.7 Ma), 2) the Alamo monogenetic field and Sierra de Tantima (7.6-6.6 Ma), 3) the Poza Rica and Metlatoyuca lava flows (1.6-1.3 Ma) and 4) the Chiconquiaco-Palma Sola area (6.9-3.2 Ma). Other two mafic volcanic fields may represent the continuation of alkaline volcanism to the southeast: the Middle Miocene lavas at Anegada High, offshore port of Veracruz, and the Middle to Late Miocene volcanism at the Los Tuxtlas. The existence of major Neogene extensional faults parallel to the Gulf of Mexico (i.e., ˜N-S to NNW-SSE) proposed in previous works was not confirmed by our geological studies. Elongation of volcanic necks, vent alignment, and faults mapped by subsurface data trend dominantly NE to ENE and NW to NNW. These directions are parallel to transform and normal faults that formed during the Late Jurassic opening of the Gulf of Mexico. Ascent of mafic magmas was likely facilitated and controlled by the existence of these pre-existing basement structures. Coupled with previous studies, our data demonstrate the occurrence of three magmatic episodes in Veracruz: 1) A Middle Miocene (˜15-11 Ma) episode in southern Veracruz (Palma Sola, Anegada, and Los Tuxtlas); 2) A Late Miocene to Early Pliocene (˜7.5-3 Ma) pulse of mafic alkaline volcanism throughout the study region; and 3) A

  12. Digital Atlas of the Upper Washita River Basin, Southwestern Oklahoma

    USGS Publications Warehouse

    Becker, Carol J.; Masoner, Jason R.; Scott, Jonathon C.

    2008-01-01

    Numerous types of environmental data have been collected in the upper Washita River basin in southwestern Oklahoma. However, to date these data have not been compiled into a format that can be comprehensively queried for the purpose of evaluating the effects of various conservation practices implemented to reduce agricultural runoff and erosion in parts of the upper Washita River basin. This U.S. Geological Survey publication, 'Digital atlas of the upper Washita River basin, southwestern Oklahoma' was created to assist with environmental analysis. This atlas contains 30 spatial data sets that can be used in environmental assessment and decision making for the upper Washita River basin. This digital atlas includes U.S. Geological Survey sampling sites and associated water-quality, biological, water-level, and streamflow data collected from 1903 to 2005. The data were retrieved from the U.S. Geological Survey National Water Information System database on September 29, 2005. Data sets are from the Geology, Geography, and Water disciplines of the U.S. Geological Survey and cover parts of Beckham, Caddo, Canadian, Comanche, Custer, Dewey, Grady, Kiowa, and Washita Counties in southwestern Oklahoma. A bibliography of past reports from the U.S. Geological Survey and other State and Federal agencies from 1949 to 2004 is included in the atlas. Additionally, reports by Becker (2001), Martin (2002), Fairchild and others (2004), and Miller and Stanley (2005) are provided in electronic format.

  13. Genetic variation in the endangered Southwestern Willow Flycatcher

    USGS Publications Warehouse

    Busch, Joseph; Miller, Mark P.; Paxton, E.H.; Sogge, M.K.; Keim, Paul

    2000-01-01

    The Southwestern Willow Flycatcher(Empidonax trailii extimus) is an endangered Neotropical migrant that breeds in isolated remnants of dense riparian habitat in the southwestern United States. We estimated genetic variation at 20 breedings sites of the Southwestern Willow Flycatcher(290 individuals) using 38 amplified fragment length polymorphisms(AFLPs). Our results suggest that considerable genetic diversity exists within the subspecies and within local breeding sites. Statistical analyses of genetic variation revealed only slight, although significant, differentiation among breeding sites( Mantel's r = 0.0705, P < 0.0005; 0 = 0.0816, 95% CI = 0.0608 to 0.1034; a??sr = 0.0458, P < 0.001). UPGMA cluster analysis of the AFLP markers indicates that extensive gene flow has occurred among breeding sites. No one site stood out as being genetically unique or isolated. Therefore the small level of genetic structure that we detected may not be biologically significant. Ongoing field studies are consistent with this conclusion. Of the banded birds that were resighted or recaptured in Arizona during the 1996 to 1998 breeding seasons, one-third moved between breeding sites and two-thirds were philopatric. Low differentiation maybe the result of historically high rangewide diversity followed by recent geographic isolation of breeding sites, although observational data indicate that gene flow is a current phenomenon. Our data suggest that breeding groups of E. t. extimus act as a metapopulation.

  14. Bloc tectonic rotations recorded in the Neogene and Quaternary magmatic rocks from Northwestern Algeria: preliminary paleomagnetic results.

    NASA Astrophysics Data System (ADS)

    El Messaoud Derder, Mohamed; Robion, Philippe; Maouche, Said; Bayou, Boualem; Amenna, Mohamed; Henry, Bernard; Missenard, Yves; Ouabadi, Aziouz; Bestandji, Rafik; Ayache, Mohamed

    2016-04-01

    The seismic activity of the Western Mediterranean area is partly concentrated in northern Africa, particularly in northern Algeria, as it was shown by the strong earthquakes of Zemmouri 21 May 2003 Mw=6.9 and the El Asnam 10 October 1980 Ms= 7.3. This seismicity is due to the convergence between Africa and Eurasia plates since the Oligocene. This convergence involves a tectonic transpression with N-S to NNW-SSE shortening direction, which is expressed by active deformation along the plate boundary. Along the Tellian Atlas (Northern Algeria), active structures define NE-SW trending folds and NE-SW sinistral transpressive faults affecting the intermountain and coastal Neogene to Quaternary sedimentary basins (e.g. Cheliff and Mitidja Plioquaternary intramontaneous basins, …). The NE-SW reverse active faults are coupled with NW-SE to E-W trending strike-slip deep faults. The active deformation in northern Algeria can be explained by a kinematics model of blocks rotation: the transpressive tectonics with NNW-SSE direction of convergence defines NE-SW oriented blocks, which have been subjected to clockwise rotation. In north Algeria, paleomagnetic studies were carried out in the central area, on Neogene sedimentary and magmatic formations (Derder et al, 2009, 2011; 2013). They pointed out tectonic rotation of large blocks, in agreement with the kinematic model. Narrow zones represent important shear zone with strong rotation of smaller blocks (Derder et al., 2013). A new paleomagnetic study was conducted on the recent magmatic rocks outcropping in the Northwestern Algeria, in order to validate this model on a regional scale. The study is still in progress and the preliminary results show presence of systematic clockwise blocks rotation. These results confirm that the Africa-Europe convergence is partly accommodated in northern Africa by blocks rotations. They highlight that rotations are not homogeneous in north Algeria and thus the importance of future works in this

  15. The mode of emplacement of Neogene flood basalts in eastern Iceland: Facies architecture and structure of simple aphyric basalt groups

    NASA Astrophysics Data System (ADS)

    Óskarsson, Birgir V.; Riishuus, Morten S.

    2014-12-01

    Simple flows (tabular) in the Neogene flood basalt sections of Iceland are described and their mode of emplacement assessed. The flows belong to three aphyric basalt groups: the Kumlafell group, the Hólmatindur group and the Hjálmadalur group. The groups can be traced over 50 km and originate in the Breiðdalur-Thingmuli volcanic zone. The groups have flow fields that display mixed volcanic facies architecture and can be classified after dominating type morphology. The Kumlafell and the Hólmatindur groups have predominantly simple flows of pāhoehoe and rubbly pāhoehoe morphologies with minor compound or lobate pāhoehoe flows. The Hjálmadalur group has simple flows of rubbly pāhoehoe, but also includes minor compound or lobate flows of rubble and 'a'ā. Simple flows are most common in the distal and medial areas from the vents, while more lobate flows in proximal areas. The simple flows are formed by extensive sheet lobes that are several kilometers long with plane-parallel contacts, some reaching thicknesses of ~ 40 m (aspect ratios < 0.01). They have overlapping contacts and are free of tubes and inflation structures. Their internal structure consists generally of a simple upper vesicular crust, a dense core and a thin basal vesicular zone. The brecciated flow-top is formed by clinker and crustal rubble, the clinker often welded or agglutinated. The simple flows erupted from seemingly short-lived fissures and have the characteristics of cooling-limited flows. We estimate the effusion rates to be ~ 105 m3/s for the simple flows of the Kumlafell and Hólmatindur groups and ~ 104 m3/s for the Hjálmadalur group. The longest flows advanced 15-20 km from the fissures, with lava streams of fast propagating flows inducing tearing and brecciation of the chilled crust. Compound or lobate areas appear to reflect areas of low effusion rates or the interaction of the lava with topographic barriers or wetlands, resulting in chaotic flowage. Slowing lobes with

  16. Deciphering Neogene Antarctic climate history is certainly important, but documenting Pleistocene events may be more relevant to prediction

    NASA Astrophysics Data System (ADS)

    Scherer, R. P.

    2004-12-01

    This AGU session description states, "Scenarios for future climate change indicate that within the next 100 to 400 years, global annual average surface temperatures will increase by several degrees. The Neogene represents the last time in Earth history when comparable warming occurred.The aim of the session is to synthesize results from marine and terrestrial proxy data for the Miocene and Pliocene and to combine them with outputs derived from numerical climate and ice-sheet models." Yes, Miocene and Pliocene proxies are critically important to understanding Cenozoic stepwise cooling and the polar climatic isolation of Antarctica. But at least equally important is understanding Antarctic climate dynamics during Pleistocene warm interglacials. These did not dramatically affect the East Antarctic ice sheet (EAIS), but the West Antarctic ice sheet (WAIS) has a history of Pleistocene advance and retreat well beyond its current configuration. Such changes have global consequences for sea-level, bottom water formation, and ocean circulation. The WAIS is the most dynamic of the world's existing large ice sheets, and it is the source of the largest ice shelves. Global warming may already be affecting the stability of the WAIS and the ice shelves. I will review geologic evidence for Quaternary warm interglacials in the Antarctic (e.g., MIS- 5e, MIS-11, MIS-31, others), including subglacial sediments, drill cores from the Antarctic marginal seas, Southern Ocean sediments, marine deposits in outcrop, sea-level records, and Antarctic terrestrial deposits including lake cores. These will be discussed in the context of WAIS and Ross Ice Shelf history and dynamics.

  17. Evidence for the development of the Andean rain shadow from a Neogene isotopic record in the Atacama Desert, Chile

    NASA Astrophysics Data System (ADS)

    Rech, Jason A.; Currie, Brian S.; Shullenberger, Eric D.; Dunagan, Stan P.; Jordan, Teresa E.; Blanco, Nicolás; Tomlinson, Andrew J.; Rowe, Harry D.; Houston, John

    2010-04-01

    Varying ages from Triassic to Pliocene have been proposed for the onset of hyperaridity in the Atacama Desert. The exact timing for the initiation of hyperaridity is critical for determining potential causes, which range from regional effects of global cooling to Andean uplift above elevations conducive to extreme rain shadows. Analysis of the stable isotopic composition of lower Miocene-Quaternary (21-0.015 Ma) palustrine and lacustrine carbonates in the Calama Basin reveals extreme changes in their oxygen and carbon isotopic composition during the Miocene. Limestone δ18O values increased by ˜ 5‰ from middle to late Miocene, ranging from - 5.5‰ at 12 Ma to - 1‰ at ˜ 6 Ma. Carbon isotopic values increase by 9‰ over the Neogene, from average values of - 3‰ at 21 Ma to + 3‰ at 12 Ma, and reaching a maximum of + 6‰ at 5 Ma. The increase in oxygen isotopic values occurred over a time span in which the catchment area of the basin experienced significant uplift, causing the δ18O value of precipitation to become more negative. We attribute the shift towards higher δ18O values to enhanced evaporative enrichment both of soil water or snow prior to infiltration, and within shallow lakes or wetlands prior to carbonate precipitation. The large increase in δ13C values was likely caused by a transition from a vegetated landscape influenced primarily by soil-respired CO 2 to a landscape largely devoid of vegetation and influenced by atmospheric and volcanic CO 2. Isotopic values of palustrine carbonates therefore indicate that hyperaridity commenced in the Calama Basin during the middle to late Miocene, in agreement with other paleoclimatic records from the basin. The cause for the onset of this climate change is thought to be due to the development of a strong Andean rain shadow associated with the uplift of the Andes to mean elevations > 2 km.

  18. Rift propagation at craton margin.: Distribution of faulting and volcanism in the North Tanzanian Divergence (East Africa) during Neogene times

    NASA Astrophysics Data System (ADS)

    Le Gall, B.; Nonnotte, P.; Rolet, J.; Benoit, M.; Guillou, H.; Mousseau-Nonnotte, M.; Albaric, J.; Deverchère, J.

    2008-02-01

    A revised kinematic model is proposed for the Neogene tectono-magmatic development of the North Tanzanian Divergence where the axial valley in S Kenya splits southwards into a wide diverging pattern of block faulting in association with the disappearance of volcanism. Propagation of rifting along the S Kenya proto-rift during the last 8 Ma is first assumed to have operated by linkage of discrete magmatic cells as far S as the Ngorongoro-Kilimanjaro transverse volcanic belt that follows the margin of cratonic blocks in N Tanzania. Strain is believed to have nucleated throughout the thermally-weakened lithosphere in the transverse volcanic belt that might have later linked the S Kenya and N Tanzania rift segments with marked structural changes along-strike. The North Tanzanian Divergence is now regarded as a two-armed rift pattern involving: (1) a wide domain of tilted fault blocks to the W (Mbulu) that encompasses the Eyasi and Manyara fault systems, in direct continuation with the Natron northern trough. The reactivation of basement fabrics in the cold and intact Precambrian lithosphere in the Mbulu domain resulted in an oblique rift pattern that contrasts with the orthogonal extension that prevailed in the Magadi-Natron trough above a more attenuated lithosphere. (2) To the E, the Pangani horst-like range is thought to be a younger (< 1 Ma) structure that formed in response to the relocation of extension S of the Kilimanjaro magmatic center. A significant contrast in the mechanical behaviour of the stretched lithosphere in the North Tanzanian diverging rift is assumed to have occurred on both sides of the Masai cratonic block with a mid-crustal decoupling level to the W where asymmetrical fault-basin patterns are dominant (Magadi-Natron and Mbulu), whereas a component of dynamical uplift is suspected to have caused the topographic elevation of the Pangani range in relation with possible far-travelled mantle melts produced at depth further N.

  19. Ant-nest ichnofossils in honeycomb calcretes, Neogene Ogallala Formation, High Plains region of western Kansas, U.S.A.

    USGS Publications Warehouse

    Smith, J.J.; Platt, B.F.; Ludvigson, Greg A.; Thomasson, J.R.

    2011-01-01

    Two new ant-nest trace fossils are described from calcic sandy paleosols of the Neogene Ogallala Formation in western Kansas. The ichnofossils are preserved within and below calcrete beds weathering in positive relief as carbonate-filled casts or as cavities in negative relief. Daimoniobarax ichnogenus nov. is established for burrow systems composed of vertically tiered, horizontally oriented pancake-shaped chambers connected by predominantly vertical and cylindrical shafts ~. 0.8. cm in diameter. Ichnospecies of Daimoniobarax are differentiated based on differences in the plan view outline of chambers, shaft orientation, and junctions between chambers and shafts.Daimoniobarax nephroides ichnospecies nov. is composed of an ~. 24-76. cm long vertical sequence of distinctly lobed chambers (~. 2-20. cm wide and ~. 1. cm high) arranged along sinuous to helical shafts. Chamber shape in plan view ranges from small teardrops to larger kidney- and U-shaped forms. Shafts intersect at chamber edges such that chambers appear to bud from the central shafts. Daimoniobarax nephroides is most similar to the nests of extant seed-harvester ants of the New World genus Pogonomyrmex. Such ants are specialized granivores and prefer sandy soils in arid to semi-arid grassland and desert regions.Daimoniobarax tschinkeli ichnospecies nov. is ~. 30-80. cm in vertical extent. Chambers (~. 2-30. cm wide and ~. 1. cm high) are circular to elongate or pseudopodial in plan view. Vertical shafts are straight to slightly sinuous and intersect most often toward the center of the chambers. The generalized architecture of D. tschinkeli is similar to that of the nests or nest portions of several extant ant genera, though it does not closely resemble any known modern nest.Ant ichnofossils provide valuable information on hidden biodiversity, paleohydrologic regimes, paleopedogenic processes, and paleoclimate during the time of nest occupation. Depth-related changes in chamber size and vertical spacing

  20. Superposed local and regional paleostresses: Fault-slip analysis of Neogene extensional faulting near coeval caldera complexes, Yucca Flat, Nevada

    SciTech Connect

    Minor, S.A.

    1995-06-10

    Numerous reduced stress tensors are computed by multiple inversions of 906 temporally and spatially partitioned fault-slip data from the Yucca Flat region in the southwest Nevada volcanic field to constrain the Neogene paleostress and faulting history and to investigate how the regional tectonic stress field was affected by local caldera magmatism. Perturbed, shallow (<400 m), pre-11 Ma paleostress configurations, determined west and northwest of present (post-11 Ma) Yucca Flat basin, existed during mild extensional faulting and are attributed to superposition of transient caldera-magmatic stresses on the regional stress field. A brief ({approximately} 0.5 m.y.) change to a strike-slip stress state occurred at about 13 Ma and was accompanied by small-offset, quasi-conjugate strike-slip faulting. This stress state was most distinct, relative to a normalslip state, near calderas where stress solutions and fault relations indicate closer affinities to a reverse-slip state. Inferred 11.6-11.45 Ma paleostress tensors indicate radial tension associated with either initial caldera collapse or local post-collapse topographic modification of the stress field. Post-11 Ma normal-slip stress tensors are associated with normal- and oblique-slip faults that accommodated subsidence and eastward extension of Yucca Flat basin away from the caldera complexes. These tensors do not indicate stress modifications due to residual caldera-related effects and thus were used to infer post-11 Ma regional stress changes. The stress field has rotated as much as 65{degrees} clockwise since 11 Ma during extensional development of Yucca Flat basin, with most of the rotation and extension occurring before about 8.5 Ma. Results suggest that shallow magmatism and caldera development can strongly alter extensional tectonic stress fields, fault patterns, and slip directions in the uppermost crust out to distances of roughly two magma chamber radii away from a magma body. 59 refs., 11 figs., 2 tabs.

  1. A Neogene Higher Plant N-Alkane Carbon and Hydrogen Isotope Record From the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Tipple, B. J.; Pagani, M.

    2006-12-01

    Water availability and a plant's capacity to cope with water stress are expressed in carbon and hydrogen isotopic compositions of leaf waxes. Therefore, coupled sedimentary n-alkane δ13C and δD isotope records provide unique continental-scale information about the paleo-hydrological cycle and its influence on biology over long time scales. In this study, we assess the relationship between Neogene North American climate and floral change, particularly C4 grass expansion, by establishing δ13C and δD records of higher-plant leaf wax n-alkanes from Gulf of Mexico sediments (DSDP site 94). Changes in the hydrogen isotope composition of leaf water can be driven by changes in evaporation/evapotranspiration or changes in the evaporative source from which precipitation derives. However, for this study changes in moisture source are unlikely because these sediments located in Gulf of Mexico likely received the majority of precipitation from the Gulf of Mexico itself over the time interval studied. In general, δ13C and δD values shift in concert, with the most positive δ13C and δD values occurring near the Epoch boundaries. N-alkane δ13C values reflect factors other than water stress alone, including the isotopic composition of atmospheric CO2, plant community, and atmospheric pCO2. Notably, 13C enrichment occurring near the Oligocene/Miocene boundary potentially reflects the rapid decrease in pCO2 at this time. In addition, between 4.5 and 5.5 Ma, n-alkane δ13C values trend more negative as δD becomes increasingly D-enriched, indicative of increased evaporation. Given that contemporaneous North American terrestrial isotope (Passey et al., 2002) and equatorial Atlantic marine (Wagner, 2002) records show similar trends, it appears that major changes in the hydrological cycle took place at this time.

  2. Siliciclastic Progradation Within a Neogene Carbonate Passive Margin - Northern Carnarvon Basin of the Northwest Shelf of Australia

    NASA Astrophysics Data System (ADS)

    Sanchez, C. M.; Fulthorpe, C. S.; Austin, J. A.

    2008-12-01

    Interpretations of extensive industry subsurface data (3D and 2D seismic data, wireline logs and completion reports) and results from previous studies suggest that relative sea level changes and ocean currents controlled observed variations in carbonate vs. siliciclastic sediment type and stratal architecture in the Northern Carnarvon Basin, Northwest Shelf of Australia, during the Neogene. The basin has been a site of predominantly carbonate sedimentation since the late Paleogene. However, significant (at least 30-70 km) siliciclastic progradation on top of this carbonate shelf started in the late middle Miocene. Carbonate- dominated sedimentation resumed in the late Miocene/Pliocene. Siliciclastic-rich seismic packages show dip- oriented progradation northwestward, as well as strike-oriented progradation northeastward. Clinoform heights, up to approx. 140 m, and a dip-elongated lobe morphology suggest deposition by a long-lived (approx. 6 My) deltaic system which is no longer active on this margin. Consistent northeastward switching of these interpreted delta lobes and their progradation over the preexisting carbonate shelf sediments suggest wave-dominated conditions, with strong northeastward long-shore currents, for this delta system during a time of relative base level fall. During this siliciclastic progradation event, carbonate sedimentation continued in the updrift direction southwest of the delta, but carbonates were not accumulated downdrift or northeast, where progressively younger deltaic siliciclastics filled available accommodation space. By the beginning of the Pliocene, siliciclastic sedimentation had retreated towards the Australian coast, allowing widespread carbonate production to resume; interpreted shallow-water carbonate platforms then developed over subtle topographic highs created by the underlying deltaic lobes.

  3. Sedimentology and depositional history of Neogene gravel deposits in lower Tornillo Creek area of Big Bend National Park, Texas

    SciTech Connect

    Thurwachter, J.E.

    1984-04-01

    Neogene gravel deposits in the lower Tornillo Creek area of Big Bend National Park, Texas, record the filling of a small structural basin formed during Basin and Range tectonism. Four lithofacies are recognized in the Late Miocene La Noria member (informal name): (1) a medial braided-stream lithofacies consisting of upward-fining packages of cross-bedded gravel, sandstone, and siltstone; (2) a distal braided-stream lithofacies consisting of poorly-defined upward-fining packages of fine gravel, sandstone, and mudstone; (3) a calcrete-rich gravel and sandstone lithofacies representing strike-valley and alluvial-fan deposition, and (4) and ephemeral lake-plain lithofacies consisting of massive and burrowed mudstones with sheet-like sandstone interbeds. Upward-fining packages in the braided-stream lithofacies represent the lateral migration and avulsion of the stream tract across the basin; together with the strike-valley and alluvial-fan deposits, these record the initial stages of basin filling. Provenance studies show that much of this sediment was derived from northern Mexico. Overlying ephemeral-lake deposits record the structural tilting and closing of the downstream (north) end of the basin. Gravels and minor sandstones of the Pleistocene Estufa member (informal name) represent basinward progradation of alluvial fans. Deposition of the Estufa member resulted from: (1) Quaternary tectonic activity in the Chisos Mountains area; (2) lowering of local base level by post-Miocene development of the Rio Grande drainage through the area; and (3) Pleistocene pluvial-period climatic changes. Subsequent Quaternary faulting has caused minor deformation of the deposits.

  4. Zircon and apatite (U-Th)/He evidence for Paleogene and Neogene extension in the Southern Snake Range, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Evans, Sarah L.; Styron, Richard H.; Soest, Matthijs C.; Hodges, Kip V.; Hanson, Andrew D.

    2015-10-01

    Despite decades of study, the timing, rates, and magnitude of extension in the Basin and Range are poorly quantified in some areas. This study integrates new zircon and apatite (U-Th)/He analyses (ZrnHe and ApHe) with published thermochronologic data to quantify these extensional parameters in the Southern Snake Range (SSR) of east-central Nevada. The new ZrnHe dates range from 40.7 ± 4.9 Ma in the western SSR to 21.0 ± 3.3 Ma near the present-day trace of the Southern Snake Range Décollement (SSRD), and the ApHe dates range from 15.1 ± 2.4 Ma in the central SSR to 13.6 ± 0.7 Ma closest to the SSRD trace. These new and previously published low-temperature thermochronologic cooling ages were inverted for the extensional history of the SSR using a Bayesian Monte Carlo method incorporating Pecube. The posterior extensional histories indicate three significant pulses of extension occurred during the Paleogene and Neogene: (1) ~50-45 to ~38 Ma (Eocene), (2) ~33-30 to ~23 Ma (Oligocene), and (3) ~23-20 to ~10-8 Ma (Miocene). Modeled rates of extension were low at ≤ 0.5 mm a-1; however, more rapid rates possibly occurred during the Eocene and the Miocene based on posterior histories. Net cumulative extension from posterior histories is 19.8 to 34.9 km, with a mean of 29.7 km. About 10-18 km of extension occurred during the Eocene and Oligocene. Model results indicate no relationship between extension and magmatism in the SSR. Our new model results and interpretations also indicate extensional collapse of the Nevadaplano initiated prior to ~17 Ma.

  5. Neogene rejuvenation of central Appalachian topography: Evidence for differential rock uplift from stream profiles and erosion rates

    NASA Astrophysics Data System (ADS)

    Miller, Scott R.; Sak, Peter B.; Kirby, Eric; Bierman, Paul R.

    2013-05-01

    The persistence of topography within ancient orogens remains one of the outstanding questions in landscape evolution. In the eastern North American Appalachians, this question is manifest in the outstanding problem of whether topographic relief is in a quasi-equilibrium state, decaying slowly over many millennia, or whether relief has increased during the late Cenozoic. Here we present quantitative geomorphic data from the nonglaciated portion of the Susquehanna River drainage basin that provide insight into these end-member models. Analysis of channel profiles draining upland catchments in the northern Valley and Ridge, Appalachian Plateau, Blue Ridge, and Piedmont provinces reveals that a large number of streams have well defined knickpoints clustered at 300-600 m elevation but not systematically associated with transitions from weak to resistant substrate. Cosmogenic 10Be inventories of modern stream sediment indicate that erosion rates are spatially variable, ranging from ~5-30 m/Myr above knickpoints to ~50-100 m/Myr below knickpoints. Overall, channel gradients, normalized for drainage area, scale linearly with catchment-averaged erosion rates. Collectively, regionally consistent spatial relationships among erosion rate, channel steepness, and knickpoints reveal an ongoing wave of transient channel adjustment to a change in relative base level. Reconstructions of relict channel profiles above knickpoints suggest that higher rates of incision are associated with ~100-150 m of relative base level fall that accompanied epierogenic rock uplift rather than a change to a more erosive climate or drainage reorganization. Channel response timescales imply that the onset of relative base level change predates ~3.5 Ma and may have begun as early as ~15 Ma. We suggest that adjustment of the channel network was likely driven by changes in mantle dynamics along the eastern seaboard of North America during the Neogene.

  6. New insights into late Neogene glacial dynamics, tectonics, and hydrocarbon migrations in the Atlantic-Arctic gateway region.

    NASA Astrophysics Data System (ADS)

    Knies, J.; Baranwal, S.; Fabian, K.; Grøsfjeld, K.; Andreassen, K.; Husum, K.; Mattingsdal, R.; Gaina, C.; De Schepper, S.; Vogt, C.; Andersen, N.

    2012-04-01

    Notwithstanding the recent IODP drilling on the Lomonosov Ridge, the Late Cenozoic history of the Arctic Ocean still remains elusive. The tectonic processes leading to the development of the only deep-water connection to the Arctic Ocean via the Fram Strait are still poorly understood. Also, the influence of the gateway region on changes in Arctic-Atlantic ocean circulation, uplift/erosion on the adjacent hinterland, as well as glacial initiation and its consequences for the petroleum systems in the regions, remain unclear. By revisiting Ocean Drilling Program (ODP) Leg 151, holes 911A and 910C and interpreting new multi-channel seismic data, we have now established a new comprehensive chronological framework for the Yermak Plateau and revealed important paleoenvironmental changes for the Atlantic-Arctic gateway during the late Neogene. The improved chronostratigraphic framework is established through continuous paleomagnetic and biostratigraphic data as well as selected intervals with stable ?18O and ?13C data derived from benthic foraminifera Cassidulina teretis. Supported by acoustic profiling, the new data indicate a continuous late Miocene/early Pliocene age (~5-6 Ma) for the base of both holes. The depositional regime north (Yermak Plateau) and south of the Fram Strait (Hovgaard Ridge) was rather shallow during the late Miocene and water mass exchange between the Arctic and Atlantic was restricted. Ice sheets on the Svalbard Platform evolved during the late Miocene, however did not reach the coastline before 3.3 Ma. Migration of gaseous hydrocarbons occurred prior to the intensification of the Northern Hemisphere Glaciations (~2.7 Ma) as indicated by high-amplitude reflections, corroborating the occurrence of greigite mineralization and stable carbon isotope excursions in planktic/benthic foraminifera. The data indicate that Pleistocene erosion and uplift in the Barents Sea region had probably only minor effects on reservoir leakages than previously thought.

  7. Late Neogene stratigraphy and tectonic control on facies evolution in the Laguna Salada Basin, northern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Martín-Barajas, A.; Vázquez-Hernández, S.; Carreño, A. L.; Helenes, J.; Suárez-Vidal, F.; Alvarez-Rosales, J.

    2001-10-01

    The Laguna Salada Basin (LSB) in northeastern Baja California records late-Neogene marine incursions in the Salton Trough and progradation of the Colorado River delta. Early subsidence and subsequent tectonic erosion are related to evolution of the Sierra El Mayor detachment fault during late Miocene time (<12 Ma). The stratigraphy of uplifted blocks on the east-central margin of the Laguna Salada Basin and from three exploratory wells allows reconstruction of the main sedimentary and tectonic events. Marine mudstone and sandstone, and subordinate conglomerate of the Imperial Formation tectonically overlie metamorphic and granitic basement. Microfossils, lithology, and sedimentary structures in the Imperial Formation define Upper Miocene (<6 Ma) outer-shelf facies that grade up-section into inner-shelf and tide-dominated delta plain deposits of the ancient Colorado River. Lower Pliocene (˜4-2 Ma) reddish, sub-arkosic fluvial sandstone and siltstone of the Palm Spring Formation defines progradation of non-marine fluvio-deltaic deposits over the marine Imperial Formation. Continuous outcrops of the Palm Spring are less than 170-m thick, but correlative deposits are more than 570 m thick in the lower part of a 2400-m deep geothermal exploratory well on the eastern margin of LSB. Interfingering fluvial-sandstone deposits and prograding alluvial fanglomerates with coarse debris-flow and rock-avalanche deposits crudely mark the onset of vertical slip along the Laguna Salada fault and rapid uplift of Sierra Cucapa and Sierra El Mayor. Up to 2 km of Quaternary alluvial-fan and lacustrine deposits accumulated along the eastern margin of LSB, whereas lower subsidence rates produced a thinner sedimentary wedge over a ramp-like crystalline basement along the western margin. In early Pleistocene time (˜2-1 Ma), the Laguna Salada became progressively isolated from the Colorado River delta complex, and the Salton Trough by activity on the Elsinore and Laguna Salada fault zones.

  8. IODP Expedition 354: A Bengal fan record of Himalayan erosion, weathering and organic carbon burial during the Neogene.

    NASA Astrophysics Data System (ADS)

    France-Lanord, C.; Spiess, V.; Klaus, A.; Galy, A.; Galy, V.

    2015-12-01

    The development of the Himalayan orogen induced a major change in continental distribution, topography and climate that impacted the global biogeochemical cycles. The development of the highest mountain range coupled to the intense monsoonal precipitation regime generated an intense erosional flux that enhanced both organic carbon burial and silicate weathering. The largest part of the sediment flux was exported to the Bengal Fan, accumulating a long-term archive of this erosion. These sediments record the nature of eroded formations in the Himalaya and allow the documentation of weathering as well as organic carbon fluxes. In February-March 2015, IODP Expedition 354 drilled an E-W transect in the middle fan at 8°N to investigate interactions between the growth of the Himalaya, the development of the Indian monsoon, and processes affecting the carbon cycle. This expedition obtained a comprehensive record of turbiditic deposition since the Late Oligocene. Shipboard results reveal that the chemical and mineralogical compositions of turbiditic sediments cored across the transect are relatively stable throughout the Neogene. They reveal a weak regime of chemical weathering with no significant variation through time. This differs from the distal fan record (Leg 116) where from ~7 to 1 Ma, weathered and smectite rich sediments dominated. This difference implies that the distal fan record is not related to a direct evolution of the erosion regime but rather is controlled by a change in sediment transport within the fan. Shipboard estimates of organic carbon loading and behavior resemble observations made in the modern Ganga-Brahmaputra river sediments, suggesting efficient terrestrial organic carbon burial in the Bengal Fan [1]. Preliminary observations support the idea that Himalayan erosion has consumed atmospheric CO2 through the burial of organic carbon, more than by silicate weathering. [1] http://dx.doi.org/10.1038/nature06273

  9. Neogene non-tropical carbonate sedimentation in a warm temperate biogeographic province (Rethymnon Formation, Eastern Crete, Greece)

    NASA Astrophysics Data System (ADS)

    Pomoni-Papaioannou, F.; Drinia, H.; Dermitzakis, M. D.

    2003-01-01

    The Apostoli Basin, in the central-west part of Crete, was formed as a fore-arc type basin related to the convergent plate boundary between the African and the Eurasian plates. Most of the Neogene sediments filling the basin were deposited in a terrestrial to shallow marine environment. The succession is a transgressive cycle, which culminates in the alternation of Rethymnon bioclastic limestones with marls, documenting the important Tortonian marine transgression. The Rethymnon limestones are classified as a typical non-tropical carbonate lithofacies. Two particular lithofacies have been recognized: (a) a rhodalgal-type lithofacies, characterized by predominance of encrusting coralline algae and bryozoans, and (b) an echinofor-type lithofacies, characterized by predominance of echinoderms and/or benthic foraminifera. The coralline algae occur mostly as in situ spheroidal or branched rhodoliths, whereas benthic foraminifera are mainly represented by larger foraminifera. In both lithofacies, typical tropical carbonate elements are lacking. Skeletal elements consisted of low- and high-Mg calcite. Although the observed lithofacies possess many similarities with facies of non-tropical carbonates, the presence of large benthic foraminifera suggests development in a warm temperate biogeographic province. The depositional environment corresponds to a shallow ramp, the sediments being deposited in a nearshore environment and under conditions analogous to those prevailing in the present-day circalittoral bottoms of the Mediterranean Sea. The main carbonate accumulation area is located at the factory area itself (rhodalgal-type sediments), and downslope from the factory area (echinofor-type sediments). In the classic zonation of Mediterranean benthic assemblages of Peres and Picard [Rec. Trav. Stn. Mar. (1964)], the rhodalgal-type sediments of the Rethymnon Fm correspond to the "Facies a Pralines", developed in areas strongly controlled by currents (e.g., tops of plateaus

  10. The Miocene Pakhna Formation, southern Cyprus and its relationship to the Neogene tectonic evolution of the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Eaton, Simon; Robertson, Alastair

    1993-08-01

    The Miocene Pakhna Formation is interpreted as relating to onset of the present northward subduction of the African plate beneath Cyprus and is, thus, critical to understanding of the Neogene evolution of the Eastern Mediterranean basin. Following a perios of deep-water pelagic chalk deposition in the Late Eocene and Oligocene (Upper Lefkara Fm.), the Pakhna Formation records heterogeneous, mainly carbonate, sedimentation. The Pakhna Formation is bounded by the Limassol Forest Block, an uplifted ophiolitic terrain to the north, and by the Akrotiri High, a ridge of exotic Mesozoic lithologies to the south. Two sub-basins, Maroni in the E and Khalassa in the W, within the Pakhna Formation were separated by the WNW-ESE-trending Yerasa lineament, located near the S margin of the ophiolite. In most areas, the Pakhna Formation overlies the Lefkara Formation disconformably. The succession begins with deep-water pelagic carbonates and shows increased input of shallow-water bioclastic and terrigenous sediment upward. During the Early to mid-Miocene, the ophiolitic terrain to the N was uplifted, deformed and eroded, followed by marine transgression and patch-reef development in the Tortonian (Late Miocene). Ophiolite-derived clastics were mixed with shallow-water bioclastic sediment, reworked in a high-energy coastal setting and transported downslope within channels into the basin, accumulating as massive sands, debris flows and calciturbidites. In the Maroni sub-basin, localised debris aprons prograded into a pelagic carbonate environment to the SE. Further west, in the Khalassa sub-basin, little uplift occurred along the basin margins and redeposited sediment was mainly bioclastic. Contrasting sediment, including chert, was derived from the allochthonous Mamonia Complex, exposed on the Akrotiri High to the S and its possible offshore extension. Bioclastic sediment, including reef talus, was also derived from an intrabasinal high in the Khalassa sub-basin. Eventually

  11. Southwestern Willow Flycatcher Breeding Site and Territory Summary - 2007

    USGS Publications Warehouse

    Durst, Scott L.; Sogge, Mark K.; Stump, Shay D.; Walker, Hira A.; Kus, Barbara E.; Sferra, Susan J.

    2008-01-01

    The Southwestern willow flycatcher (Empidonax traillii extimus; hereafter references to willow flycatcher and flycatcher refer to E.t. extimus, except where specifically noted) is an endangered bird that breeds only in dense riparian habitats in parts of six Southwestern states (Arizona, New Mexico, southern California, extreme southern Nevada, southern Utah, and southwestern Colorado). Since 1993, hundreds of Southwestern willow flycatcher surveys have been conducted each year, and many new flycatcher breeding sites located. This document synthesizes the most current information available on all known Southwestern willow flycatcher breeding sites. This rangewide data synthesis was designed to meet two objectives: (1) identify all known Southwestern willow flycatcher breeding sites and (2) assemble data to estimate population size, location, habitat, and other information for all breeding sites, for as many years as possible, from 1993 through 2007. This report provides data summaries in terms of the number of flycatcher sites and the number of territories. When interpreting and using this information, it must be kept in mind that a 'site' is a geographic location where one or more willow flycatchers establishes a territory. Sites with unpaired territorial males are considered breeding sites, even if no nesting attempts were documented. A site is often a discrete patch of riparian habitat but may also be a cluster of riparian patches; there is no standardized definition for site, and its use varies within and among states. For example, five occupied habitat patches along a 10-km stretch of river might be considered five different sites in one state but only a single site in another state. This lack of standardization makes comparisons based on site numbers problematic. Researchers for this report generally deferred to statewide summary documents or to local managers and researchers when delineating a site for inclusion in the database. However, to avoid inflating

  12. Water resources of the Redwood River watershed, southwestern Minnesota

    USGS Publications Warehouse

    Van Voast, Wayne A.; Jerabek, L.A.; Novitzki, R.P.

    1970-01-01

    The land surface slopes gently northeastward and eastward from altitudes greater than 1900 feet at the southwestern edge to less than 850 feet at the mouth of the Redwood River in the east. The area has slight local relief shaped by continental glaciation. The Redwood River and its tributaries, many of which are ephemeral, and ponds and lakes in the area provide water for local use and habitat for wildlife. The glacial drift and sedimentary rocks yield generally adequate water supplies for municipalities, households, and farms.

  13. 46. NORTH THROUGH SHEET METAL AND ASSEMBLY AREA IN SOUTHWESTERN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. NORTH THROUGH SHEET METAL AND ASSEMBLY AREA IN SOUTHWESTERN QUADRANT OF FACTORY AS SEEN FROM DOORWAY IN SOUTH FRONT WALL. ALONG WEST INTERIOR WALL ARE SHELVES BEARING WATER PUMPS, PARTS FOR PUMPS AND WATER SUPPLY EQUIPMENT, AND NEW OLD STOCK MERCHANDISE. IN FRONT OF THE WALL ARE THE CIRCA 1900 SHEET METAL SHEAR AND CIRCA 1900 SHEET METAL BRAKE. AT THE RIGHT SIDE OF THE IMAGE ALONGSIDE VERTICAL CEILING SUPPORTS IS METAL-COVERED BENCH FOR SHEET METAL WORK. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  14. Signs of continental rifting in the southwestern Japanese Island Arc

    NASA Astrophysics Data System (ADS)

    Chernysheva, E. A.; Eroshenko, D. V.

    2016-03-01

    The southwestern margin of the Japan Arc evolved in the geodynamic regime of continental rifting during the Miocene-Pleistocene. This has been verified by broad manifestations of metasomatosis of mantle peridotites that underlie the lithosphere of the Japan Islands and by episodes of deep magmatism (kimberlites and melilitites) in the region. The high enrichment of deep melts in incompatible rare and rare earth elements is partially preserved in melts of regional basalts from smaller depths. In contrast, spreading basalts of the Sea of Japan and subduction basalts from the Nankai trench at the boundary with the Philippine Plate are extremely depleted in rare elements.

  15. The character of five selected LANDSAT lineaments in Southwestern Pennsylvania

    SciTech Connect

    Moebs, N.N.; Sames, G.P.

    1987-01-01

    Five LANDSAT lineaments in the coal mining region of southwestern Pennsylvania were investigated by the Bureau of Mines to determine their geologic character, relation to subsurface conditions, and the means of discriminating one from another. The investigation included earth resistivity and very low frequency electromagnetic traverses, soil moisture sampling, and a correlation with coal mine roof conditions. The lineaments could not be detected by the methods used, suggest that they might be a surface phenomenon unrelated to subsurface geologic structures or roof stability in coal mine workings beneath.

  16. Nestling sex ratios in the southwestern willow flycatcher

    USGS Publications Warehouse

    Paxton, E.H.; Sogge, M.K.; McCarthey, Tracy; Keim, Paul

    2002-01-01

    Using molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts.

  17. Nestling sex ratio in the Southwestern Willow Flycatcher

    USGS Publications Warehouse

    Paxton, E.H.; Sogge, M.K.; McCarthey, T.D.; Keim, P.

    2002-01-01

    Using molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts. ?? The Cooper Ornithological Society 2002.

  18. Duricrusts and deep-weathering profiles in southwestern wisconsin.

    PubMed

    Dury, G H; Knox, J C

    1971-10-15

    Numerous exposures in southwestern Wisconsin display the profiles of relict deep weathering. Crusts are mainly siliceous, but many are ferruginized to some extent. The occurrence of blocky silcrete, thought to be reported for the first time, recalls the profiles in the Australian belt of transition from silcrust to ferricrust. The humid-tropical kind of pedogenesis necessary to effect this transition may have operated as late as the mid-Miocene. In some localities, the action of grotndwater has caused crusting, mottling, and reduction beneath the dolomite low surface moisture.

  19. Hydrology of melt-water channels in southwestern Minnesota

    USGS Publications Warehouse

    Thompson, Gerald L.

    1965-01-01

    Melt-water channel deposits are among the most important aquifers in southwestern Minnesota, but permeable zones within the deposits are difficult to locate. Interpretation of the depositional history of proglacial channel deposits from aerial photographs and test-hole samples indicates the position of the permeable zones. Generally, the coarse-grained deposits are in headwater areas, near the confluence of two channels, in bends, or at the junction of sluiceways. Locally, these deposits yield as much as 1,000 gallons per minute to wells.

  20. 76 FR 78641 - Southwestern Gas Storage Technical Conference; Notice of Public Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-19

    ... Energy Regulatory Commission Southwestern Gas Storage Technical Conference; Notice of Public Conference... related to natural gas storage development in the southwestern United States. The conference will be held... Recommendations, `` dditional gas storage capacity in the downstream market areas closer to demand centers...

  1. 77 FR 66600 - Southwestern Public Service Company v. Southwest Power Pool, Inc.; Notice of Complaint

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-06

    ... Federal Energy Regulatory Commission Southwestern Public Service Company v. Southwest Power Pool, Inc...'s (Commission) Rules of Practice and Procedure, 18 CFR 206 (2012), Xcel Energy Services Inc. on behalf of Southwestern Public Service Company (Complainant) filed a formal complaint against...

  2. 78 FR 1851 - Southwestern Public Service Company; Southwest Power Pool, Inc.; Notice of Complaint

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... Federal Energy Regulatory Commission Southwestern Public Service Company; Southwest Power Pool, Inc... Act (FPA), 16 U.S.C. 824e (2000), Southwestern Public Service Company (Complainant) filed a formal... and is available for review in the Commission's Public Reference Room in Washington, DC. There is...

  3. Offshore Stratigraphic Relationships in the Southern Alaska Syntaxis and Physical Properties of the Neogene Sedimentary Cover Offshore ST. Elias Mountains

    NASA Astrophysics Data System (ADS)

    Price, R. N.; Worthington, L. L.; Van Avendonk, H. J.; Ridgway, K.; Gulick, S. P. S.

    2015-12-01

    Southeastern Alaska is home to one of the most actively deforming continental margins in the world, and temperate glaciers covering the area contribute to high rates of erosion and offshore sedimentation, making the Neogene sediment covering the offshore Yakutat Block an ideal location to study interactions between climate and tectonics. In 2008, data that includes ~115 km of multichannel seismic reflection and ocean-bottom seismometer wide-angle reflection and refraction data was collected across the central Yakutat shelf in the Gulf of Alaska. We present a high-resolution two-dimensional P-wave velocity model of the glaciomarine sediment and underlying Yakutat basement in the area and compare to coincident seismic reflection profiles in order to determine lithologic boundaries and correlate with stratigraphic units observed onshore and in offshore boreholes. Detailed subsurface mapping of the offshore sedimentary units in and near Yakutat Bay is essential to understanding the long-term development of the central and northern Yakutat shelf as a depocenter, where more of the facies that record St. Elias orogenesis are preserved than onshore. The depositional environment transitions from a wide shelf incised by sea valleys that deliver sediment to slope aprons in the east to a narrow shelf across which sediment is transported to the Aleutian trench in the west. Our velocity profile used in conjunction with seismic reflection data shows transitions in dominant depositional processes over time in the central portion of the block. In Yakutat Bay, sediment velocities are high (~ 4 km/s) compared to velocities farther offshore (< 3 km/s), possibly indicating greater compaction of the sediments in the bay. In the central portion of the shelf, three distinct refractions from sedimentary layers are observed and are interpreted as the Yakataga, Poul Creek, and Kulthieth Formations. In the north, only two refractions from sedimentary layers are observed. Basement refractions

  4. Stratigraphic architecture and forcing processes of the late Neogene Miradouro da Lua sedimentary prism, Cuanza Basin, Angola

    NASA Astrophysics Data System (ADS)

    Cauxeiro, C.; Durand, J.; Lopez, M.

    2014-07-01

    The Miradouro da Lua cliffs, which are 60 km south of Luanda, record the building and uplift of the late Neogene Palaeo-Cuanza delta. The detailed study of the sedimentary architecture and stacking pattern permitted separation of the pile into five depositional units bounded by erosional surfaces and characterised by separate facies associations (genetic sequences = units in this paper). At the base of the series, aeolian deposits (Unit 1) mark the development of a possible coastal desert during the late Miocene aridification. The major Pliocene sea-level rise (Transgressive Systems Tract) led to the drowning of the continental platform into a discrete shoreface-foreshore sequence (Unit 2), followed by an expanded deltaic sequence (Unit 3) that represents the main outcrop of the area. The sedimentary fabric of this prograding wedge during the Highstand Systems Tract reveals laterally stacked pluri-hectometic mouth bars built by the abrupt switching of a bird-foot delta during the Pliocene highstand. The clinoforms are deeply incised by submarine gullies filled both by periodic river-driven turbidite and tidal currents (Unit 4) during the coeval growing of the delta. The topset of the prograding wedge and associated gullies infill is truncated by an overall erosional unconformity that marks the widespread development of an extensive braid-delta system (Unit 5) during the lower Pleistocene sea-level drop (Lowstand Systems Tract). The last 6 m of the Braid-delta unit is overprinted by a ferallitic profile, forming the surface of the plateau and indicating long-term subaerial exposure and weathering processes consistent with the maximum warming of the middle to late Pleistocene interglacial periods. The successive abrupt shifts of the depositional systems through the sedimentary pile indicate a high-amplitude sea level amplified by major coastal uplifts and the reorganisation of the fluvial network. In this context, the palaeo-Cuanza prograding wedge signals the

  5. Flow properties through a single fracture in Neogene-Quaternary siltstone on effective pressure increasing and decreasing processes

    NASA Astrophysics Data System (ADS)

    Uehara, S. I.; Noguchi, M.

    2015-12-01

    To evaluate flow (or seal) properties of mudstone layers, it is essential to reveal stress conditions at which fractures in mudstone can act as effective flow channels. Dependencies of an effective pressure Pe on a fracture permeability should be examined, because Pe conditions of mudstone layers may change in some cases such as tectonic subsidence and uplifting, or CO2 injection at geological storage processes. The purpose of this study is to reveal how a fracture permeability in mudstone changes at Pe increasing and decreasing processes, and how the features depend on yield stress condition of the rock. This study conducted water permeability tests with Neogene-Quaternary siltstones from the Kazusa Group, Japan; siltstones from the Ohara Formation (OHR3) and the Kiwada Formation (KWD2), of which the yield stress conditions are different from each other. A tensile fracture was artificially made in these cylinder rock specimens, and permeability was measured under several Pe compression-and-decompression cycles with increasing the maximum Pe (2-21 MPa). All results had two characteristic Pe cycles; a cycle at which differences in permeability between process of compression and decompression become clear (a cycle Y), and a cycle at which the permeability becomes almost the same as the intact rock permeability (a cycle C). The maximum Pe of the cycles C is 5-9 MPa for OHR3 and 17-21 MPa for KWD2, and the maximum Pe of the cycles Y is 5 MPa for OHR3 and 3-9 MPa for KWD2. The maximum Pe conditions for the cycles C almost equal the yield conditions of the intact rocks obtained by isotropic compressional test. While, the cycles Y tend to appear lower pressure conditions than the yield conditions of the intact rocks, which may be because stress at real contact areas is larger than Pe: that is, conditions for fracture closure depend on the yield condition of rock, while conditions for initiation of fracture surface yielding also depend on conditions of fracture occlusion.

  6. Neogene sedimentary history of the Outer Cilicia Basin, eastern Mediterranean: a contribution to the TopoEurope VAMP project

    NASA Astrophysics Data System (ADS)

    Piercey, Tiffany; Akhun, Selin; Hall, Jeremy; Aksu, Ali; Ćifçi, Günay

    2010-05-01

    The Vertical Anatolian Movements Project (VAMP) addresses the Neogene uplift of the Taurides and the Central Anatolian Plateau. While terrestrial studies are focussed on erosion in the sediment source area, and deposition within the Turkish landmass, our marine work is intended to provide a history of deposition in one of the ultimate sinks: the eastern Mediterranean. In particular, we are mapping the distribution in space and time of sediment deposited from the Göksu River into the Cilicia Basin. In 2008 we obtained km of high-resolution marine multi-channel seismic profiles radiating out from the river delta across the basin. Many of the profiles are processed and images of the data are presented. Interpretation of the available industry seismic reflection profiles show that during the the Miocene the northeastern Mediterranean, including the Cilicia Basin, experienced regional compression, which resulted in the formation of a broad and arcuate fold-thrust belt extending from the Taurides in the north, across the Troodos ophiolite complex into the Cyprus Arc in the south. Two prominent culminations were developed: one was located along the Misis-Kyrenia Fault Zone, another developed in the Amanos-Larnaka-Troodos Fault Zone. Stratigraphic and structural relationships demonstrated that the late Pliocene-Quaternary Cilicia-Adana Basin complex evolved as an asymmetric piggyback basin on the hanging-wall of the south-verging Misis-Kyrenia thrust culmination. Detailed mapping demonstrated that the S/SE-directed contraction culminated in the latest Miocene, and is followed in the early Pliocene by a progressive transition to partitioned contraction and extension related to the initiation of strike slip along the eastern Anatolian Transform Fault and its marine extensions. The shift in kinematics is expressed by the development of major NE-SW trending (Inner Cilicia Basin) and E-W trending (Outer Cilicia Basin) steep faults with extensional separations bounding the

  7. Relative roles of Neogene vicariance and Quaternary climate change on the historical diversification of bunchgrass lizards (Sceloporus scalaris group) in Mexico.

    PubMed

    Bryson, Robert W; García-Vázquez, Uri Omar; Riddle, Brett R

    2012-01-01

    Neogene vicariance during the Miocene and Pliocene and Quaternary climate change have synergistically driven diversification in Mexican highland taxa. We investigated the impacts of these processes on genetic diversification in the widely distributed bunchgrass lizards in the Sceloporus scalaris group. We searched for correlations between timing in diversification and timing of (1) a period of marked volcanism across the Trans-Mexican Volcanic Belt in central Mexico 3-7.5million years ago (Ma) and (2) a transition to larger glacial-interglacial cycles during the mid-Pleistocene. From our phylogenetic analyses of mitochondrial DNA we identified two major clades that contained 13 strongly supported lineages. One clade contained lineages from the two northern sierras of Mexico, and the other clade included lineages associated with the Trans-Mexican Volcanic Belt and Central Mexican Plateau. Results provided support for Neogene divergences within the S. scalaris group in response to uplift of the Trans-Mexican Volcanic Belt, a pattern observed in several co-distributed taxa, and suggested that Quaternary climate change likely had little effect on diversification between lineages. Uplift of the Trans-Mexican Volcanic Belt during specific time periods appears to have strongly impacted diversification in Mexican highland taxa.

  8. Constraints on the history and topography of the Northeastern Sierra Nevada from a Neogene sedimentary basin in the Reno-Verdi area, Western Nevada

    USGS Publications Warehouse

    Trexler, James; Cashman, Patricia; Cosca, Michael

    2012-01-01

    Neogene (Miocene–Pliocene) sedimentary rocks of the northeastern Sierra Nevada were deposited in small basins that formed in response to volcanic and tectonic activity along the eastern margin of the Sierra. These strata record an early phase (ca. 11–10 Ma) of extension and rapid sedimentation of boulder conglomerates and debrites deposited on alluvial fans, followed by fluvio-lacustrine sedimentation and nearby volcanic arc activity but tectonic quiescence, until ~ 2.6 Ma. The fossil record in these rocks documents a warmer, wetter climate featuring large mammals and lacking the Sierran orographic rain shadow that dominates climate today on the eastern edge of the Sierra. This record of a general lack of paleo-relief across the eastern margin of the Sierra Nevada is consistent with evidence presented elsewhere that there was not a significant topographic barrier between the Pacific Ocean and the interior of the continent east of the Sierra before ~ 2.6 Ma. However, these sediments do not record an integrated drainage system either to the east into the Great Basin like the modern Truckee River, or to the west across the Sierra like the ancestral Feather and Yuba rivers. The Neogene Reno-Verdi basin was one of several, scattered endorheic (i.e., internally drained) basins occupying this part of the Cascade intra-arc and back-arc area.

  9. Late Neogene changes in North America and Antarctica absolute plate motions inferred from the Mid-Atlantic and Southwest Indian Ridges spreading histories

    NASA Astrophysics Data System (ADS)

    Iaffaldano, G.; DeMets, C.

    2016-08-01

    Reconstructions of absolute plate motions underpin our understanding of the plate torque balance, but are challenging due to difficulties in inferring well-dated rates and directions of plate movements from hot spot tracks. Useful information about plate dynamics can be inferred from rapid absolute plate motion changes, as these are linked only to the torque(s) that changed. Here we infer late Neogene changes in the absolute motions of North America and possibly Antarctica from changes in the easier-to-determine relative plate motions recorded along the Arctic, northern Mid-Atlantic and Southwest Indian Ridges. We show that Eurasia/North America and Nubia/North America motions changed by the same amount between 8 and 5 Ma, as may have Nubia/Antarctica and Somalia/Antarctica plate motions. By considering additional, independent constraints on Somalia/India plate motion, we argue that a scenario in which North America and Antarctica absolute motions changed is the simplest one that explains the observed changes in relative motions. We speculate that these changes are linked to the late Neogene dynamics of the Pacific plate.

  10. Roadmap for sustainable water resources in southwestern North America.

    PubMed

    Gleick, Peter H

    2010-12-14

    The management of water resources in arid and semiarid areas has long been a challenge, from ancient Mesopotamia to the modern southwestern United States. As our understanding of the hydrological and climatological cycles has improved, and our ability to manipulate the hydrologic cycle has increased, so too have the challenges associated with managing a limited natural resource for a growing population. Modern civilization has made remarkable progress in water management in the past few centuries. Burgeoning cities now survive in desert regions, relying on a mix of simple and complex technologies and management systems to bring adequate water and remove wastewater. These systems have permitted agricultural production and urban concentrations to expand in regions previously thought to have inadequate moisture. However, evidence is also mounting that our current management and use of water is unsustainable. Physical, economic, and ecological limits constrain the development of new supplies and additional water withdrawals, even in regions not previously thought vulnerable to water constraints. New kinds of limits are forcing water managers and policy makers to rethink previous assumptions about population, technology, regional planning, and forms of development. In addition, new threats, especially the challenges posed by climatic changes, are now apparent. Sustainably managing and using water in arid and semiarid regions such as the southwestern United States will require new thinking about water in an interdisciplinary and integrated way. The good news is that a wide range of options suggest a roadmap for sustainable water management and use in the coming decades.

  11. Development of vegetation and climate in the southwestern United States.

    PubMed

    Van Devender, T R; Spaulding, W G

    1979-05-18

    Plant macrofossils in ancient packrat middens document the presence of woodland communities in most of the present Chihuahuan, Sonoran, and Mohave deserts in the southwestern United States during the late Wisconsinan (22,000 to 11,000 years before present by radiocarbon dating). Warm desert species were common in the woodlands at lower elevations and mixed conifer and subalpine forests were present at high elevations. Inferred mild, wet winters and cool summers produced unusual plant and animal associations compared to those of today. Montane communities acquired modern aspects and more mesophytic species disappeared from lower woodlands about 11,000 years ago. Early Holocene xeric woodlands and an inferred winter precipitation regime persisted until about 8000 years ago. The present circulation patterns, rainfall regimes, and biotic distributions probably formed as a result of the melting of the continental ice sheets. Southwestern communities appear to have responded quickly to climatic changes compared to the gradual responses of central and eastern United States forest communities.

  12. Roadmap for sustainable water resources in southwestern North America

    PubMed Central

    Gleick, Peter H.

    2010-01-01

    The management of water resources in arid and semiarid areas has long been a challenge, from ancient Mesopotamia to the modern southwestern United States. As our understanding of the hydrological and climatological cycles has improved, and our ability to manipulate the hydrologic cycle has increased, so too have the challenges associated with managing a limited natural resource for a growing population. Modern civilization has made remarkable progress in water management in the past few centuries. Burgeoning cities now survive in desert regions, relying on a mix of simple and complex technologies and management systems to bring adequate water and remove wastewater. These systems have permitted agricultural production and urban concentrations to expand in regions previously thought to have inadequate moisture. However, evidence is also mounting that our current management and use of water is unsustainable. Physical, economic, and ecological limits constrain the development of new supplies and additional water withdrawals, even in regions not previously thought vulnerable to water constraints. New kinds of limits are forcing water managers and policy makers to rethink previous assumptions about population, technology, regional planning, and forms of development. In addition, new threats, especially the challenges posed by climatic changes, are now apparent. Sustainably managing and using water in arid and semiarid regions such as the southwestern United States will require new thinking about water in an interdisciplinary and integrated way. The good news is that a wide range of options suggest a roadmap for sustainable water management and use in the coming decades. PMID:21149725

  13. Roadmap for sustainable water resources in southwestern North America.

    PubMed

    Gleick, Peter H

    2010-12-14

    The management of water resources in arid and semiarid areas has long been a challenge, from ancient Mesopotamia to the modern southwestern United States. As our understanding of the hydrological and climatological cycles has improved, and our ability to manipulate the hydrologic cycle has increased, so too have the challenges associated with managing a limited natural resource for a growing population. Modern civilization has made remarkable progress in water management in the past few centuries. Burgeoning cities now survive in desert regions, relying on a mix of simple and complex technologies and management systems to bring adequate water and remove wastewater. These systems have permitted agricultural production and urban concentrations to expand in regions previously thought to have inadequate moisture. However, evidence is also mounting that our current management and use of water is unsustainable. Physical, economic, and ecological limits constrain the development of new supplies and additional water withdrawals, even in regions not previously thought vulnerable to water constraints. New kinds of limits are forcing water managers and policy makers to rethink previous assumptions about population, technology, regional planning, and forms of development. In addition, new threats, especially the challenges posed by climatic changes, are now apparent. Sustainably managing and using water in arid and semiarid regions such as the southwestern United States will require new thinking about water in an interdisciplinary and integrated way. The good news is that a wide range of options suggest a roadmap for sustainable water management and use in the coming decades. PMID:21149725

  14. Neogene-Quaternary evolution of the Tefenni basin on the Fethiye-Burdur fault zone, SW Anatolia-Turkey

    NASA Astrophysics Data System (ADS)

    Aksoy, Rahmi; Aksarı, Süleyman

    2016-06-01

    The Fethiye-Burdur fault zone (FBFZ) is a complex belt of major break in the southwestern Anatolia. A number of basins occur within the FBFZ. The Tefenni basin is one of the NE-SW trending basins located in the central part of the FBFZ. The basin is 10-20 km wide and 60 km long. It contains two infills of fluvial, lacustrine and alluvial fan deposits from late Miocene to Recent. The older and folded infill rests on the pre-middle Miocene basement rocks with an angular unconformity and consists of fluvial and lacustrine sediments. The younger and undeformed Plio-Quaternary basin fill unconformably overlies the older basin fill and is composed predominantly of conglomerate, mudstone, silt, clay and recent basin floor sediments. The Tefenni basin is controlled by a series of NE-SW trending left lateral oblique-slip normal faults along its margins. The Tefenni and Mürseller faults bound the northwestern margin of the basin and the Kemer fault bounds the southeastern margin of the basin. The basin is also cut by NE-SW striking major and NW-SE, N-S and E-W striking small scale normal faults. Structural analyses in the basin show that NE-SW-trending contraction stress regime ended by Pliocene and was followed by NE-SW-trending extension from Pliocene onward.

  15. Timing and Spatial Variability of Neogene Tectonic, Climatic, and Ecologic Changes Along the Southern Puna Plateau, Northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Hynek, S. A.; Fernandez, D. P.; Cerling, T. E.; Brown, F. H.

    2008-12-01

    Tephrostratigraphic studies of Mio/Pliocene strata along the southern margin of the Puna plateau (NW Argentina) provide a framework capable of controlling the absolute timing of tectonic, climatic, and ecologic changes. 40Ar/39Ar ages and geochemical characterization of widespread volcanic ash beds indicate that the rich record of explosive volcanism changed dramatically at 5.5 Ma and maintained high frequency and large volume eruptions through 3.6 Ma. Thick conglomeratic deposits associated with basin margin uplift exhibit time-transgressive progradation beginning before 3.6 Ma. Thick Neogene strata in the area were not folded or uplifted until well after 3.6 Ma. These observations delineate a sequence of increased and sustained volcanism on the Puna, followed by plateau margin uplift, and eventual incorporation of sedimentary basins into growing topography along the plateau margin. Stable isotope values of carbonate from paleosols and fossil tooth enamel provide complementary proxies of climatic and ecologic change. Both fossil Notoungulate and Rodent enamels record the presence of C4 vegetation by 8 Ma, 1 Ma earlier than the paleosol record. At 5.6 Ma some Notoungulate taxa were consuming large proportions of C4 vegetation throughout the year, an observation consistent with the presence of grasslands. A dramatic positive shift in δ13C values of paleosol carbonate after 3.6 Ma is not accompanied by a similar shift in fossil tooth enamel, suggesting that the stratigraphic paleosol record may be recording a shift across ecotone boundaries associated with progradation of syntectonic conglomerates. The range in paleosol δ13C values indicates a mosaic of plant communities during the Pliocene. This is further supported by a bimodal distribution of δ13C values among Pliocene tooth enamel. Modern plants, soil carbonate, and tooth enamel indicate the predominance of water stressed C3 plants. The modern monsoon climate in the region is conducive to proliferation of C4

  16. Numerical analysis of palynological data from Neogene fluvial sediments as evidence for rainforest dynamics in western Amazonia

    NASA Astrophysics Data System (ADS)

    Salamanca, Sonia; van Manen, Milan; Hoorn, Carina

    2014-05-01

    Deep-time records that give an insight into the composition and dynamics of the ancestral Amazon rain forest are rare. Yet to understand the modern biodiversity patterns it is important to untangle the long-term evolution of this forest. Sampling Neogene strata requires drilling operations or complex fieldwork along the rivers where outcrops generally are small. In the nineties an exceptionally good exposure of fluvial sediments of early Miocene age (17.7-16.1 Ma) was documented near the island of Mariñame (Caquetá River, Colombian Amazonia) (Hoorn, 1994). This 60 m sediment succession consists of quartz-rich sands with a circa 10 m black, sandy clay intercalation. Palynomorphs are well preserved in these organic-rich clays and palynological analysis indicated high pollen diversity and changes in composition following changes in the sedimentary environment and water composition (see van Soelen et al., this session). A numerical analysis in R (2013) of the existing data, using a number of multivariate and other statistical techniques now shows a gradient of change in the composition of the Miocene palynological assemblages. Non-metric-multidimensional scaling using distance matrixes (Oksanen, 2012) and their visualizations in correlograms (Friendly, 2002) indicate that the regional (palm) swamp forests of Mauritiides franciscoi (Mauritia), frequently found together with other palms such as Psilamonocolpites amazonicus (Euterpe?) and Psilamonocolpites rinconii, were affected by a marine incursion. The latter is suggested by the change of composition and the presence of estuarine elements such as Zonocostites ramonae (Rhizophora), foraminifer linings and dinoflagellate cysts, which became common during the marine event. In the older part of the section, and at the top, Rhoipites guianensis (Sterculiaceae/Tiliaceae) is quite abundant, in contrast with the relatively low abundance of M. franciscoi. The numerical analysis allowed us to: a) group the pollen data into 3

  17. Episodic intraplate deformation of stable continental margins: evidence from Late Neogene and Quaternary marine terraces, Cape Liptrap, Southeastern Australia

    NASA Astrophysics Data System (ADS)

    Gardner, Thomas; Webb, John; Pezzia, Claudia; Amborn, Terri; Tunnell, Robert; Flanagan, Sarah; Merritts, Dorothy; Marshall, Jeffrey; Fabel, Derek; Cupper, Matthew L.

    2009-01-01

    for Tt 4 range from 0.01 mm/a to 0.04 mm/a (using a Late Pliocene age, ˜2 Ma), identical to the rates calculated for the Last Interglacial terrace, Qt 5. This indicates that deformation at Cape Liptrap has been ongoing at similar time-averaged rates at least since the Late Pliocene. The upper terraces in the sequence, Tt 3 (˜110 m amsl), Tt 2 (˜140 m) and Tt 1 (˜180 m) are undated, but most likely correlate to sea level highstands in the Neogene. Terraces Tt1-Tt4 show an increasing northward tilt with age. The Waratah Fault forms a prominent structural boundary in the Lachlan Fold Belt discernible from airborne magnetic and bouger gravity anomalies. Seismicity and deformation are episodic. Episodic movement on the Waratah Fault may be coincident with sea level highstands since the Late Pliocene, possibly from increased loading and elevated pore pressure within the fault zone. This suggests that intervals between major seismic events could be on the order of 100 ka.

  18. Variscan to Neogene thermal and exhumation history at the Moroccan passive continental margin assessed by low temperature thermochronology

    NASA Astrophysics Data System (ADS)

    Sehrt, M.; Glasmacher, U. A.; Stockli, D. F.; Kluth, O.; Jabour, H.

    2012-04-01

    In North Africa, a large amount of Mesozoic terrigenous sedimentary rocks are deposited in most of the basins along the continental margin indicating a major episode of erosion occurred during the rift and early post-rift period in the Central Atlantic. In the Tarfaya-Dakhla Basin, Morocco the sedimentary cover reaches thicknesses of up to 9000 m. The presence of high surface elevations in the Anti-Atlas mountain belt (2500 m) indicates a potential source area for the surrounding basins. The NE-SW oriented Anti-Atlas of Morocco is located at the northwestern fringe of the West African Craton and south of the High Atlas and represents the Phanerozoic foreland of the Late Paleozoic North African Variscides and the Cenozoic Atlas Belt. Variscan deformation affected most of Morocco. Paleozoic basins were folded and thrusted, with the major collision dated as late Devonian to Late Carboniferous. Zircon fission-track ages of 287 (±23) to 331 (±24) Ma confirmed the main exhumation referred to the Variscan folding, followed by rapid exhumation and the post-folding erosion. Currently, phases of uplift and exhumation in the Anti-Atlas during the Central Atlantic rifting and places where the associated erosion products are deposited are poorly constrained and there is little quantitative data available at present. The objective of the study is to determine the thermal and exhumation history of the Anti-Atlas and the connected Tarfaya-Dakhla Basin at the Moroccan passive continental margin. Besides zircon fission-track dating, apatite and zircon (U-Th-Sm)/He and apatite fission-track analyses and furthermore 2-D modelling with 'HeFTy' software has been carried out at Precambrian rocks of the Western Anti-Atlas and Cretaceous to Neogene sedimentary rocks from the Northern Tarfaya-Dakhla Basin. The apatite fission-track ages of 120 (±13) to 189 (±14) Ma in the Anti-Atlas and 176 (±20) to 216 (±18) Ma in the Tarfaya Basin indicate very obvious a Central Atlantic opening

  19. Age, origin and significance of SKS splitting in SE Iberia: insights from mantle xenoliths from Neogene alkaline basalts

    NASA Astrophysics Data System (ADS)

    Konc, Z.; Garrido, C. J.; Tommasi, A.; Padron Navarta, J. A.; Hidas, K.; Bosch, D.; Marchesi, C.; Szabó, Cs.

    2012-04-01

    The volcanic activity in the SE Iberian Volcanic Province (SE IVP) is the surface expression of magmatism in a complex geodynamic setting during the Cenozoic development of a Mediterranean-type back-arc basin in the Alboran realm. The late stage of this geodynamical evolution was characterized by Neogene alkaline basalt volcanism erupted at 2-3 Ma in the Tallante and Los Perez (Murcia) volcanic centers. This volcanism entrained numerous mantle xenoliths that provide a recent snapshot of the structure of the lithospheric mantle beneath this region. Xenoliths are spinel (± plagioclase ± amphibole) lherzolite, and minor harzburgite and wehrlite showing porphyroclastic to fine- to medium-grained granoblastic textures. Mantle xenoliths display a marked axial [100] pattern olivine Crystal Preferred Orientation (CPO) characterized by a strong alignment of olivine [100] axes near or parallel to the peridotite lineation and a girdle distribution of [010] axes with a maximum normal to the peridotite foliation. This CPO is consistent with dominant activation of the high temperature [100]{0kl} slip systems of olivine formed under a deformation regime dominated by simple shear or combinations of simple shear and pure shear with a transtensional component. The age of this deformation event is constrained by syn-tectonice composite xenoliths formed by reactive percolation of Si-rich melt/fluids with the lithospheric mantle during middle Miocene subduction/delamination of the paleo-iberian margin beneath the SE IVP. In order to investigate whether SKS anystropy recently measured beneath this region can be accounted by the olivine CPO of the lithospheric mantle, we have computed the theoretical seismic anisotropy of mantle xenoliths from their olivine CPOs and modal compositions. The averaged seismic properties of SE-IVP mantle xenoliths are characterized by fast propagation of P-waves and polarization of fast S-waves parallel to the peridotite lineation. The computed highest S

  20. Neogene sedimentary history of the Inner Cilicia Basin, eastern Mediterranean: a contribution to the TopoEurope VAMP project

    NASA Astrophysics Data System (ADS)

    Walsh, Susan; Kurtboǧan, Bahar; Akhun, Selin; Aksu, Ali; Hall, Jeremy; Ćifçi, Günay

    2010-05-01

    The Vertical Anatolian Movements Project (VAMP) addresses the Neogene uplift of the Taurides and the Central Anatolian Plateau. While terrestrial studies are focused on erosion in the sediment source area and deposition within the Turkish landmass, our marine work is focused to provide a history of deposition in one of the ultimate sinks: the eastern Mediterranean. In particular, we are mapping the distribution in space and time of sediment deposited from the Göksu River into the Cilicia Basin. In 2008 we collected ~2000 km of high-resolution marine multi-channel seismic reflection profiles radiating out from the present-day mouth of the Göksu River across the basin. The Göksu River delta is located on a narrow shelf at the junction of the Inner and Outer Cilicia Basins. The Inner Cilicia Basin consists of a 40 km-wide shelf linking to the onshore Adana Basin and a slope down to the deeper water (~ 1 km) of the Outer Cilicia Basin. The shelf is built out of a >2.5 km-thick sequence of Pliocene-Quaternary sediment overlying Messinian evaporites or older Miocene sediments. The evaporites have been mobilised to move down slope during the Pliocene-Quaternary so that the shelf is located above an extensional fault fan, complemented by a salt-cored fold/thrust belt in deeper water (see poster by Piercey et al., this meeting). The 2008 seismic reflection profiles show that the western margin of the Inner Cilicia Basin seaward of the mouth of the Göksu River is constructed by numerous vertically stacked and east-prograded delta successions. Detailed mapping in this region revealed that the sediment input from the Göksu River can be readily distinguished from the larger influxes from the coalescing Tarsus, Seyhan and Ceyhan Rivers to the north. The bases of major delta packages supplied by the Göksu River are marked by strong reflections, defining shelf-crossing unconformities, which can be correlated across the Inner Cilicia Basin. Industry exploration wells in the

  1. Gravity anomalies in Silurian pinnacle reef trend, southwestern Indiana

    SciTech Connect

    Malinconico, L.L. Jr.; Gognat, T.A.; Scher, P.L. )

    1989-08-01

    Structures produced over the top or along the margins of Silurian Pinnacle reefs have proven to be the source of significant oil production in the eastern Illinois basin. The authors have been able to refine gravity methods that can assist in the exploration of such reef targets. A gravity/density model was developed by combining the 1980 work of Dana at the Wilfred pool (Sullivan County, Indiana) with other lithologic and log data in southwestern Indiana. This model includes the density differences between the reef facies and surrounding lithologies as well as density variations that are the result of compaction of the sedimentary sequence above the reef. The density models suggest that positive gravity anomalies with amplitude between 1.5 to 2.5 mgals might occur over the reefs.

  2. Rib lesions in a prehistoric Puebloan sample from southwestern Colorado.

    PubMed

    Lambert, Patricia M

    2002-04-01

    An unusually high frequency of periosteal lesions of visceral rib surfaces was observed in a small, prehistoric skeletal series from southwestern Colorado. Lesions of this type have been concordant with pulmonary tuberculosis in three studies of human skeletal collections with known cause of death, and in a recent clinical investigation of rib dimensions in living patients with lung disorders. Diseases such as pneumonia and actinomycosis have also been found to cause these lesions, but in much lower frequencies. Archaeological evidence suggests that Puebloan farmers of Sleeping Ute Mountain's southern piedmont, from which the sample is drawn, endured unusually harsh environmental conditions punctuated by severe drought and exacerbated by escalating warfare. It is argued here that these environmental stressors increased susceptibility to an opportunistic respiratory infection reminiscent of tuberculosis, and possibly also some form of pneumonia, resulting in high rates of active disease previously noted only in historic Puebloan peoples.

  3. Jaguar critical habitat designation causes concern for Southwestern ranchers

    USGS Publications Warehouse

    Svancara, Colleen; Lien, Aaron M.; Vanasco, Wendy T.; Laura Lopez-Hoffman,; Ruyle, George B.

    2015-01-01

    The designation of jaguar critical habitat in April 2014 in southern Arizona and southwestern New Mexico created concern for livestock ranchers in the region. We interviewed ranchers to understand their concerns with the jaguar critical habitat designation and their attitudes toward jaguars, wildlife conservation, and resource management in general. Ranchers we interviewed were concerned about direct impacts of designated critical habitat on ranching, as well as possible alternative agendas of critical habitat advocates and issues specific to the borderlands region. The ranchers were less concerned about the presence of jaguars but were more concerned about possible limiting effects of the Endangered Species Act (ESA), distrust of government entities, and litigious environmental groups. To maximize effectiveness, government agencies should work to foster trust in the ranching community, be cognizant of sensitive issues specific to the region that may challenge endangered species conservation goals, recognize the opportunity to work with ranchers for endangered species management, and provide outreach about implications of the ESA.

  4. Weather and pheasant populations in southwestern North Dakota

    USGS Publications Warehouse

    Martinson, R.K.; Grondahl, C.R.

    1966-01-01

    High productivity and survival of ring-necked pheasants (Phasianus colchicus) were correlated with high rainfall and cool temperatures in May and June during an 8-year period in southwestern North Dakota. These findings differed markedly from those of several earlier studies in the less arid midwestern United States where cool, wet weather in the spring generally affected pheasant populations adversely. General trends in the pheasant population could be explained on the basis of precipitation in May and June. The population was relatively high during the mid-1950's when wet and dry May and June periods occurred in alternate years but declined markedly after 2 consecutive years of spring and summer drought. The population remained at a static low during 1960 through 1963 when wet and dry spring and summer periods again occurred alternately.

  5. A new species of Eumops (Chiroptera: Molossidae) from southwestern Peru.

    PubMed

    Medina, César E; Gregorin, Renato; Zeballos, Horacio; Zamora, Hugo T; Moras, Ligiane M

    2014-01-01

    The genus Eumops is the most diverse genera of molossid bats in the Neotropics. In Peru this genus is widely distributed and represented by nine species: E. auripendulus, E. delticus, E. hansae, E. maurus, E. nanus, E. patagonicus, E. perotis, E. trumbulli, and E. wilsoni. After several years of mammalian diversity surveys in the coastal desert and western slopes of southwestern Peru, a specimen of Eumops was collected whose unique set of traits allows us to assert that deserves to be described as a new species. Based on molecular and morphological evidence, the new species is related to medium-large sized species (i.e. E. glaucinus, E. auripendulus, and E. perotis). Cytochrome b genetic divergence between the new species and the other species of the genus was high (> 12%) and it is consistent with morphological divergence presented for this new species. This new species, endemic to Peru, increases the diversity of Eumops to 16 species. PMID:25544431

  6. Gazetteer of coal-mine lakes in southwestern Indiana

    USGS Publications Warehouse

    Bobo, Linda L.

    1979-01-01

    This gazetteer is a catalog of lakes formed by surface coal mining in southwestern Indiana that are 0.5 acre or larger and in nonactive mine areas. Approximately 1,000 of the lakes are listed by 7.5-minute quadrangle topographic-map name, lake-identification number, latitude and longitude, and county. Other data given are shape of lake, maximum length, mean width, length and development of shoreline, surface area, orientation, presence of a stream inlet or outlet, and geologic data (geologic formation of area surrounding the lake and the mined coal-bed member). Field data (sampling date, pH, specific conductance, apparent color of lake, and general vegetation along the shoreline) were collected for 287 of the lakes. The apparent colors of the lakes observed were varying shades of aqua, blue, brown, lime green, red, and green. Eighty percent of the lakes sampled were green. (Woodard - USGS)

  7. A new species of Eumops (Chiroptera: Molossidae) from southwestern Peru.

    PubMed

    Medina, César E; Gregorin, Renato; Zeballos, Horacio; Zamora, Hugo T; Moras, Ligiane M

    2014-10-22

    The genus Eumops is the most diverse genera of molossid bats in the Neotropics. In Peru this genus is widely distributed and represented by nine species: E. auripendulus, E. delticus, E. hansae, E. maurus, E. nanus, E. patagonicus, E. perotis, E. trumbulli, and E. wilsoni. After several years of mammalian diversity surveys in the coastal desert and western slopes of southwestern Peru, a specimen of Eumops was collected whose unique set of traits allows us to assert that deserves to be described as a new species. Based on molecular and morphological evidence, the new species is related to medium-large sized species (i.e. E. glaucinus, E. auripendulus, and E. perotis). Cytochrome b genetic divergence between the new species and the other species of the genus was high (> 12%) and it is consistent with morphological divergence presented for this new species. This new species, endemic to Peru, increases the diversity of Eumops to 16 species.

  8. Algae from the arid southwestern United States: an annotated bibliography

    SciTech Connect

    Thomas, W.H.; Gaines, S.R.

    1983-06-01

    Desert algae are attractive biomass producers for capturing solar energy through photosynthesis of organic matter. They are probably capable of higher yields and efficiencies of light utilization than higher plants, and are already adapted to extremes of sunlight intensity, salinity and temperature such as are found in the desert. This report consists of an annotated bibliography of the literature on algae from the arid southwestern United States. It was prepared in anticipation of efforts to isolate desert algae and study their yields in the laboratory. These steps are necessary prior to setting up outdoor algal culture ponds. Desert areas are attractive for such applications because land, sunlight, and, to some extent, water resources are abundant there. References are sorted by state.

  9. Formation and disruption of aquifers in southwestern Chryse Planitia, Mars

    USGS Publications Warehouse

    Rodriguez, J.A.P.; Tanaka, K.L.; Kargel, J.S.; Dohm, J.M.; Kuzmin, R.; Fairen, A.G.; Sasaki, S.; Komatsu, G.; Schulze-Makuch, D.; Jianguo, Y.

    2007-01-01

    We present geologic evidence suggesting that after the development of Mars' cryolithosphere, the formation of aquifers in southwestern Chryse Planitia and their subsequent disruption led to extensive regional resurfacing during the Late Hesperian, and perhaps even during the Amazonian. In our model, these aquifers formed preferentially along thrust faults associated with wrinkle ridges, as well as along fault systems peripheral to impact craters. The characteristics of degraded wrinkle ridges and impact craters in southwestern Chryse Planitia indicate a profound role of subsurface volatiles and especially liquid water in the upper crust (the upper one hundred to a few thousands of meters). Like lunar wrinkle ridges, the martian ones are presumed to mark the surface extensions of thrust faults, but in our study area the wrinkle ridges are heavily modified. Wrinkle ridges and nearby plains have locally undergone collapse, and in other areas they are associated with domical intrusions we interpret as mud volcanoes and mud diapirs. In at least one instance, a sinuous valley emanates from a modified wrinkle ridge, further indicating hydrological influences on these thrust-fault-controlled features. A key must be the formation of volatile-rich crust. Primary crustal formation and differentiation incorporated juvenile volatiles into the global crust, but the crustal record here was then strongly modified by the giant Chryse impact. The decipherable rock record here begins with the Chryse impact and continues with the resulting basin's erosion and infilling, which includes outflow channel activity. We propose that in Simud Vallis surface flow dissection into the base of the cryolithosphere-produced zones where water infiltrated and migrated along SW-dipping strata deformed by the Chryse impact, thereby forming an extensive aquifer in southwestern Chryse Planitia. In this region, compressive stresses produced by the rise of Tharsis led to the formation of wrinkle ridges

  10. Mapping cancer risk in southwestern Ontario with changing census boundaries.

    PubMed

    Nguyen, P; Brown, P E; Stafford, J

    2012-12-01

    Mapping disease risk often involves working with data that have been spatially aggregated to census regions or postal regions, either for administrative reasons or confidentiality. When studying rare diseases, data must be collected over a long time period in order to accumulate a meaningful number of cases. These long time periods can result in spatial boundaries of the census regions changing over time, as is the case with the motivating example of exploring the spatial structure of mesothelioma lung cancer risk in Lambton County and Middlesex County of southwestern Ontario, Canada. This article presents a local-EM kernel smoothing algorithm that allows for the combining of data from different spatial maps, being capable of modeling risk for spatially aggregated data with time-varying boundaries. Inference and uncertainty estimates are carried out with parametric bootstrap procedures, and cross-validation is used for bandwidth selection. Results for the lung cancer study are shown and discussed.

  11. Trichinella infection in wildlife of the southwestern United States.

    PubMed

    Pozio, E; Pence, D B; La Rosa, G; Casulli, A; Henke, S E

    2001-10-01

    Several potential mammalian reservoirs of sylvatic species of Trichinella were examined from Texas, New Mexico, and Arizona. During 1998-99, tongues were collected from a black bear (Ursus americanus) in Arizona; from 9 black bears, a coyote (Canis latrans), and a mountain lion (Felis concolor) in New Mexico; and from 154 coyotes, 32 raccoons (Procyon lotor), 13 opossums (Didelphis marsupialis), 4 ocelots (Leopardus pardalis), 3 bobcats (Lynx rufus), and 5 feral hogs (Sus scrofa) in southern Texas. Larvae of Trichinella murrelli were identified by a multiple-polymerase chain reaction analysis in 1 black bear (11.1%) from New Mexico and in 7 coyotes (4.5%) of Texas, whereas Trichinella spiralis larvae were detected in the black bear of Arizona. This is the first report of Trichinella infection in wildlife of New Mexico and Texas and extends the distribution of T. murrelli into the southwestern United States near the border of Mexico.

  12. Formal dementia care among first nations in southwestern Ontario.

    PubMed

    Finkelstein, Sara A; Forbes, Dorothy A; Richmond, Chantelle A M

    2012-09-01

    This article explores how dementia care is provided to First Nations communities in southwestern Ontario. Data were collected through in-depth interviews with health care providers and analysed using a constructivist grounded-theory methodology. Two interrelated frameworks for understanding dementia care were identified: a care delivery framework and a knowledge framework. The care delivery framework identified care goals, care elements being provided, care barriers, and strategies and solutions to deliver care and overcome barriers. The knowledge framework defined four groups of knowledge stakeholders: persons with dementia, informal care providers, formal care providers, and the First Nations community. It identified the knowledge each stakeholder held or needed and processes of sharing - or failing to share - knowledge in dementia care. Several barriers, many created by a lack of knowledge, negatively impacted dementia care. However, health care professionals had effective strategies for providing care, designed to overcome barriers and which encompassed elements of knowledge sharing. PMID:22828489

  13. New flutes document the earliest musical tradition in southwestern Germany.

    PubMed

    Conard, Nicholas J; Malina, Maria; Münzel, Susanne C

    2009-08-01

    Considerable debate surrounds claims for early evidence of music in the archaeological record. Researchers universally accept the existence of complex musical instruments as an indication of fully modern behaviour and advanced symbolic communication but, owing to the scarcity of finds, the archaeological record of the evolution and spread of music remains incomplete. Although arguments have been made for Neanderthal musical traditions and the presence of musical instruments in Middle Palaeolithic assemblages, concrete evidence to support these claims is lacking. Here we report the discovery of bone and ivory flutes from the early Aurignacian period of southwestern Germany. These finds demonstrate the presence of a well-established musical tradition at the time when modern humans colonized Europe, more than 35,000 calendar years ago. Other than the caves of the Swabian Jura, the earliest secure archaeological evidence for music comes from sites in France and Austria and post-date 30,000 years ago. PMID:19553935

  14. Trichinella infection in wildlife of the southwestern United States.

    PubMed

    Pozio, E; Pence, D B; La Rosa, G; Casulli, A; Henke, S E

    2001-10-01

    Several potential mammalian reservoirs of sylvatic species of Trichinella were examined from Texas, New Mexico, and Arizona. During 1998-99, tongues were collected from a black bear (Ursus americanus) in Arizona; from 9 black bears, a coyote (Canis latrans), and a mountain lion (Felis concolor) in New Mexico; and from 154 coyotes, 32 raccoons (Procyon lotor), 13 opossums (Didelphis marsupialis), 4 ocelots (Leopardus pardalis), 3 bobcats (Lynx rufus), and 5 feral hogs (Sus scrofa) in southern Texas. Larvae of Trichinella murrelli were identified by a multiple-polymerase chain reaction analysis in 1 black bear (11.1%) from New Mexico and in 7 coyotes (4.5%) of Texas, whereas Trichinella spiralis larvae were detected in the black bear of Arizona. This is the first report of Trichinella infection in wildlife of New Mexico and Texas and extends the distribution of T. murrelli into the southwestern United States near the border of Mexico. PMID:11695403

  15. Forecasting and evaluating patterns of energy development in southwestern Wyoming

    USGS Publications Warehouse

    Garman, Steven L.

    2015-01-01

    The effects of future oil and natural gas development in southwestern Wyoming on wildlife populations are topical to conservation of the sagebrush steppe ecosystem. To aid in understanding these potential effects, the U.S. Geological Survey developed an Energy Footprint simulation model that forecasts the amount and pattern of energy development under different assumptions of development rates and well-drilling methods. The simulated disturbance patterns produced by the footprint model are used to assess the potential effects on wildlife habitat and populations. A goal of this modeling effort is to use measures of energy production (number of simulated wells), well-pad and road-surface disturbance, and potential effects on wildlife to identify build-out designs that minimize the physical and ecological footprint of energy development for different levels of energy production and development costs.

  16. Deep resistivity structure in southwestern Utah and its geothermal significance

    SciTech Connect

    Wannamaker, P.E.; Ward, S.H.; Hohmann, G.W.; Sill, W.R.

    1983-02-01

    Magnetotelluric (MT) measurements in southwestern Utah have yielded a model of resistivity structure in this area to a depth of about 100 km. The MT observations are strongly affected by Great Basin graben sedimentary fill, which constitutes conductive upper-crustal lateral inhomogeneity and requires simulation using two- and three-dimensional modeling algorithms before deeper portions of the resistivity section can be resolved. Included in the model is a layer of low resistivity (20 ..cap omega..-m) residing from 35 to 65 km depth. Sensitivity tests of the data to the structure weigh strongly against the top of this layer being as shallow as 25 km and against the conductivity and thickness of the layer being highly correlated. No intra-crustal low-resistivity layer is indicated by the MT data.

  17. Feasibility study of wind-generated electricity for rural applications in southwestern Ohio

    NASA Astrophysics Data System (ADS)

    Kohring, G. W.

    The parameters associated with domestic production of wind generated electricity for direct use by small farms and rural homes in the southwestern Ohio region are discussed. The project involves direct utility interfaced electricity generation from a horizontal axis, down-wind, fixed pitch, wind powered induction generator system. Goals of the project are to determine: the ability to produce useful amounts of domestic wind generated electricity in the southwestern Ohio region; economic justification for domestic wind generated electrical production; and the potential of domestic wind generated electricity for reducing dependence on non-renewable energy resources in the southwestern Ohio region.

  18. Impact of Land Use on Soil Respiration in Southwestern Victoria

    NASA Astrophysics Data System (ADS)

    Teodosio, B.; Daly, E.; Pauwels, V. R. N.

    2015-12-01

    Land use management is one of the key contributors to the global environmental change. Considerable changes in landscapes have been experienced in Southwestern Victoria, Australia in the past two decades. Eucalyptus globulus (blue gum) plantations have expanded, resulting in possible changes in the water and carbon balances of catchments. The shift from pastures to plantations could have a significant impact on the local carbon balance with possible effects on atmospheric CO2 concentration and vegetation productivity. We present preliminary measurements from a field study comparing soil respiration in a plantation and a pasture. Adjacent catchments in Southwestern Victoria, near Gatum, were used as study areas; the prominent difference between the two catchments is the land use, with one catchment being used as a pasture for livestock grazing and the other catchment being mainly planted with blue gums. The variability of soil respiration in the pasture is governed by differences in soil moisture and substrate content due to local features of the topography and livestock grazing. Soil respiration measurements in the plantation were taken on mounds, access tracks, and open spaces. Most observations on mounds had higher soil respiration possibly due to root and mycorrhizal respiration. The measurements in open spaces had comparable values with mound measurements; this might be due to a less limited radiation. The soil respiration between trees had lower values, possibly because of radiation limitation due to the canopy cover. These preliminary measurements allow us to compare soil respiration variability across catchments with different land uses. This is important to estimate CO2 fluxes from soil to the atmosphere in large areas and will be valuable in estimating gross primary production from measurements of net ecosystem exchange.

  19. Projected Spatial and Temporal Hydroclimatic Variations Across Southwestern North America

    NASA Astrophysics Data System (ADS)

    Miller, S. M.; Gutzler, D. S.

    2013-12-01

    Climate across Southwestern North America (SWNA) is influenced by two distinct precipitation regimes. In much of the northern portion of the Southwest (roughly corresponding to the southwestern United States), midlatitude winter storm systems contribute the majority of total precipitation received each year. The southern portion of SWNA (roughly northwest Mexico) receives most of its total annual precipitation during the summer season via moist convection associated with the North American Monsoon. SWNA is projected to become drier throughout the 21st century as elevated temperatures force changes in the rates of evaporation and precipitation. This study uses climate model output to examine the relative roles of precipitation and evaporation, in the warm and cold seasons, to diagnose the cause(s) of the projected drying trend in the northern and southern halves of SWNA. We present an analysis of projected trends and variability of precipitation (P), evaporation (E), and the surface water budget (P-E) using output from the Coupled Model Intercomparison Project Phase Five (CMIP5) archive. We split SWNA into northern and southern halves corresponding to the precipitation regimes described above, and show that both subregions become drier (i.e., negative trend in P-E) in CMIP5 projections of 21st century climate. The drying trend in the northern half of SWNA is primarily driven by an increase in evaporation during the extended winter season. Summer season drying is primarily a function of decreased precipitation. The drying trend for the southern portion of SWNA is driven by a decrease in precipitation during both the summer and winter seasons, with E playing a secondary role. For both averaging boxes and seasons, precipitation appears to account for most of the interannual variability in the surface water budget. The role of temperature variability in modulating P-E is small for interannual fluctuations, but accounts for a large fraction of century-scale drying in the

  20. Landscape characteristics of disturbed shrubsteppe habitats in southwestern Idaho (USA)

    USGS Publications Warehouse

    Knick, Steven T.; Rotenberry, J.T.

    1997-01-01

    We compared 5 zones in shrubsteppe habitats of southwestern Idaho to determine the effect of differing disturbance combinations on landscapes that once shared historically similar disturbance regimes. The primary consequence of agriculture, wildfires, and extensive fires ignited by the military during training activities was loss of native shrubs from the landscape. Agriculture created large square blocks on the landscape, and the landscape contained fewer small patches and more large shrub patches than non-agricultural areas. In contrast, fires left a more fragmented landscape. Repeated fires did not change the distribution of patch sizes, but decreased the total area of remaining shrublands and increased the distance between remaining shrub patches that provide seed sources. Military training with tracked vehicles was associated with a landscape characterized by small, closely spaced, shrub patches. Our results support the general model hypothesized for conversion of shrublands to annual grasslands by disturbance. Larger shrub patches in our region, historically resistant to fire spread and large-scale fires because of a perennial bunchgrass understory, were more fragmented than small patches. Presence of cheatgrass (Bromus tectorum), an exotic annual, was positively related to landscape patchiness and negatively related to number of shrub cells. Thus, cheatgrass dominance can contribute to further fragmentation and loss of the shrub patch by facilitating spread of subsequent fires, carried by continuous fuels, through the patch. The synergistic processes of fragmentation of shrub patches by disturbance, invasion and subsequent dominance by exotic annuals, and fire are converting shrubsteppe in southwestern Idaho to a new state dominated by exotic annual grasslands and high fire frequencies.

  1. Potential for SGD induced submarine geohazard off southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Su, C.; Lin, C.; Cheng, Y.; Chiu, H.

    2013-12-01

    The submarine groundwater discharge (SGD) is not only play important roles on material exchange between land and sea, it may also trigger liquefaction process and induce further submarine geohazards in coastal zone. Since 2006, Southern Taiwan was experienced a series of natural hazards including earthquakes and typhoon that induced severe landslides and flooding and caused huge human lives and economics losses. These natural hazards also touched off submarine cable-break incidents off southwestern Taiwan from Gaoping Slope to the northern terminus of the Manila Trench. After the 2006 Pingtung Earthquake, the local fishermen reported disturbed waters at the Fangliao submarine canyon head. Although many researches conjectured the disturbed waters may caused by the eruption of submarine volcanoes which has been widely discovered off the southwestern Taiwan. The subbottom profiles reveal a series of faults and liquefaction strata exist near the head of Fanliao submarine canyon and acoustically transparent sediments with doming structures also observed at the adjacent area. Moreover, we also found pockmarks with acoustic blanking under it on the Gaoping Shelf and a series of gaseous pluming gushed from the seafloor was also observed in the shallow waters. Integrate all these data, we may reasonably infer the disturbed waters which reported by the fishermen may caused by the liquefaction process on the seafloor. In addition to geophysical observations, natural geochemical tracers (radon and radium) in conjunction with side-scan sonar were used to evaluate the distribution of SGD system in the study area. All the evidences indicate that the large earthquake in conjunction with high pore fluid pressures in the surface sediment might have easily triggered liquefaction process and generated large debris flow and swept the submarine cables away from the Fangliao submarine canyon head to the abyss.

  2. Offshore remobilization processes and deposits in low-energy temperate-water carbonate-ramp systems: Examples from the Neogene basins of the Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Puga-Bernabéu, Ángel; Martín, José M.; Braga, Juan C.; Aguirre, Julio

    2014-05-01

    General facies models developed for modern and ancient Mediterranean temperate-water carbonates in the last two decades have shown that the style of deposition on outer-ramp, slope, and basin environments in low-energy areas such as the Mediterranean Sea differs overall from that of high-energy open-ocean areas, given the wider variety of smaller-scale topographic and hydrodynamic conditions in the former setting. However, these depositional models generally lack relevant information about sedimentary processes, transport mechanisms and controlling factors on offshore sediment redeposition, which are potential sources of information for sequence stratigraphic, palaeoclimate and exploration studies. Several examples from the Neogene Betic basins of the western Mediterranean region have been selected to integrate the processes and controlling factors on the offshore sediment transport and the resulting deposits. Additional published data from other Mediterranean localities have also been considered.

  3. Late Miocene extensional tectonics in the evolution of the eastern Betics and Neogene-Quaternary basins, an example from the Sorbas basin (SE Spain).

    NASA Astrophysics Data System (ADS)

    Giaconia, Flavio; Booth-Rea, Guillermo; Martínez-Martínez, José Miguel; Azañón, José Miguel

    2013-04-01

    Neogene to Quaternary basins in the eastern Betics occur in synclines among near E/W-elongated antiformal ridges where the metamorphic basement crops out. These antiforms are related to or cut by large-scale strike-slip faults, both developed in response of the NW-SE Africa-Iberia convergence. Most literature associated the origin and evolution of the Neogene-Quaternary eastern Betics basins with this transpressional strike-slip regime. However, recent work showed the great importance of extensional tectonics in the development and evolution of these basins during the middle to late Miocene. In order to define the role of Miocene extensional tectonics in the origin and evolution of Neogene - Quaternary basins, we have carefully mapped a key area in the southeastern Betics, the western termination of Sierra Cabrera. We analyzed the age and linking relationships between brittle fault segments, and finally we constructed a balanced cross section. We identified a NW-SE listric normal fault system that was active during the Tortonian producing southwestward hanging-wall displacement. These normal faults show hard linkage relationships with E-W to N70E vertical strike-slip and oblique-slip extensional transfer faults that show both dextral and sinistral kinematics. The balanced cross section shows that listric faults probably join together into a basal detachment (about 1 km depth) inside the metamorphic basement (Nevado-Filabride complex). The fault system influenced the Tortonian sedimentary evolution of the Sorbas Basin controlling the sediments thickness. The early Tortonian sedimentary unit is missed in the hangingwall of the fault system, meanwhile the thickness of late Tortonian sediments deposited between 11 and 8 Ma change across the main faults from approximately 200 m thick in the footwall of the system to up to 800 m in the main depocentre. Furthermore, the fault system controlled the Tortonian sedimentary facies shifting from continental and deltaic

  4. What influences climate and glacier change in southwestern China?

    NASA Astrophysics Data System (ADS)

    Yasunari, Teppei J.

    2011-12-01

    The subject of climate change in the Tibetan Plateau (TP) and Himalayas has taken on increasing importance because of the availability of water resources from their mountain glaciers (Immerzeel et al 2010). Many of the glaciers over these regions have been retreating, while some are advancing and stable (Yao et al 2004, Scherler et al 2011). Other studies report that some glaciers in the Himalayas show acceleration of their shrinkage (e.g., Fujita and Nuimura 2011). However, the causes of glacier melting are still difficult to grasp because of the complexity of climatic change and its influence on glacier issues. Despite this, it is vital that we pursue further study to enable future predictions of glacier changes. The paper entitled 'Climate and glacier change in southwestern China during the past several decades' by Li et al (2011) provided carefully analyzed, quality controlled, long-term data on atmospheric temperature and precipitation during the period 1961-2008. The data were obtained from 111 Chinese stations. The researchers performed systematic analyses of temperature and precipitation over the whole southwestern Chinese domain. They discussed those changes in terms of other meteorological components such as atmospheric circulation patterns, radiation and altitude difference, and then showed how these factors could contribute to climate and glacier changes in the region. Air temperature and precipitation are strongly associated with glacier mass balance because of heat balance and the addition of mass when it snows. Temperature warming trends over many places in southwestern China were unequivocally dominant in all seasons and at higher altitudes. This indicates that the heat contribution to the glaciers has been increasing. On the other hand, precipitation has a wider variability in time and space. It is more difficult to clearly understand the effect of precipitation on the climate and glacier melting characteristics in the whole of southwestern China

  5. Anatomy of extremely thin marine sequences landward of a passive-margin hinge zone: Neogene Calvert Cliffs succession, Maryland, U.S.A.

    SciTech Connect

    Kidwell, S.M.

    1997-03-01

    Detailed examination of Neogene strata in cliffs 25--35 m high along the western shore of Chesapeake Bay, Maryland, reveals the complexity of the surviving record of siliciclastic sequences {approximately}150 km inland of the structural hinge zone of the Atlantic passive margin. Previous study of the lower to middle Miocene Calvert (Plum Point Member) and Choptank Formations documented a series of third-order sequences 7--10 m thick in which lowstand deposits are entirely lacking, transgressive tracts comprise a mosaic of condensed bioclastic facies, and regressive (highstand) tracts are present but partially truncated by the next sequence boundary; smaller-scale (fourth-order) cyclic units could not be resolved. Together, these sequences constitute the transgressive and early highstand tracts of a larger (second-order Miocene) composite sequence. The present paper documents stratigraphic relations higher in the Calvert Cliffs succession, including the upper Miocene St. Marys Formation, which represents late highstand marine deposits of the Miocene second-order sequence, and younger Neogene fluvial and tidal-inlet deposits representing incised-valley deposits of the succeeding second-order cycle. The St. Marys Formation consists of a series of tabular units 2--5 m thick, each with an exclusively transgressive array of facies and bounded by stranding surfaces of abrupt shallowing. These units, which are opposite to the flooding-surface-bounded regressive facies arrays of model parasequences, are best characterized as shaved sequences in which only the transgressive tract survives, and are stacked into larger transgressive, highstand, and forced-regression sets.

  6. Inheritance of Jurassic rifted margin architecture into the Apennines Neogene mountain building: a case history from the Lucretili Mts. (Latium, Central Italy)

    NASA Astrophysics Data System (ADS)

    Bollati, Andrea; Corrado, Sveva; Marino, Maurizio

    2012-06-01

    The western Lucretili Mts. in the central Apennines (Latium, Italy) have been recently re-mapped in great detail and are the subject of combined stratigraphic, sedimentological and structural investigations. In this paper, we present a new stratigraphic interpretation of the Jurassic paleogeography of western Lucretili Mts., where a rift-derived intrabasinal paleo-high of the Alpine Tethys has been identified for the first time by means of facies analysis and biostratigraphic dating. Recognised facies associations, combined with dated stratigraphic sections, allow to define the morphology of the structural paleo-high and to identify the associated gravity-driven deposits (olistoliths) accumulated in the surrounding basin. Furthermore, we investigated the modes of interaction between Jurassic extensional structures and the subsequent contractional patterns developed during the Tertiary mountain building. In detail, the role played during Apennines tectonics by the paleo-escarpments bounding the paleo-high and by the surrounding olistoliths has been analysed. The paleo-escarpments either acted as focussing features for ENE-directed frontal thrust ramp localisation and were offset with small shortening amounts or reactivated as NNE striking high angle transpressional faults or preserved the original geometries as a result of variable orientation of paleo-escarpments with respect to the Neogene compressive stress field (with ENE oriented sigma1). Newly formed ENE striking tear faults connect these either inherited or neo-formed discontinuities. This complex stratigraphic and structural pattern is substantially different from the previous interpretations of this portion of the central Apennines based on a hypothesised layer-cake stratigraphy deformed by neo-formed Neogene thrusts. This contribution strengthens the importance of integrating facies analyses and structural investigations to detect the influence of pre-orogenic structures on compressive structural patterns

  7. New insight on the recent tectonic evolution and uplift of the southern Ecuadorian Andes from gravity and structural analysis of the Neogene-Quaternary intramontane basins

    NASA Astrophysics Data System (ADS)

    Tamay, J.; Galindo-Zaldívar, J.; Ruano, P.; Soto, J.; Lamas, F.; Azañón, J. M.

    2016-10-01

    The sedimentary basins of Loja, Malacatos-Vilcabamba and Catamayo belong to the Neogene-Quaternary synorogenic intramontane basins of South Ecuador. They were formed during uplift of the Andes since Middle-Late Miocene as a result of the Nazca plate subduction beneath the South American continental margin. This E-W compressional tectonic event allowed for the development of NNE-SSW oriented folds and faults, determining the pattern and thickness of sedimentary infill. New gravity measurements in the sedimentary basins indicate negative Bouguer anomalies reaching up to -292 mGal related to thick continental crust and sedimentary infill. 2D gravity models along profiles orthogonal to N-S elongated basins determine their deep structure. Loja Basin is asymmetrical, with a thickness of sedimentary infill reaching more than 1200 m in the eastern part, which coincides with a zone of most intense compressive deformation. The tectonic structures include N-S, NW-SE and NE-SW oriented folds and associated east-facing reverse faults. The presence of liquefaction structures strongly suggests the occurrence of large earthquakes just after the sedimentation. The basin of Malacatos-Vilcabamba has some folds with N-S orientation. However, both Catamayo and Malacatos-Vilcabamba basins are essentially dominated by N-S to NW-SE normal faults, producing a strong asymmetry in the Catamayo Basin area. The initial stages of compression developed folds, reverse faults and the relief uplift determining the high altitude of the Loja Basin. As a consequence of the crustal thickening and in association with the dismantling of the top of the Andes Cordillera, extensional events favored the development of normal faults that mainly affect the basins of Catamayo and Malacatos-Vilcabamba. Gravity research helps to constrain the geometry of the Neogene-Quaternary sedimentary infill, shedding some light on its relationship with tectonic events and geodynamic processes during intramontane basin

  8. Morphology and growth history of Delgada Fan: implications for the Neogene evolution of Point Arena Basin and the Mendocino Triple Junction

    USGS Publications Warehouse

    Drake, D.E.; Cacchione, D.A.; Gardner, J.V.; McCulloch, D.S.; Masson, D.

    1989-01-01

    Long-range side scan (GLORIA) sonographs and seismic reflection data acquired during a survey of the western US Exclusive Economic Zone in 1984, coupled with information from Deep Sea Drilling Project sites, provide new insights into the growth and evolution of the Delgada Fan. Construction of the fan commenced in the latest Miocene (~6 Ma) following the filling of the Neogene Point Arena Basin. The large size of the fan is incompatible with the small present-day supply of sediment to the canyon system. The GLORIA data show the Delgada Fan to be a hybrid-type fan, exhibiting characteristics of both elongate and radial fans. The morphology and volume of the fan, along with evidence for a decline in accumulation rates on the lower fan during the Quaternary period, suggest that the fan experienced an early growth phase (latest Miocene and Pliocene) characterized by relatively rapid progradation of elongate fan lobes followed by a period (Quaternary) of slower growth that has featured a shift of depocenters to sites closer to the canyons and a transition to distributary channels bordered by less prominent levees and overbank deposits. We examine the growth of Delgada Fan in relation to the Neogene evolution of the North American-Pacific plate boundary using a series of paleogeographic reconstructions based on recently published time displacement histories of the Mendocino triple junction (MTJ), the San Andreas fault (SAF), and the Pacific plate, upon which the fan rests. The time displacement curves for the SAF and the MTJ suggest that the MTJ and Mendocino Fracture Zone overtook and passed Point Arena Basin at about 10 Ma when the basin lay immediately southwest of the present San Francisco Bay area. We suggest that the MTJ joined the SAF at approximately that time and location, thus making the SAF the master fault in the transform system. -from Authors

  9. Characteristics and distributions of atmospheric mercury emitted from anthropogenic sources in Guiyang, southwestern China

    EPA Science Inventory

    Continuous measurements of speciated atmospheric mercury (Hg), including gaseous elemental mercury (GEM), particulate mercury (PHg), and reactive gaseous mercury (RGM) were conducted in Guizhou Province, southwestern China. Guiyang Power Plant (GPP), Guiyang Wujiang Cement Plant,...

  10. 1:75K-Scale Geologic Mapping of Southwestern Melas Chasma, Mars

    NASA Astrophysics Data System (ADS)

    Edgar, L. A.; Skinner, J. A.

    2016-06-01

    The goal of this work is to document the geologic evolution of southwestern Melas Chasma, and to place localized observations into a broader, standardized context for comparison to other similar regions within the Valles Marineris basin system.

  11. Epidemiological Aspects of Dermatophytosis in Khuzestan, southwestern Iran, an Update.

    PubMed

    Rezaei-Matehkolaei, Ali; Rafiei, Abdollah; Makimura, Koichi; Gräser, Yvonne; Gharghani, Maral; Sadeghi-Nejad, Batool

    2016-08-01

    Dermatophytosis is among the most common superficial mycoses in Iran. The purpose of this report was to update the clinical and mycological features of human dermatophytosis in the Khuzestan, southwestern Iran. In the framework of a one-year survey, a total of 4120 skin, hair and nail samples obtained from the outpatients with symptoms suggestive of tinea were analyzed by using direct microscopy, culture and molecular identification methods. Strains isolated from cultures were subjected to amplification of the nuclear rDNA ITS regions in a PCR assay followed by an early established RFLP analysis. For confirmation of species identification, 100 isolates as representatives of all presumable species were subjected to ITS sequencing. Infection was confirmed in 1123 individuals (27.25 %) in the age range of 1-89 years by direct microscopy and/or culture including 603 males versus 520 females. Frequencies of infections were the highest and the lowest in age groups of 21-30 and 11-20 years, respectively. Tinea corporis was the most prevalent clinical manifestation followed by tinea cruris, tinea capitis, tinea manuum, tinea pedis, tinea unguium, tinea faciei and tinea barbae. Trichophyton interdigitale (58.7 %) was the most dominant isolate followed by Epidermophyton floccosum (35.4 %), Microsporum canis (3 %), T. rubrum (1.5 %), T. species of Arthroderma benhamiae (0.5 %), T. tonsurans (0.3 %) and T. violaceum (0.3 %). Other species included M. gypseum, M. fulvum and T. verrucosum (each one 0.1 %). Such a high occurrence of infection with T. interdigitale, which has not been reported from Iran, is due to the use of accurate molecular methods based on new species concept in dermatophytes. The prevalence of dermatophytoses caused by zoophilic species remarkably increased and Trichophyton species of A. benhamiae has emerged as a new agent of dermatophytosis in southwestern Iran, while infections due to anthropophilic species, except E. floccosum, took a

  12. Atmospheric Impacts of Marcellus Shale Gas Activities in Southwestern Pennsylvania

    NASA Astrophysics Data System (ADS)

    Presto, A. A.; Lipsky, E. M.; Saleh, R.; Donahue, N. M.; Robinson, A. L.

    2012-12-01

    Pittsburgh and the surrounding regions of southwestern Pennsylvania are subject to intensive natural gas exploration, drilling, and extraction associated with the Marcellus Shale formation. Gas extraction from the shale formation uses techniques of horizontal drilling followed by hydraulic fracturing. There are significant concerns about air pollutant emissions from the development and production of shale gas, especially methane emissions. We have deployed a mobile monitoring unit to investigate the atmospheric impacts of Marcellus Shale gas activities. The mobile sampling platform is a van with an on-board generator, a high-resolution GPS unit, cameras, and instrumentation for measuring methane, criteria gases (SO2, NOx, CO, O3), PM size distributions (scanning mobility particle sizer), black carbon mass (multi-angle absorption photometer), particle-bound polycyclic aromatic hydrocarbons, volatile organic compounds (gas chromatograph with flame ionization detection), and meteorological data. A major advantage of the mobile sampling unit over traditional, stationary monitors is that it allows us to rapidly visit a variety of sites. Sampling at multiple sites allows us to characterize the spatial variability of pollutant concentrations related to Marcellus activity, particularly methane. Data collected from the mobile sampling unit are combined with GIS techniques and dispersion models to map pollutants related to Marcellus Shale operations. The Marcellus Shale gas activities are a major and variable source of methane. The background methane concentration in Pittsburgh is 2.1 +/- 0.2 ppm. However, two southwestern Pennsylvania counties with the highest density of Marcellus Shale wells, Washington and Greene Counties, have many areas of elevated methane concentration. Approximately 11% of the sampled sites in Washington County and nearly 50% of the sampled sites in Greene County have elevated (>2.3 ppm) methane concentrations, compared to 1.5% of sites with elevated

  13. Holocene climate variability in south-western France

    NASA Astrophysics Data System (ADS)

    Oliveira, D.; Naughton, F.; Trigo, R.; Rodrigues, T.; Jouanneau, J.-M.; Weber, O.

    2012-04-01

    Vegetation and climate changes in western France/northern Spain are documented for the last c. 9000 cal. yr BP in a well dated shelf core, KS05-10, retrieved in the southwestern margin of the Bay of Biscay (Basque country) (43°22'765N, 2°16'744W). The continuous high resolution pollen record shows orbital and suborbital climate fluctuations similar to those noticed for the North Atlantic region and Greenland. A long-term Pinus, Quercus and Corylus forest reduction follows the cooling trend in Greenland and the general decrease of mid-latitude summer insolation until approximately 350 yr cal. BP. Within the millennial scale variability, the southwestern Bay of Biscay pollen record shows 6 main phases: The first phase, c. 9000 and 6600 cal. yr BP, is marked by a Pinus and deciduous Quercus forest with Corylus, indicating a humid and temperate climate. During the phase, c. 6600 - 4500 cal. yr BP, the pollen record shows a stable period of rich, mixed Quercus forest. During this interval occurred the establishment of Alnus, Ulmus, Tilia, Fraxinus excelsior-type and Fagus trees and the reduction of Pinus forest. This vegetation assemblage probably indicates an increase in moisture in relatively mild conditions. Fagus became continuously present in the region after c. 4500 c. cal. yr BP in agreement with what have been noticed by continental pollen sequences. An important contraction of Pinus, deciduous Quercus and Corylus forest occur after c. 3600 cal. yr BP. This evolution is contemporaneous to the maximum expansion of Fagus and the increase of heaths, which may be linked to a weakening of seasonality and more humid summer conditions. A strong forest reduction, involving all trees except pine, and a marked spread of herbaceous plants took place after c. 1400 cal. years BP. The presence of Juglans, Cerealia type and Castanea after c. 550 cal. yr BP and the re-expansion of Pinus after c. 350 cal. yr BP testify the increasing role played by the human activity in the

  14. Eddies in the southwestern East/Japan Sea

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Kyu; Niiler, Peter

    2010-10-01

    Closed loop mesoscale eddies were identified and tracked in the Ulleung Basin of the southwestern Japan/East Sea (JES) using the winding-angle (WA) methodology, for mapping the absolute geostrophic currents into surface streamlines of flow. The geostrophic velocity used here was the sum of the Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO), time variable velocity and the 1992-2007 mean geostrophic velocity. Local sampling bias was removed using the drifter observations. This WA methodology of deriving the Lagrangian path lines that drifters followed over a 7-day period was validated by individual drifter tracks and it demonstrated closed looping eddy motions. The WA method demonstrated that less than 6% of the closed streamlines appeared when drifters did not show a closed loop in their vicinity, compared to 30% of the excess detection rate by the Okubo-Weiss method of locating closed loop structures. Three groups of eddies were identified: (1) Coastal Cold and Warm Eddies, which appeared in the area between the coast of southern Korea and the East Korean Warm Current (EKWC), when a southward coastal current was present, (2) Frontal Cold and Warm Eddies, which were formed in the region of the seaward extension of the meandering EKWC, north of Ulleung Island and (3) Ulleung Warm Eddies (UWE) and Dok Cold Eddies (DCE), which appeared during meanders of the EKWC, in the Ulleung Basin. No seasonal concentration for eddy generation and eddy population was found. The average radius of eddies was about 38-60 km. These were born, moved in an erratic pattern and then died in the vicinity where the EKWC separated from the coast and formed a large meander. The time-mean large meander formed meridionally concentrated bands of positive and negative relative vorticity. The cyclonic (cold) eddies tend to reside within the band of positive time-mean relative vorticity, and the anticyclonic (warm) eddies reside within the bands of negative relative

  15. Neogene Tectonics of Part of the Junction of Cyprus and Hellenic Arcs in the Eastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Küçük, H. M.; Dondurur, D.; ćifçi, G.; Gürçay, S.; Hall, J.; Yaltırak, C.; Aksu, A. E.

    2012-04-01

    The junction between the Hellenic and Cyprus Arcs is one of the tectonically most active regions of the eastern Mediterranean. This junction developed in association with convergence between the African and Eurasian Plates, and the re-organization of the smaller Aegean-Anatolian and Arabian Microplates. Recent studies have shown that the predominant Miocene deformation process in the eastern Mediterranean is compressional tectonism. However, many studies have also shown that the strain is partitioned in the Pliocene-Quaternary and the area displays regions dominated by compression, strike slip and extensional tectonism. The junction between the Hellenic and Cyprus Arcs exhibits complex morphological features including submarine mountains, rises, ridges and trenches. Approximately 600 km of high resolution 72-channel seismic profiles were collected from the junction of Cyprus and Hellenic Arcs using a 450 m long 6.25 m hydrophone spacing streamer and a seven gun array with a 200 cubic inch total volume. This project was part of the joint scientific venture between Dokuz Eylül University (Turkey) and Memorial University of Newfoundland (Canada), and was funded by TÜBITAK and NSERC. The study area includes the southwestern Antalya Basin and the Anaxagoras Mountain of the larger Anaximander Mountains. The multichannel data were processed both at Dokuz Eylül and Memorial University of Newfoundland, using the Landmark Graphics ProMAX software, with automatic gain control, short-gap deconvolution, velocity analysis, normal move-out correction, stack, filter (typically 50-200 Hz bandpass), f-k time migration, and adjacent trace sum. Despite the fact that the source volume was modest, reflections are imaged to 2-3 s two-way time below seabed, even in 2 km water depth. The processed seismic reflection profiles show that there are three distinct sedimentary units, separated by two prominent markers: the M-reflector separates the Pliocene-Quaternary from the underlying

  16. Bird diversity and conservation of Alto Balsas (southwestern Puebla), Mexico.

    PubMed

    Ramírez-Albores, Jorge E

    2007-03-01

    Knowledge of the composition of the bird community in Alto Balsas (southwestern Puebla, Central Mexico) is needed for management programs aiming at protection and conservation of bird species and their habitats I studied sites with tropical deciduous forest. Data were obtained during 1666 hours of field work in 238 days from March 1998 to September 2000. Six permanent transect (3.5 km long and 100 m wide; 30 to 40 ha in each transect) were used to determine species richness in the study sites. The Shannon-Wiener diversity index was calculated for each site and Sorensen's index was used to assess similarity between sites. One-way analysis of variance was used to test for differences between sites in species richness and diversity values. A total of 128 species were recorded, Tepexco (n=75, H' = 3.76) and Puente Márquez (n=61, H' = 3.62) were the sites that showed the greatest specific richness and diversity. However, species richness and diversity seasonally patterns were similar among sites (ANOVA p > 0.05), with highest diversity during the rainy season. Most species were resident; 42 were migrants. The avifauna was represented by 30 species associated with tropical deciduous forest and 12 from open habitats or heavily altered habitats. Insectivores were the best represented trophic category, followed by carnivores and omnivores.

  17. Homicide-suicide events in Southwestern Croatia, 1986-2009.

    PubMed

    Cengija, Morana; Cuculic, Drazen; Petaros, Anja; Sosa, Ivan; Bosnar, Alan

    2012-10-01

    The aim of this study was to investigate the occurrence and characteristics of homicide-suicide events in Southwestern Croatia from 1986-2009 relying on autopsy reports of the Department of Forensic Medicine and Criminalistics, Rijeka and police records. A total of 17 cases involving 19 victims were identified. The perpetrators were most often men (82%), living in a spousal relationship with the victim. In 76.5% cases, suicide was committed immediately after homicide, and the same mean (most often an illegal firearm) was used for both. After examining the belongings of those involved in homicide-suicides, two factors differentiated our study from others, i.e. more victims and perpetrators were from the lower socioeconomic class and explosives were used in two homicide-suicide (12%) cases. The greater frequency of explosive used in homicide-suicide events may be a result of factors associated with the recent war fought in Croatia. These data prove the influence of sociological, historical and also political factors on the characteristics of a rare event such as homicide-suicide.

  18. Energy map of southwestern Wyoming, Part A - Coal and wind

    USGS Publications Warehouse

    Biewick, Laura R.H.; Jones, Nicholas R.

    2012-01-01

    To further advance the objectives of the Wyoming Landscape Conservation Initiative (WLCI) the U.S. Geological Survey (USGS) and the Wyoming State Geological Survey (WSGS) have compiled Part A of the Energy Map of Southwestern Wyoming. Focusing primarily on electrical power sources, Part A of the energy map is a compilation of both published and previously unpublished coal (including coalbed gas) and wind energy resources data, presented in a Geographic Information System (GIS) data package. Energy maps, data, documentation and spatial data processing capabilities are available in a geodatabase, published map file (pmf), ArcMap document (mxd), Adobe Acrobat PDF map (plate 1) and other digital formats that can be downloaded at the USGS website. Accompanying the map (plate 1) and the geospatial data are four additional plates that describe the geology, energy resources, and related infrastructure. These tabular plates include coal mine (plate 2), coal field (plate 3), coalbed gas assessment unit (plate 4), and wind farm (plate 5) information with hyperlinks to source publications and data on the internet. The plates can be printed and examined in hardcopy, or accessed digitally. The data represent decades of research by the USGS, WSGS, BLM and others, and can facilitate landscape-level science assessments, and resource management decisionmaking.

  19. Acoustic habitat of an oceanic archipelago in the Southwestern Atlantic

    NASA Astrophysics Data System (ADS)

    Bittencourt, Lis; Barbosa, Mariana; Secchi, Eduardo; Lailson-Brito, José; Azevedo, Alexandre

    2016-09-01

    Underwater soundscapes can be highly variable, and in natural conditions are often dominated by biological signals and physical features of the environment. Few studies, however, focused on oceanic islands soundscapes. Islands in the middle of ocean basins can provide a good example of how untouched marine soundscapes are. Autonomous acoustic recordings were carried out in two different seasons in Trindade-Martin Vaz Archipelago, Southwestern Atlantic, providing nearly continuous data for both periods. Sound levels varied daily and between seasons. During summer, higher frequencies were noisier than lower frequencies, with snapping shrimp being the dominating sound source. During winter, lower frequencies were noisier than higher frequencies due to humpback whale constant singing. Biological signal detection had a marked temporal pattern, playing an important role in the soundscape. Over 1000 humpback whale sounds were detected hourly during winter. Fish vocalizations were detected mostly during night time during both summer and winter. The results show an acoustic habitat dominated by biological sound sources and highlight the importance of the island to humpback whales in winter.

  20. Credit BG. View looking northeast at southwestern side of Test ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit BG. View looking northeast at southwestern side of Test Stand "D" complex. Test Stand "D" workshop (Building 4222/E-23) is at left; shed to its immediate right is an entrance to underground tunnel system which interconnects all test stands. To the right of Test Stand "D" tower are four Clayton water-tube flash boilers once used in the Steam Generator Plant 4280/E-81 to power the vacuum ejector system at "D" and "C" stands. A corner of 4280/E-81 appears behind the boilers. Boilers were removed as part of stand dismantling program. The Dv (vertical vacuum) Test Cell is located in the Test Stand "D" tower, behind the sunscreen on the west side. The top of the tower contains a hoist for lifting or lowering rocket engines into the Dv Cell. Other equipment mounted in the tower is part of the steam-driven vacuum ejector system - Jet Propulsion Laboratory Edwards Facility, Test Stand D, Edwards Air Force Base, Boron, Kern County, CA

  1. Daily movements of female mallards wintering in Southwestern Louisiana

    USGS Publications Warehouse

    Link, P.T.; Afton, A.D.; Cox, R.R.; Davis, B.E.

    2011-01-01

    Understanding daily movements of waterfowl is crucial to management of winter habitats, especially along the Gulf Coast where hunting pressure is high. Radio-telemetry was used to investigate movements of female Mallards (Anas platyrchychos) wintering in southwestern Louisiana. Movement distances were analyzed from 2,455 paired locations (diurnal and nocturnal) of 126 Mallards during winters 2004-2005 and 2005-2006 to assess effects of winter, female age, areas closed (Lacassine National Wildlife Refuge [LAC], Cameron Prairie National Wildlife Refuge [CAM], Amoco Pool [AMOCO] or open to hunting [OPEN]), and habitat type, including all interactions. Movement distances from the various land management categories were not consistent by age, date, or by winter. Flight distances from LAC increased with date, whereas those from CAM and OPEN did not vary significantly by date. Female Mallards moved short distances between diurnal and nocturnal sites (ranging from 3.1 to 15.0 km by land management category), suggesting that they are able to meet their daily energy requirements within a smaller area than Northern Pintails (Anas acuta, hereafter Pintails), and thus minimize transit energy costs.

  2. Source rock potential of middle Cretaceous rocks in southwestern Montana

    SciTech Connect

    Dyman, T.S.; Palacas, J.G.; Tysdal, R.G.; Perry, W.J. Jr.; Pawlewicz, M.J.

    1996-08-01

    The middle Cretaceous in southwestern Montana is composed of a marine and nonmarine succession of predominantly clastic rocks that were deposited along the western margin of the Western Interior Seaway. In places, middle Cretaceous rocks contain appreciable total organic carbon (TOC), such as 5.59% for the Mowry Shale and 8.11% for the Frontier Formation in the Madison Range. Most samples, however, exhibit less than 1.0% TOC. The genetic or hydrocarbon potential (S{sub 1}+S{sub 2}) of all the samples analyzed, except one, yield less than 1 mg HC/g rock, strongly indicating poor potential for generating commercial amounts of hydrocarbons. Out of 51 samples analyzed, only one (a Thermopolis Shale sample from the Snowcrest Range) showed a moderate petroleum potential of 3.1 mg HC/g rock. Most of the middle Cretaceous samples are thermally immature to marginally mature, with vitrinite reflectance ranging from about 0.4 to 0.6% R{sub o}. Maturity is high in the Pioneer Mountains, where vitrinite reflectance averages 3.4% R{sub o}, and at Big Sky, Montana, where vitrinite reflectance averages 2.5% R{sub o}. At both localities, high R{sub o} values are due to local heat sources, such as the Pioneer batholith in the Pioneer Mountains.

  3. Allochthonous Matter Input in Five Headwater Streams in Southwestern Colombia

    NASA Astrophysics Data System (ADS)

    Chara, J.; Baird, D.; Telfer, T.

    2005-05-01

    In order to determine the interactions between riparian vegetation and the stream environment in relation to the provision and seasonality of allochthonous energy, a study was done measuring the amount of litter inputs in five streams at mid altitude in southwestern Colombia during one year. Direct and lateral litter traps were placed in a 100m reach of each stream. Total amount of litter fall ranged from 1406 to 2812 g-m-2 year-1. Leaves were the most important component of the litter representing between 56 to 72% of direct and between 68 to 81% of lateral inputs. Seasonality of litter fall was minimal and only in one stream direct input was negatively correlated with rainfall (r=-0.62; p=0.033). According to these results, low-order streams in middle altitude in Colombia receive one of the highest amounts of litter fall reported so far. This supply is constant throughout the year providing a continuous source of food and substrate for the stream environment. As in temperate streams litterfall in the Andean zone is an important link between streams and the riparian environment. The higher amount recorded and the constant supply demonstrate that deforestation of riparian forests may be more negative for the streams in tropical areas.

  4. Permian karst topography in the Wichita uplift, southwestern Oklahoma

    SciTech Connect

    Donovan, R.N. Busbey, A.B. . Geology Dept.)

    1993-02-01

    The Wichita uplift in southwestern Oklahoma is one part of a record of Pennsylvania and early Permian deformation that affected the Southern Oklahoma aulacogen. As a result of a partial inversion, the Lower Paleozoic section of this aulacogen was sequentially stripped off an uplift between the Wichita uplift and the Anadarko basin, resulting in the exposure of ultrabasic rocks deep in the Cambrian igneous fill of the aulacogen. Following the late Paleozoic tectonism, the topography of the uplift was entombed beneath Permian sediments and remained essentially undisturbed until exhumation during the present erosional cycle. Modern erosion is gradually exposing this topography, permitting morphometric analysis of the Permian hill forms. Because of the variation of lithology in the uplift, it is possible to isolate the effects of weathering processes such as intense hydrolysis of the igneous rocks (producing, among other features, or topography) and limestone dissolution, in the form of a surface and subsurface karst imprint. The latter process resulted in a network of small caves that are essentially fissures eroded along tectonic fractures. These small caves can be found in all the exposed areas of limestone. They are particularly noteworthy for three reasons: in at least five examples they contain a complex fauna of Permian vertebrates (mostly fragmentary), speleothems in some examples contain hydrocarbon inclusions, derived from the underlying Anadarko basin, some of the caves yield evidence of post burial evolution in the form of clay infiltration from the surface and brine flushing from the underlying Anadarko basin.

  5. Strain accumulation and rotation in western Oregon and southwestern Washington

    USGS Publications Warehouse

    Svarc, J.L.; Savage, J.C.; Prescott, W.H.; Murray, M.H.

    2002-01-01

    Velocities of 75 geodetic monuments in western Oregon and southwestern Washington extending from the coast to more than 300 km inland have been determined from GPS surveys over the interval 1992-2000. The average standard deviation in each of the horizontal velocity components is ??? 1 mm yr-1. The observed velocity field is approximated by a combination of rigid rotation (Euler vector relative to interior North America: 43. 40??N ?? 0.14??, 119.33??W ?? 0.28??, and 0.822 ?? 0.057?? Myr-1 clockwise; quoted uncertainties are standard deviations), uniform regional strain rate (??EE = -7.4 ?? 1.8, ??EN = -3.4 ?? 1.0, and ??NN = -5.0 ?? 0.8 nstrain yr-1, extension reckoned positive), and a dislocation model representing subduction of the Juan de Fuca plate beneath North America. Subduction south of 44.5??N was represented by a 40-km-wide locked thrust and subduction north of 44.5??N by a 75-km-wide locked thrust.

  6. Source rock potential of middle cretaceous rocks in Southwestern Montana

    USGS Publications Warehouse

    Dyman, T.S.; Palacas, J.G.; Tysdal, R.G.; Perry, W.J.; Pawlewicz, M.J.

    1996-01-01

    The middle Cretaceous in southwestern Montana is composed of a marine and nonmarine succession of predominantly clastic rocks that were deposited along the western margin of the Western Interior Seaway. In places, middle Cretaceous rocks contain appreciable total organic carbon (TOC), such as 5.59% for the Mowry Shale and 8.11% for the Frontier Formation in the Madison Range. Most samples, however, exhibit less than 1.0% TOC. The genetic or hydrocarbon potential (S1+S2) of all the samples analyzed, except one, yield less than 1 mg HC/g rock, strongly indicating poor potential for generating commercial amounts of hydrocarbons. Out of 51 samples analyzed, only one (a Thermopolis Shale sample from the Snowcrest Range) showed a moderate petroleum potential of 3.1 mg HC/g rock. Most of the middle Cretaceous samples are thermally immature to marginally mature, with vitrinite reflectance ranging from about 0.4 to 0.6% Ro. Maturity is high in the Pioneer Mountains, where vitrinite reflectance averages 3.4% Ro, and at Big Sky Montana, where vitrinite reflectance averages 2.5% Ro. At both localities, high Ro values are due to local heat sources, such as the Pioneer batholith in the Pioneer Mountains.

  7. Jurassic petroleum geology of southwestern Clarke County, Mississippi

    SciTech Connect

    Jackson, J.B.; Harris, P.M.

    1983-01-24

    The Jurassic stratigraphy of southwestern Clark County, Mississippi, is representative of the central Gulf Coast. Evaporites, carbonates, and siliciclastics were deposited in restricted marine, shallow marine, transitional, and continental environments; structural development during and after deposition by regional faulting, local faulting, and salt movement directly affected hydrocarbon accumulation. Subsurface electric log data were studied from West Nancy, Nancy, East Nancy, Prairie Branch, and Lake Utopia fields and from the surrounding wildcats for the structural relations in and between producing fields and for the thickness and stratigraphic relations that affect production in three major units: the Norphlet and Smackover formations and the Buckner member of the Haynesville formation. Results suggest that (1) the East Nancy field probably has the best potential for future development because the original depositional feature is larger and older than that at the other fields and faulting has not greatly influenced entrapment or deposition, (2) the Smackover pay zone in the Prairie Branch field may be successfully developed on the south flank, and (3) the Nancy field might be developed on its southeast and northwest flanks in the upper oolite zone seen in the flank wells.

  8. Early Callovian ingression in southwestern Gondwana. Palaeoenvironmental evolution of the carbonate ramp (Calabozo Formation) in southwestern Mendoza, Neuquen basin, Argentina

    NASA Astrophysics Data System (ADS)

    Armella, Claudia; Cabaleri, Nora G.; Cagnoni, Mariana C.; Panarello, Héctor O.

    2013-08-01

    The carbonatic sequence of the Calabozo Formation (Lower Callovian) developed in southwestern Gondwana, within the northern area of the Neuquén basin, and is widespread in thin isolated outcrops in southwestern Mendoza province, Argentina. This paper describes the facies, microfacies and geochemical-isotopic analysis carried out in five studied localities, which allowed to define the paleoenvironmental conditions of a homoclinal shallow ramp model, highly influenced by sea level fluctuations, where outer, mid and inner ramp subenvironments were identified. The outer ramp subenvironment was only recognized in the south of the depocenter and is characterized by proximal outer ramp facies with shale levels and interbedded mudstone and packstone layers. The mid ramp subenvironment is formed by low energy facies (wackestone) affected by storms (packstones, grainstones and floatstones). The inner ramp subenvironment is the most predominant and is characterized by tidal flat facies (wackestones, packstones and grainstones) over which a complex of shoals (grainstones and packstones) dissected by tidal channels (packstone, grainstones and floatstones) developed. In the north area, protected environment facies were recorded (bioturbated wackestones and packstones). The vertical distribution of facies indicates that the paleoenvironmental evolution of the Calabozo Formation results from a highstand stage in the depocenter, culminating in a supratidal environment, with stromatolitic levels interbedded with anhydrite originated under restricted water circulation conditions due to a progressive isolation of the basin. δ13C and δ18O values of the carbonates of the Calabozo Formation suggest an isotopic signature influenced by local palaeoenvironmental parameters and diagenetic overprints. The δ13C and δ18O oscillations between the carbonates of the different studied sections are related with lateral facies variations within the carbonate ramp accompanied with dissimilar

  9. Complex Proterozoic crustal assembly of southwestern North America in an arcuate subduction system:Tthe Black Canyon of the Gunnison, southwestern Colorado

    NASA Astrophysics Data System (ADS)

    Jessup, Micah J.; Kalstrom, Karl E.; Connelly, James; Williams, Michael; Livaccari, Richard; Tyson, Amanda; Rogers, Steven A.

    The dominant orogenic fabric in Proterozoic rocks of the southwestern U.S. includes a series of NE-striking shear zones that are commonly interpreted as suture zones across which blocks of juvenile crust were assembled to the southern margin of Laurentia. New structural and geochronological data from southwestern Colorado suggest that fabrics related to assembly of tectonostratigraphic terranes in this area strike northwest. The NW-striking foliations represent deformation at ca. 10-20 km paleodepths (ca. 1.77-1.71 Ga), and are parallel to magnetic anomalies and to gradients in mantle velocity structure. The agreement between these data sets suggests that the NW-striking structures are important at lithospheric scale, extend to >100 km depth, and may record assembly of southwestern Colorado across NW-striking tectonic boundaries. Geochronologic data indicate that northwest (central Colorado)—and northeast (Cheyenne belt)—striking boundaries developed simultaneously during accretion of southwestern Laurentia between ca. 1.78-1.73 Ga. We propose that the Yavapai province at ca. 1.75 Ga may have involved a complex arcuate subduction system, with multiple arcs, analogous to that of the modern Banda Sea, in the Indonesia region.

  10. Magnetostratigraphy of the Quebrada La Porcelana section, Sierra de Ramos, Salta Province, Argentina: age limits for the Neogene Orán Group and uplift of the southern Sierras Subandinas

    NASA Astrophysics Data System (ADS)

    Reynolds, J. H.; Hernández, R. M.; Galli, C. I.; Idleman, B. D.

    2001-12-01

    We present a magnetostratigraphic investigation of Neogene Orán Group strata at Quebrada La Porcelana. The area is located in the southern Sierras Subandinas of northwestern Argentina within the zone of 'normal' subduction. The oldest datable Neogene strata were deposited ˜8.1 Ma at the base of the Terciário Subandino. We estimate that the youngest strata are considerably younger than 1 m.y. The basal age is millions of years younger than lateral correlative units farther to the south in the Transition Zone. These chronostratigraphic results suggest that foreland thrusting was initiated much later in northernmost Argentina than it was in the Transition Zone. The data suggest that generation and migration of hydrocarbons from the Los Monos source horizon began about 3.8 Ma. Growth strata deposition began at ˜4.2 Ma, suggesting that trapping structures were available in the region when migration began.

  11. The Structure of the Crust and Uppermost Mantle Beneath the Central Andes from Ambient Noise Tomography: Imaging the Neogene to Modern Batholith

    NASA Astrophysics Data System (ADS)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Porter, R. C.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2012-12-01

    The Central Andes of southern Peru, Bolivia, and northern Chile (between ~10°S and ~35°S) comprise the largest orogenic plateau in the world associated with abundant arc volcanism, the Central Andean Plateau (CAP). The goal of this continental-scale Ambient Noise Tomography (ANT) project is to incorporate broadband seismic data from ~20 seismic networks deployed incrementally in the Central and Southern Andes from May 1994 through March 2012, to image the vertically polarized shear-wave velocity (Vsv) structure of the CAP. First-order correlations with our shallow results (~5 km) and the morphotectonic provinces as well as subtler geological features indicate our results are robust. Our major results include mapping a pervasive mid-crustal low-velocity zone (<3.25 km/s) underneath the western portion of the CAP and a locally ultra-low-velocity anomaly (~2.0 km/s) beneath the Altiplano-Puna Volcanic Complex (APVC). The presence of a large and laterality extensive low-velocity zone suggests either a zone of partial melt ("mush") associated with batholith formation at depth, a thermally weakened crust capable of lateral flow, or the presence of aqueous fluids. Magnetotelluric studies that overlap our images do not resolve a high conductivity anomaly across our low-velocity zone as expected in the presence of aqueous fluids or large interconnected zones of partial melt. Therefore, we dismiss them as likely explanations for our imaged low-velocity body outside of the APVC location. Working under the hypothesis that voluminous ignimbrites are the surface expression of batholith formation at depth as exemplified by the APVC, we combine our results with the locations of known Neogene ignimbrite eruptive centers and negative isostatic residual gravity anomalies and suggest the 3.25 km/s shear-wave velocity contour at 15 km depth generally outlines the extent of a Neogene to modern batholith, with isolated pockets of partial melt where velocities dip below 3.0 km/s. A

  12. Spatio-temporal autocorrelation of Neogene-Quaternary volcanic and clastic sedimentary rocks in SW Montana and SE Idaho: Relationship to Cenozoic tectonic and thermally induced extensional events

    NASA Astrophysics Data System (ADS)

    Davarpanah, A.; Babaie, H. A.; Dai, D.

    2013-12-01

    Two systems of full and half grabens have been forming since the mid-Tertiary through tectonic and thermally induced extensional events in SW Montana and neighboring SE Idaho. The earlier mid-Tertiary Basin and Range (BR) tectonic event formed the NW- and NE-striking mountains around the Snake River Plain (SRP) in Idaho and SW Montana, respectively. Since the mid-Tertiary, partially synchronous with the BR event, diachronous bulging and subsidence due to the thermally induced stress field of the Yellowstone hotspot (YHS) has produced the second system of variably-oriented grabens through faulting across the older BR fault blocks. The track of the migration of the YHS is defined by the presence of six prominent volcanic calderas along the SRP which become younger toward the present location of the YHS. Graben basins bounded by both the BR faults and thermally induced cross-faults (CF) systems are now filled with Tertiary-Quaternary clastic sedimentary and volcanic-volcaniclastic rocks. Neogene mafic and felsic lava which erupted along the SRP and clastic sedimentary units (Sixmile Creek Fm., Ts) deposited in both types of graben basins were classified based on their lithology and age, and mapped in ArcGIS 10 as polygon using a combination of MBMG and USGS databases and geological maps at scales of 1:250.000, 1:100,000, and 1:48,000. The spatio-temporal distributions of the lava polygons were then analyzed applying the Global and Local Moran`s I methods to detect any possible spatial or temporal autocorrelation relative to the track of the YHS. The results reveal the spatial autocorrelation of the lithology and age of the Neogene lavas, and suggest a spatio-temporal sequence of eruption of extrusive rocks between Miocene and late Pleistocene along the SRP. The sequence of eruptions, which progressively becomes younger toward the Yellowstone National Park, may track the migration of the YSH. The sub-parallelism of the trend of the SRP with the long axis of the

  13. Geologic history of the Neogene “Qena Lake” developed during the evolution of the Nile Valley: A sedimentological, mineralogical and geochemical approach

    NASA Astrophysics Data System (ADS)

    Philobbos, Emad R.; Essa, Mahmoud A.; Ismail, Mustafa M.

    2015-01-01

    Siliciclastic and carbonate sediments were laid down in southern Wadi Qena and around the Qena Nile bend (Middle Egypt) in a lacustrine-alluvial environment which dominated a relatively wide lake, the "Qena Lake" that interrupted the Nile course during the Neogene time. These sediments are represented mainly by the oldest dominantly lacustrine chocolate brown mudstones of the Khuzam Formation that accumulated nearer to the center of that lake (now forming a 185 m terrace above sea level), overlain by the dominantly lacustrine carbonates and marls of the Durri Formation which accumulated during semi-arid conditions, mainly nearer to the periphery of the lake (now forming 170, 180 and 185 m terraces a.s.l. in the studied sections). The water level of the "Qena Lake" reached 240 m. above sea level, as indicated by the maximum carbonate elevation reached in the region. Finally fanglomerates of the Higaza Formation with its chert and limestone conglomerates accumulated during torrential periods at higher elevations (forming 240, 300 and 400 m terraces a.s.l.). These three formations accumulated in this particular area before and during the unroofing of the basement rocks of the Eastern Desert, west of the watershed. According to the known Early Miocene initial development of the Nile Valley, beside the occurrence of similar deposits of Oligocene age along the eastern side of the basement range, the earlier known Pliocene age given for these sediments in the Qena area is here questioned. It might belong to earlier Miocene?-Pliocene times. As the basement rocks of the Eastern Desert were still covered by Cretaceous-Paleogene sedimentary rocks while the Khuzam, Durri and Higaza Formations were accumulating in the Qena Lake region, it is believed, contrary to the belief of some authors, that the basement rocks of the Eastern Desert were not the source of these sediments. The carbonate petrographic study, beside the X-ray, and the11 major oxides and 22 trace elements

  14. Ecology of subtropical evergreen broad-leaved forests of Yunnan, southwestern China as compared to those of southwestern Japan.

    PubMed

    Tang, Cindy Q; Ohsawa, Masahiko

    2009-05-01

    Subtropical evergreen broad-leaved forests of Yunnan, China, including mid-montane moist, monsoon, and semi-humid categories, were studied in terms of ecological attributes of pertinent species, diversity, structure, dynamics and succession, as compared with the subtropical/warm-temperate evergreen broad-leaved rain forest of southwestern (SW) Japan. The genera and species of the forests of Yunnan and SW Japan are East Asian elements and indicate a very close relationship between the respective floras, though different assemblages of species occur in the two regions. Diversity indices and numerical data on taxon richness at family, genus and species level were similar in both regions. Four types of gap-regeneration behaviors among the major tree species were recognized in the two areas. In both, as a result of long-term human activity, the plant communities ranged from pioneer deciduous broad-leaved and/or pioneer coniferous stands to late-successional evergreen broad-leaved stands. Succession in the two regions followed parallel paths, beginning with pioneer Alnus in Yunnan and Alnus, Mallotus and Styrax in Japan, accompanied by coniferous Pinus in the two areas, and with late-successional evergreen broad-leaved Cyclobalanopsis and Castanopsis as their final stage. PMID:19277828

  15. Ecology of subtropical evergreen broad-leaved forests of Yunnan, southwestern China as compared to those of southwestern Japan.

    PubMed

    Tang, Cindy Q; Ohsawa, Masahiko

    2009-05-01

    Subtropical evergreen broad-leaved forests of Yunnan, China, including mid-montane moist, monsoon, and semi-humid categories, were studied in terms of ecological attributes of pertinent species, diversity, structure, dynamics and succession, as compared with the subtropical/warm-temperate evergreen broad-leaved rain forest of southwestern (SW) Japan. The genera and species of the forests of Yunnan and SW Japan are East Asian elements and indicate a very close relationship between the respective floras, though different assemblages of species occur in the two regions. Diversity indices and numerical data on taxon richness at family, genus and species level were similar in both regions. Four types of gap-regeneration behaviors among the major tree species were recognized in the two areas. In both, as a result of long-term human activity, the plant communities ranged from pioneer deciduous broad-leaved and/or pioneer coniferous stands to late-successional evergreen broad-leaved stands. Succession in the two regions followed parallel paths, beginning with pioneer Alnus in Yunnan and Alnus, Mallotus and Styrax in Japan, accompanied by coniferous Pinus in the two areas, and with late-successional evergreen broad-leaved Cyclobalanopsis and Castanopsis as their final stage.

  16. Using vegetation model-to-data comparisons to test the role of abiotic factors in the Neogene and Quaternary origins of modern C4 grasslands

    NASA Astrophysics Data System (ADS)

    Fox, D. L.; Strömberg, C.; Pau, S.; Taylor, L.; Lehmann, C.; Osborne, C.; Beerling, D. J.; Still, C. J.

    2014-12-01

    Grasslands dominated by taxa using the C4 photosynthetic pathway evolved on several continents during the Neogene and Quaternary, long after C4 photosynthesis first evolved among grasses. The histories of these ecosystems are relatively well documented in the geological record from stable carbon isotopes (fossil vertebrate herbivores, paleosols) and the plant microfossil record (pollen, phytoliths). The distinct biogeography and ecophysiology of modern C3 and C4 grasses have led to hypotheses explaining the origins of C4 grasslands in terms of long term changes in the Earth system such as increased aridity and decreasing atmospheric pCO2. However, proxies for key parameters of these hypotheses (e.g., temperature, precipitation, pCO2) are still in development, not yet widely applied, or remain contentious, so testing the hypotheses globally remains difficult. To understand better possible links between changes in the Earth system and the origin of C4 grasslands on different continents, we are undertaking a global scale comparison between observational records of C4 grass abundances in Miocene and Pliocene localities compiled from the literature, and three increasingly complex models of C4 dominance and abundance. The literature compilation comprises >2,600 δ13C values of both fossil vertebrates and of paleosol carbonates and >6,700 paleobotanical records. We are using paleoclimate output from the HadCM3L GCM over a range of pCO2 values for each epoch to model C4 dominance or abundance in grid cells as (Model 1) months per year exceeding the temperature at which net assimilation is greater for C4 than C3 photosynthesis (crossover temperature); (Model 2) the number of months per year exceeding the crossover temperature and having sufficient precipitation for growth (≥25 cm/yr; Collatz model); and (Model 3) the Sheffield Dynamic Global Vegetation Model (SDGVM), output from which includes biomass (g C/m2/yr) for distinct structural components (roots, stems, leaves

  17. Bedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf

    USGS Publications Warehouse

    Grantz, Arthur; Pease, Victoria L.; Willard, Debra A.; Phillips, R.L.; Clark, David L.

    2001-01-01

    Two piston cores from the Eurasian flank of Lomonosov Ridge near lat 88.9°N, long 140°E provide the first samples of bedrock from this high-standing trans-Arctic ridge. Core 94-PC27 sampled nonmarine siltstone similar in facies and age to uppermost Triassic to lower Lower Jurassic and mid– Lower Cretaceous beds in the 4 to > 5 km Mesozoic section on Franz Josef Land, on the outer Barents shelf. A ca. 250 Ma peak in the cumulative frequency curve of detrital zircons from the siltstone, dated by U- Th-Pb analysis, suggests a source in the post-tectonic syenites of northern Taymyr and nearby islands in the Kara Sea. Textural trends reported in the literature indicate that the Lower Jurassic nonmarine strata of Franz Josef Land coarsen to the southeast; this suggests the existence of a sedimentary system in which detrital zircons could be transported from the northern Taymyr Peninsula to the outer Barents shelf near the position of core 94-PC27 prior to opening of the Eurasia Basin. Correlation of the coaly siltstone in core 94-PC27 with part of the Mesozoic section on Franz Josef Land is compatible with the strong evidence from seafloor magnetic anomalies and bathymetry that Lomonosov Ridge is a continental fragment rifted from the Barents shelf during the Cenozoic. It also suggests that Lomonosov Ridge near the North Pole is underlain by a substantial section of unmetamorphosed Mesozoic marine and nonmarine sedimentary strata. Core 94-PC29 sampled cyclical deposits containing ice-rafted debris (IRD) overlying weakly consolidated laminated olive-black anoxic Neogene siltstone and mudstone with an average total organic carbon (TOC) of 4.1 wt%. The high TOC content of the mudstone indicates that during the Neogene, prior to the introduction of IRD into the Arctic seas about 3.3 Ma (early late Pliocene), the shallow waters of the central Arctic Ocean supported significant primary photosynthetic organic production near the North Pole. These deposits also contain fine

  18. Neogene-quaternary Ostracoda and paleoenvironments, of the Limón basin, Costa Rica, and Bocas del Toro basin, Panama

    USGS Publications Warehouse

    Borne, P.F.; Cronin, T. M.; Hazel, J.E.

    1999-01-01

    Tropical marine ostracodes from Neogene and Quaternary sediments of the Central American Caribbean region have been the subject of biostratigraphic, ecological, taxonomic, and evolutionary studies. As part of the Panama Paleontology Project (PPP), Neogene and Quaternary ostracodes are being studied from the Central American region. The overall goal of this research is to evaluate the impact of the emergence of the Central American Isthmus as a land barrier between the Caribbean/tropical Atlantic and the Pacific oceans on marine ostracode biodiversity and the oceanic environments in which extant ostracodes evolved. Due to the ecological specificity of many living tropical ostracode species, they are ideally suited for reconstructing paleoenvironments on the basis of their occurrence in fossil assemblages, which in turn can lead to a better understanding of the tropical climatic and tectonic history of Central America. The principal aims of this chapter are: (a) to document the composition of the ostracode assemblages from the Limón Basin of Costa Rica and the Bocas del Toro Basin of Panama, two areas yielding extensive ma rine ostracode assemblages; (b) to describe the environments of deposition within these basins; and (c) to document the stratigraphic distribution of potentially agediagnostic ostracode species in the Limón and Bocas del Toro basins in order to enhance their use in Central American biostratigraphy. A secondary, but none-the-less important goal is to assemble a database on the distribution of modem ostracode species in the Caribbean and adjacent areas as a basis for comparison with fossil assemblages. Although the ecological, biostratigraphic and paleoenvironmental conclusions presented here will improve as additional material is studied, these fossil and modem ostracode databases constitute the foundation for future evolutionary and geochernical studies of tropical Caribbean and eastern Pacific Ocean ostracodes. Moreover, we present here evidence

  19. Using Milankovitch Cyclicity as a High-Resolution Dating and Correlation Tool to Understand the Stratigraphic Evolution of the Late Neogene Central California Margin

    NASA Astrophysics Data System (ADS)

    Hill, P. S.; Behl, R. J.

    2003-12-01

    Natural gamma ray logs from Ocean Drilling Program (ODP) sites off the Central California margin and from oil wells on the outer continental shelf show cyclical variation at Milankovitch periodicities in the Neogene upper-Monterey and Sisquoc Formations and their offshore equivalents. The well-dated ODP Site 1016, 150 km offshore of Point Conception, provides the basis for development of an orbital cyclicity-refined age/depth scale that can be applied to the mid-latitude North American margin region. We correlate silica-rich/detritus-rich cycles in logs from this site to cycles in more proximal offshore and onshore oil wells in a transect across the Santa Maria Basin, thereby helping to refine dating of these rapidly-accumulated, biostratigraphically-impoverished, fine-grained sediments, which are otherwise difficult to date. The higher resolution, orbitally-based age-depth scale provides refined dating of oil well logs, revision of the numerical age range of biostratigraphic markers, recognition and quantification of changes in sedimentation rates over time and in space, and identification of generalized climatic/sedimentation trends along the Alta-Baja California margin. For example: the new age model indicates that regional age ranges of some radiolarian biostratigraphic markers extend later than previously documented in other regions. Linear sedimentation rates decrease by an order of magnitude from 45-75 cm/ky to 7-8.5 cm/ky between proximal offshore locations and the distal Site 1016A. Analysis of the frequency modulation of the major harmonic in the frequency spectrum of the gamma ray vs. depth curve reveals the presence of condensed sections between ~4.4-4.8 Ma and ~5.3-5.6 Ma at Site 1016A. These two intervals may be associated with Neogene Hiatus 7 of Keller and Barron (1983). Natural gamma ray logs from deep-sea sites of ODP Leg 167 and the proximal Santa Maria basin wells show a similarity in gross secular trends along a 1300 km stretch of the Alta

  20. Geology of the Yucca Mountain site area, southwestern Nevada

    USGS Publications Warehouse

    Keefer, W.R.; Whitney, J.W.; Buesch, D.C.

    2006-01-01

    Yucca Mountain in southwestern Nevada is a prominent, irregularly shaped upland formed by a thick apron of Miocene pyroclastic-flow and fallout tephra deposits, with minor lava flows, that was segmented by through-going, large-displacement normal faults into a series of north-trending, eastwardly tilted structural blocks. The principal volcanic-rock units are the Tiva Canyon and Topopah Spring Tuffs of the Paintbrush Group, which consist of volumetrically large eruptive sequences derived from compositionally distinct magma bodies in the nearby southwestern Nevada volcanic field, and are classic examples of a magmatic zonation characterized by an upper crystal-rich (>10% crystal fragments) member, a more voluminous lower crystal-poor (<5% crystal fragments) member, and an intervening thin transition zone. Rocks within the crystal-poor member of the Topopah Spring Tuff, lying some 280 m below the crest of Yucca Mountain, constitute the proposed host rock to be excavated for the storage of high-level radioactive wastes. Separation of the tuffaceous rock formations into subunits that allow for detailed mapping and structural interpretations is based on macroscopic features, most importantly the relative abundance of lithophysae and the degree of welding. The latter feature, varying from nonwelded through partly and moderately welded to densely welded, exerts a strong control on matrix porosities and other rock properties that provide essential criteria for distinguishing hydrogeologic and thermal mechanical units, which are of major interest in evaluating the suitability of Yucca Mountain to host a safe and permanent geologic repository for waste storage. A thick and varied sequence of surficial deposits mantle large parts of the Yucca Mountain site area. Mapping of these deposits and associated soils in exposures and in the walls of trenches excavated across buried faults provides evidence for multiple surface-rupturing events along all of the major faults during

  1. Evaluation of elemental enrichments in surface sediments off southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Chen-Tung; Kandasamy, Selvaraj

    2008-05-01

    Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O{3/T} suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C-S-Fe relationship owing to authigenic precipitation of Fe-Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.

  2. Petrogenesis of pegmatites and granites in southwestern Maine

    SciTech Connect

    Tomascak, P.B.; Walker, R.J.; Krogstad, E.J. . Dept. of Geology)

    1993-03-01

    Granitic pegmatites occurring near the town of Topsham in southwestern Maine are mineralogically diverse, featuring abundant dikes and contain rare earth element minerals as well as one pegmatite that contains Li minerals. The pegmatite series crops out near the Brunswick granite, a texturally diverse granitic pluton, and lies 13 km southeast of the Mississippian age Sebago batholith. Areas intruded by pegmatites that possess such different mineral assemblages are globally rare. The origins of these mixed'' pegmatite series have not been comprehensively investigated. There is no known pattern of regional zonation (mineral/chemical) among Topsham series pegmatites, hence simple fractionation processes are probably not responsible for the compositional variations. The authors are attempting to clarify pegmatite petrogenesis using common Pb isotopic ratios of feldspars and Sm-Nd isotopic data from whole rocks and minerals. Pb isotopic ratios from leached feldspars reflect the Pb ratios of the source from which they were derived. The range of Pb isotopic compositions of alkali feldspars from 7 granitic pegmatites is as follows: [sup 206]Pb/[sup 204]Pb = 18.5-19.1; [sup 207]Pb/[sup 204]Pb = 15.53-15.69; [sup 208]Pb/[sup 204]Pb = 38.3-38.6. The Brunswick granite has K-feldspars with [sup 206]Pb/[sup 204]Pb = 18.40-18.47, [sup 207]/[sup 204]Pb = 15.64-15.66 and [sup 208]Pb/[sup 204]Pb = 38.29-38.39. The Pb isotopic compositions of both pegmatites and granites are significantly more radiogenic than existing data for the Sebago granite and argue against the consanguinity of Topsham pegmatites and the Sebago batholith. These data instead support a genetic link between the pegmatites and the Brunswick granite, which ranges from a fine-grained two-mica granite to a garnet-bearing pegmatitic leucogranite.

  3. Quantification of the aridity process in South-Western Romania.

    PubMed

    Peptenatu, Daniel; Sîrodoev, Igor; Pravalie, Remus

    2013-01-01

    The report released by the Intergovernmental Committee for Climate Change indicates that Romania ranks among the top seven countries in Europe that would be strongly impacted by aridity in the next few years, with climate changes consisting in a rise of average annual temperatures by as much as 5°C. The research work was conducted in the South of the Oltenia South-Western Development Region, where more than 700,000 hectares of farmland is impacted by aridification, more than 100,000 hectares among them impacted by aridity. Research methodology encompassed the analysis of average annual temperatures over the time span data was available for, at three weather stations, an analysis of average annual precipitations, an analysis of the piezometric data, the evolution of land use as a result of the expansion of the aridity process. The assessment of the aridity process also involved taking into consideration the state of the vegetation by means of the normalized difference vegetation index (NDVI), used to assess the quality of the vegetal stratum, an important element in the complex analysis of the territory. The aridity process is an effect of global warming, and, based on the results of this study, the post-1990 escalation of its effects was brought about by socio-economic factors. The destruction of the irrigation systems and protective forest belts because of the uncertain situation of land ownership are the main factors that contributed to amplification of the effects of aridity on the efficiency of agricultural systems that nowadays are exposed to very high risks. PMID:24499565

  4. Permian evaporites in the Permian basin of southwestern United States

    USGS Publications Warehouse

    Johnson, K.S.

    1997-01-01

    During Permian time, a broad and shallow inland sea covered much of southwestern United States, extending northward from west Texas into northwestern Kansas. Slow but continual subsidence beneath all parts of this vast Permian basin caused deposition of a thick sequence of Permian red beds and evaporites, including dolomite, gypsum/anhydrite, salt, and potash. Evaporite units are notably thick and laterally persistent throughout the Permian basin. The entire Permian System ranges up to 2,000 m thick in various parts of the basin, and individual formations, consisting mostly of gypsum/anhydrite and salt, commonly are 60-500 m thick. Evaporite deposits are oldest in the northern part of the Permian basin, and they generally are progressively younger toward the south. The site of principal salt deposition during early Leonardian time (Wellington evaporites) was in Kansas and northwestern Oklahoma; it then shifted southward into western Oklahoma and the Texas Panhandle during late Leonardian and early Guadalupian time (Lower Clear Fork/Lower Cimarron evaporites, Upper Clear Fork/Upper Cimarron evaporites, and San Andres/Blaine evaporites); and finally into west Texas and southeastern New Mexico during late Guadalupian and Ochoan time (Artesia, Castile, Salado, and Rustler evaporites). These evaporites comprise a significant resource for the region: rock salt is produced from dry mines, brine fields, and solar-salt operations at 18 locations; gypsum is mined at 13 sites; potash is produced from 5 underground mines in the world-famous Carlsbad potash district; and sulfur is produced by the Frasch process at one site.

  5. Orchid conservation in the biodiversity hotspot of southwestern China.

    PubMed

    Liu, Qiang; Chen, Jin; Corlett, Richard T; Fan, XuLi; Yu, DongLi; Yang, HongPei; Gao, JiangYun

    2015-12-01

    Xishuangbanna is on the northern margins of tropical Asia in southwestern China and has the largest area of tropical forest remaining in the country. It is in the Indo-Burma hotspot and contains 16% of China's vascular flora in <0.2% of the country's total area (19,690 km(2) ). Rapid expansion of monoculture crops in the last 20 years, particularly rubber, threatens this region's exceptional biodiversity. To understand the effects of land-use change and collection on orchid species diversity and determine protection priorities, we conducted systematic field surveys, observed markets, interviewed orchid collectors, and then determined the conservation status of all orchids. We identified 426 orchid species in 115 genera in Xishuangbanna: 31% of all orchid species that occur in China. Species richness was highest at 1000-1200 m elevation. Three orchid species were assessed as possibly extinct in the wild, 15 as critically endangered, 82 as endangered, 124 as vulnerable, 186 as least concern, and 16 as data deficient. Declines over 20 years in harvested species suggested over-collection was the major threat, and utility value (i.e., medicinal or ornamental value) was significantly related to endangerment. Expansion of rubber tree plantations was less of a threat to orchids than to other taxa because only 75 orchid species (17.6%) occurred below the 1000-m-elevation ceiling for rubber cultivation, and most of these (46) occurred in nature reserves. However, climate change is projected to lift this ceiling to around 1300 m by 2050, and the limited area at higher elevations reduces the potential for upslope range expansion. The Xishuangbanna Tropical Botanical Garden is committed to achieving zero plant extinctions in Xishuangbanna, and orchids are a high priority. Appropriate in and ex situ conservation strategies, including new protected areas and seed banking, have been developed for every threatened orchid species and are being implemented. PMID:26372504

  6. Physical and hydrologic characteristics of Matlacha Pass, southwestern Florida

    SciTech Connect

    Kane, R.L. ); Russell, G.M. )

    1994-03-01

    Matlacha Pass is part of the connected inshore waters of the Charlotte Harbor estuary in southwestern Florida. Bathymetry indicates that depths in the main channel of the pass range from 4 to 14 feet below sea level. The channel averages about 8 feet deep in the northern part of the pass and about 5 feet deep in the southern part. Additionally, depths average about 4 feet in a wide section of the middle of the pass and about 2 feet along the mangrove swamps near the shoreline. Tidal flow within Matlacha Pass varies depending on aquatic vegetation densities, oyster beds, and tidal flats. Surface-water runoff occurs primarily during the wet season (May to September), with most of the flow entering the Matlacha Pass through two openings in the spreader canal system near the city of Matlacha. Freshwater flow into the pass from the north Cape Coral spreader canal system averaged 113 cubic feet per second from October 1987 to September 1992. Freshwater inflow from the Aries Canal of the south Cape Coral spreader canal system averaged 14.1 cubic feet per second from October 1989 to September 1992. Specific conductance throughout Matlacha Pass ranged from less than 1,000 to 57,000 microsiemens per centimeter. Specific conductance, collected from a continuous monitoring data logger in the middle of the pass from February to September 1992, averaged 36,000 microsiemens per centimeter at 2 feet below the water surface and 40,000 microsiemens per centimeter at 2 feet above the bottom. During both the wet and dry seasons, specific conductance indicated that the primary mixing of tidal waters and freshwater inflow occurs in the mangrove swamps along the shoreline.

  7. Resilience of southwestern Amazon forests to anthropogenic edge effects.

    PubMed

    Phillips, Oliver L; Rose, Sam; Mendoza, Abel Monteagudo; Vargas, Percy Núñez

    2006-12-01

    Anthropogenic edge effects can compromise the conservation value of mature tropical forests. To date most edge-effect research in Amazonia has concentrated on forests in relatively seasonal locations or with poor soils in the east of the basin. We present the first evaluation from the relatively richer soils of far western Amazonia on the extent to which mature forest biomass, diversity, and composition are affected by edges. In a southwestern Amazonian landscape we surveyed woody plant diversity, species composition, and biomass in 88x0.1 ha samples of unflooded forest that spanned a wide range in soil properties and included samples as close as 50 m and as distant as >10 km from anthropogenic edges. We applied Mantel tests, multiple regression on distance matrices, and other multivariate techniques to identify anthropogenic effects before and after accounting for soil factors and spatial autocorrelation. The distance to the nearest edge, access point, and the geographical center of the nearest community ("anthropogenic-distance effects") all had no detectable effect on tree biomass or species diversity. Anthropogenic-distance effects on tree species composition were also below the limits of detection and were negligible in comparison with natural environmental and spatial factors. Analysis of the data set's capacity to detect anthropogenic effects confirmed that the forests were not severely affected by edges, although because our study had few plots within 100 m of forest edges, our confidence in patterns in the immediate vicinity of edges is limited. It therefore appears that the conservation value of most "edge" forests in this region has not yet been compromised substantially. We caution that because this is one case study it should not be overinterpreted, but one explanation for our findings may be that western Amazonian tree species are naturally faster growing and more disturbance adapted than those farther east.

  8. A multiscaled model of southwestern willow flycatcher breeding habitat

    USGS Publications Warehouse

    Hatten, J.R.; Paradzick, C.E.

    2003-01-01

    The southwestern willow flycatcher (SWFL; Empidonax traillii extimus) is an endangered songbird whose habitat has declined dramatically over the last century. Understanding habitat selection patterns and the ability to identify potential breeding areas for the SWFL is crucial to the management and conservation of this species. We developed a multiscaled model of SWTL breeding habitat with a Geographic Information System (GIS), survey data, GIS variables, and multiple logistic regressions. We obtained presence and absence survey data from a riverine ecosystem and a reservoir delta in south-central Arizona, USA, in 1999. We extracted the GIS variables from satellite imagery and digital elevation models to characterize vegetation and floodplain within the project area. We used multiple logistic regressions within a cell-based (30 X 30 m) modeling environment to (1) determine associations between GIS variables and breeding-site occurrence at different spatial scales (0.09-72 ha), and (2) construct a predictive model. Our best model explained 54% of the variability in breeding-site occurrence with the following variables: vegetation density at the site (0.09 ha), proportion of dense vegetation and variability in vegetation density within a 4.5-ha neighborhood, and amount of floodplain or flat terrain within a 41-ha neighborhood. The density of breeding sites was highest in areas that the model predicted to be most suitable within the project area and at an external test site 200 km away. Conservation efforts must focus on protecting not only occupied patches, but also surrounding riparian forests and floodplain to ensure long-term viability of SWTL. We will use the multiscaled model to map SWTL breeding habitat in Arizona, prioritize future survey effort, and examine changes in habitat abundance and quality over time.

  9. Monazite geochronology of the Bodonch metamorphic complex, southwestern Mongolia

    NASA Astrophysics Data System (ADS)

    Cina, S. E.; Yin, A.; Dash, B.; Manning, C.

    2007-12-01

    The Bodonch metamorphic complex in southwestern Mongolia is a steeply dipping assemblage of low to high grade metamorphic rocks exposed along a ~30 km stretch of the Bodonch River which has been variably regarded as either a microcontinental block, due to presence of gneissic foliation; a metamorphic core complex; or an accretionary complex in the Central Asian Orogenic System. Metamorphic grade generally increases from subgreenschist facies at the southern margin of the complex to amphibolite facies in the central section, and decreases again to subgreenschist facies further to the north. Foliation is approximately E-W striking and predominately dips northward, although isoclinal folding is pervasive at all scales. Lithologically, the complex consists primarily of metapelites, with minor interbedded metavolcanics and metacherts. Carbonates and quartzites are generally absent and are observed only in thin depositional lenses. The entire complex is intruded by granitic dikes ranging from ~1 m in thickness to several tens of meters which postdate the metamorphism. The most striking feature of the Bodonch metamorphic complex is the occurrence of garnet bearing schist in the central section which contains zones of almost pure garnet mineralization. Along its southern margin, the assemblage is thrust over a sequence of unmetamorphosed to low grade Devonian-Carboniferous volcanics and sediments which are classified as belonging to an oceanic island arc terrane. Based on the observed lithologies, lack of crystalline basement, and style of deformation we favor the accretionary complex model for the tectonic origin of the Bodonch metamorphic complex. We present new Th-Pb ages of monazite inclusions in garnets obtained using in situ ion-microprobe techniques, which are interpreted to correspond to the timing of accretion related metamorphism.

  10. Groundwater fluoride and dental fluorosis in southwestern Nigeria.

    PubMed

    Gbadebo, A M

    2012-10-01

    This study was carried out to assess the fluoride levels of groundwater from open wells, consumed by the residents of three communities located in two distinct geological terrains of southwestern Nigeria. Fluoride concentration was determined using spectrophotometric technique, while analysis of other parameters like temperature, pH and total dissolve solids followed standard methods. Results of the analysis indicated that groundwater samples from Abeokuta Metropolis (i.e., basement complex terrain) had fluoride content in the range of 0.65 ± 0.21 and 1.20 ± 0.14. These values were found to be lower than the fluoride contents in the groundwater samples from Ewekoro peri-urban and Lagos metropolis where the values ranged between 1.10 ± 0.14-1.45 ± 0.07 and 0.15 ± 0.07-2.20 ± 1.41 mg/l, respectively. The fluoride contents in almost all locations were generally higher than the WHO recommended 0.6 mg/l. Analysis of Duncan multiple range test indicated that there is similarity in the level of significance of fluoride contents between different locations of same geological terrain at p ≤ 0.05. It was also observed that fluoride distribution of groundwater samples from the different geological terrain was more dependent on factors like pH and TDS than on temperature. The result of the analyzed social demographic characteristics of the residents indicated that the adults (between the age of 20 and >40 years) showed dental decay than the adolescent (<20 years). This signifies incidence of dental fluorosis by the high fluoride content in the drinking water of the populace. Further investigation on all sources of drinking water and other causes of tooth decay in the area is suggested.

  11. Orchid conservation in the biodiversity hotspot of southwestern China.

    PubMed

    Liu, Qiang; Chen, Jin; Corlett, Richard T; Fan, XuLi; Yu, DongLi; Yang, HongPei; Gao, JiangYun

    2015-12-01

    Xishuangbanna is on the northern margins of tropical Asia in southwestern China and has the largest area of tropical forest remaining in the country. It is in the Indo-Burma hotspot and contains 16% of China's vascular flora in <0.2% of the country's total area (19,690 km(2) ). Rapid expansion of monoculture crops in the last 20 years, particularly rubber, threatens this region's exceptional biodiversity. To understand the effects of land-use change and collection on orchid species diversity and determine protection priorities, we conducted systematic field surveys, observed markets, interviewed orchid collectors, and then determined the conservation status of all orchids. We identified 426 orchid species in 115 genera in Xishuangbanna: 31% of all orchid species that occur in China. Species richness was highest at 1000-1200 m elevation. Three orchid species were assessed as possibly extinct in the wild, 15 as critically endangered, 82 as endangered, 124 as vulnerable, 186 as least concern, and 16 as data deficient. Declines over 20 years in harvested species suggested over-collection was the major threat, and utility value (i.e., medicinal or ornamental value) was significantly related to endangerment. Expansion of rubber tree plantations was less of a threat to orchids than to other taxa because only 75 orchid species (17.6%) occurred below the 1000-m-elevation ceiling for rubber cultivation, and most of these (46) occurred in nature reserves. However, climate change is projected to lift this ceiling to around 1300 m by 2050, and the limited area at higher elevations reduces the potential for upslope range expansion. The Xishuangbanna Tropical Botanical Garden is committed to achieving zero plant extinctions in Xishuangbanna, and orchids are a high priority. Appropriate in and ex situ conservation strategies, including new protected areas and seed banking, have been developed for every threatened orchid species and are being implemented.

  12. Tectonic development of southwestern Montana and east-central Idaho

    SciTech Connect

    Lopez, D.A.

    1984-07-01

    The region of southwestern Montana and east-central Idaho, north of the Snake River plain and east of the Idaho batholith, has been affected by a complex sequence of orogenic events from the Proterozoic through Holocene time. Deposition of Proterozoic Belt Supergroup rocks and rocks of similar age in east-central Idaho occurred in basins that were clearly fault controlled. Many of these faults were reactivated repeatedly at later times and controlled or affected the development of younger tectonic features. This study encompasses the entire width of the Sevier orogenic belt in this part of the Cordilleran fold and thrust belt. The thrust belt comprises several major eastward-transported thrust plates that are successively younger to the east. These plates juxtapose distinct stratigraphic packages that were deposited in eugeoclinal, miogeoclinal, and continental platform settings. As a consequence, the thrust plates can be distinguished on the basis of facies and thickness distribution as well as, to some extent, structural style. In southwest Montana, Sevier-type structures overlap with, and butt against, basement-involved Laramide structures. The extension of southwest Montana basement trends into Idaho suggests that this overlap may extend into east-central Idaho. Superimposed on these older structures are mid-Tertiary to Holocene normal faults that formed present-day basins and ranges. Many of these are reactivated older fault zones, some of which can be shown to have Precambrian ancestry. The region has excellent oil and gas potential, because reservoir and source rocks and trapping mechanisms are all clearly present. However, an understanding of the effect of overlapping tectonic elements is necessary to predict accurately where favorable rock packages are preserved.

  13. Evidence of slope instability in the Southwestern Adriatic Margin

    NASA Astrophysics Data System (ADS)

    Minisini, D.; Trincardi, F.; Asioli, A.

    2006-01-01

    The Southwestern Adriatic Margin (SAM) shows evidence of widespread failure events that generated slide scars up to 10 km wide and extensive slide deposits with run out distances greater than 50 km. Chirp-sonar profiles, side-scan sonar mosaics, multibeam bathymetry and sediment cores document that the entire slope area underwent repeated failures along a stretch of 150 km and that mass-transport deposits, covering an area of 3320 km2, are highly variable ranging from blocky slides to turbidites, and lay on the lower slope and in the basin. The SAM slope between 300-700 m is impacted by southward bottom currents shaping sediment drifts (partly affected by failure) and areas of dominant erosion of the seafloor. When slide deposits occur in areas swept by bottom currents their fresh appearence and their location at seafloor may give the misleading impression of a very young age. Seismic-stratigraphic correlation of these deposits to the basin floor, however, allow a more reliable age estimate through sediment coring of the post-slide unit. Multiple buried failed masses overlap each other in the lower slope and below the basin floor; the most widespread of these mass-transport deposits occurred during the MIS 2-glacial interval on a combined area of 2670 km2. Displacements affecting Holocene deposits suggest recent failure events during or after the last phases of the last post-glacial eustatic rise. Differences in sediment accumulation rates at the base or within the sediment drifts and presence of downlap surfaces along the slope and further in the basin may provide one or multiple potential weak layers above which widespread collapses take place. Neotectonic activity and seismicity, together with the presence of a steep slope, represent additional elements conducive to sediment instability and failure along the SAM. Evidence of large areas still prone to failure provides elements of tsunamogenic hazard.

  14. "Actionable" Climate Scenarios for Natural Resource Managers in Southwestern Colorado

    NASA Astrophysics Data System (ADS)

    Rangwala, I.; Rondeau, R.; Wyborn, C.

    2014-12-01

    Locally relevant projections of climate change provide critical insights for natural resource managers seeking to adapt their management activities to climate change. To provide such information, we developed narrative scenarios of future climate change and its impacts on different ecosystems in southwestern Colorado. This multi-institution and trans-disciplinary project seeks to provide useful and useable knowledge to facilitate climate change adaptation in the context of uncertainty. The narratives are intended to provide detailed insights into the range of changes that natural resource managers may face in the future. These scenarios were developed in an iterative process through interactions between ecologists, social and climate scientists. In our scenario development process, climate uncertainty is acknowledged by having multiple scenarios, where each scenario is regarded as a storyline with equal probability as another scenario. Rather than a qualitative narration of the general direction of change and range in responses, we quantified changes in several decision relevant climate and ecological responses based on our best available understanding and provided a tight storyline for each scenario to facilitate (a) a more augmented use of scientific information in a decision-making process, (b) differential responses from stakeholders across the different scenarios, and (c) identification of strategies that could work across these multiple scenarios. This presentation will discuss the process of selecting the scenarios, quantifying climate and ecological responses, and the criteria for building the narrative for each scenario. We will also cover the process by which these scenarios get used, and how the user feedbacks are integrated in further developing the tools and processes.

  15. Boron toxicity of coal mining areas in southwestern Wyoming

    SciTech Connect

    Hanson, R.L.; Smith, P.W.; Smith, J.A.

    1990-12-31

    Boron tolerance of native plant species is not generally known. This study was conducted to determine the B tolerance of thickspike wheatgrass [Agropyron dasystachyum (Hook.) Scribn.], a species commonly used to reclaim minelands in the semiarid and arid West. Pre-germinated thickspike wheatgrass seeds were planted in three soil materials obtained from a coal mine in southwestern Wyoming. Soils were taken from an undisturbed bottomland (clay), a topsoil stockpile (sand), and a carbonaceous shale outcrop (shale) with inherent hot water extractable-B (HWE-B) levels of 2.8, 1.3, and 3.5 mg/kg soil, respectively. Each soil material was treated with boric acid solutions to produce seven different HWE-B levels. B levels ranged from inherent conditions up to 57.9 mg/kg. Plants were grown under greenhouse conditions for 100 days in pots containing 2.9 kg of clay or shale or 3.4 kg sand. Wheatgrass shoot and root dry matter production were measured. Toxicity symptoms (leaf tip necrosis) were observed in all treatments but the controls during the study. Levels of 11.6 and 20.5 mg/kg HWE-B produced an average of 10 and 20% reductions in shoot production, respectively. Ten and 20% reductions in root growth were observed with 3.8 and 6.6 mg/kg HWE-B, respectively. Plants grown in the sand were most B sensitive. This is postulated to be a result of the drier conditions attendant in that soil. Results indicate that thickspike wheatgrass can tolerate HWE-B levels in excess of 5 mg/kg. However, actual field tolerance levels will be dependent on climatic and soil environmental conditions, particularly moisture availability.

  16. Paleozoic lithofacies in southwestern Sinai and their depositional environments

    SciTech Connect

    Bhattacharyya, D.P.; Peck, N.R.; Mansour, S.E.

    1983-03-01

    Major breaks in sedimentation, accompanied by well-developed paleosols, have been successfully used to subdivide the 600 m (1968 ft) of Paleozoic sandstone and shale sequence of southwestern Sinai, Egypt, into five smaller facies association units (i.e., formations). The lowest unit (the Araba Formation) is dominated by 1 to 10 m (3 to 32 ft) thick coarsening-up sequences of parallel-bedded, varicolored, fine-grained arkosic sandstone and muddy sandstone. This is the deposit of a low-energy prograding sandy coastal plain complex that grades upward into a thin, fining-up channel-overbank deposits with poorly developed paleosols. The overlying Naqus Formation scours deep into the Araba, and is characterized by lenticular, coarse to medium-grained, cross-bedded quartz sandstone with only a few clayey intervals. Cross-beds are common. The Naqus is interpreted as alluvial fanbraided stream deposits. A 15 to 20 m (40 to 66 ft) thick, conspicuous dark brown, ferruginous shale, ochre-yellow dolomitic sandstone and fossiliferous gray siltstone sequence, persistent all along the Qabeliat valley, overlies the Naqus and represents lagoonal deposits laterally equivalent to the shallow marine shale-dolomite sequence of the Um Bogma Formation farther north. Basal fluvial channel sands of the succeeding Ataqa Formation cut into the Um Bogma paleosol, and grade upward into the fossiliferous green-red marine shales and subordinate sandstones in shoaling-upward sequences. Southward in the Qabeliat valley, a parallel-bedded sequence of thick green shales and thin brown sandstones, both nonfossiliferous, intervenes in the middle of the Budra Formation and represents ephemeral lake deposits related to the fluvial system.

  17. Reinterpretation of age and correlation between tectonostratigraphic units, southwestern Maine

    SciTech Connect

    Hussey, A.M. . Geology Dept.); Aleinikoff, J. ); Marvinney, R. )

    1993-03-01

    Tectonostratigraphic sequence within the Coastal Lithotectonic Belt of southwestern Maine include the Merrimack Group (MG), Casco Bay Group (CBG), Falmouth-Brunswick sequence (FBS), and Central Maine sequence (CMS). Formations of FBS (Nehumkeag Pond, Mt. Ararat, Torrey Hill, and Richmond Corner), all west of the Norumbega Fault Zone, constitute a separate sequence unrelated to the Casco Bay Group east of the Fault. The age of these rocks is uncertain. The Mt. Ararat and Nehumkeag Pond Fms. are tentatively correlated with lithically similar parts of the Massabesic Gneiss in New Hampshire, and with the Monson Gneiss in Massachusetts. The Mt. Ararat and Nehumkeag Pond Formations, now no longer correlated with the Cushing Fm. may form a basement to the CMS. The CBG, a package of metamorphosed volcanic and pelitic rocks crops out only east of the Norumbega Fault. Felsic metavolcanic rocks of the Cushing Fm. at the base of the CBG give a 471[+-]3 MA U/Pb age on zircons, indicating a Middle Ordovician age for the base of the CBG. The Sebascodegan Fm., an easterly felspathic and calcareous volcaniclastic facies of the upper part of the Cushing Fm., is correlated with the Bucksport Fm. of southeastern coastal Maine, suggesting a Middle Ordovician age for that formation. The Sebascodegan Fm may be equivalent to the Kittery Formation of the MG. The Macworth Fm. of the CBG is equivalent to the Elliot Fm. of the MG, and the Cape Elizabeth Fm. stratigraphically above the Cushing Fm in the CBG, may be equivalent in part to the Elliot Fm. Units of the CBG above the Cape Elizabeth Fm. are not present to the south in the MG due either to faulting or stratigraphic pinchout.

  18. Glowing seashells: diversity of fossilized coloration patterns on coral reef-associated cone snail (Gastropoda: Conidae) shells from the Neogene of the Dominican Republic.

    PubMed

    Hendricks, Jonathan R

    2015-01-01

    The biology of modern Conidae (cone snails)--which includes the hyperdiverse genus Conus--has been intensively studied, but the fossil record of the clade remains poorly understood, particularly within an evolutionary framework. Here, ultraviolet light is used to reveal and characterize the original shell coloration patterns of 28 species of cone snails from three Neogene coral reef-associated deposits from the Cibao Valley, northern Dominican Republic. These fossils come from the upper Miocene Cercado Fm. and lower Pliocene Gurabo Fm., and range in age from about 6.6-4.8 Ma. Comparison of the revealed coloration patterns with those of extant species allow the taxa to be assigned to three genera of cone snails (Profundiconus, Conasprella, and Conus) and at least nine subgenera. Thirteen members of these phylogenetically diverse reef faunas are described as new species. These include: Profundiconus? hennigi, Conasprella (Ximeniconus) ageri, Conus anningae, Conus lyelli, Conus (Atlanticonus?) franklinae, Conus (Stephanoconus) gouldi, Conus (Stephanoconus) bellacoensis, Conus (Ductoconus) cashi, Conus (Dauciconus) garrisoni, Conus (Dauciconus?) zambaensis, Conus (Spuriconus?) kaesleri, Conus (Spuriconus?) lombardii, and Conus (Lautoconus?) carlottae. Each of the three reef deposits contain a minimum of 14-16 cone snail species, levels of diversity that are similar to modern Indo-Pacific reef systems. Finally, most of the 28 species can be assigned to modern clades and thus have important implications for understanding the biogeographic and temporal histories of these clades in tropical America.

  19. Tectonic versus eustatic control on Neogene sedimentation in the Cibao basin of the Dominican Republic: Tectonic dominance near an active plate boundary

    SciTech Connect

    Erikson, J.P. )

    1991-03-01

    Continuous Neogene subsidence, transgression, and brief periods of accelerated subsidence are indicated by the Yaque Group sediments of the Cibao basin of northern Dominican Republic, in which the generally fining-upward sediments are punctuated by two, thick, conglomeratic sequences. Lithologic and paleontologic evidence support continuous subsidence and a tectonic control on sedimentation and is in conflict with an interpretation of one or both of the conglomeratic sequences as being due to a rapid regressive-transgressive cycle and a correlation with a second-order fluctuation (supercycle) on a Vail-type sea-level curve. Subsidence generally outpaced sedimentation, such that water depths almost continuously increased during deposition of all but the uppermost Yaque Group (when the basin shallowed prior to the subaerial exposure), as interpreted from detailed paleontological analyses. The depositional history of the entire {approximately}1 km exposed section and {approximately}5 km subsurface section of the Yaque Group is best explained by a single, continuous, east to west, middle Miocene to earliest Pliocene transgression due to asymmetric basin subsidence. Deposition of the igneous clast-rich conglomerates was probably caused by accelerated basement subsidence at the northern edge of the basin, which oversteepened the depositional slope, led to accelerated transgression of the northern flank of the Central Cordillera, and produced brief pulses of coarse, partially Cordilleran-derived conglomerates. Varying subsidence of the Cibao basin is correlated with episodic uplift and sedimentation in the Cordillera Septentrional.

  20. ELISA Detection of 30 New Amphetamine Designer Drugs in Whole Blood, Urine and Oral Fluid using Neogen® "Amphetamine" and "Methamphetamine/MDMA" Kits.

    PubMed

    Nieddu, Maria; Burrai, Lucia; Baralla, Elena; Pasciu, Valeria; Varoni, Maria Vittoria; Briguglio, Irene; Demontis, Maria Piera; Boatto, Gianpiero

    2016-09-01

    Amphetamine designer drugs are central nervous system stimulants that are widely disseminated in the illegal market. Generally, in forensic laboratories, immunoassay methods are the first line of screening for these types of drugs in a biological specimen (typically blood, urine or oral fluid). In this article, we describe the cross-reactivity profiles of 30 new amphetamine designer drugs, using the Neogen(®) [Amphetamine Specific and Methamphetamine/3,4-Methylenedioxymethamphetamine (MDMA) assays] drug tests. To assess the potential matrix influence on the response, each assay was tested on whole blood, urine and oral fluid. Concentrations of 10,000 ng/mL were not sufficient to produce a positive response for the majority of the analyzed amphetamines. This clearly demonstrates that, although these kits are extremely effective for the target drugs for which they are intended (amphetamine, methamphetamine and MDMA), they cannot be used to reliably identify the tested designer drugs in real cases, as these concentrations greatly exceed those expected to be found in forensic samples. PMID:27405364

  1. Glowing Seashells: Diversity of Fossilized Coloration Patterns on Coral Reef-Associated Cone Snail (Gastropoda: Conidae) Shells from the Neogene of the Dominican Republic

    PubMed Central

    Hendricks, Jonathan R.

    2015-01-01

    The biology of modern Conidae (cone snails)—which includes the hyperdiverse genus Conus—has been intensively studied, but the fossil record of the clade remains poorly understood, particularly within an evolutionary framework. Here, ultraviolet light is used to reveal and characterize the original shell coloration patterns of 28 species of cone snails from three Neogene coral reef-associated deposits from the Cibao Valley, northern Dominican Republic. These fossils come from the upper Miocene Cercado Fm. and lower Pliocene Gurabo Fm., and range in age from about 6.6-4.8 Ma. Comparison of the revealed coloration patterns with those of extant species allow the taxa to be assigned to three genera of cone snails (Profundiconus, Conasprella, and Conus) and at least nine subgenera. Thirteen members of these phylogenetically diverse reef faunas are described as new species. These include: Profundiconus? hennigi, Conasprella (Ximeniconus) ageri, Conus anningae, Conus lyelli, Conus (Atlanticonus?) franklinae, Conus (Stephanoconus) gouldi, Conus (Stephanoconus) bellacoensis, Conus (Ductoconus) cashi, Conus (Dauciconus) garrisoni, Conus (Dauciconus?) zambaensis, Conus (Spuriconus?) kaesleri, Conus (Spuriconus?) lombardii, and Conus (Lautoconus?) carlottae. Each of the three reef deposits contain a minimum of 14–16 cone snail species, levels of diversity that are similar to modern Indo-Pacific reef systems. Finally, most of the 28 species can be assigned to modern clades and thus have important implications for understanding the biogeographic and temporal histories of these clades in tropical America. PMID:25830769

  2. Mud volcanism and authigenic carbonates related to methane-rich fluids migration in the late Neogene marls of S.E. Spain

    NASA Astrophysics Data System (ADS)

    Pierre, C.; Blanc-Valleron, M. M.; Rouchy, J. M.

    2015-12-01

    Methane-rich fluids that are generated at depth in organic-rich deposits migrate within the sediments to the seafloor where they are expelled to form mud volcanoes or pockmarks. Moreover, these migrating fluids are involved in diagenetic processes as authigenic carbonate formation and they may participate to gas hydrate formation. These features are well-known in the present-day continental margins but their fossil records are relatively scarce. The outcropping Tortonian and Messinian marls in S.E. Spain basins (Lorca, Fortuna, Columbares, Huercal Overa) contain abundant authigenic dolomite nodules. The oxygen and carbon isotopic compositions of these dolomites exhibit wide ranges (-1.4 < δ18O < +5.6 ; -25.6 < δ13C < +9.3) indicating that carbonate precipitation occurred within the marly sediments due to circulation of fluids modified by gas hydrates formation/dissociation, where anaerobic oxidation of methane and methanogenesis were active. In the Huercal Overa basin, there is a well-preserved mud volcano intruding vertically the Messinian marls. These two features, methane derived authigenic dolomites and mud volcanism, are testifying of the intense methane-rich fluid migration in the marly deposits of the western Mediterranean basins during the late Neogene, which was the time of major paleoenvironmental changes in the Mediterranean sea climaxing during the Messinian salinity crisis.

  3. Energy map of southwestern Wyoming, Part B: oil and gas, oil shale, uranium, and solar

    USGS Publications Warehouse

    Biewick, Laura R.H.; Wilson, Anna B.

    2014-01-01

    The U.S. Geological Survey (USGS) has compiled Part B of the Energy Map of Southwestern Wyoming for the Wyoming Landscape Conservation Initiative (WLCI). Part B consists of oil and gas, oil shale, uranium, and solar energy resource information in support of the WLCI. The WLCI represents the USGS partnership with other Department of the Interior Bureaus, State and local agencies, industry, academia, and private landowners, all of whom collaborate to maintain healthy landscapes, sustain wildlife, and preserve recreational and grazing uses while developing energy resources in southwestern Wyoming. This product is the second and final part of the Energy Map of Southwestern Wyoming series (also see USGS Data Series 683, http://pubs.usgs.gov/ds/683/), and encompasses all of Carbon, Lincoln, Sublette, Sweetwater, and Uinta Counties, as well as areas in Fremont County that are in the Great Divide and Green River Basins.

  4. 77 FR 75589 - Prevailing Rate Systems; Redefinition of the Minneapolis-St. Paul, MN, and Southwestern Wisconsin...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-21

    ... boundaries of the Minneapolis- St. Paul, MN, and Southwestern Wisconsin appropriated fund Federal Wage System... of the Federal Prevailing Rate Advisory Committee to best match Wabasha County to a nearby FWS survey... boundaries of the Minneapolis-St. Paul, MN, and Southwestern Wisconsin appropriated fund Federal Wage...

  5. 75 FR 69520 - Indiana Southwestern Railway Co.-Abandonment Exemption-in Posey and Vanderburgh Counties, IN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-12

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Surface Transportation Board Indiana Southwestern Railway Co.--Abandonment Exemption--in Posey and Vanderburgh Counties, IN Indiana Southwestern Railway Co. (ISW) filed a verified notice of exemption under 49 CFR part 1152 subpart...

  6. The Otay Mesa Higher Education Center: An Off-Campus Facility of the Southwestern Community College District. Commission Report.

    ERIC Educational Resources Information Center

    California State Postsecondary Education Commission, Sacramento.

    This report to the California Governor and legislature reviews the proposal submitted by the Southwestern Community College District (SCCD) (California) to establish a state-approved educational center in Otay Mesa, to be known as the Southwestern Community College's Higher Education Center at Otay Mesa. The proposed state-supported center allows…

  7. SHOCK-CLOUD INTERACTION AND PARTICLE ACCELERATION IN THE SOUTHWESTERN LIMB OF SN 1006

    SciTech Connect

    Miceli, M.; Orlando, S.; Bocchino, F.; Acero, F.; Decourchelle, A.

    2014-02-20

    The supernova remnant SN 1006 is a powerful source of high-energy particles and evolves in a relatively tenuous and uniform environment despite interacting with an atomic cloud in its northwestern limb. The X-ray image of SN 1006 reveals an indentation in the southwestern part of the shock front and the H I maps show an isolated (southwestern) cloud, having the same velocity as the northwestern cloud, whose morphology fits perfectly in the indentation. We performed spatially resolved spectral analysis of a set of small regions in the southwestern nonthermal limb and studied the deep X-ray spectra obtained within the XMM-Newton SN 1006 Large Program. We also analyzed archive H I data, obtained by combining single-dish and interferometric observations. We found that the best-fit value of N {sub H} derived from the X-ray spectra significantly increases in regions corresponding to the southwestern cloud, while the cutoff energy of the synchrotron emission decreases. The N {sub H} variation corresponds perfectly with the H I column density of the southwestern cloud, as measured from the radio data. The decrease in the cutoff energy at the indentation clearly reveals that the back side of the cloud is actually interacting with the remnant. The southwestern limb therefore presents a unique combination of efficient particle acceleration and high ambient density, thus being the most promising region for γ-ray hadronic emission in SN 1006. We estimate that such emission will be detectable with the Fermi telescope within a few years.

  8. On plate tectonics and the geologic evolution of southwestern North America

    USGS Publications Warehouse

    Ward, P.L.

    1991-01-01

    Very rapid subduction of the Farallon plate under southwestern North America between 60 and 40 Ma was accompanied by a relatively low volume of magmatism throughout the southwestern United States and northern Mexico. Between 40 and 20 Ma, when subduction slowed significantly and in one area may have even stopped, magmatism became widespread and voluminous from Nevada and Utah to central Mexico. This correlation of rapid subduction with a relatively low volume of magmatism can be explained by the observation that subduction-related andesitic arc volcanism, often formed in a Laramide-style compressional regime, is relatively low volume compared to continental volcanism. -from Author

  9. Habitat preferences of phlebotomine sand flies (Diptera: Psychodidae) in southwestern Morocco.

    PubMed

    Guernaoui, S; Boumezzough, A

    2009-09-01

    Data from a 4-yr study of phlebotomine sand flies in 44 stations in southwestern Morocco are presented. Correspondence analysis is used to describe the habitat preferences of nine sand fly species on a meso-scale (station) and a micro-scale (biotope). This work, based on highly diversified data from various stations, comprising several biotopes sampled during different seasons, provides new information on the ecology of sand flies in southwestern Morocco. It highlights many natural and artificial factors that affect the abundance and distribution of sand fly populations. The impact of climate, urbanization, proximity of humans and domestic animals, organic matter in the soil, shelter, and vegetation type is discussed.

  10. Consumption of seeds of southwestern white pine (Pinus strobiformis) by Black Bear (Ursus americanus)

    USGS Publications Warehouse

    Mattson, David J.; Arundel, Terry A.

    2013-01-01

    We report a discovery of black bears (Ursus americanus) consuming seeds of southwestern white pine (Pinus strobiformis) on north slopes of the San Francisco Peaks near Flagstaff, Arizona, in high-elevation, mixed-species conifer forest. In one instance, a bear had obtained seeds from cones excavated from a larder horde made by a red squirrel (Tamiasciurus hudsonicus). Consumption of seeds of southwestern white pine by bears had not been previously documented. This discovery adds to the number of species of pine used by bears for food as well as the geographic range within which the behavior occurs.

  11. Lower and lower Middle Pennsylvanian coal palynofloras, southwestern Virginia

    USGS Publications Warehouse

    Eble, C.F.

    1996-01-01

    Lower and lower Middle Pennsylvanian coals, recovered from an exploratory drilling program in southwestern Virginia, were analyzed for their palynomorph content. Results show them to be dominated by spores produced by arboreous lycopsids. Lycospora pellucida and Lycospora pusilla generally are the most common species, with others, namely Lycospora granulata, L. micropapillata and Lycospora orbicula being locally abundant. Densosporites, Cristatisporites, Radiizonates and Cingulizonates, representing small lycopsids, and Granulatisporites, produced by small ferns, and perhaps some pteridosperms typically are sub-dominant taxa. The recovered palynofloras are similar in overall composition making individual coal bed identification and correlation very difficult, if not impossible. However, the introduction and extinction of a few forms do assist the correlation of packages of strata, on both an intra- and interbasinal scale. Dictyotriletes bireticulatus is first observed in basal Lee Formation strata, at about the level of the Cove Creek coal bed. Radiizonates aligerans and R. striatus also appear more abundantly at this level, although some forms have been observed in older, Pocahontas Formation coals. This level essentially coincides with the Namurian C/Westphalian A boundary, based on plant megafossil evidence. Laevigatosporites minor, L. vulgaris, Endosporites globiformis, E. zonalis and Granasporites medius are first seen consistently just above the Sewell coal bed. Radiizonates aligerans, R. striatus and Densosporites irregularis are last seen in the early Middle Pennsylvanian, at about the level of the Splash Dam coal bed. Schulzospora rara occurs throughout Early and early Middle Pennsylvanian strata, and is last seen in the Manchester coal. The Manchester is directly overlain by the Betsie Shale, a widespread marine unit; the base of the Betsie marks the Westphalian A/B contact. When compared with palynomorph assemblage zonations published for the Western

  12. Gazetteer of coal-mine lakes in southwestern Indiana

    USGS Publications Warehouse

    Bobo, Linda L.

    1979-01-01

    This gazetteer is a catalog of lakes formed by surface coal mining in southwestern Indiana that are 0.5 acre or larger and in nonactive mine areas. Approximately 1,000 of the lakes are listed by 7.5-minute quadrangle topographic-map name, lake-identification number, latitude and longitude, and county. Other data given are shape of lake, maximum length, mean width, length and development of shoreline, surface area, orientation, presence of a stream inlet or outlet, and geologic data (geologic formation of area surrounding the lake and the mined coal-bed member). Field data (sampling date, pH, specific conductance, apparent color of lake, and general vegetation along the shoreline) were collected for 287 of the lakes. Two hundred eighty-seven lakes were sampled once for pH and specific conductance. Vegetation along the shoreline and apparent color of each lake were identified at the same time. Although these data are not sufficient to quantify the water quality of the lakes, they do illustrate the variability of these characteristics. The pH of the 287 lakes ranged from 2.5 to 10.0; however, the pH of 80 percent of them ranged from 6 to 9. Specific conductance ranged from 99 to 3,800 micromhos per centimeter at 25? Celsius. Specific conductance for approximately 70 percent of the lakes in the Staunton and Brazil formations was less than 500 micromhos per centimeter at 25? Celsius, but for approximately 65 percent in the Dugger and Petersburg Formations it was greater than 1,000 micromhos per centimeter at 25? Celsius. The apparent colors of the lakes observed were varying shades of aqua, blue, brown, lime green, red, and green. Eighty percent of the lakes sampled were green. Lake sizes ranged from a chosen minimum of 0.5 acre to a maximum of 344 acres. Maximum length ranged from 0.1 to 2 miles, and the mean width was generally less than 0.8 mile.

  13. Reconnaissance study of the Taylor Mountains pluton, southwestern Alaska

    USGS Publications Warehouse

    Hudson, Travis L.; Miller, Marti L.; Klimasauskas, Edward P.; Layer, Paul W.

    2010-01-01

    The Taylor Mountains pluton is a Late Cretaceous to early Tertiary (median age 65 + or ? 2 Ma) epizonal, composite biotite granite stock located about 235 km (145 mi) northeast of Dillingham in southwestern Alaska. This 30 km2 (12 mi2) pluton has sharp and discordant contacts with hornfels that developed in Upper Cretaceous clastic sedimentary rocks of the Kuskokwim Group. The three intrusive phases in the Taylor Mountains pluton, in order of emplacement, are (1) porphyritic granite containing large K-feldspar phenocrysts in a coarse-grained groundmass, (2) porphyritic granite containing large K-feldspar and smaller, but still coarse, plagioclase, quartz, and biotite phenocrysts in a fine-grained groundmass, and (3) fine-grained, leucocratic, equigranular granite. The porphyritic granites have different emplacement histories, but similar compositions; averages are 69.43 percent SiO2, 1.62 percent CaO, 5.23 percent FeO+MgO, 3.11 percent Na2O, and 4.50 percent K2O. The fine-grained, equigranular granite is distinctly felsic compared to porphyritic granite; it averages 75.3 percent SiO2, 0.49 percent CaO, 1.52 percent FeO+MgO, 3.31 percent Na2O, and 4.87 percent K2O. Many trace elements including Ni, Cr, Sc, V, Ba, Sr, Zr, Y, Nb, La, Ce, Th, and Nd are strongly depleted in fine-grained equigranular granite. Trace elements are not highly enriched in any of the granites. Known hydrothermal alteration is limited to one tourmaline-quartz replacement zone in porphyritic granite. Mineral deposits in the Taylor Mountains area are primarily placer gold (plus wolframite, cassiterite, and cinnabar); sources for these likely include scattered veins in hornfels peripheral to the Taylor Mountain pluton. The granite magmas that formed the Taylor Mountains pluton are thought to represent melted continental crust that possibly formed in response to high heat flow in the waning stage of Late Cretaceous subduction beneath interior Alaska.

  14. Geologic Map of the Central Marysvale Volcanic Field, Southwestern Utah

    USGS Publications Warehouse

    Rowley, Peter D.; Cunningham, Charles G.; Steven, Thomas A.; Workman, Jeremiah B.; Anderson, John J.; Theissen, Kevin M.

    2002-01-01

    The geologic map of the central Marysvale volcanic field, southwestern Utah, shows the geology at 1:100,000 scale of the heart of one of the largest Cenozoic volcanic fields in the Western United States. The map shows the area of 38 degrees 15' to 38 degrees 42'30' N., and 112 degrees to 112 degrees 37'30' W. The Marysvale field occurs mostly in the High Plateaus, a subprovince of the Colorado Plateau and structurally a transition zone between the complexly deformed Great Basin to the west and the stable, little-deformed main part of the Colorado Plateau to the east. The western part of the field is in the Great Basin proper. The volcanic rocks and their source intrusions in the volcanic field range in age from about 31 Ma (Oligocene) to about 0.5 Ma (Pleistocene). These rocks overlie sedimentary rocks exposed in the mapped area that range in age from Ordovician to early Cenozoic. The area has been deformed by thrust faults and folds formed during the late Mesozoic to early Cenozoic Sevier deformational event, and later by mostly normal faults and folds of the Miocene to Quaternary basin-range episode. The map revises and updates knowledge gained during a long-term U.S. Geological Survey investigation of the volcanic field, done in part because of its extensive history of mining. The investigation also was done to provide framework geologic knowledge suitable for defining geologic and hydrologic hazards, for locating hydrologic and mineral resources, and for an understanding of geologic processes in the area. A previous geologic map (Cunningham and others, 1983, U.S. Geological Survey Miscellaneous Investigations Series I-1430-A) covered the same area as this map but was published at 1:50,000 scale and is obsolete due to new data. This new geologic map of the central Marysvale field, here published as U.S. Geological Survey Geologic Investigations Series I-2645-A, is accompanied by gravity and aeromagnetic maps of the same area and the same scale (Campbell and

  15. Site correction of stochastic simulation in southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Lun Huang, Cong; Wen, Kuo Liang; Huang, Jyun Yan

    2014-05-01

    Peak ground acceleration (PGA) of a disastrous earthquake, is concerned both in civil engineering and seismology study. Presently, the ground motion prediction equation is widely used for PGA estimation study by engineers. However, the local site effect is another important factor participates in strong motion prediction. For example, in 1985 the Mexico City, 400km far from the epicenter, suffered massive damage due to the seismic wave amplification from the local alluvial layers. (Anderson et al., 1986) In past studies, the use of stochastic method had been done and showed well performance on the simulation of ground-motion at rock site (Beresnev and Atkinson, 1998a ; Roumelioti and Beresnev, 2003). In this study, the site correction was conducted by the empirical transfer function compared with the rock site response from stochastic point-source (Boore, 2005) and finite-fault (Boore, 2009) methods. The error between the simulated and observed Fourier spectrum and PGA are calculated. Further we compared the estimated PGA to the result calculated from ground motion prediction equation. The earthquake data used in this study is recorded by Taiwan Strong Motion Instrumentation Program (TSMIP) from 1991 to 2012; the study area is located at south-western Taiwan. The empirical transfer function was generated by calculating the spectrum ratio between alluvial site and rock site (Borcheret, 1970). Due to the lack of reference rock site station in this area, the rock site ground motion was generated through stochastic point-source model instead. Several target events were then chosen for stochastic point-source simulating to the halfspace. Then, the empirical transfer function for each station was multiplied to the simulated halfspace response. Finally, we focused on two target events: the 1999 Chi-Chi earthquake (Mw=7.6) and the 2010 Jiashian earthquake (Mw=6.4). Considering the large event may contain with complex rupture mechanism, the asperity and delay time for each

  16. Kinematics of the Southwestern Caribbean from New Geodetic Observations

    NASA Astrophysics Data System (ADS)

    Ruiz, G.; La Femina, P. C.; Tapia, A.; Camacho, E.; Chichaco, E.; Mora-Paez, H.; Geirsson, H.

    2014-12-01

    The interaction of the Caribbean, Cocos, Nazca, and South American plates has resulted in a complex plate boundary zone and the formation of second order tectonic blocks (e.g., the North Andean, Choco and Central America Fore Arc blocks). The Panama Region [PR], which is bounded by these plates and blocks, has been interpreted and modeled as a single tectonic block or deformed plate boundary. Previous research has defined the main boundaries: 1) The Caribbean plate subducts beneath the isthmus along the North Panama Deformed Belt, 2) The Nazca plate converges at very high obliquity with the PR and motion is assumed along a left lateral transform fault and the South Panama Deformed Belt, 3) The collision of PR with NW South America (i.e., the N. Andean and Choco blocks) has resulted in the Eastern Panama Deformed Belt, and 4) collision of the Cocos Ridge in the west is accommodated by crustal shortening, Central American Fore Arc translation and deformation across the Central Costa Rican Deformed Belt. In addition, there are several models that suggest internal deformation of this region by cross-isthmus strike-slip faults. Recent GPS observations for the PR indicates movement to the northeast relative to a stable Caribbean plate at rates of 6.9±4.0 - 7.8±4.8 mm a-1 from southern Costa Rica to eastern Panama, respectively (Kobayashi et al., 2014 and references therein). However, the GPS network did not have enough spatial density to estimate elastic strain accumulation across these faults. Recent installation and expansion of geodetic networks in southwestern Caribbean (i.e., Costa Rica, Panama, and Colombia) combined with geological and geophysical observations provide a new input to investigate crustal deformation processes in this complex tectonic setting, specifically related to the PR. We use new and existing GPS data to calculate a new velocity field for the region and to investigate the kinematics of the PR, including elastic strain accumulation on the

  17. Status of Water Levels in Aquifers in the Nacatoch Sand of Southwestern and Northeastern Arkansas and the Tokio Formation of Southwestern Arkansas, February 2005

    USGS Publications Warehouse

    Schrader, T.P.

    2007-01-01

    The Nacatoch Sand and Tokio Formation aquifers in southwestern Arkansas and the Nacatoch Sand aquifer in northeastern Arkansas are sources of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 60 wells completed in the Nacatoch Sand and 50 wells completed in the Tokio Formation during February 2005. Aquifers in the Nacatoch Sand and Tokio Formation are hereafter referred to as the Nacatoch aquifer and Tokio aquifer, respectively. The direction of ground-water flow in the Nacatoch aquifer in northeastern Arkansas generally is towards the southeast. The potentiometric high is located along the north and northwestern boundaries of the area. The direction of ground-water flow in the Nacatoch aquifer in southwestern Arkansas is towards the south-southeast in Little River, Miller, and Hempstead Counties and to the east-southeast in Nevada and Clark Counties. The potentiometric high is located within the outcrop area in north-central Hempstead County. A cone of depression exists in the Nacatoch aquifer at Hope in southeastern Hempstead County. The direction of ground-water flow in the Tokio aquifer in southwestern Arkansas generally is towards the south or southeast. The potentiometric high is within the outcrop area. An area of artesian flow exists in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties. One apparent cone of depression might exist northwest of Hope in Hempstead County. In northeastern Arkansas, withdrawals from the Nacatoch aquifer increased by 516 percent from 1965 to 2000. In southwestern Arkansas, withdrawals from Nacatoch aquifer and Tokio aquifer increased by 125 percent and 201 percent, respectively, from 1965 to 1980 and decreased by 93 percent and 80 percent, respectively, from 1980 to 2000. Long-term hydrographs were prepared for 10 wells in the study areas. Changes in water levels in some wells may be associated with

  18. Status of Water Levels in Aquifers in the Nacatoch Sand of Southwestern and Northeastern Arkansas and the Tokio Formation of Southwestern Arkansas, 1999

    USGS Publications Warehouse

    Schrader, Tony P.

    1999-01-01

    Nacatoch Sand and Tokio Formation aquifers in southwestern Arkansas and the Nacatoch Sand aquifer in northeastern Arkansas are a source of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 59 wells completed in the Nacatoch Sand and 45 wells completed in the Tokio Formation from April through May 1999. The direction of ground-water flow in the aquifer in the Nacatoch Sand in northeastern Arkansas generally is towards the southeast. The potentiometric high is located along the north and northwestern boundaries. The direction of ground-water flow in the aquifer in the Nacatoch Sand in southwestern Arkansas is towards the south-southeast in Little River, Miller, and Hempstead Counties and to the east-southeast in Nevada and Clark Counties. The potentiometric high is located within the outcrop area in north-central Hempstead County. A cone of depression exists in the aquifer in the Nacatoch Sand at Hope in southeastern Hempstead County. The direction of ground-water flow in the aquifer in the Yokio Formation in southwestern Arkansas generally is towards the southeast. The potentiometric high is within the outcrop area. An area of artesian flow exists in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties. One apparent cone of depression might exist northwest of Hope in Hempstead County. In northeastern Arkansas, withdrawals from the Nacatoch Sand increased by 736 percent from 1965 to 1995. In southwestern Arkansas withdrawals from aquifers in the Nacatoch Sand and Yokio Formation increased by 125 percent and 201 percent, respectively, from 1965 to 1980 and decreased by 78 percent and 63 percent, respectively, from 1980 to 1995. Long-term hydrographs were prepared for 13 wells in the study area. Changes in water levels in some wells may be associated with changes in withdrawals from the respective aquifers.

  19. Status of water levels in aquifers in the Nacatoch Sand of southwestern and northeastern Arkansas and the Tokio Formation of southwestern Arkansas, 2002

    USGS Publications Warehouse

    Schrader, Tony P.; Scheiderer, Rheannon M.

    2004-01-01

    Aquifers in the Nacatoch Sand and Tokio Formation in southwestern Arkansas and the Nacatoch Sand in northeastern Arkansas are sources of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 60 wells completed in the Nacatoch Sand and 48 wells completed in the Tokio Formation during January and February 2002. In northeastern Arkansas, withdrawals from the Nacatoch Sand increased by 784 percent from 1965 to 1990 and decreased by 30 percent from 1990 to 2000. In southwestern Arkansas withdrawals from aquifers in the Nacatoch Sand and Tokio Formation increased by 125 percent and 201 percent, respectively, from 1965 to 1980 and decreased by 93 percent and 81 percent, respectively, from 1980 to 2000. Long-term hydrographs were prepared for 13 wells in the study area. Changes in water levels in some wells may be associated with changes in withdrawals from the respective aquifers. The direction of ground-water flow in the aquifer in the Nacatoch Sand in northeastern Arkansas generally is towards the southeast. The potentiometric high is located along the north and northwestern boundaries of the subarea. The direction of ground-water flow in the aquifer in the Nacatoch Sand in southwestern Arkansas is towards the south-southeast in Little River, Miller, and Hempstead Counties and to the east-southeast in Nevada and Clark Counties. The potentiometric high is located within the outcrop area in north-central Hempstead County. Cones of depression exist in the aquifer in the Nacatoch Sand in southeastern Hempstead County and in southwestern Clark County. The direction of ground-water flow in the aquifer in the Tokio Formation in southwestern Arkansas generally is towards the south or southeast. The potentiometric high is located where the aquifer outcrops in the northwestern part of the study area. An area of artesian flow exists in southeastern Pike, northeastern Hempstead, and

  20. Water levels in the aquifers of the Nacatoch Sand of southwestern and northeastern Arkansas and the Tokio Formation of southwestern Arkansas, February–March 2011

    USGS Publications Warehouse

    Schrader, T.P.; Rodgers, Kirk D.

    2013-01-01

    The aquifers in the Nacatoch Sand and Tokio Formation in southwestern Arkansas and the Nacatoch Sand in northeastern Arkansas are sources of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 47 wells completed in the Nacatoch Sand and 45 wells completed in the Tokio Formation during February and March 2011. Aquifers in the Nacatoch Sand and Tokio Formation are hereafter referred to as the Nacatoch aquifer and the Tokio aquifer, respectively. The direction of groundwater flow in the Nacatoch aquifer in southwestern Arkansas is towards the southeast in Hempstead, Little River, and Miller Counties and east-southeast in Clark and Nevada Counties. A potentiometric high is located within the outcrop area of north-central Hempstead County. Two cones of depression exist in the Nacatoch aquifer, one at Hope in southeastern Hempstead County and one in Clark County. The direction of groundwater flow in the Nacatoch aquifer in northeastern Arkansas generally is towards the southeast. A potentiometric high in the study area is located along the north and northwestern boundaries of the area, but water levels may be higher outside the study area. In northeastern Arkansas, groundwater withdrawals from the Nacatoch aquifer increased by 564 percent from 1965 to 2010. In southwestern Arkansas, groundwater withdrawals from the Nacatoch Sand increased by 125 percent from 1965 to 1980, and withdrawals decreased by 85 percent from 1980 to 2010. In southwestern Arkansas, groundwater withdrawals from the Tokio aquifer increased by 201 percent from 1965 to 1980, and withdrawals decreased by 81 percent from 1980 to 2000. Withdrawals from the Tokio aquifer increased by 291 percent from 2000 to 2005, and withdrawals decreased by 32 percent from 2005 to 2010. The direction of groundwater flow in the Tokio aquifer in southwestern Arkansas generally is towards the south or southeast. The

  1. 77 FR 25162 - Golden Spread Electric Cooperative, Inc. v. Southwestern Public Service Company; Notice of Complaint

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... Public Service Company (Respondent or SPS) alleges that the formula rate of Replacement Power Sales... Federal Energy Regulatory Commission Golden Spread Electric Cooperative, Inc. v. Southwestern Public Service Company; Notice of Complaint Take notice that on April 20, 2012, pursuant to sections 201,...

  2. Macintosh and Photo-CD Technologies Provide Orientations to Southwestern College Library.

    ERIC Educational Resources Information Center

    Alexander, William J.; And Others

    Due to a rapidly increasing demand for bibliographic instruction, Southwestern College in San Ysidro, California, devised an interactive English-Spanish multimedia library skills program using Macintosh and Kodak PhotoCD technologies. First, a PhotoCD containing 100 photos of library services was produced. Then, an interactive Macintosh program…

  3. Increasing the percentage of renewable energy in the Southwestern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An analysis was performed on the states in the Southwestern United States to determine methods to increase the proportion of wind and solar generated electricity in those states to levels as high as 40% of total electricity used. This analysis was performed by comparing the monthly and diurnal elect...

  4. An Investigation of Southwestern Area Principals and the Enactment of Crisis Plans in High Schools

    ERIC Educational Resources Information Center

    Parker, Kerry L.

    2012-01-01

    The purpose of this study was to identify what southwestern area high school principals reported as the enactment of school crisis plans as described in the Center for Mental Health in Schools at UCLA (CMHS, 2008), "Resource Aid: Responding to a Crisis at School." The conceptual framework guiding the study was an adaptation of the Crisis…

  5. Migrant Programs in the Southwestern States -- Arizona, Colorado, Kansas, Nevada, New Mexico, and Utah.

    ERIC Educational Resources Information Center

    National Migrant Information Clearinghouse, Austin, TX. Juarez-Lincoln Center.

    Part of the "Comprehensive National Survey of Migrant Programs" series, this directory was prepared for use by agencies working with migrant and seasonal farmworkers in the Southwestern states of Arizona, Colorado, Kansas, Nevada, New Mexico, and Utah. The directory lists programs, services, and resources available to migrants in these states.…

  6. ASSESSING THE WATER QUALITY IMPACTS OF GLOBAL CLIMATE CHANGE IN SOUTHWESTERN OHIO, U.S.A

    EPA Science Inventory

    This paper uses a watershed-scale hydrologic model (Soil and Water Assessment Tool) to simulate the water quality impacts of future climate change in the Little Miami River (LMR) watershed in southwestern Ohio. The LMR watershed, the principal source of drinking water for 1.6 mi...

  7. Dietary Diversity as a Correlate of Undernutrition among School-Age Children in Southwestern Nigeria

    ERIC Educational Resources Information Center

    Olumakaiye, M. F.

    2013-01-01

    Purpose/Objectives: This study was conducted to determine the association between undernutrition and dietary diversity among school-age children in southwestern Nigeria. Methods: A total of 600 school children were randomly selected from six private and six public schools in the region. A standardized FAO-published 24-hour diet recall…

  8. Hypervirulent emm59 Clone in Invasive Group A Streptococcus Outbreak, Southwestern United States.

    PubMed

    Engelthaler, David M; Valentine, Michael; Bowers, Jolene; Pistole, Jennifer; Driebe, Elizabeth M; Terriquez, Joel; Nienstadt, Linus; Carroll, Mark; Schumacher, Mare; Ormsby, Mary Ellen; Brady, Shane; Livar, Eugene; Yazzie, Del; Waddell, Victor; Peoples, Marie; Komatsu, Kenneth; Keim, Paul

    2016-04-01

    The hyper-virulent emm59 genotype of invasive group A Streptococcus was identified in northern Arizona in 2015. Eighteen isolates belonging to a genomic cluster grouped most closely with recently identified isolates in New Mexico. The continued transmission of emm59 in the southwestern United States poses a public health concern. PMID:26982330

  9. Adoption of Internet2 in a Southwestern University: Human Resources Concerns

    ERIC Educational Resources Information Center

    Mendoza-Diaz, Noemi V.; Dooley, Larry M.; Dooley, Kim E.

    2007-01-01

    Human Resources are often times challenged by the integration of new technologies (Benson, Johnson, & Kichinke, 2002). Universities pose a unique challenge since they reluctantly adapt to changes (Torraco & Hoover, 2005; Watkins 2005). This is a dissertation study of the human resource concerns about adopting Internet2 in a Southwestern-RU/VH:…

  10. A Study of the W Grade at Southwestern College, Fall 1971.

    ERIC Educational Resources Information Center

    Galvin, Kevin

    The purpose of this study was to identify the factors in attrition over which Southwestern College might exercise some control and through which experimentation could be conducted toward changing the patterns of attrition. Data were gathered from college files on every student who withdrew from one or more classes for the fall 1971 semester. A…

  11. Citizen-volunteer and professional monitoring to identify fecal sources of contamination in southwestern Puerto Rico

    EPA Science Inventory

    High concentrations of nutrients, fecal microorganisms, and sediments in surface waters can be a public health threat and can impact fringing coral reefs in Guánica Bay in southwestern Puerto Rico. Yet, the main factors and sources contributing to water quality degradation...

  12. 77 FR 35618 - Establishment of Area Navigation (RNAV) Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-14

    ... routes in the southwestern United States (77 FR 24157). Interested parties were invited to participate in... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation...

  13. Bonanza Club: 35 Years of Maximum Crop Production and Extension Education in Southwestern Kansas.

    ERIC Educational Resources Information Center

    Henson, D.; And Others

    1992-01-01

    Describes the success of a county extension crops program, the Bonanza Club, in providing timely and useful information regarding new and successful agronomic practices. The program is cited for its beneficial influence on changing crop-production practices in southwestern Kansas. (MCO)

  14. New combinations in Habranthus (Amaryllidaceae) in Mexico and Southwestern U.S.A.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New combinations in Habranthus (Amaryllidaceae) are made for four species which were previously treated as Zephyranthes (Z. arenicola Brandegee, Z. chichimeca T.M. Howard & S. Ogden, Z. conzattii Greenm., and Z. longifolia Hemsl.) and which are endemic to Mexico and southwestern U.S.A.: Habranthus a...

  15. Documentation and Revitalization of the Zhuang Language and Culture of Southwestern China through Linguistic Fieldwork

    ERIC Educational Resources Information Center

    Bodomo, Adams

    2010-01-01

    This article outlines innovative strategies, methods, and techniques for the documentation and revitalization of "Zhuang" language and culture through linguistic fieldwork. Zhuang, a Tai-Kadai language spoken mainly in the rural areas of the Guangxi Zhuang Autonomous Region of southwestern China, is the largest minority language in China, with…

  16. Lesser-known European wine grape cultivars in southwestern Idaho: cold hardiness, berry maturity and yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cold tolerance, phenology, yield and fruit maturity of lesser-known red and white-skinned wine grape cultivars (Vitis vinifera, L.) of European origin were compared to that of ‘Merlot’ and ‘Cabernet Sauvignon’ over two growing seasons in southwestern Idaho. Variability among cultivars was detec...

  17. 77 FR 40490 - Establishment of Area Navigation (RNAV) Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-10

    ... the southwestern United States (77 FR 35618). Subsequent to publication, an error was found in the... June 14, 2012 (77 FR 35618) (FR Doc. 2012-14406) for RNAV route T- 310, is corrected under the.../longitude coordinates for the NOCHI waypoint (WP) as appears in the description of RNAV route T-310....

  18. Hogfish Lachnolaimus maximus (Labridae) confirmed in the south-western Atlantic Ocean.

    PubMed

    Sampaio, C L S; Santander-Neto, J; Costa, T L A

    2016-09-01

    Based on material deposited in collections, photographic records and other reports from fishermen and divers, the occurrence of the hogfish Lachnolaimus maximus (Labridae) is confirmed in the south-western Atlantic Ocean, near the Brazilian coast as far south as southern Brazil. The recognized range of this species should therefore be extended c. 3000 km further south. PMID:27397557

  19. 77 FR 24156 - Proposed Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... continues to read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3... of Air Traffic Service Routes; Southwestern United States AGENCY: Federal Aviation...

  20. 77 FR 35836 - Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-15

    ... routes in the southwestern United States (78 FR 24156). An NPRM correction published in the Federal Register of May 23, 2012 (77 FR 30437) corrected the description of VOR Federal airway V-16. Interested... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a...

  1. Fire in desert grassland region of the southwestern USA: Where and why

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire is an important driver of ecological processes in semiarid systems and serves a vital role in shrub-grass interactions. In desert grasslands of the Southwestern US, the loss of fire has been implicated as a primary cause of shrub encroachment. Where fires can currently be re-introduced and mana...

  2. Hogfish Lachnolaimus maximus (Labridae) confirmed in the south-western Atlantic Ocean.

    PubMed

    Sampaio, C L S; Santander-Neto, J; Costa, T L A

    2016-09-01

    Based on material deposited in collections, photographic records and other reports from fishermen and divers, the occurrence of the hogfish Lachnolaimus maximus (Labridae) is confirmed in the south-western Atlantic Ocean, near the Brazilian coast as far south as southern Brazil. The recognized range of this species should therefore be extended c. 3000 km further south.

  3. Disadvantaged-Handicapped Identification and Supportive Service Delivery System, Southwestern College, Spring 1974.

    ERIC Educational Resources Information Center

    MacDougall, Allan

    A system of identification and notification designed and implemented at Southwestern College to speed supportive services to the disadvantaged and handicapped students in vocational programs is discussed. The system is comprised of the following procedures: (1) Self-identification (Student Services Information Form filled out by each student at…

  4. Hypervirulent emm59 Clone in Invasive Group A Streptococcus Outbreak, Southwestern United States

    PubMed Central

    Valentine, Michael; Bowers, Jolene; Pistole, Jennifer; Driebe, Elizabeth M.; Terriquez, Joel; Nienstadt, Linus; Carroll, Mark; Schumacher, Mare; Ormsby, Mary Ellen; Brady, Shane; Livar, Eugene; Yazzie, Del; Waddell, Victor; Peoples, Marie; Komatsu, Kenneth; Keim, Paul

    2016-01-01

    The hyper-virulent emm59 genotype of invasive group A Streptococcus was identified in northern Arizona in 2015. Eighteen isolates belonging to a genomic cluster grouped most closely with recently identified isolates in New Mexico. The continued transmission of emm59 in the southwestern United States poses a public health concern. PMID:26982330

  5. Hypervirulent emm59 Clone in Invasive Group A Streptococcus Outbreak, Southwestern United States.

    PubMed

    Engelthaler, David M; Valentine, Michael; Bowers, Jolene; Pistole, Jennifer; Driebe, Elizabeth M; Terriquez, Joel; Nienstadt, Linus; Carroll, Mark; Schumacher, Mare; Ormsby, Mary Ellen; Brady, Shane; Livar, Eugene; Yazzie, Del; Waddell, Victor; Peoples, Marie; Komatsu, Kenneth; Keim, Paul

    2016-04-01

    The hyper-virulent emm59 genotype of invasive group A Streptococcus was identified in northern Arizona in 2015. Eighteen isolates belonging to a genomic cluster grouped most closely with recently identified isolates in New Mexico. The continued transmission of emm59 in the southwestern United States poses a public health concern.

  6. 77 FR 30437 - Proposed Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-23

    ... (77 FR 24156). The description of V-16 in the NPRM did not reflect a previous amendment of the route that was published on September 19, 2011 (76 FR 57902). The incorrect part of the V-16 description in...; Southwestern United States as published in the Federal Register of April 23, 2010 (77 FR 24156) FR Doc....

  7. Vulnerabilities of Southwestern U.S. rangeland-based animal agriculture to climate change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Southwestern US is a 5-state region that has supported animal agriculture since the late 16th Century when European settlers crossed the Rio Grande into present day west Texas and southern New Mexico with herds of cattle, sheep, goats and horses. For the past 400 years the rangeland livestock i...

  8. Agronomic and kernel compositional traits of blue maize landraces from the southwestern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multiple races of maize have been cultivated for centuries in the southwestern USA and northern Mexico. These landraces, used primarily for human food consumption, display considerable genetic variation for traits such as kernel color and texture. Traditional cultivation of these landraces has decli...

  9. Adults Who Learn: Sharing Literacy Project Experience from South-Western Nigeria

    ERIC Educational Resources Information Center

    Kolawole, Oluwatoyin Dare

    2011-01-01

    The paper reports the outcome of a funded non-formal, functional adult literacy project embarked upon in the university-based "Isoya" rural development programme area in south-western Nigeria from 2005-2007. It specifically presents the approaches used in legitimising the literacy project amongst community people; and reports the positive impact…

  10. Teacher Quality, Modern Technology Applications and Teaching at a South-Western Nigerian University

    ERIC Educational Resources Information Center

    Adeyanju, Lade J.

    2006-01-01

    Increase in enrolment of learners at the different levels of the educational system and particularly in the south-western Nigerian universities motivates this paper. The stretched facilities, infrastructure, poor funding and attitude of stressed teachers to adoption of new technologies affect quality teaching and thus demand the attention of…

  11. Valuing preservation and restoration alternatives for ecosystem services in the southwestern U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conservation of freshwater systems in the semi-arid southwestern U.S. is a critical issue as these systems support habitat for wildlife and provide for consumptive use for humankind. Economists have utilized stated preference techniques to value non-marketed goods and services such as freshwater sy...

  12. Faculty Adoption of Distance Education Innovations in a Southwestern Rural Community College: A Longitudinal Study

    ERIC Educational Resources Information Center

    Klassen, Diane June

    2010-01-01

    The purpose of this longitudinal case study was to examine the faculty adoption of distance education in a rural community college over a span of ten years in the southwestern United States, beginning in 1999 with the adoption and implementation of an instructional television (ITV) system and ending in 2009 with the adoption and implementation of…

  13. 40 CFR 81.57 - Eastern Tennessee-Southwestern Virginia Interstate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Eastern Tennessee-Southwestern Virginia Interstate Air Quality Control Region. 81.57 Section 81.57 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of Air Quality...

  14. Increasing the percentage of renewable energy in the Southwestern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Combining the output of wind farms with that of Concentrating Solar Power (CSP) plants (including a heat storage system) resulted in a substantial percentage (40%) of the total utility electrical generation in the Southwestern United States being met by renewable energy. Using wind and solar resourc...

  15. Sensitivity of a semi-arid riparian ecosystem to climatic variability in the southwestern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climatic change will have strong impacts on riverine ecosystems and their associated riparian zones. In the southwestern United States, conservation and restoration of riparian habitats has become a priority for resource management agencies and conservation groups, and these areas are biodiversity h...

  16. Critical Thinking Dispositions of Undergraduate Nursing Students and Nursing Faculty in Southwestern Nigeria

    ERIC Educational Resources Information Center

    Ojewole, Foluso O.

    2013-01-01

    The purpose of this quantitative research study was to identify the critical thinking dispositions of undergraduate nursing students and nursing faculty in Southwestern Nigeria. Critical thinking dispositions are required for critical thinking skills. People who have critical thinking disposition exhibit seven traits: truth-seeking,…

  17. BEHAVIOR AND PREY OF NESTING RED-SHOULDERED HAWKS IN SOUTHWESTERN OHIO

    EPA Science Inventory

    We used direct observations to quantify prey types, prey delivery rate, and adult and nestling behavior at nests of Red-shouldered Hawks (Buteo lineatus) in suburban southwestern Ohio. Twenty-one nests were observed for a total of 256 hr in 1997-2001. Small mammals made up the ...

  18. A Study of Cooperative, Networking, and Computer Activities in Southwestern Libraries.

    ERIC Educational Resources Information Center

    Corbin, John

    The Southwestern Library Association (SWLA) conducted an inventory and study of the SWLA libraries in cooperative, network, and computer activities to collect data for use in planning future activities and in minimizing duplication of efforts. Questionnaires were mailed to 2,060 academic, public, and special libraries in the six SWLA states.…

  19. Why Veteran Teachers in a Southwestern Border State Choose to Stay in the Education Profession

    ERIC Educational Resources Information Center

    Lopez, J. Blanca O.

    2009-01-01

    This phenomenological qualitative study provided a venue for veteran teachers in a southwestern border state to voice their thinking of what they believed had made them stay in the education profession. The "maestros veterans" in this study had a minimum of 10 years in the education profession and were currently teaching within the "Mexica"…

  20. Diallel Analysis of Southwestern Corn Borer Leaf Feeding Damage in Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Southwestern corn borer [Diatraea grandiosella (Dyar)] is an important pest of maize in the southern United States. It feeds extensively within the leaf whorls of plants in the vegetative stages of growth. This reduces both the quantity and quality of harvestable grain. Germplasm lines with resistan...

  1. Spatial probability models of fire in the desert grasslands of the southwestern USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire is an important driver of ecological processes in semiarid environments; however, the role of fire in desert grasslands of the Southwestern US is controversial and the regional fire distribution is largely unknown. We characterized the spatial distribution of fire in the desert grassland region...

  2. Indian Communities in Action: A Case Study Approach to Community Development Among Southwestern Indians.

    ERIC Educational Resources Information Center

    Roessel, Robert A., Jr.

    Designed as a stimulus for American Indian educational development, these examples of community development programs among the Southwestern Indians are presented via the case study approach in the interest of analyzation of both positive and negative experiences. Specifically, this book presents case studies of: (1) the Round Rock School on the…

  3. Late Neogene evolution of the East Asian monsoon revealed by terrestrial mollusk record in Western Chinese Loess Plateau: From winter to summer dominated sub-regime

    NASA Astrophysics Data System (ADS)

    Li, Fengjiang; Rousseau, Denis-Didier; Wu, Naiqin; Hao, Qingzhen; Pei, Yunpeng

    2008-10-01

    More and more evidence indicates that the onset of the East Asian (EA) monsoon can be traced back to the Oligocene-Miocene boundary (at about 23 Ma). However, the process of its evolution is still less well-known until now. Here we investigate its late Neogene evolution by analyzing a terrestrial mollusk sequence, from the Chinese Loess Plateau (CLP), covering the period between 7.1 and 3.5 Ma. Considering the modern ecological requirements of these organisms, we were able to define two groups of cold-aridiphilous (CA) and thermo-humidiphilous (TH) species, representing the EA winter and summer monsoon variations, respectively, as previously defined in the Quaternary glacial-interglacial cycles. Variations in these two groups indicate two different monsoon dominated periods during 7.1-3.5 Ma. First, between 7.1 and 5.5 Ma, the EA winter monsoon, with a 100-kyr periodicity, was dominant. Second, between 5.1 and 4 Ma, the EA summer monsoon dominated, with a 41-kyr periodicity. Furthermore, our mollusk record yields valuable evidence for a late Miocene-Pliocene transition of about 400 kyr from winter monsoon dominated towards summer monsoon dominated, associated with a periodicity transition from weak 100 kyr to 41 kyr. The strengthened winter monsoon interval, with a 100-kyr periodicity, is coeval with orbital-scale global ice-volume changes, in conjunction with the uplift of the Tibetan Plateau which probably reinforced the winter monsoon sub-regime. Conversely, closures of the Panama and Indonesian seaways, associated with changes in obliquity between 5.1 and 4 Ma, are probably major forcing factors for the observed dominant summer monsoon with 41-kyr frequency, favoring heat and moisture transports between low and high latitudes to allow TH mollusks to grow and develop in the CLP.

  4. Neogene carbonate exploration play concepts for Northern New Guinea: New iteration from field work and seismic stratigraphy along the Northern New Guinea Fault Zone

    SciTech Connect

    Pigott, J.D.; Geiger, C. )

    1994-07-01

    Recent field reconnaissance, petrography, nanno and foraminifera age determinations, and seismic stratigraphy of the Sepik and Piore subbasins of northern New Guinea reveal the existence of an extensive, tectonically unstable, Miocene-Pliocene carbonate shelf system. These findings represent the first recorded evidence of northern Papuan limestones coeval in age to those of the hydrocarbon productive Salawati Basin of Irian Jaya. Moreover, these observations also demonstrate the significance of episodic activities of the northern New Guinea fault zone upon the changes in carbonate sedimentation and diagenesis. During the Neogene, algal biosparites to foraminiferal biomicrites defined the clean portion of a mixed clastic-carbonate shelf system of the northern New Guinea basin, which began at the central New Guinea cordillera and deepened northward. This shelf was interrupted by coral-coralline algal boundstone fringing- to patch-reef buildups with associated skeletal grainstones. Clean carbonates were spatially and temporally restricted to basement blocks, which episodically underwent uplift while terrigenous dilutes carbonates were more common in adjacently subsiding basement block bathymetric lows. These tectonic expressions were caused by the spatially transient nature of constraining bends of the evolving north New Guinea faults. As shown by seismic stratigraphy, by the late Miocene to the early Pliocene the uplift of the Bewani-Torricelli Mountains sagittally divided the shelf of the northern New Guinea basin into the Ramu-Sepik and the Piore basins. Continued regional sinistral transpression between the Pacific and the New Guinea leading edge of the Indo-Australian plates led to the reverse tilting of the Piore basin, the shallowing of the former distal shelf with concomitant extensive biolithite development (e.g., on subsiding volcanic islands) eventual uplifting of the Oenake Range, and en echelon faulting of the Bewani-Torricelli Mountains.

  5. Phylogenetic relationships within Bothrops neuwiedi group (Serpentes, Squamata): geographically highly-structured lineages, evidence of introgressive hybridization and Neogene/Quaternary diversification.

    PubMed

    Machado, Taís; Silva, Vinícius X; Silva, Maria José de J

    2014-02-01

    Eight current species of snakes of the Bothrops neuwiedi group are widespread in South American open biomes from northeastern Brazil to southeastern Argentina. In this paper, 140 samples from 93 different localities were used to investigate species boundaries and to provide a hypothesis of phylogenetic relationships among the members of this group based on 1122bp of cyt b and ND4 from mitochondrial DNA and also investigate the patterns and processes occurring in the evolutionary history of the group. Combined data recovered the B. neuwiedi group as a highly supported monophyletic group in maximum parsimony, maximum likelihood and Bayesian analyses, as well as four major clades (Northeast I, Northeast II, East-West, West-South) highly-structured geographically. Monophyly was recovered only for B. pubescens. By contrast, B. diporus, B. lutzi, B. erythromelas, B. mattogrossensis, B. neuwiedi, B. marmoratus, and B. pauloensis, as currently defined on the basis of morphology, were polyphyletic. Sympatry, phenotypic intergrades and shared mtDNA haplotypes, mainly between B. marmoratus and B. pauloensis suggest recent introgressive hybridization and the possible occurrence of a narrow hybrid zone in Central Brazil. Our data suggest at least three candidate species: B. neuwiedi from Espinhaço Range, B. mattogrossensis (TM173) from Serra da Borda (MT) and B. diporus (PT3404) from Castro Barros, Argentina. Divergence estimates highlight the importance of Neogene events in the origin of B. neuwiedi group, and the origin of species and diversification of populations of the Neotropical fauna from open biomes during the Quaternary climate fluctuations. Data reported here represent a remarkable increase of the B. neuwiedi group sampling size, since representatives of all the current recognized species from a wide geographic range are included in this study, providing basic information for understanding the evolution and conservation of Neotropical biodiversity. PMID:24140980

  6. Cryptic Neogene vicariance and Quaternary dispersal of the red-spotted toad (Bufo punctatus): insights on the evolution of North American warm desert biotas.

    PubMed

    Jaeger, Jef R; Riddle, Brett R; Bradford, David F

    2005-09-01

    We define the geographical distributions of mitochondrial DNA (mtDNA) lineages embedded within a broadly distributed, arid-dwelling toad, Bufo punctatus. These patterns were evaluated as they relate to hypothesized vicariant events leading to the formation of desert biotas within western North America. We assessed mtDNA sequence variation among 191 samples from 82 sites located throughout much of the species' range. Parsimony-based haplotype networks of major identified lineages were used in nested clade analysis (NCA) to further elucidate and evaluate shallow phylogeographic patterns potentially associated with Quaternary (Pleistocene-Holocene) vicariance and dispersal. Phylogenetic analyses provided strong support for three monophyletic lineages (clades) within B. punctatus. The geographical distributions of the clades showed little overlap and corresponded to the general boundaries of the Peninsular Desert, and two continental desert regions, Eastern (Chihuahuan Desert-Colorado Plateau) and Western (Mojave-Sonoran deserts), geographically separated along the Rocky Mountains and Sierra Madre Occidental. The observed divergence levels and congruence with postulated events in earth history implicate a late Neogene (latest Miocene-early Pliocene) time frame for separation of the major mtDNA lineages. Evaluation of nucleotide and haplotype diversity and interpretations from NCA reveal that populations on the Colorado Plateau resulted from a recent, likely post-Pleistocene, range expansion from the Chihuahuan Desert. Dispersal across historical barriers separating major continental clades appear to be recent, resulting in secondary contacts in at least two areas. Given the observed contact between major clades, we speculated as to why the observed deep phylogeographic structure has not been eroded during the multiple previous interglacials of the Pleistocene. PMID:16101772

  7. Two areas of probable holocene deformation in southwestern Utah

    USGS Publications Warehouse

    Anderson, R.E.; Bucknam, R.C.

    1979-01-01

    Recent geologic studies in southwestern Utah indicate two areas of probable Holocene ground deformation. 1. (1)A narrow arm of Lake Bonneville is known to have extended southward into Escalante Valley as far as Lund, Utah. Remnants of weakly developed shoreline features, which we have recently found, suggest that Lake Bonnevile covered an area of about 800 km2 beyond its previously recognized limits near Lund. Shoreline elevations show a gradual increase from 1553 m near Lund to 1584 m at a point 50 km further southwest, representing a reversal of the pattern that would result from isostatic rebound. The conspicuously flat floor of Escalante Valley covers an additional 100 km2 southward toward Enterprise, where its elevation is greater than 1610 m, but no shoreline features are recognizable; therefore, the former presence of the lake is only suspected. The measured 31-m rise over 50 km and the suspected 57-m rise in elevation over 70 km apparently occurred after Lake Bonnevile abandoned this area. The abandonment could have occurred as recently as 13,000 years ago, in which case the uplift is mainly of Holocene age. It probably has a deep-seated tectonic origin because it is situated above an inferred 9-km upwarp of the mantle that has been reported beneath the southern part of Escalante Valley on the basis of teleseismic P-wave residuals. 2. (2)Numerous closed topographic basins, ranging from a few hundred square meters to 1 km2 in area, are found at various elevations along the west margin of the Colorado Plateau northeast of Cedar City. Geologic mapping in that area indicates that the basins are located over complex structural depressions in which the rocks are faulted and folded. Several of the depressions are perched along the walls of the West Fork of Braffits Creek, one of a few north-draining creeks that have incised deeply into the plateau margin. Extremely active modern erosion by the creek has produced a 6-km-long gorge along which excellent exposures

  8. Preliminary soil-slip susceptibility maps, southwestern California

    USGS Publications Warehouse

    Morton, Douglas M.; Alvarez, Rachel M.; Campbell, Russell H.; Digital preparation by Bovard, Kelly R.; Brown, D.T.; Corriea, K.M.; Lesser, J.N.

    2003-01-01

    This group of maps shows relative susceptibility of hill slopes to the initiation sites of rainfall-triggered soil slip-debris flows in southwestern California. As such, the maps offer a partial answer to one part of the three parts necessary to predict the soil-slip/debris-flow process. A complete prediction of the process would include assessments of “where”, “when”, and “how big”. These maps empirically show part of the “where” of prediction (i.e., relative susceptibility to sites of initiation of the soil slips) but do not attempt to show the extent of run out of the resultant debris flows. Some information pertinent to “when” the process might begin is developed. “When” is determined mostly by dynamic factors such as rainfall rate and duration, for which local variations are not amenable to long-term prediction. “When” information is not provided on the maps but is described later in this narrative. The prediction of “how big” is addressed indirectly by restricting the maps to a single type of landslide process—soil slip-debris flows. The susceptibility maps were created through an iterative process from two kinds of information. First, locations of sites of past soil slips were obtained from inventory maps of past events. Aerial photographs, taken during six rainy seasons that produced abundant soil slips, were used as the basis for soil slip-debris flow inventory. Second, digital elevation models (DEM) of the areas that were inventoried were used to analyze the spatial characteristics of soil slip locations. These data were supplemented by observations made on the ground. Certain physical attributes of the locations of the soil-slip debris flows were found to be important and others were not. The most important attribute was the mapped bedrock formation at the site of initiation of the soil slip. However, because the soil slips occur in surficial materials overlying the bedrocks units, the bedrock formation can only serve as

  9. Petrogenesis of pillow basalts from Baolai in southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, Chih-Chun; Yang, Huai-Jen

    2016-04-01

    The pillow basalts from Baolai in southwestern Taiwan have been inferred to bear Dupal signautres based on their Th/Ce ratio, linking the Baolai basalts to the South China Sea (SCS) seamounts that are characterized by Dupal Pb isotope signatures (Smith and Lewis, 2007). In this study, thirty-two Baolai basalt samples were analyzed for abundances of major and trace elements as well as Pb and Nd isotope ratios to verify their Dupal characters and to constrain their petrogenesis significance. The Baolai basalts contain 4-10 % L.O.I.. Three stages of alteration are inferred from plots of L.O.I. abundance versus concentrations major oxides as well as mineral textures and compositions. The first alteration stage was characterized by albitization that converted Ca-rich plagioclase to albite. The second alteration stage was dominated by chloritization of olivine and augite, resulting in increases in L.O.I. abundance. The last alteration stage is represented by formation of secondary calcite in vesicles and cracks. These alteration processes reflect interaction with seawater and apparently did not affect the magmatic Pb isotope composition for the low Pb concentration in seawater. Relative to the North Hemisphere Reference Line (NHRL), the Baolai pillow basalts have higher 208Pb/204Pb ratios at a given 206Pb/204Pb value, showing Dupal anomaly. For their relatively higher 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios, the Baolai basalts are distinct from majority of the Cenozoic basalts in the Hainan-Leizhou peninsula, the Indochina peninsula, and the SCS seamounts, for which derivation from the Hainan mantle plume has been recently proposed (Wang et al., 2013). In contrast, the Baolai basalts and the Cenozoic basalts from eastern Guangdong at southeastern China have similar Pb and Nd isotope compositions, indicating derivation from similar mantle sources. However, the Baolai basalts have lower abundance ratios of Zr/Hf (40.3-45.6 versus 46.5-50.5), La/Yb (12

  10. Calcic soils and calcretes in the southwestern United States

    USGS Publications Warehouse

    Bachman, George Odell; Machette, Michael N.

    1977-01-01

    Secondary calcium carbonate of diverse origins, 'caliche' of many authors, is widespread in the southwestern United States. 'Caliche' includes various carbonates such as calcic soils and products of groundwater cementation. The term 'caliche' is generally avoided in this report in favor of such terms as calcrete, calcic soils, and pervasively cemented deposits. Criteria for the recognition of various types of calcrete of diverse origins include field relations and laboratory data. Calcic soils provide a comprehensive set of characteristics that aid in their recognition in the field. These characteristics include a distinctive morphology that is zoned horizontally and can frequently be traced over tens to hundreds of square kilometers. The major process in the formation of pedogenic calcrete and calic soils is the leaching of calcium carbonate from upper soil horizons by downward percolating soil solutions and reprecipitation of the carbonate in alluvial horizons near the base of the soil profile. The formation of pedogenic calcrete involves many factors including climate, source of carbonate, and tectonic stability of the geomorphic surface on which the calcrete is deposited. Most of the carbonate in pedogenic calcrete is probably derived from windblown sand, dust, and rain. Calcic soils and pedogenic calcretes follow a six-stage sequence morphologic development and is based on a classification devised by Gile, Peterson and Grossman in 1966. The .six morphologic stages of carbonate deposition in soils are related to the relative age of the soil and are as follows: I. The first or youngest stage includes filamentous or faint coatings of carbonate on detrital grains. II. The second stage includes pebble coatings which are continuous; firm carbonate nodules are few to common. III. The third stage includes coalesced nodules which occur in a friable or disseminated carbonate matrix. IV. The fourth stage includes platy, firmly cemented matrix which engulfs nodules

  11. Geology, geochemistry, geochronology, and economic potential of Neogene volcanic rocks in the Laguna Pedernal and Salar de Aguas Calientes segments of the Archibarca lineament, northwest Argentina

    NASA Astrophysics Data System (ADS)

    Richards, J. P.; Jourdan, F.; Creaser, R. A.; Maldonado, G.; DuFrane, S. A.

    2013-05-01

    This study presents new geochemical, geochronological, isotopic, and mineralogical data, combined with new geological mapping for a 2400 km2 area of Neogene volcanic rocks in northwestern Argentina near the border with Chile, between 25°10‧S and 25°45‧S. The area covers the zone of intersection between the main axis of the Cordillera Occidental and a set of NW-SE-trending structures that form part of the transverse Archibarca lineament. This lineament has localized major ore deposits in Chile (e.g., the late Eocene La Escondida porphyry Cu deposit) and large volcanic centers such as the active Llullaillaco and Lastarría volcanoes on the border between Chile and Argentina, and the Neogene Archibarca, Antofalla, and Cerro Galán volcanoes in Argentina. Neogene volcanic rocks in the Laguna Pedernal and Salar de Aguas Calientes areas are mostly high-K calc-alkaline in composition, and range from basaltic andesites, through andesites and dacites, to rhyolites. Magmatic temperatures and oxidation states, estimated from mineral compositions, range from ~ 1000 °C and ∆FMQ ≈ 1.0-1.5 in andesites, to ~ 850 °C and ∆FMQ ≈ 1.5-2.0 in dacites and rhyolites. The oldest rocks consist of early-middle Miocene andesite-dacite plagioclase-pyroxene-phyric lava flows and ignimbrites, with 40Ar/39Ar ages ranging from 17.14 ± 0.10 Ma to 11.76 ± 0.27 Ma. Their major and trace element compositions are typical of the Andean Central Volcanic Zone, and show strong crustal contamination trends for highly incompatible elements such as Cs, Rb, Th, and U. These rocks are geochemically grouped as sub-suite 1. This widespread intermediate composition volcanism was followed in the middle-late Miocene by a period of more focused rhyodacitic flow-dome complex formation. These felsic rocks are characterized by less extreme enrichments in highly incompatible elements, and increasing depletion of heavy rare earth elements. These rocks are geochemically grouped as sub-suite 2. The

  12. Forest responses to increasing aridity and warmth in the southwestern United States

    USGS Publications Warehouse

    Williams, A.P.; Allen, C.D.; Millar, C.I.; Swetnam, T.W.; Michaelsen, J.; Still, C.J.; Leavitt, Steven W.

    2010-01-01

    In recent decades, intense droughts, insect outbreaks, and wildfires have led to decreasing tree growth and increasingmortality inmany temperate forests. We compared annual tree-ring width data from 1,097 populations in the coterminous United States to climate data and evaluated site-specific tree responses to climate variations throughout the 20th century. For each population, we developed a climate-driven growth equation by using climate records to predict annual ring widths. Forests within the southwestern United States appear particularly sensitive to drought and warmth.We input 21st century climate projections to the equations to predict growth responses. Our results suggest that if temperature and aridity rise as they are projected to, southwestern trees will experience substantially reduced growth during this century. As tree growth declines, mortality rates may increase at many sites. Increases in wildfires and bark-beetle outbreaks in the most recent decade are likely related to extreme drought and high temperatures during this period. Using satellite imagery and aerial survey data, we conservatively calculate that ???2.7% of southwestern forest and woodland area experienced substantialmortality due to wildfires from1984 to 2006, and???7. 6%experiencedmortality associated with bark beetles from 1997 to 2008. We estimate that up to ???18% of southwestern forest area (excluding woodlands) experienced mortality due to bark beetles or wildfire during this period. Expected climatic changes will alter future forest productivity, disturbance regimes, and species ranges throughout the Southwest. Emerging knowledge of these impending transitions informs efforts to adaptively manage southwestern forests.

  13. Iberian Plio-Pleistocene biochronology: micromammalian evidence for MNs and ELMAs calibration in southwestern Europe

    NASA Astrophysics Data System (ADS)

    Hernández Fernández, Manuel; Azanza, Beatriz; Ángeles Álvarez Sierra, María

    2004-09-01

    A multivariate biochronological analysis of the Plio-Pleistocene Iberian rodent fossil record is presented. Among more than 300 fossil sites, 49 sites have been selected. The ordination of the fossil sites selected from the Iberian Peninsula has been achieved by the appearance event ordination method. After calibration of this ordination with geochronological dates at some of the localities, numerical dates are proposed for all the localities studied. Hence, mammal fossil sites non-datable by other means (palaeomagnetism, radiometric dating, etc.) have been dated with a relatively high degree of confidence. Final results allow dating of boundaries between the Plio-Pleistocene European Land Mammal Ages (ELMAS) or the Mammal Neogene (MN) units. These boundaries agree with previous studies using magnetostratigraphical calibration of these scales. Copyright

  14. Establishing the SouthWestern Academic Health Network (SWAHN): A Survey Exploring the Needs of Academic and Community Networks in SouthWestern Ontario.

    PubMed

    Nicholson, Kathryn; Randhawa, Jasmine; Steele, Margaret

    2015-10-01

    With the evolving fields of health research, health professional education and advanced clinical care comes a need to bring researchers, educators and health care providers together to enhance communication, knowledge-sharing and interdisciplinary collaboration. There is also a need for active collaboration between academic institutions and community organizations to improve health care delivery and health outcomes in the community setting. In Canada, an Academic Health Sciences Network model has been proposed to achieve such activities. The SouthWestern Academic Health Network (SWAHN) has been established among three universities, three community colleges, community hospitals, community-based organizations and health care providers and two Local Health Integrated Networks (LHINs) in Southwestern Ontario. A survey was conducted to understand the characteristics, activities, existing partnerships, short- and long-term goals of the academic and community health networks in SouthWestern Ontario to inform the development of SWAHN moving forward. A total of 114 health networks were identified from the two participating LHINs, 103 community health networks and 11 academic health networks. A mailed survey was sent to all networks and responses were analyzed using both quantitative and qualitative approaches. The short- and long-term goals of these networks were categorized into five main themes: Public Health, Education, Research, System Delivery and Special Populations. Overall, this study helped to elicit important information from the academic and community based networks, which will inform the future work of SWAHN. This research has also demonstrated the significance of collecting information from both academic and community partners during the formation of other interdisciplinary health networks.

  15. Water levels in aquifers in the Nacatoch Sand of southwestern and northeastern Arkansas and the Tokio Formation of southwestern Arkansas, spring 2008

    USGS Publications Warehouse

    Schrader, T.P.; Blackstock, Joshua M.

    2010-01-01

    The Nacatoch Sand and Tokio Formation aquifers in southwestern Arkansas and the Nacatoch Sand in northeastern Arkansas are sources of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 61 wells completed in the Nacatoch Sand and in 50 wells completed in the Tokio Formation during spring 2008. Aquifers in the Nacatoch Sand and Tokio Formation are hereafter referred to as the Nacatoch aquifer and the Tokio aquifer, respectively. The direction of groundwater flow in the Nacatoch aquifer in northeastern Arkansas generally is towards the southeast. A potentiometric high is located along the north and northwestern boundaries of the area. The direction of groundwater flow in the Nacatoch aquifer in southwestern Arkansas is towards the south-southeast in Little River, Miller, and Hempstead Counties and to the east-southeast in Nevada and Clark Counties. A potentiometric high is located within the outcrop area in north-central Hempstead County. A cone of depression exists in the Nacatoch aquifer at Hope in southeastern Hempstead County. The direction of groundwater flow in the Tokio aquifer in southwestern Arkansas generally is towards the south or southeast. A potentiometric high is located within the outcrop area. Artesian conditions exist in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties. One apparent cone of depression might exist northwest of Hope in Hempstead County. In northeastern Arkansas, groundwater withdrawals from the Nacatoch aquifer increased by 480 percent from 1965 to 2005. In southwestern Arkansas, withdrawals from the Nacatoch aquifer and Tokio aquifer increased by 125 percent and 201 percent, respectively, from 1965 to 1980 and decreased by 93 percent and 80 percent, respectively, from 1980 to 2000. Withdrawals from Nacatoch aquifer and Tokio aquifer increased by 690 percent and 291 percent, respectively, from 2000 to 2005

  16. Kinematically - controlled deep contact of the East European Platform and the Carpathian Orogen in the Vrancea Bending Zone and contact with the Neogene Volcanic Zone

    NASA Astrophysics Data System (ADS)

    Dragut, Dorina-Alina

    2016-04-01

    The complex zone between the Moesian and East European platforms to the south and east and the Southern Europe continental units were amalgamated in the last 20 million years in an intricate dynamics of what was thought to be the eastern component of the Alpine Tethys. By seismic tomography and attenuation studies, a high velocity body extended from the near surface to deeper levels than 300 km was pointed out as having a very complex geometry which suggests a very active three dimensional evolution. Most of the frequent, persistent and clustered seismic events from this contact area known as Vrancea Seismogenic Zone are located into this high velocity body. The origin of this seismicity is highly controversial. Among most of the accepted assumptions on its origins, two look like most robust: (a) the recent studies consider the subduction of the Tehys oceanic lithosphere, and (b) delamination of a portion of the East European / Moesian continental mantle after the oceanic lithosphere subduction ended sometimes in the mid-Miocene. The delamination zone was probably a near-horizontal mid-lithospheric interface dripping down into the mantle. Towards the internal part of the Bend Zone, the volcanic activity, dominant in the Neogene time, ceased some 400,000 years ago but there are evidences that the last stages of the alkali-basaltic volcanic activity has post-volcanic effects even at present. We integrate satellite geodesy results with various seismological studies in order to explain the very small values of the present-day horizontal component of the velocity field, almost at the edge of technological detectability. The vectors have a very peculiar distribution which we interpret as supporting the idea of the mantle flow around the high seismic velocity body detected via seismological investigations. We estimate an anti-clockwise deep rotation flow around the lithospheric "slab" which is seated adjacent to the astensosphere advancing towards the surface, having

  17. Detrital fission-track-compositional signature of an orogenic chain-hinterland basin system: The case of the late Neogene Quaternary Valdelsa basin (Northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Balestrieri, M. L.; Benvenuti, M.; Tangocci, F.

    2013-05-01

    Detrital thermochronological data collected in syn-tectonic basin deposits are a promising tool for deciphering time and processes of the evolution of orogenic belts. Our study deals with the Valdelsa basin, one of the wider basins of central Tuscany, Italy. The Valdelsa basin is located at the rear of the Northern Apennines, a collisional orogen whose late Neogene Quaternary development is alternatively attributed to extensional and compressional regimes. These contrasting interpretations mostly rely on different reconstructions of the tectono-sedimentary evolution of several basins formed at the rear of the chain since the late Tortonian. Here, we explore the detrital thermochronological-compositional signature of tectonic and surface processes during the Valdelsa basin development. For this aim, detrital apatite fission-track analysis of 21 sand samples from the latest Messinian Gelasian fluvial to shallow marine basin deposits, has been accompanied by a clast composition analysis of 7 representative outcrops of the conglomerate facies. The grain-age distributions of the sediment samples are generally characterized by two distinct components, one younger peak (P1) varying between 5.5 ± 2.8 and 9.5 ± 1.0 Ma and one older peak (P2) varying from 15.0 ± 8.0 to 41.0 ± 10 Ma. By comparison with some bedrock ages obtained from the E-NE basin shoulder, we attributed the P2 peak to the Ligurian Units and the P1 peak to the Macigno Formation (Tuscan Units). These units are arranged one upon the other in the complex nappe pile forming the Northern Apennines orogen. While the gravel composition indicates a predominant feeding from the Ligurian units all along the sedimentary succession with a subordinate occurrence of Macigno pebbles slightly increasing upsection, the P1 peak is present even in the oldest collected sandy sediments. The early P1 occurrence reveals that the Macigno was exposed in the E-NE basin shoulder since at least the latest Messinian-early Zanclean

  18. Late Neogene East Asian monsoon: from winter to summer dominated sub-regime and periodicity transition from 100 kyr to 41 kyr

    NASA Astrophysics Data System (ADS)

    Li, F.; Rousseau, D.-D.; Wu, N.; Hao, Q.; Pei, Y.

    2009-04-01

    More and more evidence indicates that the onset of the East Asian (EA) monsoon can be traced back to the Oligocene-Miocene boundary (at about 23 Ma). However, the process of its evolution is still less well known until now. Here we investigate its late Neogene evolution by analyzing a terrestrial mollusk sequence, from the Chinese Loess Plateau (CLP), covering the period between 7.1 and 3.5 Ma. Considering the modern ecological requirements of these organisms, we were able to define two groups of cold-aridiphilous (CA) and thermo-humidiphilous (TH) species, representing the EA winter and summer monsoon variations, respectively, as previously defined in the Quaternary glacial-interglacial cycles. Variations in these two groups indicate two different monsoon dominated periods during 7.1-3.5 Ma. First, between 7.1 and 5.5 Ma, the EA winter monsoon, with a 100 kyr periodicity, was dominant. Second, between 5.1 and 4 Ma, the EA summer monsoon dominated, with a 41 kyr periodicity. Furthermore, our mollusk record yields valuable evidence for a late Miocene-Pliocene transition of about 400 kyr from winter monsoon dominated towards summer monsoon dominated, associated with a periodicity transition from weak 100 kyr to 41 kyr. The strengthened winter monsoon interval, with a 100 kyr periodicity, is coeval with orbital-scale global ice volume changes, in conjunction with the uplift of the Tibetan Plateau which probably reinforced the winter monsoon sub-regime. Conversely, closures of the Panama and Indonesian seaways, associated with changes in obliquity between 5.1 and 4 Ma, are probably major forcing factors for the observed dominant summer monsoon with 41 kyr frequency, favoring heat and moisture transports between low and high latitudes to allow TH mollusks to grow and develop in the CLP. The transition from a 100 kyr dominated interval towards a 41 kyr dominated one is contrary to the mid-Pleistocene transition (MPT), which corresponds to ice volume expansion at high

  19. A Neogene back-arc origin for the Banda Sea basins: geochemical and geochronological constraints from the Banda ridges (East Indonesia)

    NASA Astrophysics Data System (ADS)

    Honthaas, Christian; Réhault, Jean-Pierre; Maury, René C.; Bellon, Hervé; Hémond, Christophe; Malod, Jacques-André; Cornée, Jean-Jacques; Villeneuve, Michel; Cotten, Joseph; Burhanuddin, Safri; Guillou, Hervé; Arnaud, Nicolas

    1998-12-01

    Dredgings conducted during the French-Indonesian cruises Banda Sea II and III collected volcanic rocks from several ridges of the Banda Sea area (Tukang Besi ridge, site 218; Lucipara ridge, sites 214 and 305; Nieuwerkerk-Emperor of China, sites 219 and 220). With the exception of one 46-Ma-old N-MORB type basalt, thought to belong to an ophiolitic complex, K-Ar and Ar-Ar datings indicate that all the dredged volcanics are Neogene. They range in age from ca. 10 Ma (Tukang Besi back-arc basalts) to 8-7 Ma (Nieuwerkerk-Emperor of China calc-alkaline andesites) and to 7-3 Ma (Lucipara OIB-type transitional basalts and cordierite-bearing andesites). Radiogenic isotopic signatures of andesites are consistent with an AFC (Assimilation coupled with Fractional Crystallization) process involving assimilation of continental crust. 8-3-Ma-old calc-alkaline volcanic activity is also recorded on the Wetar segment, an inactive part of the East Sunda arc, and corresponding isotopic compositions are also consistent with an AFC process involving continental crust. These features suggest that Lucipara-Nieuwerkerk-Emperor of China ridges and the Wetar segment were representing a single volcanic arc 8-7 Ma ago. The corresponding calc-alkaline activity was related to the subduction of the Indian oceanic lithosphere beneath continental blocks of Australian origin. Back-arc opening processes occurred from 6 to 3 Ma as a multi-rift opening for the Wetar basin and as a single-rift opening for the Damar basin while subduction-related magmatism was still active in the Wetar segment. Volcanic activity stopped at 7 Ma in the Nieuwerkerk-Emperor of China ridge. On Lucipara ridge, 6-3 Ma volcanic activity emplaced concomitantly transitional basalts and cordierite-bearing andesites. The mineralogical and chemical features of the latter are consistent with an AFC process involving assimilation of continental crust by mantle-derived basaltic magmas. The end of magmatic activity on both volcanic

  20. Ductile and Brittle Neogene Deformation of Late Permian Orthogneiss in the Northern Ailao Shan-Red River Shear Zone: View from the Xuelong Shan Block

    NASA Astrophysics Data System (ADS)

    Wintsch, R. P.; Yi, D.; Yi, K.; Wang, Q. F.; Wang, G. H.

    2014-12-01

    ASRRSZ based on data obtained in the southern Diancang Shan block. Permian granitoids were intruded and ductily deformed in the Early Triassic. The left lateral shearing that brought these blocks to the surface was delayed until the Neogene extrusion of the Indochina block.