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Sample records for early cenozoic origin

  1. Early cenozoic differentiation of polar marine faunas.

    PubMed

    Crame, J Alistair

    2013-01-01

    The widespread assumption that the origin of polar marine faunas is linked to the onset of major global cooling in the Late Eocene-Early Oligocene is being increasingly challenged. The Antarctic fossil record in particular is suggesting that some modern Southern Ocean taxa may have Early Eocene or even Paleocene origins, i.e. well within the Early Cenozoic greenhouse world. A global analysis of one of the largest marine clades at the present day, the Neogastropoda, indicates that not only is there a decrease in the number of species from the tropics to the poles but also a decrease in the evenness of their distribution. A small number of neogastropod families with predominantly generalist trophic strategies at both poles points to the key role of seasonality in structuring the highest latitude marine assemblages. A distinct latitudinal gradient in seasonality is temperature-invariant and would have operated through periods of global warmth such as the Early Cenozoic. To test this concept a second global analysis was undertaken of earliest Cenozoic (Paleocene) neogastropods and this does indeed show a certain degree of faunal differentiation at both poles. The Buccinidae, s.l. is especially well developed at this time, and this is a major generalist taxon at the present day. There is an element of asymmetry associated with this development of Paleocene polar faunas in that those in the south are more strongly differentiated than their northern counterparts; this can in turn be linked to the already substantial isolation of the southern high latitudes. The key role of seasonality in the formation of polar marine faunas has implications for contemporary ecosystem structure and stability. PMID:23342090

  2. Early Cenozoic Differentiation of Polar Marine Faunas

    PubMed Central

    Crame, J. Alistair

    2013-01-01

    The widespread assumption that the origin of polar marine faunas is linked to the onset of major global cooling in the Late Eocene – Early Oligocene is being increasingly challenged. The Antarctic fossil record in particular is suggesting that some modern Southern Ocean taxa may have Early Eocene or even Paleocene origins, i.e. well within the Early Cenozoic greenhouse world. A global analysis of one of the largest marine clades at the present day, the Neogastropoda, indicates that not only is there a decrease in the number of species from the tropics to the poles but also a decrease in the evenness of their distribution. A small number of neogastropod families with predominantly generalist trophic strategies at both poles points to the key role of seasonality in structuring the highest latitude marine assemblages. A distinct latitudinal gradient in seasonality is temperature-invariant and would have operated through periods of global warmth such as the Early Cenozoic. To test this concept a second global analysis was undertaken of earliest Cenozoic (Paleocene) neogastropods and this does indeed show a certain degree of faunal differentiation at both poles. The Buccinidae, s.l. is especially well developed at this time, and this is a major generalist taxon at the present day. There is an element of asymmetry associated with this development of Paleocene polar faunas in that those in the south are more strongly differentiated than their northern counterparts; this can in turn be linked to the already substantial isolation of the southern high latitudes. The key role of seasonality in the formation of polar marine faunas has implications for contemporary ecosystem structure and stability. PMID:23342090

  3. Origin, migration, and accumulation of petroleum in Gulf Coast Cenozoic

    SciTech Connect

    Jones, R.W.

    1986-05-01

    Explanations of the origin, migration, and accumulation of petroleum in the Gulf Coast upper Cenozoic must accommodate the following facts. (1) No specific source of the petroleum has ever been identified. (2) The most probable source section is 10,000-20,000 ft of low TOC (0.4-1.0 wt %) shale that underlies the reservoirs. (3) Tremendous volumes of dry gas have been generated in the middle and basal part of the source section. (4) More gas than oil is in the reservoirs. (5) The distribution of oil and gas accumulations in the Cenozoic is not primarily controlled by the distribution of terrestrial gas-prone organic facies and marine oil-prone organic facies, but by the relative ease of migration of the two hydrocarbon phases. For example, gas preferentially accumulates in the simpler structures, oil in the intrusive salt domes. (6) High pressure and high porosity in the source rock indicates that neither water movement nor continuous phase oil movement out of the source rock are likely to be significant factors in primary migration. (7) The situation is very dynamic, with generation, migration, and accumulation occurring today. (8) Faults are very important as controls on migration and accumulation of the petroleum. The interaction of these (and other) factors suggests that most oil reservoirs in the Gulf Coast upper Cenozoic sediments probably initially became mobile after being dissolved in gas in the source rock. The gas-oil mixture moved toward lower pressure areas adjacent to and in faults, and moved upward into reservoirs and traps along faults.

  4. Eocene Arctic Ocean and earth's Early Cenozoic climate

    SciTech Connect

    Clark, D.L.

    1985-01-01

    Seasonal changes of the Arctic Ocean are an approximate microcosm of the present advanced interglacial climate of the Earth. A similar relationship has existed for several million years but was the Early Cenozoic Arctic Ocean an analog of Earth's climate, as well. Absence of polar ice during the Cretaceous is relatively well established. During the Cenozoic a worldwide decrease in mean annual ocean temperature resulted from such factors as altered oceanic circulation and lower atmospheric CO/sub 2/ levels. Limited Arctic Ocean data for the middle or late Eocene indicate the presence of upwelling conditions and accompanying high productivity of diatoms, ebridians, silicoflagellates and archaeomonads. During this interval, some seasonality is suggested from the varve-like nature of a single sediment core. However, the absence of drop stones or any ice-rafted sediment supports the idea of an open water, ice-free central Arctic Ocean during this time. Latest Cretaceous Arctic Ocean sediment is interpreted to represent approximately the same conditions as those suggested for the Eocene and together with that data suggest that the central Arctic Ocean was ice-free during part if not all of the first 20 my of the Cenozoic. Sediment representing the succeeding 30 my has not been recovered but by latest Miocene or earl Pliocene, ice-rafted sediment was accumulating, both pack ice and icebergs covered the Arctic Ocean reflecting cyclic glacial climate.

  5. Early Cenozoic "dome like" exhumation around the Irish Sea

    NASA Astrophysics Data System (ADS)

    Doepke, Daniel; Cogné, Nathan; Chew, David; Stuart, Fin

    2016-04-01

    Despite decades of research the Early Cenozoic exhumation history of Ireland and Britain is still poorly understood and subject to contentious debate (see Davis et al., 2012 and subsequent comments). Previous studies have attributed the Cenozoic exhumation history of Ireland and Britain mainly to: (a) Paleogene - Neogene far-field stress between the opening of the North Atlantic Ocean and the Alpine collision (Ziegler et al., 1995; Hillis et al., 2008) or (b) early Paleogene mantle driven magmatic underplating associated with the development of the proto-Iceland mantle plume beneath the Irish Sea (Brodie and White, 1994; Al-Kindi et al., 2003). The major differences between the two hypotheses are the pattern and timing of spatial exhumation. This project thus seeks to investigate the timing and mechanisms of late Mesozoic - early Cenozoic exhumation on the onshore part of the British Isles by using a combination of apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) data, which we then model using the QTQt program of Gallagher (2012) to better constrain the modelled thermal histories. Our studied area centres on the margins of the Irish Sea, but includes all Ireland and western Britain. Overall we analysed 74 samples for AFT and 66 samples for AHe dating. In particular, our results include ten pseudo-vertical profiles. The AFT ages display a wide range of ages from early Carboniferous in Scotland to early Eocene in central Ireland. Our AHe ages range from mid Permian on Shetland to Eocene Ft-corrected. The AFT data do not show any specific spatial distribution, however, the Ft-corrected AHe ages around the Irish Sea only focus around late Cretaceous to Eocene suggesting an important thermal event around this time. The modelled thermal histories of samples located around the Irish Sea and western Scotland show a clear late Cretaceous to early Paleogene cooling event which is not present elsewhere. The distribution of this cooling event is broadly consistent

  6. Equatorial convergence of India and early Cenozoic climate trends

    PubMed Central

    Kent, Dennis V.; Muttoni, Giovanni

    2008-01-01

    India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO2 concentration (pCO2) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO2 delivery to the atmosphere capable to maintain high pCO2 levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at ≈50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO2 by efficient silicate weathering further perturbed the delicate equilibrium between CO2 input to and removal from the atmosphere toward progressively lower pCO2 levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary. PMID:18809910

  7. Flexural analysis of two broken foreland basins; Late Cenozoic Bermejo basin and Early Cenozoic Green River basin

    SciTech Connect

    Flemings, P.B.; Jordan, T.E.; Reynolds, S.

    1986-05-01

    Lithospheric flexure that generates basin in a broke foreland setting (e.g., the Laramide foreland of Wyoming) is a three-dimensional system related to shortening along basin-bounding faults. The authors modeled the elastic flexure in three dimensions for two broken foreland basins: the early Cenozoic Green River basin and the analogous late Cenozoic Bermejo basin of Argentina. Each basin is located between a thrust belt and a reverse-fault-bounded basement uplift. Both basins are asymmetric toward the basement uplifts and have a central basement high: the Rock Springs uplift and the Pie de Palo uplift, respectively. The model applies loads generated by crustal thickening to an elastic lithosphere overlying a fluid mantle. Using the loading conditions of the Bermejo basin based on topography, limited drilling, and reflection and earthquake seismology, the model predicts the current Bermejo basin geometry. Similarly, flexure under the loading conditions in the Green River basin, which are constrained by stratigraphy, well logs, and seismic profiling and summed for Late Cretaceous (Lance Formation) through Eocene (Wasatch Formation), successfully models the observed geometry of the pre-Lance surface. Basin depocenters (> 4 km for the Green River basin; > 7 km for the Bermejo basin) and central uplifts are predicted to result from constructive interference of the nonparallel applied loads. Their Bermejo model implies that instantaneous basin geometry is successfully modeled by crustal loading, whereas the Green River basin analysis suggests that basin evolution can be modeled over large time steps (e.g., 20 Ma). This result links instantaneous basin geometry to overall basin evolution and is a first step in predicting stratigraphic development.

  8. Early-Middle Cenozoic Andean mammal faunas: Integrated analyses of biochronology, geochronology, and paleoecology (Invited)

    NASA Astrophysics Data System (ADS)

    Flynn, J. J.

    2010-12-01

    For almost two centuries, understanding of the South American Cenozoic terrestrial biota was derived largely from the extensive but gap-riddled record from Patagonia and nearby lowland, high-latitude sites. But discoveries and analyses of Andean and tropical fossil mammal assemblages have increased substantially in recent years, and integrating these new paleontological data with those typically used in geochronologic and tectonic studies can yield new or deeper insights into the timing, origin, and magnitude of biotic responses to environmental, climatic and other physical changes, including the influences of regional (e.g., tectonism) versus global (e.g., climate change) events. More than two decades of collaborative research with R. Charrier (U. Chile), A. Wyss and P. Gans (UC-Santa Barbara), D. Croft (Case Western), the National Museum of Chile, and other investigators in the Main Range of the Chilean Andes is creating one of the premier archives of early-middle Cenozoic terrestrial mammal fossils. The active margin setting and thick volcaniclastic sequences accumulating in Andean extensional basins foster preservation of a unique record of mammalian evolution, and development of a more precise and reliable terrestrial geochronology integrating biochronology, magnetostratigraphy and high-precision radioisotopic dating, including the first calibration for some South American Land Mammal “Ages” (SALMAs). Intensive work within the Andes of Chile (particularly the Abanico Fm. and its equivalents, from 33°-38°30’S) has yielded more than 3,000 specimens from > 2 dozen sets of localities, spanning some 30° of latitude and ranging in age from at least 40 to 10 Ma (late Eocene to late Miocene). Exemplar “case-studies” illustrate how these new fossils and dates provide key data for understanding mammalian evolution and paleoecology, documenting faunal change through time (during periods of profound environmental and biotic restructuring), assessing

  9. Origin and pre-Cenozoic evolution of the Qiangtang terrane basement, central Tibet

    NASA Astrophysics Data System (ADS)

    Zhao, Zhongbao; Bons, Paul D.; Wang, Genhou

    2013-04-01

    Central Tibet, with its high-pressure rocks, is a key area to unravel the evolution of the Proto-, Paleo- and Meso-Tethys. However, due to its remoteness and difficult field conditions, relative little is known of the area. Here we present new evidence on the Paleozoic and Mesozoic evolution of the Qiangtang Terrane, located between the Jinsha suture zone in the north and Banggong-Nujiang suture zone in the south. A >500-km-long east-west trending high-pressure metamorphic belt divides the Qiangtang Terrane into the North Qiangtang Terrane and the South Qiangtang terrane. Different hypotheses have been proposed for the origin and pre-Cenozoic evolution of the Qiangtang Terrane. In the Central Qiangtang Terrane, an unconformity with basal conglomerate separates the basement from overlying middle Ordovician strata. Based on structural analysis of basement and cover units, detailed geochronology (including detrital and magmatic zircons) and comparison with surrounding micro-plates (such as Lhasa Terrane, Himalaya Terrane and Southern China Terrane) we conclude that the basement of the Qiangtang Terrane was connected with Gondwana as a passive margin of the Proto-Tethys during the Early Paleozoic. The occurrence of Late Triassic eclogite and glaucophane-bearing schists in the Central Qiangtang Terrane indicates the existence of a suture zone between the North and South Qiangtang Terrane before the Late Triassic (Liu et al., 2011). This suture zone resulted from closure of the Palaeo-Tethys between the two terranes and obduction of the melange onto the basement of South Qiangtang before 210 Ma. ~275 Ma E-W oriented dyke swarms in the north of the South Qiangtang Terrane indicate opening of the Palaeo-Tethys in a back-arc setting between the North and South Qiangtang Terrane, during roll-back retreat of the Proto-Tethys further north. Late Permian to Early Triassic subduction related volcanism and the 236-219 Ma adakitic volcanic series are related to southward

  10. Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?

    NASA Astrophysics Data System (ADS)

    Hoareau, G.; Bomou, B.; van Hinsbergen, D. J. J.; Carry, N.; Marquer, D.; Donnadieu, Y.; Le Hir, G.; Vrielynck, B.; Walter-Simonnet, A.-V.

    2015-12-01

    The 58-51 Ma interval was characterized by a long-term increase of global temperatures (+4 to +6 °C) up to the Early Eocene Climate Optimum (EECO, 52.9-50.7 Ma), the warmest interval of the Cenozoic. It was recently suggested that sustained high atmospheric pCO2, controlling warm early Cenozoic climate, may have been released during Neo-Tethys closure through the subduction of large amounts of pelagic carbonates and their recycling as CO2 at arc volcanoes. To analyze the impact of Neo-Tethys closure on early Cenozoic warming, we have modeled the volume of subducted sediments and the amount of CO2 emitted along the northern Tethys margin. The impact of calculated CO2 fluxes on global temperature during the early Cenozoic have then been tested using a climate carbon cycle model (GEOCLIM). We show that CO2 production may have reached up to 1.55 × 1018 mol Ma-1 specifically during the EECO, ~ 4 to 37 % higher that the modern global volcanic CO2 output, owing to a dramatic India-Asia plate convergence increase. The subduction of thick Greater Indian continental margin carbonate sediments at ~ 55-50 Ma may also have led to additional CO2 production of 3.35 × 1018 mol Ma-1 during the EECO, making a total of 85 % of the global volcanic CO2 outgassed. However, climate modeling demonstrates that timing of maximum CO2 release only partially fits with the EECO, and that corresponding maximum pCO2 values (750 ppm) and surface warming (+2 °C) do not reach values inferred from geochemical proxies, a result consistent with conclusions arising from modeling based on other published CO2 fluxes. These results demonstrate that CO2 derived from decarbonation of Neo-Tethyan lithosphere may have possibly contributed to, but certainly cannot account alone for early Cenozoic warming. Other commonly cited sources of excess CO2 such as enhanced igneous province volcanism also appear to be up to 1 order of magnitude below fluxes required by the model to fit with proxy data of pCO2 and

  11. Origin of the Adventure Subglacial Trench linked to Cenozoic extension in the East Antarctic Craton

    NASA Astrophysics Data System (ADS)

    Cianfarra, P.; Salvini, F.

    2016-02-01

    The Antarctic plate occupies a unique geodynamic setting being mostly surrounded by divergent or transform margins. Major intracontinental basins and highlands characterize its bedrock, buried under the 34 Ma East Antarctic Ice Sheet (EAIS). Their formation atop of the cratonic lithosphere in the interior of East Antarctica remains a major open question. Post-Mesozoic intraplate extensional tectonic activity has been proposed for their development and is supported by this work. Here we focus on the Adventure Subglacial Trench (AST) whose origin is poorly constrained and controversial, as currently available geophysical models suggest either extensional or compressional tectonic origin. The AST is an over 250-km-long, 60-km-wide subglacial trough, elongated in the NNW-SSE direction adjacent to the westernmost flank of the Wilkes Subglacial Basin, and is parallel to regional scale alignments of magnetic and gravimetric anomalies. Geophysical campaigns allowed better definition of the AST physiography showing its typical half-graben geometry. The rounded morphology of the western flank of the AST was simulated through tectonic numerical modelling. We consider the subglacial landscape to primarily reflect a preserved relict of the tectonic processes affecting the interior of East Antarctica in the Cenozoic, due to the negligible erosion/deposition capability of the EAIS. The bedrock morphology was replicated through the activity of the listric Adventure Fault, characterized by a basal detachment at the base of the crust (34 km) and a vertical displacement of 2.5 km. This length suggests its regional/crustal importance. The predicted displacement is interpreted either as a newly formed fault or as the partial reactivation of a weaker zone along a major Precambrian crustal-scale tectonic boundary. The extensional regime in the AST is part of a more extensive 800-km long intraplate corridor characterized by nearly along-strike extension in Cenozoic times with a left

  12. Insect herbivory, plant defense, and early Cenozoic climate change.

    PubMed

    Wilf, P; Labandeira, C C; Johnson, K R; Coley, P D; Cutter, A D

    2001-05-22

    Insect damage on fossil leaves from the Central Rocky Mountains, United States, documents the response of herbivores to changing regional climates and vegetation during the late Paleocene (humid, warm temperate to subtropical, predominantly deciduous), early Eocene (humid subtropical, mixed deciduous and evergreen), and middle Eocene (seasonally dry, subtropical, mixed deciduous and thick-leaved evergreen). During all three time periods, greater herbivory occurred on taxa considered to have short rather than long leaf life spans, consistent with studies in living forests that demonstrate the insect resistance of long-lived, thick leaves. Variance in herbivory frequency and diversity was highest during the middle Eocene, indicating the increased representation of two distinct herbivory syndromes: one for taxa with deciduous, palatable foliage, and the other for hosts with evergreen, thick-textured, small leaves characterized by elevated insect resistance. Leaf galling, which is negatively correlated with moisture today, apparently increased during the middle Eocene, whereas leaf mining decreased. PMID:11353840

  13. Early Cenozoic radiations in the Antarctic marine realm and their evolutionary implications

    NASA Astrophysics Data System (ADS)

    Crame, Alistair

    2014-05-01

    The extensive and very well exposed Late Cretaceous - Early Paleogene sedimentary succession of Seymour Island, NE Antarctic Peninsula presents a unique opportunity to examine Early Cenozoic evolutionary radiations in a variety of macrofaunal taxa. Building on the extensive pioneer studies by US and Argentinian palaeontologists, recent investigations have focused on refining litho-, bio- and chronostratigraphies, and taxonomic revisions to a number of key groups. Within the numerically dominant Mollusca, the balance of faunas changes significantly across the Cretaceous/Paleogene boundary, with gastropods becoming numerically dominant for the first time in the Early Paleocene Sobral Formation (SF). At this level seven of the 31 gastropod genera present (= 23%) can be referred to modern Southern Ocean taxa and the same figure is maintained in the Early Eocene La Meseta Formation (LMF) where 21 of 63 genera are modern. A major reason for the rise of the gastropods in the earliest Cenozoic of Antarctica is a significant radiation of the Neogastropoda, which today forms one of the largest clades in the sea. 50% of the SF gastropod fauna and 53% of the LMF at the species level are neogastropods. This important burst of speciation is linked to a major pulse of global warming from ~63 - 43Ma when warm temperate conditions prevailed for long intervals of time at 65ºS. The marked Early Paleogene radiation of neogastropods in Antarctica represents a distinct pulse of southern high-latitude taxa that was coeval with similar tropical/subtropical radiations in localities such as the US Gulf Coast and NW Europe. Thus it would appear that the Early Cenozoic radiation of this major taxon was truly global in scale and not just confined to one latitudinal belt. Whereas it is possible to regard a significant proportion of the modern bivalve fauna as relicts, and thus Antarctica as an evolutionary refugium, or sink, it is much less easy to do so for the Neogastropoda. At least in the

  14. Mesozoic and Early Cenozoic sediment influx in the Mozambique basin.

    NASA Astrophysics Data System (ADS)

    Castelino, Jude; Reichert, Christian; Klingelhoefer, Frauke; Aslanian, Daniel; Jokat, Wilfried

    2015-04-01

    Mozambique Basin is together with the Somali Basin the oldest rifted sedimentary basin developed along the eastern African margin in Jurassic times. The basin hosts a continuous record of sediments since Jurassic times, when Antarctica separated from Africa. The primary objectives of this study were to extend the regional stratigraphic framework north of the Zambezi Delta and to review geological events documented in the Mozambique Basin. Nine Multi-Channel seismic reflection profiles are used to extend the regional stratigraphy in to the deep abyssal plains of the basin. We identify six major stratigraphic units that correlate to Jurassic, Early Cretaceous, Late Cretaceous, Paleogene, Neogene and Quaternary periods. Mesozoic sedimentation rates of 3-5 cm/kyr are observed in the deeper basin and 1-2 cm /kyr during Paleogene (neither compensated for compaction). The presence of Domo shales from existing wells point to a restricted circulation in the basin until mid-Cretaceous. Mesozoic sediments have a high velocity that exceed 4.5 km/s with an exception of a distinct low-velocity zone of 3.7 km/s in the mid-Cretaceous that may indicate under-compacted overpressured shales. Higher sedimentation rate in Late Cretaceous can be attributed to rapid denudation of the African continent after a major tectonic uplift episode at approximately 90 Ma and simultaneous increase in the catchment area of the proto-Zambezi. Increased sediment influx into the basin from the Zambezi in Late Cretaceous resulted in the formation a submarine delta fan lobe progressing into the Mozambique Channel around the northern periphery of Beira High. Strong north-south bottom currents commenced within the channel in Late Cretaceous that forced the aggradation of sediments of the submarine fan lobe on the southern flank. In addition, we observe several current-controlled drift bodies in the deeper basin that are influenced by the north-south bottom current. Low sedimentation rates in Paleogene are

  15. Origin of low δ26Mg Cenozoic basalts from South China Block and their geodynamic implications

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Li, Shu-Guang; Xiao, Yilin; Ke, Shan; Li, Wang-Ye; Tian, Ye

    2015-09-01

    Origin of low δ26Mg basalts is a controversial subject and has been attributed to interaction of isotopically light carbonatitic melts derived from a subducted oceanic slab with the mantle (Yang et al., 2012), or alternatively, to accumulation of isotopically light ilmenite (FeTiO3) in their mantle source (Sedaghatpour et al., 2013). To study the origin of low δ26Mg basalts and evaluate whether Mg isotope ratios of basalts can be used to trace deeply recycled carbon, high-precision major and trace element and Mg isotopic analyses on the Cenozoic alkaline and tholeiitic basalts from the South China Block (SCB), eastern China have been carried out in this study. The basalts show light Mg isotopic compositions, with δ26Mg ranging from -0.60 to -0.35. The relatively low TiO2 contents (<2.7 wt.%) of our basalts, roughly positive correlations between δ26Mg and Ti/Ti∗ and their constant Nb/Ta ratios (16.4-20) irrespective of variable TiO2 contents indicate no significant amounts of isotopically light ilmenite accumulation in their mantle source. Notably, the basalts display negative correlations between δ26Mg and the amounts of total alkalis (i.e., Na2O + K2O) and incompatible trace elements (e.g., Ti, La, Nd, Nb, Th) and trace element abundance ratios (e.g., Sm/Yb, Nb/Y). Generally, with decrease of δ26Mg values, their Hf/Hf∗ and Ti/Ti∗ ratios decrease, whereas Ca/Al and Zr/Hf ratios increase. These features are consistent with incongruent partial melting of an isotopically light carbonated mantle, suggesting that large variations in Mg isotope ratios occurred during partial melting of such carbonated mantle under high temperatures. The isotopically light carbonated mantle were probably formed by interaction of the mantle with low δ26Mg carbonatitic melts derived from the deeply subducted low δ26Mg carbonated eclogite transformed from carbonate-bearing oceanic crust during plate subduction. As only the Pacific slab has an influence on both the North China

  16. Improved Late Cretaceous and early Cenozoic Paleomagnetic apparent polar wander path for the Pacific plate

    NASA Astrophysics Data System (ADS)

    Beaman, Melissa; Sager, William W.; Acton, Gary D.; Lanci, Luca; Pares, Josep

    2007-10-01

    Understanding of Pacific plate tectonics and geodynamics is aided by refinement of the plate's apparent polar wander path (APWP). We improved the Late Cretaceous and early Cenozoic APWP by analyzing a large, diverse paleomagnetic data set that combines core sample, seamount magnetic anomaly model, and marine magnetic anomaly skewness data. Our preferred APWP has five mean paleomagnetic poles representing the Oligocene (30 Ma), Late (39 Ma) and Early (49 Ma) Eocene, and Paleocene (61 Ma) epochs and the Maastrichtian (68 Ma) stage. Along with a published 80 Ma pole, the APWP shows a stillstand from ˜ 80 to ˜ 49 Ma punctuating the large overall northward drift of the plate. The two youngest poles imply resumption of northward motion during mid-Eocene time with another change of polar motion after ˜ 30 Ma. If unaffected by other phenomena (e.g., true polar wander or change in time-averaged magnetic field geometry), the stillstand implies negligible northward plate motion during the period of Emperor Seamounts formation, contrary to most accepted plate motion models. The stillstand is consistent with paleomagnetic data from the Emperor Seamounts, which imply southward motion of the Hawaiian melting anomaly. It also implies significant westward drift of the hotspot if the Pacific plate was moving west at rates similar to the later Cenozoic. In addition, changes in polar wander after ˜ 49 Ma are consistent with changes of north Pacific plate boundaries.

  17. Upper Mantle Seismic Velocity Structure Beneath Eastern Africa and the Origin of Cenozoic Extensional Tectonism (Invited)

    NASA Astrophysics Data System (ADS)

    Nyblade, A.; Julia, J.; Adams, A. N.; Mulibo, G. D.; Tugume, F. A.

    2009-12-01

    The seismic structure of the upper mantle beneath eastern Africa will be reviewed using results from body wave tomography, surface wave tomography, and images of the 410 and 660 km discontinuities. Most of the data used for obtaining these results come from temporary deployments of broadband seismic stations in Ethiopia, Kenya, Uganda and Tanzania over the past decade. The ensemble of seismic results point to a deep-seated low velocity zone beneath the East African rift system that extends from the uppermost mantle, through the upper mantle, and into the mantle transition zone. The low velocity anomaly may also extend through the mantle transition zone and link with the low velocity zone in the lower mantle under southern Africa, commonly referred to as the African Superplume. This is in contrast to southern Africa, were there is little evidence for a pronounced low velocity anomaly in the upper mantle. The existence of a seismic low velocity zone beneath eastern African that extends to depths of more than 500 km supports the possibility that there is a geodynamic connection between the African Superplume and the origin of Cenozoic extensional tectonism in eastern Africa.

  18. Lower crustal flow: The origin of Late Cenozoic extension north of the eastern Snake River Plain

    SciTech Connect

    Anders, M.H.; Hopper, J.R.; Abad, R.; Spiegelman, M. . Lamont-Doherty Earth Observatory)

    1993-04-01

    Recent work has shown that the initiation of late Cenozoic faulting and concomitant footwall uplift north of the eastern Snake River Plain (eSRP) are much younger than previously thought. Examples of these young ages include the Centennial Range (< 2.0 Ma), Gravely Range (< 2.0 Ma), Lemhi Range (< 6.6 Ma), Beaverhead Mts. (< 6.6 Ma), Tendoy Mts. (< 6.6 Ma). Basins south of the eSRP exhibit a bi-modal distribution of growth ages during the Neogene. Seismic moment tensor and earthquake rupture data define extension directions that are both oblique to and symmetric about the axis of the eSRP. However, extension directions on the eSRP itself are parallel to the axis. The authors propose that the orientations of extension are a response to lower crustal flow in a conduit formed between the mid-crust and the upper mantle. Estimates of the lower crustal pressure gradients, geothermal gradient, and channel dimensions are used calculate a lower crustal flux between the extending regions north of the eSRP and the eSRP. This value is three orders of magnitude greater than the estimated flux based on geologically determined strain rates. These calculations suggest that lower crustal flow is a viable mechanism to explain extension north of the eSRP as well as to explain the origin of the extension throughout the Intermountain seismic belt. The advantage of this model is that upper crustal extension does not have to couple with upper mantle extension and thereby it is not necessary to invoke far field stress changes to explain changes in the local stress field.

  19. Origin and geodynamic setting of Late Cenozoic granitoids in Sulawesi, Indonesia

    NASA Astrophysics Data System (ADS)

    Maulana, Adi; Imai, Akira; Van Leeuwen, Theo; Watanabe, Koichiro; Yonezu, Kotaro; Nakano, Takanori; Boyce, Adrian; Page, Laurence; Schersten, Anders

    2016-07-01

    Late Cenozoic granitoids are widespread in a 1600 km long belt forming the Western and Northern Sulawesi tectono-magmatic provinces. They can be divided into three rock series: shoshonitic (HK), high-K felsic calc-alkaline (CAK), and normal calc-alkaline to tholeiitic (CA-TH). Representative samples collected from eleven plutons, which were subjected to petrography, major element, trace element, Sr, Nd, Pb isotope and whole-rock δ18O analyses, are all I-type and metaluminous to weakly peraluminous. The occurrence of the two K-rich series is restricted to Western Sulawesi, where they formed in an extensional, post-subduction tectonic setting with astenospheric upwelling providing thermal perturbation and adiabatic decompression. Two parental magma sources are proposed: enriched mantle or lower crustal equivalent for HK magmas, and Triassic igneous rocks in a Gondwana-derived fragment thrust beneath the cental and northern parts of Western Sulawesi for CAK magmas. The latter interpretation is based on striking similarities in radiogenic isotope and trace element signatures. CA-TH granitoids are found mostly in Northern Sulawesi. Partial melting of lower-middle crust amphibolites in an active subduction environment is the proposed origin of these rocks. Fractional crystallization and crustal contamination have played a significant role in magma petrogenesis, particularly in the case of the HK and CAK series. Contamination by organic carbon-bearing sedimentary rocks of the HK and CAK granitoids in the central part of Western Sulawesi is suggested by their ilmenite-series (reduced) character. The CAK granitoids further to the north and CA-TH granitoids in Northern Sulawesi are typical magnetite-series (oxidized). This may explain differences in mineralization styles in the two regions.

  20. Cenozoic analogues support a plate tectonic origin for the Earth’s earliest continental crust

    NASA Astrophysics Data System (ADS)

    Hastie, A. R.; Kerr, A. C.; Mitchell, S. F.; McDonald, I.; Pearce, J. A.; Millar, I. L.; Wolstencroft, M.

    2009-12-01

    crust. The Newcastle magmas ascended and erupted without coming into contact with a mantle wedge thus forming the low MgO, Ni and Cr contents. Most Cenozoic adakites have compositions similar to the middle-late Archaean TTG suite of igneous rocks. In contrast, early (>3.5 Ga) Archaean TTG crustal rocks have lower Sr, MgO, Ni and Cr concentrations and prior to this study had no modern adakite analogue. However, the Newcastle adakites have similar compositions to the, early Archaean TTG. The discovery of these rocks has important implications for our understanding of the formation of the Earth’s earliest continental crust and so it is proposed that the Newcastle lavas be classified as a unique sub-group of adakites: Jamaican-type adakite.

  1. Evidence of a Cooler Continental Climate in East China during the Warm Early Cenozoic.

    PubMed

    Zhang, Qian-Qian; Smith, Thierry; Yang, Jian; Li, Cheng-Sen

    2016-01-01

    The early Cenozoic was characterized by a very warm climate especially during the Early Eocene. To understand climatic changes in eastern Asia, we reconstructed the Early Eocene vegetation and climate based on palynological data of a borehole from Wutu coal mine, East China and evaluated the climatic differences between eastern Asia and Central Europe. The Wutu palynological assemblages indicated a warm temperate vegetation succession comprising mixed needle- and broad-leaved forests. Three periods of vegetation succession over time were recognized. The changes of palynomorph relative abundance indicated that period 1 was warm and humid, period 2 was relatively warmer and wetter, and period 3 was cooler and drier again. The climatic parameters estimated by the coexistence approach (CA) suggested that the Early Eocene climate in Wutu was warmer and wetter. Mean annual temperature (MAT) was approximately 16°C and mean annual precipitation (MAP) was 800-1400 mm. Comparison of the Early Eocene climatic parameters of Wutu with those of 39 other fossil floras of different age in East China, reveals that 1) the climate became gradually cooler during the last 65 million years, with MAT dropping by 9.3°C. This cooling trend coincided with the ocean temperature changes but with weaker amplitude; 2) the Early Eocene climate was cooler in East China than in Central Europe; 3) the cooling trend in East China (MAT dropped by 6.9°C) was gentler than in Central Europe (MAT dropped by 13°C) during the last 45 million years. PMID:27196048

  2. Evidence of a Cooler Continental Climate in East China during the Warm Early Cenozoic

    PubMed Central

    Zhang, Qian-Qian; Smith, Thierry; Yang, Jian; Li, Cheng-Sen

    2016-01-01

    The early Cenozoic was characterized by a very warm climate especially during the Early Eocene. To understand climatic changes in eastern Asia, we reconstructed the Early Eocene vegetation and climate based on palynological data of a borehole from Wutu coal mine, East China and evaluated the climatic differences between eastern Asia and Central Europe. The Wutu palynological assemblages indicated a warm temperate vegetation succession comprising mixed needle- and broad-leaved forests. Three periods of vegetation succession over time were recognized. The changes of palynomorph relative abundance indicated that period 1 was warm and humid, period 2 was relatively warmer and wetter, and period 3 was cooler and drier again. The climatic parameters estimated by the coexistence approach (CA) suggested that the Early Eocene climate in Wutu was warmer and wetter. Mean annual temperature (MAT) was approximately 16°C and mean annual precipitation (MAP) was 800–1400 mm. Comparison of the Early Eocene climatic parameters of Wutu with those of 39 other fossil floras of different age in East China, reveals that 1) the climate became gradually cooler during the last 65 million years, with MAT dropping by 9.3°C. This cooling trend coincided with the ocean temperature changes but with weaker amplitude; 2) the Early Eocene climate was cooler in East China than in Central Europe; 3) the cooling trend in East China (MAT dropped by 6.9°C) was gentler than in Central Europe (MAT dropped by 13°C) during the last 45 million years. PMID:27196048

  3. Late Cenozoic intraplate faulting in eastern Australia

    NASA Astrophysics Data System (ADS)

    Babaahmadi, Abbas; Rosenbaum, Gideon

    2014-12-01

    The intensity and tectonic origin of late Cenozoic intraplate deformation in eastern Australia is relatively poorly understood. Here we show that Cenozoic volcanic rocks in southeast Queensland have been deformed by numerous faults. Using gridded aeromagnetic data and field observations, structural investigations were conducted on these faults. Results show that faults have mainly undergone strike-slip movement with a reverse component, displacing Cenozoic volcanic rocks ranging in ages from ˜31 to ˜21 Ma. These ages imply that faulting must have occurred after the late Oligocene. Late Cenozoic deformation has mostly occurred due to the reactivation of major faults, which were active during episodes of basin formation in the Jurassic-Early Cretaceous and later during the opening of the Tasman and Coral Seas from the Late Cretaceous to the early Eocene. The wrench reactivation of major faults in the late Cenozoic also gave rise to the occurrence of brittle subsidiary reverse strike-slip faults that affected Cenozoic volcanic rocks. Intraplate transpressional deformation possibly resulted from far-field stresses transmitted from the collisional zones at the northeast and southeast boundaries of the Australian plate during the late Oligocene-early Miocene and from the late Miocene to the Pliocene. These events have resulted in the hitherto unrecognized reactivation of faults in eastern Australia.

  4. Constraining Early Cenozoic exhumation of the British Isles with vertical profile modelling

    NASA Astrophysics Data System (ADS)

    Doepke, Daniel; Cogné, Nathan; Chew, David

    2016-04-01

    Despite decades of research is the Early Cenozoic exhumation history of Ireland and Britain still poorly understood and subject to contentious debate (e.g., Davis et al., 2012 and subsequent comments). One reason for this debate is the difficultly of constraining the evolution of onshore parts of the British Isles in both time and space. The paucity of Mesozoic and Cenozoic onshore outcrops makes direct analysis of this time span difficult. Furthermore, Ireland and Britain are situated at a passive margin, where the amount of post-rift exhumation is generally very low. Classical thermochronological tools are therefore near the edge of their resolution and make precise dating of post-rift cooling events challenging. In this study we used the established apatite fission track and (U-Th-Sm)/He techniques, but took advantage of the vertical profile approach of Gallagher et al. (2005) implemented in the QTQt modelling package (Gallagher, 2012), to better constrain the thermal histories. This method allowed us to define the geographical extent of a Late Cretaceous - Early Tertiary cooling event and to show that it was centered around the Irish Sea. Thus, we argue that this cooling event is linked to the underplating of hot material below the crust centered on the Irish Sea (Jones et al., 2002; Al-Kindi et al., 2003), and demonstrate that such conclusion would have been harder, if not impossible, to draw by modelling the samples individually without the use of the vertical profile approach. References Al-Kindi, S., White, N., Sinha, M., England, R., and Tiley, R., 2003, Crustal trace of a hot convective sheet: Geology, v. 31, no. 3, p. 207-210. Davis, M.W., White, N.J., Priestley, K.F., Baptie, B.J., and Tilmann, F.J., 2012, Crustal structure of the British Isles and its epeirogenic consequences: Geophysical Journal International, v. 190, no. 2, p. 705-725. Jones, S.M., White, N., Clarke, B.J., Rowley, E., and Gallagher, K., 2002, Present and past influence of the Iceland

  5. Paleoclimate from fossil plants and application to the early Cenozoic Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Wing, S. L.

    2011-12-01

    Wladimir Köppen called vegetation "crystallized, visible climate," and his metaphor encouraged paleobotanists to climb the chain of inference from fossil plants to paleovegetation to paleoclimate. Inferring paleovegetation from fossils has turned out to be very difficult, however, and today most paleobotanical methods for inferring paleoclimate do not try to reconstruct paleovegetation as a first step. Three major approaches are widely use to infer paleoclimate from plant fossils: 1) phylogenetic inferences rely on the climatic distributions of extant relatives of fossils, 2) morphological inferences use present-day correlations of climate with plant morphology (e.g, leaf shape, wood anatomy), and 3) chemical inferences rely on correlations between climate and the stable isotopic composition of plants or organic compounds. Each approach makes assumptions that are hard to verify. Phylogenetic inference depends on accurate identification of fossils, and also assumes that evolution and/or extinction has not shifted the climatic distributions of plant lineages through time. On average this assumption is less valid for older time periods, but probably it is not radically wrong for the early Cenozoic. Morphological approaches don't require taxonomic identification of plant fossils, but do assume that correlations between plant form and climate have been constant over time. This assumption is bolstered if the ecophysiological cause of the morphology-climate correlation is well understood, but often it isn't. Stable isotopic approaches assume that present-day correlations between isotopic composition and climate apply to the past. Commonly the chemical and physiological mechanisms responsible for the correlation are moderately well known, but often the variation among different taxonomic and functional groups of plants is poorly characterized. In spite of limitations and uncertainties on all methods for inferring paleoclimate from fossil plants, broad patterns emerge from

  6. High but not Super High Atmospheric CO2 During the Early Cenozoic

    NASA Astrophysics Data System (ADS)

    Anagnostou, E.; John, E. H.; Edgar, K. M.; Pearson, P. N.; Ridgwell, A. J.; Palike, H.; Foster, G. L.

    2014-12-01

    The early Cenozoic (~53-33Ma) marks the most recent climatic shift in Earth's history from a greenhouse to an icehouse world. This interval is characterized by a gradual deep-sea [1] and high-latitude [2, 3] cooling of ~10oC, and only moderate cooling of the tropics [e.g. 2] leading to the Eocene/Oligocene transition (EOT) marked by widespread continental Antarctic glaciation. The cause of long-term Eocene cooling is currently poorly known but a gradual decline in the concentration of atmospheric CO2 is most frequently invoked. However, the majority of available early Eocene CO2 records are uncertain and only weakly correlated with climate variability. The exception to that is the final transition into the icehouse [4] where a decline in the CO2 content of the atmosphere has been suggested as the trigger. Therefore we generated new records of boron isotopes (δ11B) in planktonic foraminifera, a proven proxy of seawater pH [e.g. 5], using multicollector ICPMS [6]. We utilised depth profiles of very well preserved multi-species planktonic foraminifera recovered by the Tanzanian Drilling Project for five time slices spanning 53-37 Ma. Additionlly, we generated approximately 0.8My resolution planktonic foraminifera δ11B records from the Ocean Drilling Program (ODP) Sites 865 and 1258/1260. Our new records show consistent results of elevated atmospheric CO2 in the early Eocene that decreases through to the late Eocene. We will discuss our new reconstructions of seawater pH and derived atmospheric CO2 concentrations, not only in view of diagenesis, but also of estimates of seawater δ11B composition and alkalinity and their significance for Eocene Antarctic glaciation, in light of potential mechanisms for modulating climate. [1] Zachos et al. (2001) Science 292. [2] Bijl et al. (2009) Nature 461. [3] Brassell (2014) Paleoceanography 29. [4] Pearson et al. (2009) Nature 461. [5] Sanyal et al. (1996) Paleoceanography 11. [6] Foster (2008) EPSL 271.

  7. A chilling perspective on Greenland's early Cenozoic climate from coupled Hf-Nd isotopes

    NASA Astrophysics Data System (ADS)

    Scher, H. D.; Bizimis, M.; Buckley, W. P., Jr.; Duggan, B.; Bohaty, S. M.; Wilson, P. A.

    2015-12-01

    The prevailing view of northern hemisphere glaciation has been of ice sheets forming on Greenland after 2.7 Ma, with iceberg rafting as early as 15 Ma. This view is incompatible with recent results from global climate/ice sheet models that predict northern hemisphere glaciation only after CO2 falls below ~280 ppmv (occurring at 25 Ma) and with recent sediment evidence for Arctic iceberg rafting as early as the middle Eocene. However, the amount of northern hemisphere ice represented by these sediments is ambiguous and global ice budget calculations for the early Cenozoic are controversial. Here we use coupled Hf-Nd isotopes of oxyhydroxides in sediments from the upper Eocene to lower Oligocene section in ODP Site U1411 (Newfoundland Ridge) to determine when the circum-North Atlantic came under the influence of a mechanical weathering regime. Leached oxyhydroxide Hf-Nd isotopes are an indicator of weathering intensity because mechanical weathering by ice sheets mobilizes the zircon-bound Hf reservoir in the crust, which has extreme unradiogenic eHf values. Chemical weathering produces a distinct seawater array on Hf-Nd diagrams, while seawater exposed to the products of mechanical weathering plot on divergent arrays closer to the Terrestrial Array. Hf-Nd isotopes of Site U1411 leachates are grouped in a near vertical trend between the seawater and terrestrial global reference arrays. Within this group there are four distinct arrays that can be delineated by age. Samples that are late Eocene in age fall along an array that is slightly divergent from the seawater array. The aspect of the Hf-Nd isotope data changes permanently after the first step of the EOT, falling along arrays that are systematically offset in the direction of the terrestrial arrays. The steepest array, most proximal to the terrestrial array, is comprised of samples deposited between 33.7 and 32.2 Ma. These results indicate a circum-North Atlantic weathering regime appeared in the earliest Oligocene.

  8. Origin of north Queensland Cenozoic volcanism: Relationships to long lava flow basaltic fields, Australia

    NASA Astrophysics Data System (ADS)

    Sutherland, F. L.

    1998-11-01

    A plume model proposed for north Queensland late Cenozoic volcanism and long lava flow distribution combines basalt ages with recent seismic studies of Australia's mantle, regional stress fields, and plate motion. Several basalt fields overlie mantle "thermal" anomalies, and other fields outside these anomalies can be traced to them through past lithospheric motion. Elsewhere, anomalies close to Australia's eastern rift margin show little volcanism, probably due to gravity-enhanced compression. Since final collision of north Queensland with New Guinea, areas of basaltic volcanism have developed over 10 Myr, and episodes appear to migrate southward from 15° to 20°S. Long lava flows increase southward as area/volume of fields increases, but topography, vent distributions, and uplifts play a role. This is attributed to magmatic plume activation within a tensional zone, as lithosphere moves over mantle thermal anomalies. The plume model predicts peak magmatism under the McBride field, coincident with the Undara long lava flow and that long lava flow fields will erupt for another 5-10 Myr. Queensland's movement over a major N-S thermal system imparts a consistent isotopic signature to its northern younger basalts, distinct to basalts from older or more southern thermal systems. Australia's motion toward this northern thermal system will give north Queensland fields continued vigorous volcanism, in contrast to the Victorian field which is leaving its southern thermal system.

  9. The deformation and tectonic evolution of the Huahui Basin, northeast China, during the Cretaceous-Early Cenozoic

    NASA Astrophysics Data System (ADS)

    Huang, Shiqi; Dong, Shuwen; Zhang, Yueqiao; Zhang, Fuqin; Huang, Dezhi; Wei, Shi; Li, Zhenhong; Miao, Laicheng; Zhu, Mingshuai

    2015-12-01

    The Cretaceous Huahui basin lies along the Dunhua-Mishan fault (Dun-Mi fault), which is one of the northern branches of Tan-Lu fault in northeastern China. The study of the formation and the tectonic movements that took place in the basin can provide very important information for deciphering the tectonic evolution of northeastern China during Cretaceous-Early Cenozoic. The field analysis of fault-slip data collected from different units in the basin, demonstrates changes in the paleo-stress state that reveals a three-stage tectonic movement during the Cretaceous-Early Cenozoic. The earliest tectonic movement was NW-SE extension, which was responsible for the formation of the basin and sedimentary infilling during the Early Cretaceous. Dating of the andesite in the fill indicates it began during about 119.17 ± 0.80 Ma. The extensional structures formed in the Latest Early Cretaceous imply that this tectonic movement lasted until the beginning of the Late Cretaceous. The second stage began during the Late Cretaceous when the tectonic stress state changed and was dominated by NW-SE compression and NE-SW extension, which caused the inversion of the extensional basin. This compression folded the Early Cretaceous deposits and reactivated pre-existing faults and uplifted pre-existing granite in the basin. The strata and the unconformity in the basin shows that this compressive phase probably took place during the Late Cretaceous and ended in the Early Paleogene by a compressional regime with NE-SW compression and NW-SE extension that constitutes the third stage. The tectonic stress fields documented in the Huahui basin provide insight into the influences of plate tectonics on the crustal evolution of northeastern China during the Cretaceous to Early Cenozoic. These results show that the development of Huahui basin was controlled by the northwestward subduction of the paleo-Pacific plate during the Cretaceous, and later by the far-field effects of India-Asia collision in

  10. Geochemical Evidence for Early to Mid-Cenozoic “Flat-Slab” Subduction Beneath the Western North American Interior

    NASA Astrophysics Data System (ADS)

    Farmer, G.; Fornash, K. F.

    2009-12-01

    The voluminous intermediate to silicic composition magmatism that occurred during the mid-Cenozoic ignimbrite flare-up in western North America is generally attributed to a melting event in the upper mantle, related in some fashion to shallowing and resteepening of the subduction angle of oceanic lithosphere underthrust beneath the continent. The exact trigger mechanism for melting is unclear, but one possibility is that the addition of slab-derived volatiles, and the refrigeration of, the uppermost mantle during early Cenozoic “flat” subduction primed the upper mantle for melting during a later period of slab rollback. But is this mechanism viable for portions of the ignimbrite flare-up found in the Rocky Mountains region of the western United States, some 1,000 km inboard of the western edge of the continent? Did slab-related volatile addition occur in the mantle source region of this essentially intraplate magmatism? To address this issue we reexamined space-time-composition patterns in mid-Cenozoic magmatism in the Rocky Mountain region, using >5,500 individual rock chemical analyses now compiled in the on-line North American Volcanic and Intrusive Rock Database (NAVDAT) for rocks of this age. We divided the Rocky Mountains region and northern Mexico into fifteen 5o x 5o grid elements and interrogated volcanic rock ages and compositions from each. At this scale, the ignimbrite flare- up clearly occurs in two pulses; from 40-60 Ma north of ~ 45oN latitude and from 20-40 Ma to the south in Colorado, New Mexico, west Texas and northern Mexico. The chemical compositions of the mid-Cenozoic volcanic rocks, in contrast, vary little with latitude (age) but instead show longitudinal variations, from largely calc-alkaline (Challis, San Juan and Mogollon-Datil volcanic fields) in the west to alkaline (Trans Pecos V. F.) compositions to the east, as noted by many previous workers. Large ion lithophile element/high field strength element (LILE/HFSE) ratios in more

  11. Early Cenozoic Shortening and Foreland Basin Sedimentation in the Marañon Fold-thrust Belt, Central Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Jackson, L. J.; Carlotto, V.; Horton, B. K.; Rosell, L. N.

    2015-12-01

    The Marañon fold-thrust belt in the westernmost Andes of Peru has long been considered a robust signature of early Cenozoic shortening in the Andean orogenic belt. However, the structural details and potential records of coeval synorogenic sedimentation remain elusive. We report results from new geologic mapping (1:50,000), cross-section construction, and U-Pb geochronology for the Matucana-Ticlio region at 11-12°S along the Lima-La Oroya highway. Zircon U-Pb age data from volcanic rocks and clastic basin fill provide a maximum depositional age of ~43 Ma for a middle Eocene syndeformational unit that we identify as the Anta Formation, which overlies the Paleocene Casapalca Formation. Sedimentary lithofacies and unconformable relationships within the volcaniclastic Anta Formation reveal mixed fluvial, alluvial-fan, and volcanic depositional conditions during shortening accommodated by a NE-verging thrust/reverse fault and corresponding backthrust (here named the Chonta fault system). Our cross-section reconstruction and geochronological data indicate that the region is a critical, possibly unique, zone of the broader NE-directed Marañon fold-thrust belt where pre-Neogene synorogenic sediments and their associated structures are preserved. We interpret this combined structural and basin system as an Eocene-age (Incaic) frontal thrust belt and corresponding foredeep to wedge-top depozone in central Peru. As one of the better-constrained segments of the Marañon fold-thrust belt, this zone provides insight into potential linkages with elusive early Cenozoic (Incaic) structures and foreland basin fill of the Western Cordillera and Altiplano farther south in the central Andean plateau.

  12. Isotopic evidence for the origin of Cenozoic volcanic rocks in the Pinacate volcanic field, northwestern Mexico

    NASA Astrophysics Data System (ADS)

    Lynch, D. J.; Musselman, T. E.; Gutmann, J. T.; Patchett, P. J.

    1993-02-01

    Six volcanic rocks, reconnaissance samples representing most of the temporal and compositional variation in the Pinacate volcanic field of Sonora and Arizona, are characterized for major element and NdSr isotopic compositions. The samples consist of basanite through trachyte of an early shield volcano, and alkali basalts and a tholeiite from later craters and cinder cones. With the exception of the trachyte sample, which has increased 87Sr/ 86Sr due to crustal effects, all 87Sr/ 86Sr values fall between 0.70312 and 0.70342, while ɛNd values are all between + 5.0 and + 5.7. Clinopyroxene in a rare spinel-lherzolite nodule derived from the uppermost mantle beneath the field has 87Sr/ 86Sr of 0.70320 but ɛNd of + 8.8, three ɛNd units higher than the volcanic rocks. Both the volcanic rocks and the nodule record the presence of asthenospheric, rather than enriched lithospheric mantle beneath Pinacate. This is consistent with one or both of (a) proximity of Pinacate to the Gulf of California spreading center and (b) presence of similar asthenospheric mantle signatures in volcanic rocks over a wide contiguous area of the southwestern USA. We consider the comparison to other southwestern USA magma sources as the more relevant alternative, although a definite conclusion is not possible at this stage.

  13. Developmental origins of early antisocial behavior.

    PubMed

    Calkins, Susan D; Keane, Susan P

    2009-01-01

    Early antisocial behavior has its origins in childhood behavior problems, particularly those characterized by aggressive and destructive behavior. Deficits in self-regulation across multiple domains of functioning, from the physiological to the cognitive, are associated with early behavior problems, and may place children at greater risk for the development of later antisocial behavior. Data are presented from a longitudinal study of early self-regulation and behavior problems, the RIGHT Track Research Project, demonstrating that children at greatest risk for early and persistent problem behavior display patterns of physiological and emotional regulation deficits early in life. Parenting behavior and functioning have also been examined as predictors of trajectories of early problem behavior, and some data support the interaction of parenting and self-regulation as significant predictors of patterns of problematic behavior and ongoing problems with the regulation of affect. Peer relationships also affect and are affected by early self-regulation skills, and both may play a role in academic performance and subsequent school success. These data provide evidence that the social contexts of early family and peer relationships are important moderators of the more proximal mechanism of self-regulation, and both types of processes, social and biobehavioral, are likely implicated in early antisocial tendencies. Implications of these findings on self-regulation and early behavior problems are discussed in terms of future research and treatment approaches. PMID:19825259

  14. Greenland ice reveals imprint of the Early Cenozoic passage of the Iceland mantle plume

    NASA Astrophysics Data System (ADS)

    Rogozhina, I.; Petrunin, A. G.; Vaughan, A. P.; Kaban, M. K.; Mulvaney, R.; Steinberger, B. M.; Koulakov, I.; Thomas, M.; Johnson, J. V.

    2013-12-01

    Modelling and observation of ice sheet basal conditions suggests that elevated values of geothermal heat flow (GHF) result in enhanced basal melting. For the Greenland Ice Sheet (GIS), radar soundings and deep ice core measurements indicate unexpectedly high local values of GHF in areas where thick and stable Early Proterozoic lithosphere suggests they should be low. Rapid basal ice melt and accelerated ice flow, linked to abnormal GHF, indicate that regional heat flow patterns strongly influence the present-day thermodynamic state of the GIS and may affect its evolution in the future. Using a coupled model of climate-driven GIS and lithosphere, constrained by a wide range of interdisciplinary data, we detect a laterally continuous west-to-east area of high GHF in central-northern Greenland. The area of elevated heat flow closely coincides with a west-to-east negative anomaly in seismic velocity, which recent high-resolution tomography models tie to the present-day location of the Iceland mantle plume. Plate paleoreconstructions and analysis of magmatism in eastern and western Greenland suggest passage of the Greenland lithosphere over a mantle plume between around 80 and 35 Ma. Independent evidence under the GIS for magmatism along the putative mantle plume track comes from local gravity anomalies, igneous rock fragments recovered from the bedrock beneath the deep ice core GISP2, and radar sounding evidence of a caldera-like bedrock structure under the central GIS. We argue that long-lived, non-stationary effects of the mantle plume still affect the thermal state of the present-day Greenland lithosphere and are the origin of rapid basal ice melting over vast areas of central and northern Greenland.

  15. Various depths of origin of clinopyroxene megacrysts from Cenozoic alkaline lavas of occurrences in Lower Silesia (SW Poland)

    NASA Astrophysics Data System (ADS)

    Lipa, Danuta; Puziewicz, Jacek; Ntaflos, Theodoros; Woodland, Alan

    2016-04-01

    to use the geobarometer of Nimis & Ulmer (1998), which yielded the following pressures of crystallization: Księginki 1.05 - 1.23 GPa, Ostrzyca 0.06 - 0.19 GPa, Lutynia 1.08 - 1.13 GPa. The pressure of crystallization of the Księginki megacrysts fits well the interpretation of Puziewicz et al. (2011) who considered the megacrysts to come from syn-volcanic host magma cumulates formed in lava batches temporarily residing at uppermost mantle depth. By analogy, we are of the opinion that the Lutynia megacrysts are of similar origin, except the "LREE depleted" one. The Ostrzyca megacrysts were interpreted by Lipa et al. (2014) to crystallize from the host lava at mid-crustal depths. The 87Sr/86Sr and 143Nd/144Nd isotope ratios of the Ostrzyca and Lutynia megacrysts are identical to those of the European Asthenospheric Reservoir and are consistent with their proposed syn-volcanic origin, except the "LREE depleted" megacryst, for which isotopic ratios have not been analysed. The 87Sr/86Sr and 143Nd/144Nd isotope ratios of the Księginki megacrysts are slightly enriched in radiogenic Sr. Funding. This study was possible thanks to the project NCN UMO-2014/15/B/ST10/00095 of Polish National Centre for Science. References Badura, J., Pécskay, Z., Koszowska, E., Wolska, A., Zuchiewicz, W., Przybylski, B., 2006. Przegląd Geologiczny 54.2., 145-153. Lipa, D., Puziewicz, J., Ntaflos, T., Matusiak-Małek, M., 2014. Geoscience Notes 2.2. 49-72. Nimis, P., Ulmer, P., 1998. Contributions to Mineralogy and Petrology 133, 122-135. Pécskay, Z., Birkenmajer, K., 2013. In: Büchner, J., Rapprich, V., Tietz, O., (eds.) Basalt 2013 - Cenozoic Magmatism in Central Europe. Abstracts & Excursion Guides, Czech Geological Survey, Prague & Senckenberg Museum of Natural History, Görlitz, 66-67. Puziewicz, J., Koepke, J., Grégoire, M., Ntaflos, T., Matusiak-Małek, M., 2011. J. of Petrology 52, 2107-2145.

  16. Improving the Ginkgo CO2 barometer: Implications for the early Cenozoic atmosphere

    NASA Astrophysics Data System (ADS)

    Barclay, Richard S.; Wing, Scott L.

    2016-04-01

    Stomatal properties of fossil Ginkgo have been used widely to infer the atmospheric concentration of CO2 in the geological past (paleo-pCO2). Many of these estimates of paleo-pCO2 have relied on the inverse correlation between pCO2 and stomatal index (SI - the proportion of epidermal cells that are stomata) observed in recent Ginkgo biloba, and therefore depend on the accuracy of this relationship. The SI - pCO2 relationship in G. biloba has not been well documented, however. Here we present new measurements of SI for leaves of G. biloba that grew under pCO2 from 290 to 430 ppm. We prepared and imaged all specimens using a consistent procedure and photo-documented each count. As in prior studies, we found a significant inverse relationship between SI and pCO2, however, the relationship is more linear, has a shallower slope, and a lower correlation coefficient than previously reported. We examined leaves of G. biloba grown under pCO2 of 1500 ppm, but found they had highly variable SI and a large proportion of malformed stomata. We also measured stomatal dimensions, stomatal density, and the carbon isotope composition of G. biloba leaves in order to test a mechanistic model for inferring pCO2. This model overestimated observed pCO2, performing less well than the SI method between 290 and 430 ppm. We used our revised SI-pCO2 response curve, and new observations of selected fossils, to estimate late Cretaceous and Cenozoic pCO2 from fossil Ginkgo adiantoides. All but one of the new estimates is below 800 ppm, and together they show little long-term change in pCO2 or relation to global temperature. The low Paleogene pCO2 levels indicated by the Ginkgo SI proxy are not consistent with the high pCO2 inferred by some climate and carbon cycle models. We cannot currently resolve the discrepancy, but greater agreement between proxy data and models may come from a better understanding of the stomatal response of G. biloba to elevated pCO2, better counts and measurements of

  17. Early origins of chronic obstructive pulmonary disease.

    PubMed

    Narang, Indra; Bush, Andrew

    2012-04-01

    Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and a significant challenge for adult physicians. However, there is a misconception that COPD is a disease of only adult smokers. There is a growing body of evidence to support the hypothesis that chronic respiratory diseases such as COPD have their origins in early life. In particular, adverse maternal factors will interact with the environment in a susceptible host promoting altered lung growth and development antenatally and in early childhood. Subsequent lung injury and further gene-environment interactions may result in permanent lung injury manifest by airway obstruction predisposing to COPD. This review will discuss the currently available data regarding risk factors in early life and their role in determining the COPD phenotype. PMID:22265926

  18. Antarctic Peninsula Late Cretaceous-Early Cenozoic pal˦oenvironments and Gondwana pal˦ogeographies

    NASA Astrophysics Data System (ADS)

    Dingle, R. V.; Lavelle, M.

    2000-07-01

    A review is made of stratigraphical, geochemical and pal˦ogeographical data from the northern Antarctic Peninsula and the Southern Ocean for Late Mesozoic-Early Cenozoic times. Clay mineral and S/total organic C ratios are used to re-assess earlier scenarios, and it is suggested that eight climatic episodes affected the northern Antarctic Peninsula between Late Aptian and Pal˦ogene times. Evolving pal˦ogeographies in southern Gondwana allowed the connection of the inter-continental western Weddell Basin to the proto-Indian Ocean during Albian to Cenomanian times, and it is suggested that this caused an initial cooling of ambient temperatures in the northern Antarctic Peninsula area. This situation altered when the South Atlantic seaway was opened to equatorial regions, producing a Campanian warm episode. Throughout this period, the climate was humid and non-seasonal (ever-wet) and the adjacent seas were dominated by mineralwalled phytoplankton. A Maastrichtian to Mid-Pal˦ocene cool period is postulated following the establishment of more-polar ocean circulation routes along the southern edge of the Pacific Basin, and the climate became seasonally humid with phytoplankton production switching to organicwalled dominant. The global Pal˦ogene climatic optimum was a warm, ever-wet episode but as it waned from Mid-Eocene times, a further, relatively short, period of marked seasonality is recognised. Later, Eocene climates were again ever-wet and became progressively cooler. The Late Eocene-Early Oligocene opening of the Tasman Sea and Drake Passage seaways caused cold conditions on Seymour Island, followed rapidly by the earliest glacial sediments on King George Island and the establishment of mineral-walled phytoplankton dominance in the seas.

  19. Early origin of the bilaterian developmental toolkit

    PubMed Central

    Erwin, Douglas H.

    2009-01-01

    Whole-genome sequences from the choanoflagellate Monosiga brevicollis, the placozoan Trichoplax adhaerens and the cnidarian Nematostella vectensis have confirmed results from comparative evolutionary developmental studies that much of the developmental toolkit once thought to be characteristic of bilaterians appeared much earlier in the evolution of animals. The diversity of transcription factors and signalling pathway genes in animals with a limited number of cell types and a restricted developmental repertoire is puzzling, particularly in light of claims that such highly conserved elements among bilaterians provide evidence of a morphologically complex protostome–deuterostome ancestor. Here, I explore the early origination of elements of what became the bilaterian toolkit, and suggest that placozoans and cnidarians represent a depauperate residue of a once more diverse assemblage of early animals, some of which may be represented in the Ediacaran fauna (c. 585–542 Myr ago). PMID:19571245

  20. Molecular phylogenetic analysis of nuclear genes suggests a Cenozoic over-water dispersal origin for the Cuban solenodon.

    PubMed

    Sato, Jun J; Ohdachi, Satoshi D; Echenique-Diaz, Lazaro M; Borroto-Páez, Rafael; Begué-Quiala, Gerardo; Delgado-Labañino, Jorge L; Gámez-Díez, Jorgelino; Alvarez-Lemus, José; Nguyen, Son Truong; Yamaguchi, Nobuyuki; Kita, Masaki

    2016-01-01

    The Cuban solenodon (Solenodon cubanus) is one of the most enigmatic mammals and is an extremely rare species with a distribution limited to a small part of the island of Cuba. Despite its rarity, in 2012 seven individuals of S. cubanus were captured and sampled successfully for DNA analysis, providing new insights into the evolutionary origin of this species and into the origins of the Caribbean fauna, which remain controversial. We conducted molecular phylogenetic analyses of five nuclear genes (Apob, Atp7a, Bdnf, Brca1 and Rag1; total, 4,602 bp) from 35 species of the mammalian order Eulipotyphla. Based on Bayesian relaxed molecular clock analyses, the family Solenodontidae diverged from other eulipotyphlan in the Paleocene, after the bolide impact on the Yucatan Peninsula, and S. cubanus diverged from the Hispaniolan solenodon (S. paradoxus) in the Early Pliocene. The strikingly recent divergence time estimates suggest that S. cubanus and its ancestral lineage originated via over-water dispersal rather than vicariance events, as had previously been hypothesised. PMID:27498968

  1. Molecular phylogenetic analysis of nuclear genes suggests a Cenozoic over-water dispersal origin for the Cuban solenodon

    PubMed Central

    Sato, Jun J.; Ohdachi, Satoshi D.; Echenique-Diaz, Lazaro M.; Borroto-Páez, Rafael; Begué-Quiala, Gerardo; Delgado-Labañino, Jorge L.; Gámez-Díez, Jorgelino; Alvarez-Lemus, José; Nguyen, Son Truong; Yamaguchi, Nobuyuki; Kita, Masaki

    2016-01-01

    The Cuban solenodon (Solenodon cubanus) is one of the most enigmatic mammals and is an extremely rare species with a distribution limited to a small part of the island of Cuba. Despite its rarity, in 2012 seven individuals of S. cubanus were captured and sampled successfully for DNA analysis, providing new insights into the evolutionary origin of this species and into the origins of the Caribbean fauna, which remain controversial. We conducted molecular phylogenetic analyses of five nuclear genes (Apob, Atp7a, Bdnf, Brca1 and Rag1; total, 4,602 bp) from 35 species of the mammalian order Eulipotyphla. Based on Bayesian relaxed molecular clock analyses, the family Solenodontidae diverged from other eulipotyphlan in the Paleocene, after the bolide impact on the Yucatan Peninsula, and S. cubanus diverged from the Hispaniolan solenodon (S. paradoxus) in the Early Pliocene. The strikingly recent divergence time estimates suggest that S. cubanus and its ancestral lineage originated via over-water dispersal rather than vicariance events, as had previously been hypothesised. PMID:27498968

  2. An Early Cenozoic Ichthyolith Record from Demerara Rise (ODP Site 1258: Equatorial Atlantic Ocean)

    NASA Astrophysics Data System (ADS)

    Bryant, R. M.; Sibert, E. C.; Norris, R. D.

    2014-12-01

    Peak global warmth during the early Eocene is a partial analog to the future structure of marine ecosystems in a high pCO2 world. Early Eocene oceans are generally regarded as supporting warmer oceans with lower overall productivity than today owing to the low concentrations of preserved organic matter in pelagic sediments. It has also been proposed that Eocene oceans were about as productive as now, but higher respiration rates in a warmer-than-modern ocean more efficiently recycled organic matter and nutrients. We investigated Eocene export productivity and its link to taxonomic diversity using the pelagic ichthyolith record. Ichthyoliths are calcium phosphate microfossils including fish teeth and shark denticles and their fragments, and are a unique paleoceanographic proxy because they represent a fossil record for marine vertebrates, a charismatic and tangible part of the ecosystem that generally goes unrepresented in the fossil record. Analysis of the ichthyolith record in Ocean Drilling Program Site 1258 (NE South America) shows a remarkable increase in accumulation rate of ichthyoliths from the Paleocene into the Eocene, suggesting that onset of the Early Eocene Climatic Optimum in the equatorial Atlantic was favorable to fish production. Our results suggest that, if anything, the early Eocene maintained higher productivity than in the late Paleocene. These results compare favorably with a record of ichthyolith accumulation in the South Pacific (DSDP 596), which also indicates unusually high rates of fish productivity in the peak of Eocene warm climates. Low resolution data sets from the Pacific suggest an explosion of morphotypes during the warm period associated with an increase in ichthyolith mass accumulation rates. Peak global warmth, therefore, appears to be associated with both higher fish production and higher taxonomic diversity than suggested by previous reconstructions of Eocene primary production. Increasing the amount of continuous records of

  3. Polyphase exhumation in the western Qinling Mountains, China: Rapid Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed Cenozoic uplift

    PubMed Central

    Heberer, Bianca; Anzenbacher, Thomas; Neubauer, Franz; Genser, Johann; Dong, Yunpeng; Dunkl, István

    2014-01-01

    The western sector of the Qinling–Dabie orogenic belt plays a key role in both Late Jurassic to Early Cretaceous “Yanshanian” intracontinental tectonics and Cenozoic lateral escape triggered by India–Asia collision. The Taibai granite in the northern Qinling Mountains is located at the westernmost tip of a Yanshanian granite belt. It consists of multiple intrusions, constrained by new Late Jurassic and Early Cretaceous U–Pb zircon ages (156 ± 3 Ma and 124 ± 1 Ma). Applying various geochronometers (40Ar/39Ar on hornblende, biotite and K-feldspar, apatite fission-track, apatite [U–Th–Sm]/He) along a vertical profile of the Taibai Mountain refines the cooling and exhumation history. The new age constraints record the prolonged pre-Cenozoic intracontinental deformation as well as the cooling history mostly related to India–Asia collision. We detected rapid cooling for the Taibai granite from ca. 800 to 100 °C during Early Cretaceous (ca. 123 to 100 Ma) followed by a period of slow cooling from ca. 100 Ma to ca. 25 Ma, and pulsed exhumation of the low-relief Cretaceous peneplain during Cenozoic times. We interpret the Early Cretaceous rapid cooling and exhumation as a result from activity along the southern sinistral lithospheric scale tear fault of the recently postulated intracontinental subduction of the Archean/Palaeoproterozoic North China Block beneath the Alashan Block. A Late Oligocene to Early Miocene cooling phase might be triggered either by the lateral motion during India–Asia collision and/or the Pacific subduction zone. Late Miocene intensified cooling is ascribed to uplift of the Tibetan Plateau. PMID:27065503

  4. Polyphase exhumation in the western Qinling Mountains, China: Rapid Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed Cenozoic uplift

    NASA Astrophysics Data System (ADS)

    Heberer, Bianca; Anzenbacher, Thomas; Neubauer, Franz; Genser, Johann; Dong, Yunpeng; Dunkl, István

    2014-03-01

    The western sector of the Qinling-Dabie orogenic belt plays a key role in both Late Jurassic to Early Cretaceous "Yanshanian" intracontinental tectonics and Cenozoic lateral escape triggered by India-Asia collision. The Taibai granite in the northern Qinling Mountains is located at the westernmost tip of a Yanshanian granite belt. It consists of multiple intrusions, constrained by new Late Jurassic and Early Cretaceous U-Pb zircon ages (156 ± 3 Ma and 124 ± 1 Ma). Applying various geochronometers (40Ar/39Ar on hornblende, biotite and K-feldspar, apatite fission-track, apatite [U-Th-Sm]/He) along a vertical profile of the Taibai Mountain refines the cooling and exhumation history. The new age constraints record the prolonged pre-Cenozoic intracontinental deformation as well as the cooling history mostly related to India-Asia collision. We detected rapid cooling for the Taibai granite from ca. 800 to 100 °C during Early Cretaceous (ca. 123 to 100 Ma) followed by a period of slow cooling from ca. 100 Ma to ca. 25 Ma, and pulsed exhumation of the low-relief Cretaceous peneplain during Cenozoic times. We interpret the Early Cretaceous rapid cooling and exhumation as a result from activity along the southern sinistral lithospheric scale tear fault of the recently postulated intracontinental subduction of the Archean/Palaeoproterozoic North China Block beneath the Alashan Block. A Late Oligocene to Early Miocene cooling phase might be triggered either by the lateral motion during India-Asia collision and/or the Pacific subduction zone. Late Miocene intensified cooling is ascribed to uplift of the Tibetan Plateau.

  5. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

    NASA Astrophysics Data System (ADS)

    Anagnostou, Eleni; John, Eleanor H.; Edgar, Kirsty M.; Foster, Gavin L.; Ridgwell, Andy; Inglis, Gordon N.; Pancost, Richard D.; Lunt, Daniel J.; Pearson, Paul N.

    2016-05-01

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500–3,000 parts per million, and in the absence of tighter constraints carbon–climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ11B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  6. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate.

    PubMed

    Anagnostou, Eleni; John, Eleanor H; Edgar, Kirsty M; Foster, Gavin L; Ridgwell, Andy; Inglis, Gordon N; Pancost, Richard D; Lunt, Daniel J; Pearson, Paul N

    2016-05-19

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ(11)B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  7. Cenozoic Planktonic Marine Diatom Diversity and Correlation to Climate Change

    PubMed Central

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂18O (climate) and carbon cycle records (∂13C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p<.001; detrended, r = .6, p = .01). Diatoms were 20% less diverse in the early late Miocene, when temperatures and pCO2 were only moderately higher than today. Diversity is strongly correlated to both ∂13C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic

  8. The Cenozoic Diversity of Agglutinated Foraminifera - Evidence for a late Oligocene to early Miocene diversification event

    NASA Astrophysics Data System (ADS)

    Kaminski, Michael; Setoyama, Eiichi; Kender, Sev; Cetean, Claudia

    2014-05-01

    their poorly established taxonomy. Genera such as Alveovalvulina, Guppyella, Goesella, and Alveovalvulinella, are typical of assemblages found in subtropical oxygen minimum zones, especially in West Africa and the Caribbean. These agglutinated genera are not found in coeval assemblages from the northern high latitudes (Kaminski et al. 2005), suggesting they are restricted to the low-latitude OMZ. It is likely that the global warming of the latest Oligocene to Early Miocene contributed to intensification of dysoxic conditions in low-latitude upwelling regions, possibly from enhanced productivity and reduced deep-sea ventilation, creating an expanded niche for these organisms that flourished in low-oxygen conditions with high particulate organic matter input. We believe a more detailed phylogenetic approach to these agglutinated genera would result in the description of new genera for individual lineages and refinement of the foraminiferal diversity record.

  9. The origin and early radiation of dinosaurs

    NASA Astrophysics Data System (ADS)

    Brusatte, Stephen L.; Nesbitt, Sterling J.; Irmis, Randall B.; Butler, Richard J.; Benton, Michael J.; Norell, Mark A.

    2010-07-01

    Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of the most important evolutionary radiations in earth history. Our understanding of this keystone event has dramatically changed over the past 25 years, thanks to an influx of new fossil discoveries, reinterpretations of long-ignored specimens, and quantitative macroevolutionary analyses that synthesize anatomical and geological data. Here we provide an overview of the first 50 million years of dinosaur history, with a focus on the large-scale patterns that characterize the ascent of dinosaurs from a small, almost marginal group of reptiles in the Late Triassic to the preeminent terrestrial vertebrates of the Jurassic and Cretaceous. We provide both a biological and geological background for early dinosaur history. Dinosaurs are deeply nested among the archosaurian reptiles, diagnosed by only a small number of characters, and are subdivided into a number of major lineages. The first unequivocal dinosaurs are known from the late Carnian of South America, but the presence of their sister group in the Middle Triassic implies that dinosaurs possibly originated much earlier. The three major dinosaur lineages, theropods, sauropodomorphs, and ornithischians, are all known from the Triassic, when continents were joined into the supercontinent Pangaea and global climates were hot and arid. Although many researchers have long suggested that dinosaurs outcompeted other reptile groups during the Triassic, we argue that the ascent of dinosaurs was more of a matter of contingency and opportunism. Dinosaurs were overshadowed in most Late Triassic ecosystems by crocodile-line archosaurs and

  10. Rethinking Controls on the Long-Term Cenozoic Carbonate Compensation Depth: Case Studies across Late Paleocene - Early Eocene Warming and Late Eocene - Early Oligocene Cooling

    NASA Astrophysics Data System (ADS)

    Greene, S. E.; Ridgwell, A. J.; Schmidt, D. N.; Kirtland Turner, S.; Paelike, H.; Thomas, E.

    2014-12-01

    The carbonate compensation depth (CCD) is the depth below which negligible calcium carbonate is preserved in marine sediments. The long-term position of the CCD is often considered to be a powerful constraint on palaeoclimate and atmospheric CO2 concentration due to the requirement that carbonate burial balance riverine weathering over long timescales. The requirement that weathering and burial be in balance is clear, but it is less certain that burial compensates for changes in weathering via shoaling or deepening of the CCD. Because most carbonate burial occurs well above the CCD , changes in weathering fluxes may be primarily accommodated by increasing or decreasing carbonate burial at shallower depths, i.e., at or near the lysocline, the depth range over which carbonate dissolution markedly increases. Indeed, recent earth system modelling studies have suggested that the position of the CCD is relatively insensitive to changes in atmospheric pCO2. Additionally, studies have questioned the nature and strength of the relationship between the CCD, carbonate saturation state in the water column, and lysocline. To test the relationship between palaeoclimate and the location of the CCD, we reconstructed the global, long-term CCD behaviour across major Cenozoic climate transitions: the late Paleocene - early Eocene long-term warming trend (study interval ~58 to 49 Ma) and the late Eocene - early Oligocene cooling and glaciation (study interval ~38 to 27 Ma). We use Earth system modelling (GENIE) to explore the links between atmospheric pCO2 and the CCD, isolating and teasing apart the roles of total dissolved inorganic carbon, temperature, circulation, and productivity in determining the CCD.

  11. Timing of Cenozoic Basin Formation in Northern Sundaland, Southeast Asia

    SciTech Connect

    Liew, K.K. )

    1994-07-01

    The present shorelines of northern Sundaland show preferential northwest-southeast elongation. This trend is parallel for subparallel to major faults and suture in this region. Continental wrench/shear basins developed on the western portion of this region and back-arc basins developed on the western portion of this region and back-arc basins in the rest of the region are also aligned to this trend. Different basin geometries and structural patterns among Cenozoic basins in northern Sundaland indicate different origins and/or timing of basin formation. Wrench faulting has played a significant role in the formation of these Cenozoic basins. The continued collision of the Indian subplate with the Eurasian plate during early Cenozoic has caused a redistribution of stress within this region. Zones of weakness have been reactivated or created with large lateral displacements by these changes, thus initiating the subsidence of these basins. The episodic initiation of Cenozoic basins may have begun as early as Jurassic and continued till Oligocene.

  12. Diversity history of Cenozoic marine siliceous plankton

    NASA Astrophysics Data System (ADS)

    Lazarus, David; Renaudie, Johan

    2014-05-01

    Marine planktonic diatoms and polycystine radiolarians, both with shells of opaline silica, make up a large part of the deep-sea sediment fossil record. Diatom export of organic material to the deep ocean and sediments strongly affects the global carbon cycle; while both groups compete for, and are regulated by the availability of, dissolved silica derived from global weathering. Diatoms and radiolarians also both have a relatively (compared to foraminifera or coccolithophores) complex biogeography, with diverse, endemic polar and tropical assemblages. Changes in past diatom and radiolarian diversity can be used to understand how the ocean's biologic pump has evolved, how co-evolution between groups occurs, and how nutrient availability controls evolutionary change. Lazarus et al. (2014) recently showed that diatom diversity increased by a factor of ca 3.5X over the Cenozoic, with a temporary peak in the latest Eocene, a late Oligocene-early Miocene low interval, very strong diversification in the late Miocene-early Pliocene, and minor decline in the late Pliocene-Recent. Only Phanerozoic scale radiolarian diversity estimates have been available until now, and these are strongly biased by sample size. We employed similar data (NSB database) and methods (1 my bins, 'sqs' subsampling, outlier removal using Pacman trims) as Lazarus et al. (2014) to calculate, for the first time, a detailed estimate of radiolarian diversity history, and origination and extinction rates over the last 50 my, the period for which sufficient NSB data is available. Radiolarian diversity increases almost monotonically by a factor of 5, with relatively rapid increases in the mid Eocene (high relative origination) and early Miocene (due to low extinction rates), and a moderate decline in the Plio-Pleistocene due to high extinction rates. Combined high rates of both extinction and origination, with little diversity change, are seen at the Eocene-Oligocene boundary. Most of these events can be

  13. The origin and early evolution of dinosaurs.

    PubMed

    Langer, Max C; Ezcurra, Martin D; Bittencourt, Jonathas S; Novas, Fernando E

    2010-02-01

    The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as "all descendants of the most recent common ancestor of birds and Triceratops". Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and

  14. Tectonic Implications of the Coupled Motions of India and Africa in the Late Cretaceous and Early Cenozoic

    NASA Astrophysics Data System (ADS)

    Cande, S. C.; Stegman, D. R.

    2010-12-01

    Two classic tectonic puzzles are 1) the fast motion of India in the Late Cretaceous and Early Cenozoic and 2) the decreased convergence rate between Africa and Eurasia in the Paleocene corresponding to a period of tectonic quiescence in the Alps (Trümpy’s “Paleocene restoration”). We have reexamined plate motion constraints in the Indo-Atlantic Oceans and tied together a series of related observations that suggest that both of these events were strongly influenced, and perhaps even driven, by the arrival of the Reunion plume. Fast motion of India, as recorded by sea floor spreading, began around 68 Ma and ended around 45 Ma. The period of fast spreading started with a short pulse of superfast spreading between 66 and 63 Ma that peaked (Ind-Ant = 200 mm/yr) during Chron 29R, the time of the maximum eruption rate of Deccan flood basalts, and was followed by a longer period of fast (but not superfast) spreading (Ind-Ant = 130 mm/yr). A few Ma before the start of the fast motion of India, around 70 Ma, Africa started an unusual 30 Ma episode of variable motion. This consisted of a 15 Ma gradually intensifying retardation of Africa’s rate of rotation about the Euler pole for Africa-Eurasia convergence (near 32° N, 16° W), followed by a 15 Ma period in which Africa’s rate of rotation gradually recovered. The gradual slowing down and speeding up of Africa caused the stage poles of Afr-NoAm, Afr-SoAm, Afr-Ant and Afr-Mantle to migrate in a systematic way, first away from and then back towards the Africa-Eurasia Euler pole. These excursions are reflected in the large bends of the fractures zones and the systematic changes in spreading rates on all three ridge systems between 70 and 40 Ma. Additionally, coeval bends in the Tristan da Cunha and St. Helena hotspot tracks are consistent with this variable motion of Africa. The retarding motion peaked between 57 and 54 Ma and then gradually faded away with the motion of Africa returning roughly to its pre-70 Ma

  15. Mantle structure beneath eastern Africa: Evidence for a through going-mantle anomaly and its implications for the origin of Cenozoic tectonism in eastern Africa

    NASA Astrophysics Data System (ADS)

    Mulibo, G.; Tugume, F.; Julia, J.

    2012-12-01

    In this study, teleseismic earthquakes recorded on over 60 temporary AfricaArray seismic stations deployed in Uganda, Kenya, Tanzania and Zambia between 2007 and 2011 are used to invert P and S travel time residuals, together with travel time residuals from previous deployments, for a 3D image of mantle wave speeds and for examining relief on transition zone discontinuities using receiver function stacks. Tomographic images reveal a low wave speed anomaly (LWA) that dips to the SW beneath northern Zambia, extending to a depth of at least 900 km. The anomaly appears to be continuous across the transition zone, extending into the lower mantle. Receiver function stacks reveal an average transition zone thickness (TZT) across a wide region extending from central Zambia to the NE through Tanzania and into Kenya, which is ~30-40 km thinner than the global average. These results are not easily explained by models for the origin of the Cenozoic tectonism in eastern Africa that invoke a plume head or small scale convection either by edge flow or passive stretching of the lithosphere. However, the depth extent of the LWA coincident with a thin transition zone is consistent with a model invoking a through-going mantle anomaly beneath eastern Africa that links anomalous upper mantle to the African Superplume anomaly in the lower mantle beneath southern Africa. This finding indicates that geodynamic processes deep in the lower mantle are influencing surface dynamics across the Afro-Arabian rift system.

  16. Cretaceous to Cenozoic evolution of the northern Lhasa Terrane and the Early Paleogene development of peneplains at Nam Co, Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Haider, Vicky L.; Dunkl, István; von Eynatten, Hilmar; Ding, Lin; Frei, Dirk; Zhang, Liyun

    2013-07-01

    Highly elevated and well-preserved peneplains are characteristic geomorphic features of the Tibetan plateau in the northern Lhasa Terrane, north-northwest of Nam Co. The peneplains were carved in granitoids and in their metasedimentary host formations. We use multi-method geochronology (zircon U-Pb and [U-Th]/He dating and apatite fission track and [U-Th]/He dating) to constrain the post-emplacement thermal history of the granitoids and the timing and rate of final exhumation of the peneplain areas. LA-ICP-MS U-Pb geochronology of zircons yields two narrow age groups for the intrusions at around 118 Ma and 85 Ma, and a third group records Paleocene volcanic activity (63-58 Ma) in the Nam Co area. The low-temperature thermochronometers indicate common age groups for the entire Nam Co area: zircon (U-Th)/He ages cluster around 75 Ma, apatite fission track ages around 60 Ma and apatite (U-Th)/He ages around 50 Ma. Modelling of the thermochronological data indicates that exhumation of the basement blocks took place in latest Cretaceous to earliest Paleogene time. By Middle Eocene time the relief was already flat, documented by a thin alluvial sediment sequence covering a part of the planated area. The present-day horst and graben structure of the peneplains is a Late Cenozoic feature triggered by E-W extension of the Tibetan Plateau. The new thermochronological data precisely bracket the age of the planation to Early Eocene, i.e. between ca. 55 and 45 Ma. The erosional base level can be deduced from the presence of Early Cretaceous zircon grains in Eocene strata of Bengal Basin. The sediment generated during exhumation of the Nam Co area was transported by an Early Cenozoic river system into the ocean, suggesting that planation occurred at low elevation.

  17. Early origins of asthma (and allergy).

    PubMed

    Kabesch, Michael

    2016-12-01

    Asthma is the most common chronic disease starting in childhood and persisting into adulthood in many cases. During childhood, different forms of asthma and wheezing disorders exist that can be discriminated by the mechanisms they are caused by. Specific genetic constellations and exposure against environmental factors during early childhood and in utero play a decisive role in the early development of the disease. Epigenetic mechanisms which are master regulators of gene transcription and thus govern the accessibility and use of genome information, have recently been identified as a "third power" determining many features in the early development of asthma and allergy. PMID:27510897

  18. Upper mantle structure under western Saudi Arabia from Rayleigh wave tomography and the origin of Cenozoic uplift and volcanism on the Arabian Shield

    SciTech Connect

    Park, Y; Nyblade, A; Rodgers, A; Al-Amri, A

    2007-11-09

    The shear velocity structure of the shallow upper mantle beneath the Arabian Shield has been modeled by inverting new Rayleigh wave phase velocity measurements between 45 and 140 s together with previously published Rayleigh wave group velocity measurement between 10 and 45 s. For measuring phase velocities, we applied a modified array method that minimizes the distortion of raypaths by lateral heterogeneity. The new shear velocity model shows a broad low velocity region in the lithospheric mantle across the Shield and a low velocity region at depths {ge} 150 km localized along the Red Sea coast and Makkah-Madinah-Nafud (MMN) volcanic line. The velocity reduction in the upper mantle corresponds to a temperature anomaly of {approx}250-330 K. These finding, in particular the region of continuous low velocities along the Red Sea and MMN volcanic line, do not support interpretations for the origin of the Cenozoic plateau uplift and volcanism on the Shield invoking two separate plumes. When combined with images of the 410 and 660 km discontinuities beneath the southern part of the Arabian Shield, body wave tomographic models, a S-wave polarization analysis, and SKS splitting results, our new model supports an interpretation invoking a thermal upwelling of warm mantle rock originating in the lower mantle under Africa that crosses through the transition zone beneath Ethiopia and moves to the north and northwest under the eastern margin of the Red Sea and the Arabian Shield. In this interpretation, the difference in mean elevation between the Platform and Shield can be attributed to isostatic uplift caused by heating of the lithospheric mantle under the Shield, with significantly higher region along the Red Sea possibly resulting from a combination of lithosphere thinning and dynamic uplift.

  19. Origin of the oceanic basalt basement of the Solomon Islands arc and its relationship to the Ontong Java Plateau-insights from Cenozoic plate motion models

    USGS Publications Warehouse

    Wells, R.E.

    1989-01-01

    Cenozoic global plate motion models based on a hotspot reference frame may provide a useful framework for analyzing the tectonic evolution of the Solomon Islands convergent margin. A postulated late Miocene collision of the Ontong Java Plateau (OJP) with a NE-facing arc is consistent with the predicted path of the OJP across the Pacific Basin and its Miocene arrival at the trench. Late-stage igneous activity (65-30 Ma) predicted for the OJP as it rode over the Samoan hotspot occurred in correlative stratigraphic sections on Malaita, the supposed accreted flake of OJP in the Solomon Islands arc. Convergence similar to the present velocities between Australia and the Pacific plates was characteristic of the last 43 million years. Prior to 43 Ma Pacific-Australia plate motions were divergent, seemingly at odds with geologic evidence for early Tertiary convergence, particularly in Papua New Guinea. A postulated South Pacific plate may have existed between Australia and the Pacific plate and would have allowed implied northward subduction along the northeastern Australia plate boundary that lasted into the early Eocene. Subsequent reorganization of plate motions in the middle Eocene correlates with middle Eocene marginal basin formation along ridges oblique to the main plate boundary. Cessation of spreading on the Pacific-South Pacific Ridge and its subsequent subduction beneath Asia followed the change in Pacific plate motion at 43 Ma. A trapped remnant of the extinct, NW-trending ridge may still lie beneath the western Philippine Sea. The terminal deformation, metamorphism and ophiolite obduction in the Eocene orogen of the southwest Pacific also correlates with the major change in Pacific plate motion at 43 Ma and the subsequent compression of the dying Eocene arc against outlying continental and oceanic crustal blocks of the Australian plate. The Solomon Islands oceanic basement may represent juxtaposition of oceanic plateaus of the Australian plate beneath

  20. Early origin of adult renal disease.

    PubMed

    Maringhini, Silvio; Corrado, Ciro; Maringhini, Guido; Cusumano, Rosa; Azzolina, Vitalba; Leone, Francesco

    2010-10-01

    Observational studies in humans and experimental studies in animals have clearly shown that renal failure may start early in life. 'Fetal programming' is regulated by adaptations occurring in uterus including maternal nutrition, placental blood supply, and epigenetic changes. Low birth weight predisposes to hypertension and renal insufficiency. Congenital abnormalities of the kidney and urinary tract, adverse postnatal events, wrong nutritional habits may produce renal damage that will become clinically relevant in adulthood. Prevention should start early in children at risk of renal disease. PMID:20822331

  1. Origin and early evolution of land plants

    PubMed Central

    2008-01-01

    The origin of the sporophyte in land plants represents a fundamental phase in plant evolution. Today this subject is controversial, and scarcely considered in textbooks and journals of botany, in spite of its importance. There are two conflicting theories concerning the origin of the alternating generations in land-plants: the “antithetic” theory and the “homologous” theory. These have never been fully resolved, although, on the ground of the evidences on the probable ancestors of land plants, the antithetic theory is considered more plausible than the homologous theory. However, additional phylogenetic dilemmas are the evolution of bryophytes from algae and the transition from these first land plants to the pteridophytes. All these very large evolutionary jumps are discussed on the basis of the phyletic gradualist neo-Darwinian theory and other genetic evolutionary mechanisms. PMID:19513262

  2. Origin and early evolution of photosynthesis

    NASA Technical Reports Server (NTRS)

    Blankenship, R. E.

    1992-01-01

    Photosynthesis was well-established on the earth at least 3.5 thousand million years ago, and it is widely believed that these ancient organisms had similar metabolic capabilities to modern cyanobacteria. This requires that development of two photosystems and the oxygen evolution capability occurred very early in the earth's history, and that a presumed phase of evolution involving non-oxygen evolving photosynthetic organisms took place even earlier. The evolutionary relationships of the reaction center complexes found in all the classes of currently existing organisms have been analyzed using sequence analysis and biophysical measurements. The results indicate that all reaction centers fall into two basic groups, those with pheophytin and a pair of quinones as early acceptors, and those with iron sulfur clusters as early acceptors. No simple linear branching evolutionary scheme can account for the distribution patterns of reaction centers in existing photosynthetic organisms, and lateral transfer of genetic information is considered as a likely possibility. Possible scenarios for the development of primitive reaction centers into the heterodimeric protein structures found in existing reaction centers and for the development of organisms with two linked photosystems are presented.

  3. The origin and early evolution of roots.

    PubMed

    Kenrick, Paul; Strullu-Derrien, Christine

    2014-10-01

    Geological sites of exceptional fossil preservation are becoming a focus of research on root evolution because they retain edaphic and ecological context, and the remains of plant soft tissues are preserved in some. New information is emerging on the origins of rooting systems, their interactions with fungi, and their nature and diversity in the earliest forest ecosystems. Remarkably well-preserved fossils prove that mycorrhizal symbionts were diverse in simple rhizoid-based systems. Roots evolved in a piecemeal fashion and independently in several major clades through the Devonian Period (416 to 360 million years ago), rapidly extending functionality and complexity. Evidence from extinct arborescent clades indicates that polar auxin transport was recruited independently in several to regulate wood and root development. The broader impact of root evolution on the geochemical carbon cycle is a developing area and one in which the interests of the plant physiologist intersect with those of the geochemist. PMID:25187527

  4. 1. Photocopy of an early etching (Original in collection of ...

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

    1. Photocopy of an early etching (Original in collection of the Historical Society of Montana) BROADWAY AND JACKSON ELEVATIONS - Second Masonic Temple, Broadway & Jackson Streets, Helena, Lewis and Clark County, MT

  5. Phenocryst He-Ar isotopic and whole-rock geochemical constraints on the origin of crustal components in the mantle source of Cenozoic continental basalt in eastern China

    NASA Astrophysics Data System (ADS)

    Xu, Zheng; Zheng, Yong-Fei; He, Huai-Yu; Zhao, Zi-Fu

    2014-02-01

    Continental basalts commonly exhibit similar geochemical compositions to oceanic island basalts, but their origin is still enigmatic in chemical geodynamics. This involves a resolution to the nature of crustal components in their mantle sources. For this purpose, we have studied the He and Ar isotopic compositions of mineral phenocrysts from Cenozoic continental basalts in eastern China. The results are combined with existing data for whole-rock geochemistry, yielding two trends between noble gas isotopic and other geochemical indicators. First is high 3He/4He ratios of 6.6 to 7.5 RA and low 4He/40Ar* ratios of 0.07 to 1.39 in association with varying (La/Yb)N values from 10.4 to 31.8. Second is low 3He/4He ratios of 0.6 to 2.4 RA and variable 4He/40Ar* ratios from 0.68 to 15.47 in association with low (La/Yb)N values of 11.3 to 12.0. Phenocryst 40Ar/36Ar ratios vary from 331.0 to 1677.4, in which the low ratios are associated with the low (La/Yb)N values. In combination with whole-rock Ba/Th and Sr/Y ratios as well as initial Sr and Nd isotopic ratios, we suggest three-component mixing between enriched MORB mantle, altered oceanic basalt and seafloor sediment to generate the mantle sources. The two kinds of crustal components would be incorporated into the mantle sources in the form of felsic melts. One is adakitic melt deriving from the altered oceanic basalt and thus low in Ba/Th ratios but high in Sr/Y, (La/Yb)N and εNd(t) values. The other is sialic melt originating from the seafloor sediment and thus high in Ba/Th ratios but low in Sr/Y, (La/Yb)N and εNd(t) values. The atmospheric Ar and crustal He noble gas components would be carried by the both seawater-hydrothermally altered basalt and seafloor sediment on the oceanic crust. These oceanic crust-derived melts would serve as a metasomatic agent to transfer the supracrustal He and Ar isotopic signatures to the mantle sources. The felsic melts would react with the mantle wedge peridotite during slab

  6. The Armorican Massif (Western France) - A buried relief two times exhumed in response to Iberia-Eurasia movements (Early Cretaceous, base of Cenozoic)

    NASA Astrophysics Data System (ADS)

    Bessin, Paul; Guillocheau, François; Robin, Cécile; Bauer, Hugues; Schroëtter, Jean-Michel

    2014-05-01

    The Armorican Massif is an outcropping Variscan basement located in Western France. The age of its exhumation is debated, as most of the outcropping European basements: Is this relief a remnant of the planation of the Variscan Belt or a buried and then exhumed relief at time of the North-Atlantic (Biscay Bay) opening during Early Cretaceous or/and during the Africa-Eurasia convergence? We performed a geomorphological study (based on DEM analysis and field controls) of the different landforms of the Armorican Massif. The dating of those relief forms is based on their geometrical relationships with the weatherings and dated preserved sediments. Our results allow to propose a model of evolution of the Armorican Massif and of its relief for the Mesozoic to Cenozoic period and underscore four main points: (1) The Armorican relief preserved old landforms - planation surfaces (mainly pediments and pediplains) - of Triassic (?) to Early Cretaceous age buried by Jurassic and Upper Cretaceous (chalk) carbonate platforms. (2) Those paleo-landforms were exhumed at two periods (i) Early Cretaceous in response to the opening of the Biscay Bay and (ii) Upermost Cretaceous-Paleocene at time of the Iberia-Eurasia increasing of convergence. (3) A major planation surface - called the Armorican Surface - result from the Early Cretaceous physical and chemical (laterite) erosion when the Armorican Massif was the North rift shoulder of the Biscay Bay. This planation surface is later deformed (buckling?) and eroded during Uppermost Cretaceous and Paleocene. (4) During Paleogene times, a last generation of pediments is shaped and then flooded by the Mid-Miocene eustatic sea-level rise. (5) The Armorican relief and landforms is later incised by rivers, (i) during Upper Miocene to Pliocene and (ii) at the Early to Middle Pleistocene transition with the incision of the present-day valleys in both response to uplift (Apulia-Eurasia convergence) and climate (precipitation) change.

  7. The Border Ranges fault system in Glacier Bay National Park, Alaska: Evidence for major early Cenozoic dextral strike-slip motion

    USGS Publications Warehouse

    Smart, K.J.; Pavlis, T.L.; Sisson, V.B.; Roeske, S.M.; Snee, L.W.

    1996-01-01

    The Border Ranges fault system of southern Alaska, the fundamental break between the arc basement and the forearc accretionary complex, is the boundary between the Peninsular-Alexander-Wrangellia terrane and the Chugach terrane. The fault system separates crystalline rocks of the Alexander terrane from metamorphic rocks of the Chugach terrane in Glacier Bay National Park. Mylonitic rocks in the zone record abundant evidence for dextral strike-slip motion along north-northwest-striking subvertical surfaces. Geochronologic data together with regional correlations of Chugach terrane rocks involved in the deformation constrain this movement between latest Cretaceous and Early Eocene (???50 Ma). These findings are in agreement with studies to the northwest and southeast along the Border Ranges fault system which show dextral strike-slip motion occurring between 58 and 50 Ma. Correlations between Glacier Bay plutons and rocks of similar ages elsewhere along the Border Ranges fault system suggest that as much as 700 km of dextral motion may have been accommodated by this structure. These observations are consistent with oblique convergence of the Kula plate during early Cenozoic and forearc slivering above an ancient subduction zone following late Mesozoic accretion of the Peninsular-Alexander-Wrangellia terrane to North America.

  8. Rate of Cenozoic explosive volcanism in the North Atlantic Ocean inferred from deep sea cores

    NASA Astrophysics Data System (ADS)

    Donn, W. L.; Ninkovich, D.

    1980-10-01

    On the basis of all available piston and DSDP cores taken from the seafloor around Iceland an attempt is made to establish a history of major explosive North Atlantic Cenozoic volcanism from the distribution of volcanic ash layers. The earliest sediment reached is early Eocene. After interpolating for missing data and correcting for effects of prevailing winds and regional plate tectonics, the analysis provides an estimate of the rate of explosive Cenozoic volcanism. Two epochs appear outstanding in rates of volcanism; middle Eocene shows the highest rate, and Pliocene, next highest, has about half the Eocene rate. These are followed in decreasing order by Pleistocene, Miocene, and Oligocene. The analysis further suggests that the Cenozoic ash layers originated in subaerial volcanism related to the growth of Iceland.

  9. Early to Late Cenozoic structural inheritance of Paleozoic basement structures in the northern Alpine foreland: examples from eastern France and northern Switzerland

    NASA Astrophysics Data System (ADS)

    Madritsch, Herfried

    2014-05-01

    During his time at the Geological Institute of the University of Basel, Peter Ziegler was the main initiator of the EUCOR-URGENT project, a joint multi-disciplinary research and training programme aiming at a better understanding of seismic hazard, neotectonics and evolution of the Upper Rhine Graben and surrounding areas. Throughout the duration of the programme from 1999 to 2007 the EUCOR-URGENT network embraced more than 40 Ph.D. students, 20 Post-Docs and 18 senior researchers, who were based at one of the 25 involved universities or national organizations. Peter's natural drive, networking capabilities and scientific enthusiasm were without doubt the main reasons for this success story. The Rhine-Bresse Transfer Zone (RBTZ) in eastern France, one of the natural laboratories investigated within the EUCOR-URGENT framework, is a major segment of the European Cenozoic Rift system (Ziegler, 1992) and formed by structural inheritance of the pre-existing Late Paleozoic Burgundy Trough. The Mid-Eocene to Oligocene evolution of the sinistral transtensional RBTZ was kinematically linked to crustal extension across the Upper Rhine and Bresse Grabens (Lacombe et al., 1993). From the Early Miocene onward the RBTZ further evolved under the influence of the far field effects of the Alpine collision involving Late Miocene to Pliocene NW-ward propagation of the thin-skinned Jura Thrust Belt but also thick-skinned reactivation of the Late Paleozoic and Paleogene fault systems in the RBTZ. In fact, shortening throughout the RBTZ appears to be still mildly active, as is indicated by one of the very few clearly oblique-compressive focal mechanisms in the northern Alpine foreland and evidenced by geomorphologic investigations that yielded Late Quaternary folding of fluvial meanders in the area of Besançon (Madritsch et al. 2010). The Late Paleozoic Burgundy Trough as well as the Jura Thrust Belt continue eastward into northern Switzerland. In this area, reprocessed and newly

  10. Overview of ophiolites and related units in the Late Palaeozoic-Early Cenozoic magmatic and tectonic development of Tethys in the northern part of the Balkan region

    NASA Astrophysics Data System (ADS)

    Robertson, Alastair; Karamata, Stevan; Šarić, Kristina

    2009-03-01

    Vardar zone. The Dinaride ocean in the south closed during Late Jurassic-Early Cretaceous time (Tithonian-Berriasian). Deformed oceanic crust, melange and magmatic arc rocks further north (Main Vardar zone) were transgressed by mainly clastic sediments during the Early Cretaceous. However, part of the Vardar ocean (Vardar zone western belt, or Sava zone) remained partially open until latest Cretaceous time. Generally northward subduction within this remnant ocean triggered further supra-subduction zone ophiolite genesis during the Late Cretaceous. The ocean closed by the Maastrichtian, followed by Early Cenozoic regional-scale southward thrusting that locally intercalated older and younger Mesozoic ophiolites and melanges. Future progress particularly depends on determining the crystallisation ages of the ophiolites, obtaining better structural data on the direction of initial ophiolite emplacement and unravelling the Palaeozoic tectonic development of the Eurasian continental margin.

  11. Early origin of parental care in Mesozoic carrion beetles

    PubMed Central

    Cai, Chen-Yang; Thayer, Margaret K.; Engel, Michael S.; Newton, Alfred F.; Ortega-Blanco, Jaime; Wang, Bo; Wang, Xiang-Dong; Huang, Di-Ying

    2014-01-01

    The reconstruction and timing of the early stages of social evolution, such as parental care, in the fossil record is a challenge, as these behaviors often do not leave concrete traces. One of the intensely investigated examples of modern parental care are the modern burying beetles (Silphidae: Nicrophorus), a lineage that includes notable endangered species. Here we report diverse transitional silphids from the Mesozoic of China and Myanmar that provide insights into the origins of parental care. Jurassic silphids from Daohugou, sharing many defining characters of Nicrophorinae, primitively lack stridulatory files significant for parental care communications; although morphologically similar, Early Cretaceous nicrophorines from the Jehol biota possess such files, indicating that a system of parental care had evolved by this early date. More importantly, burying beetles of the genus Nicrophorus have their earliest first record in mid-Cretaceous Burmese amber, and document early evolution of elaborate biparental care and defense of small vertebrate carcasses for their larvae. Parental care in the Early Cretaceous may have originated from competition between silphids and their predators. The rise of the Cretaceous Nicrophorinae implies a biology similar to modern counterparts that typically feed on carcasses of small birds and mammals. PMID:25225362

  12. The Origin of Dust in the Early Universe

    NASA Technical Reports Server (NTRS)

    Dwek, Eli

    2011-01-01

    In this talk I will describe the origin of dust in the early universe. I will be presenting observations of the spectral energy distribution of the galaxy J1148+5251, and present estimates of the dust mass in this high redshift (z=6.4) object. I will then discuss the origin of this dust, and the role of SN and AGB stars as dust sources, and the effect of SNRs on the destruction of dust in the interstellar medium of this galaxy.

  13. The Origin of Dust in the Early Universe

    NASA Technical Reports Server (NTRS)

    Dwek, Eliahu

    2010-01-01

    In this talk I will describe the origin of dust in the early universe. I will be presenting observations of the spectral energy distribution of the galaxy J1148+5251, and present estimates of the dust mass in this high redshift (z=6.4) object. I will then discuss the origin of this dust, and the role of SN and AGB stars as dust sources, and the effect of SNRs on the destruction of dust in the interstellar medium of this galaxy.

  14. An atmosphere-ocean GCM modelling study of the climate response to changing Arctic seaways in the early Cenozoic.

    NASA Astrophysics Data System (ADS)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2008-12-01

    The report of fossil Azolla (a freshwater aquatic fern) in sediments from the Lomonosov Ridge suggests low salinity conditions occurred in the Arctic Ocean in the early Eocene. Restricted passages between the Arctic Ocean and the surrounding oceans are hypothesized to have caused this Arctic freshening. We investigate this scenario using a water-isotope enabled atmosphere-ocean general circulation model with Eocene boundary conditions including 4xCO2, 7xCH4, altered bathymetry and topography, and an estimated distribution of Eocene vegetational types. In one experiment, oceanic exchange between the Arctic Ocean and other ocean basins was restricted to two shallow (~250 m) seaways, one in the North Atlantic, the Greenland-Norwegian seaway, and the second connecting the Arctic Ocean with the Tethys Ocean, the Turgai Straits. In the restricted configuration, the Greenland-Norwegian seaway was closed and exchange through the Turgai Straits was limited to a depth of ~60 m. The simulations suggest that the severe restriction of Arctic seaways in the early Eocene may have been sufficient to freshen Arctic Ocean surface waters, conducive to Azolla blooms. When exchange with the Arctic Ocean is limited, salinities in the upper several hundred meters of the water column decrease by ~10 psu. In some regions, surface salinity is within 2-3 psu of the reported maximum modern conditions tolerated by Azolla (~5 psu). In the restricted scenario, salt is stored preferentially in the North Atlantic and Tethys oceans, resulting in enhanced meridional overturning, increased poleward heat transport in the North Atlantic western boundary current, and warming of surface and intermediate waters in the North Atlantic by several degrees. Increased sensible and latent heat fluxes from the North Atlantic Ocean, combined with a reduction in cloud albedo, also lead to an increase in surface air temperature of over much of North America, Greenland and Eurasia. Our work is consistent with

  15. Epigenetics and early life origins of chronic noncommunicable diseases.

    PubMed

    Wang, Guoying; Walker, Sheila O; Hong, Xiumei; Bartell, Tami R; Wang, Xiaobin

    2013-02-01

    In light of the increasing threats of chronic noncommunicable diseases in developing countries, the growing recognition of the early life origins of chronic disease, and innovative breakthroughs in biomedical research and technology, it is imperative that we harness cutting-edge data to improve health promotion and maintenance. It is well recognized that chronic diseases are complex traits affected by a wide range of environmental and genetic factors; however, the role of epigenetic factors, particularly with regard to early life origins, remains largely unexplored. Given the unique properties of the epigenome-functionality during critical time windows, such as the intrauterine period, heritability, and reversibility-enhancing our understanding of epigenetic mechanisms may offer new opportunities for the development of novel early prediction and prevention paradigms. This may present an unparalleled opportunity to offer maternal and child health professionals important tools with the translational value to predict, detect, and prevent disease at an early age, long before its clinical occurrence, and as such, break lifelong and transgenerational cycles of disease. In doing so, modern technology can be leveraged to make great contributions to population health, quality of life, and reducing the burdensome economic costs of noncommunicable diseases in developing countries. PMID:23332566

  16. The origin of Cenozoic basalts from central Inner Mongolia, East China: The consequence of recent mantle metasomatism genetically associated with seismically observed paleo-Pacific slab in the mantle transition zone

    NASA Astrophysics Data System (ADS)

    Guo, Pengyuan; Niu, Yaoling; Sun, Pu; Ye, Lei; Liu, Jinju; Zhang, Yu; Feng, Yue-xing; Zhao, Jian-xin

    2016-01-01

    We present new major element, trace element and Sr-Nd-Hf isotope data on Cenozoic basalts from central Inner Mongolia (CIM) in eastern China to study the origin of the incompatible-element enriched component in these basalts by testing whether or not the paleo-Pacific plate lying in the mantle transition zone beneath eastern China is the immediate cause. The Cenozoic CIM basalts have a large variation in major element, trace element and isotope compositions. Fractional crystallization of olivine and clinopyroxene can readily explain much of the major element compositional variation, while trace element and isotope ratio variation largely reflect source heterogeneities and source histories. The variably low 87Sr/86Sr, high εNd, high εHf and elevated ratios of high field strength element over large ion lithophile element (HFSE/LILE, e.g., Nb/U, Nb/La) indicate that the CIM basalts are of asthenospheric origin, which is characterized by mixing between DMM and EM1. However, the CIM basalts are enriched in incompatible elements and enriched in the progressively more incompatible elements (e.g., variably high [La/Sm]N = 1.66-3.38), suggesting that the magma source(s) must have been enriched prior to the major episode of the magmatism. Participation of subducted ocean crust in the mantle source region of these basalts is recognized, but cannot be the major source material because the subducted ocean crust is expectedly too depleted in incompatible elements (e.g., [La/Sm]N ≪ 1) to produce magmas highly enriched in incompatible elements with [La/Sm]N ≫ 1. With the new data, we consider that low mass fraction (low-F) melt metasomatism in the seismic low velocity zone (LVZ) beneath eastern China as the most likely process to generate incompatible-element enriched source(s) for mantle melts parental to the Cenozoic CIM basalts. The low-F metasomatic agent most likely resulted from dehydration melting of the transition-zone paleo-Pacific slab, which has been taking place

  17. Magnetostratigraphy of the Lowermost Paleocene Fort Union Formation in the Williston Basin of North Dakota: Base of a Terrestrial Reference Section for Early Cenozoic Global Change

    NASA Astrophysics Data System (ADS)

    Peppe, D. J.; Evans, D. D.

    2006-05-01

    lead to more accurate and detailed correlations of the terrestrial and marine climate records through the early Cenozoic.

  18. The origin and early evolution of life on earth

    NASA Technical Reports Server (NTRS)

    Oro, J.; Miller, Stanley L.; Lazcano, Antonio

    1990-01-01

    Results of the studies that have provided insights into the cosmic and primitive earth environments are reviewed with emphasis on those environments in which life is thought to have originated. The evidence bearing on the antiquity of life on the earth and the prebiotic significance of organic compounds found in interstellar clouds and in primitive solar-system bodies such as comets, dark asteroids, and carbonaceous chondrites are assessed. The environmental models of the Hadean and early Archean earth are discussed, as well as the prebiotic formation of organic monomers and polymers essential to life. The processes that may have led to the appearance in the Archean of the first cells are considered, and possible effects of these processes on the early steps of biological evolution are analyzed. The significance of these results to the study of the distribution of life in the universe is evaluated.

  19. The Origin, Early History and Diversification of Lepidosauromorph Reptiles

    NASA Astrophysics Data System (ADS)

    Evans, Susan E.; Jones, Marc E. H.

    The reptilian group Lepidosauria diversified through the Mesozoic, survived the end-Cretaceous extinction relatively unscathed, and has more than 7,000 living species. Although originally constituted as a "waste-bin" for non-archosaurian diapsids, modern definitions limit Lepidosauria to its two constituent groups, Rhynchocephalia and Squamata, and their most recent common ancestor. To date, the earliest known lepidosaurs are from the Late Triassic (Carnian) of Europe and India, but their derived morphology provides indirect evidence of a longer, unrecorded, history. Rhynchocephalians and squamates probably diverged in the Early-Middle Triassic, and new material from the Early Triassic of Poland sheds some light on their common ancestor. The roots of Lepidosauria may extend into the Palaeozoic, but there are critical gaps in the fossil record.

  20. Evolutionary origin and early biogeography of otophysan fishes (Ostariophysi: Teleostei).

    PubMed

    Chen, Wei-Jen; Lavoué, Sébastien; Mayden, Richard L

    2013-08-01

    The biogeography of the mega-diverse, freshwater, and globally distributed Otophysi has received considerable attention. This attraction largely stems from assumptions as to their ancient origin, the clade being almost exclusively freshwater, and their suitability as to explanations of trans-oceanic distributions. Despite multiple hypotheses explaining present-day distributions, problems remain, precluding more parsimonious explanations. Underlying previous hypotheses are alternative phylogenies for Otophysi, uncertainties as to temporal diversification and assumptions integral to various explanations. We reexamine the origin and early diversification of this clade based on a comprehensive time-calibrated, molecular-based phylogenetic analysis and event-based approaches for ancestral range inference of lineages. Our results do not corroborate current phylogenetic classifications of otophysans. We demonstrate Siluriformes are never sister to Gymnotiformes and Characiformes are most likely nonmonophyletic. Divergence time estimates specify a split between Cypriniformes and Characiphysi with the fragmentation of Pangea. The early diversification of characiphysans either predated, or was contemporary with, the separation of Africa and South America, and involved a combination of within- and between-continental divergence events for these lineages. The intercontinental diversification of siluroids and characoids postdated major intercontinental tectonic fragmentations (<90 Mya). Post-tectonic drift dispersal events are hypothesized to account for their current distribution patterns. PMID:23888847

  1. Early and multiple origins of metastatic lineages within primary tumors.

    PubMed

    Zhao, Zi-Ming; Zhao, Bixiao; Bai, Yalai; Iamarino, Atila; Gaffney, Stephen G; Schlessinger, Joseph; Lifton, Richard P; Rimm, David L; Townsend, Jeffrey P

    2016-02-23

    Many aspects of the evolutionary process of tumorigenesis that are fundamental to cancer biology and targeted treatment have been challenging to reveal, such as the divergence times and genetic clonality of metastatic lineages. To address these challenges, we performed tumor phylogenetics using molecular evolutionary models, reconstructed ancestral states of somatic mutations, and inferred cancer chronograms to yield three conclusions. First, in contrast to a linear model of cancer progression, metastases can originate from divergent lineages within primary tumors. Evolved genetic changes in cancer lineages likely affect only the proclivity toward metastasis. Single genetic changes are unlikely to be necessary or sufficient for metastasis. Second, metastatic lineages can arise early in tumor development, sometimes long before diagnosis. The early genetic divergence of some metastatic lineages directs attention toward research on driver genes that are mutated early in cancer evolution. Last, the temporal order of occurrence of driver mutations can be inferred from phylogenetic analysis of cancer chronograms, guiding development of targeted therapeutics effective against primary tumors and metastases. PMID:26858460

  2. A new integrated tectonic model for the Mesozoic-Early Cenozoic subduction, spreading, accretion and collision history of Tethys adjacent to the southern margin of Eurasia (NE Turkey)

    NASA Astrophysics Data System (ADS)

    Robertson, Alastair; Parlak, Osman; Ustaömer, Timur; Taslı, Kemal; İnan, Nurdan; Dumitrica, Paulian; Karaoǧlan, Fatih

    2014-05-01

    A major Tethyan suture zone (İzmir-Ankara-Erzincan-Kars Suture Zone) borders the southern margin of Eurasia throughout the Pontides. In eastern Turkey the suture zone includes a range of redeposited terrigenous and volcanogenic sedimentary rocks, pelagic sedimentary rocks and also igneous/metamorphic rocks. The igneous rocks are mostly basaltic blocks and thrust sheets within melange, plus relatively intact, to dismembered, ophiolitic rocks (oceanic crust). Two alternative hypotheses have been developed and tested during this work: 1. The suture zone preserves a single Andean-type active continental margin associated with northward subduction, accretion and arc magmatism during Mesozoic-early Cenozoic time; 2. The suture zone preserves the remnants of two different subduction zones, namely a continental margin subduction zone (as above) and an intra-ocean subduction zone (preferred model). To determine the age of the oceanic crust, relevant to both hypotheses, zircons were extracted from basic ophiolitic rocks (both intact and dismembered) and dated by the U/Pb method (U238/U236) using an ion probe at Edinburgh University. This yielded the following results for the intact ophiolites (Ma): plagiogranite cutting sheeted dykes of the Refahiye ophiolite (east of Erzincan), 183.6±1.7 (2σ); isotropic gabbro from the Karadaǧ ophiolite (northeast of Erzurum), 179.4±1.7 (2σ). In addition, dismembered ophiolites gave the following ages: gabbro cumulate (Bayburt area), 186.2±1.4 (2σ), gabbro cumulate (N of Horasan), 178.1±1.8 (2σ). Furthermore, two samples from a kilometre-sized (arc-related) tonalite body, mapped as cutting a thrust sheet of ophiolitic isotropic gabbro in the Kırdaǧ area, yielded ages of 182.1±3.2 (2σ) and 185.1±3.0 (2σ) Ma. We infer that the ophiolitic and related magmatic arc rocks formed by spreading in a supra-subduction zone setting during the late Early Jurassic (Pliensbachian-Toarcian). This amends former assumptions of a Late

  3. The Origin of Dwarf Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Toloba, Elisa

    2012-10-01

    Abridge. We have conducted a spectrophotometric study of dwarf early-type galaxies (dEs) in the Virgo cluster and in regions of lower density. We have found that these galaxies show many properties in common with late-type galaxies but not with more massive early-types (E/S0). The properties of the dEs in Virgo show gradients within the cluster. dEs in the outer parts of the Virgo cluster are kinematically supported by rotation, while those in the center are supported by the random motions of their stars (i.e. pressure supported). The rotationally supported dEs have disky isophotes and faint underlying spiral/irregular substructures, they also show younger ages than those pressure supported, which have boxy isophotes and are smooth and regular, without any substructure. We compare the position of these dEs with massive early-type galaxies in the Faber-Jackson and Fundamental Plane relations, and we find that, although there is no difference between the position of rotationally and pressure supported dEs, both deviate from the relations of massive early-type galaxies in the direction of dwarf spheroidal systems (dSphs). We have used their offset with respect to the Fundamental Plane of E/S0 galaxies to estimate their dark matter fraction. All the properties studied in this work agree with a ram pressure stripping scenario, where late-type galaxies infall into the cluster, their interaction with the intergalactic medium blows away their gas and, as a result, they are quenched in a small amount of time. However, those dEs in the center of the cluster seem to have been fully transformed leaving no trace of their possible spiral origin, thus, if that is the case, they must have experienced a more violent mechanism in combination with ram pressure stripping.

  4. The Early Earth vs. the Origin of Life

    NASA Astrophysics Data System (ADS)

    Shock, E. L.; Amend, J. P.; Zolotov, M. Y.

    Irrefutable evidence on how life originated does not exist. Hypotheses regarding its origin, however, are plentiful. Those that have prevailed for most of this century require an atmosphere dominated by ammonia (NH3) and methane (CH4), organic synthesis driven by energy sources that are external to the hydrosphere/lithosphere, and a first organism that makes its living by consuming the resulting supply of organic compounds. Diverse lines of evidence have been amassed over the last several decades that refute these particular origin of life hypotheses. For example, geologic evidence, atmospheric photochemistry, and current constraints on the formation of terrestrial planets indicate that a plausible early atmosphere was not dominated by NH3 and CH4, but rather by nitrogen (N2) and carbon dioxide (CO2). In addition, the location, duration, and quantity of external energy sources are not particularly predictable or reliable, and are not generally effective in driving the reduction reactions required to make organic compounds from N2 and CO2. Finally, revolutions in molecular biology have led to the observation that organisms that synthesize biomass from inorganic starting materials like CO2 populate the deepest and shortest branches on the universal phylogenetic tree of life on Earth. These fundamental developments have permitted new and more geologically consistent ideas about the emergence of life. We argue that plausible hypotheses of the emergence of life on Earth call for a network of energetically favorable gradual synthesis processes in response to normal geologic forces. Inescapable chemical disequilibrium states, established and at least partially maintained in the hydrosphere at or near the dynamic surface of early Earth, can provide the energy for organic and biomolecule synthesis from inorganic source materials. Geologic conditions conducive to the formation of aqueous organic compounds, including precursors to complex biopolymers such as nucleic acids and

  5. The origin and early phylogenetic history of jawed vertebrates

    PubMed Central

    Brazeau, Martin D.; Friedman, Matt

    2015-01-01

    The focus of study for nearly two centuries1, fossils of early gnathostomes—or jawed vertebrates—yield key clues about the evolutionary assembly of the bodyplan common to the group, as well the divergence of the two living gnathostome lineages: the cartilaginous and bony fishes2,3. A series of remarkable new palaeontological discoveries4-10, analytical advances and innovative reinterpretations of old fossils11-14 have fundamentally altered a decades-old consensus on the relationships of extinct gnathostomes15,16, delivering a new evolutionary framework3,6,10-14 for exploring major questions which remain unanswered, including the origin of jaws17-19. PMID:25903631

  6. Early Archean Spherule Beds-Confirmation of Impact Origin

    NASA Technical Reports Server (NTRS)

    Shukolyukov, A.; Kyte, F. T.; Lugmair, G. W.; Lowe, D. R.; Byerly, G. R.

    2000-01-01

    The oldest record of major impact events on Earth may be a number of early Archean (3.5 to 3.2 Ga) spherule beds that have been identified in the Barberton Greenstone Belt, South Africa. Several field, petrographic, and geochemical criteria distinguish these beds from typical volcanic and clastic sediments. These criteria include the wide geographic distribution of two beds in a variety of depositional environments, the presence of relict quench textures, absence of juvenile volcaniclastic debris within the beds, and extreme enrichment of Ir and other platinum group elements (PGE) as compared to surrounding sediments. Some researchers, however, argued for a terrestrial origin for spherule bed formation, possibly related to volcanism and gold mineralization.

  7. The effect of mantle plume heads on the motion between the African and Antarctic plates in the Late Cretaceous and Early Cenozoic

    NASA Astrophysics Data System (ADS)

    Cande, S. C.; Patriat, P.

    2012-12-01

    Indo-Atlantic plate kinematics during the Late Cretaceous and Early Cenozoic were dominated by a period of roughly 25 million years during which the motions of India and Africa appear to have been coupled: a rapid speedup of India's absolute motion starting around 68 Ma was accompanied by a dramatic slowdown of Africa's absolute motion and the subsequent slowdown of India between 52 and 45 Ma was accompanied by a speedup of Africa. Cande and Stegman (2011) proposed that the coupled nature of these plate motions was caused by the arrival of the Reunion plume head at the Earth's surface: the speedup of India (slowdown of Africa) was due to the onset of the plume head, while the slowdown of India (speedup of Africa) was due to the waning of the plume head. This hypothesis is controversial since the slowdown of India has long been attributed to the initial collision of India with Eurasia and it is not clear how mantle plume heads affect plate motions. In order to better understand the cause of the coupled motions of India and Africa we have re-examined the motion of Africa relative to Antarctica as constrained by magnetic anomalies and fracture zones on the Southwest Indian Ridge (SWIR). The bends of the SWIR fracture zones contain a particularly important record of plate motion changes: a gradual ccw bend starting at Chron 32 is followed by a sharp cw bend at Chron 24. We present here a set of 13 revised rotations for the SWIR for the time interval from Chron 34 to Chron 18. These rotations quantify in more detail than in previous studies the changes recorded by the SWIR fracture zones. The onset of the ccw change in spreading direction and start of a rapid decrease in spreading rate on the SWIR occurs around Chron 32 (71 Ma). From Chron 32 to Chron 24 the motion between Africa and Antarctica is characterized by a continuous and apparently smooth migration of the Africa-Antarctic stage pole. The most dramatic change in motion along the SWIR is the sudden cw bend of

  8. The epilog of the western paleo-Pacific subduction: Inferred from spatial and temporal variations and geochemistry of the Late Cretaceous to Early Cenozoic silicic magmatism in coastal South China

    NASA Astrophysics Data System (ADS)

    Chen, Cheng-Hong; Lee, Chi-Yu; Shinjo, Ryuichi

    2016-01-01

    The Late Cretaceous to Early Cenozoic magmatism in the South China coastal area produced some amounts of rhyolitic rocks in two phases, which may be used to unravel the geohistory of the epilog of the paleo-Pacific plate subduction system. Essence of the Phase I rocks is the high temperature rhyolite (A-type)-trachydacite association in north Fujian (95-91 Ma) that was coeval with regional A-type granites. They succeeded the vast rhyolite-dacite-andesite (RDA) associations and I-type granitoids (113.5-96 Ma) and preceded the silicic-dominating rhyolite/basalt bimodal suites or monolithologic rhyolite in Zhejiang (89-86 Ma). Phase II rocks include (a) the RDA association or rhyolite alone in some drifted continental fragments nearby (83-56 Ma) and (b) the following rift-basin related rhyolite-trachyte/basalt bimodal suites in Guangdong and west Taiwan (56-38 Ma). The silicic volcanism, spatially changed from a NE-SW to the nearly E-W direction after 83 Ma, may reflect tectonic-driven eruptions occurred in the post-orogenic extensional (Phase I), resumed plate subducting (Phase IIa) and continental margin rifting (Phase IIb) stages. Rhyolitic rocks basically are shoshonitic to high-K calc-alkaline affinities while the Phase IIa RDA associations are mostly concentrated in the high-K to medium-K calc-alkaline series. All these rocks generally possess a continental arc character in tectonic discrimination diagrams, except shoshonitic rocks that have within-plate signatures. Based on the trace element and Nd-Pb isotope data, A-type rocks are suggested to have derived from mixing between trachydacitic (or syenitic) magmas and crustal melts of various sources under the high temperature condition (±metasomatism), and the succeeding silicic rocks are derivatives of the contaminated lithospheric mantle melts through crystal fractionation. On the other hand, Phase II silicic rocks are mainly the fractionation products of mafic magmas originated either from the lithospheric or

  9. Origins and Early Evolution of the tRNA Molecule

    PubMed Central

    Tamura, Koji

    2015-01-01

    Modern transfer RNAs (tRNAs) are composed of ~76 nucleotides and play an important role as “adaptor” molecules that mediate the translation of information from messenger RNAs (mRNAs). Many studies suggest that the contemporary full-length tRNA was formed by the ligation of half-sized hairpin-like RNAs. A minihelix (a coaxial stack of the acceptor stem on the T-stem of tRNA) can function both in aminoacylation by aminoacyl tRNA synthetases and in peptide bond formation on the ribosome, indicating that it may be a vestige of the ancestral tRNA. The universal CCA-3′ terminus of tRNA is also a typical characteristic of the molecule. “Why CCA?” is the fundamental unanswered question, but several findings give a comprehensive picture of its origin. Here, the origins and early evolution of tRNA are discussed in terms of various perspectives, including nucleotide ligation, chiral selectivity of amino acids, genetic code evolution, and the organization of the ribosomal peptidyl transferase center (PTC). The proto-tRNA molecules may have evolved not only as adaptors but also as contributors to the composition of the ribosome. PMID:26633518

  10. Origin of Bacteriochlorophyll a and the Early Diversification of Photosynthesis

    PubMed Central

    Cardona, Tanai

    2016-01-01

    Photosynthesis originated in the domain Bacteria billions of years ago; however, the identity of the last common ancestor to all phototrophic bacteria remains undetermined and speculative. Here I present the evolution of BchF or 3-vinyl-bacteriochlorophyll hydratase, an enzyme exclusively found in bacteria capable of synthetizing bacteriochlorophyll a. I show that BchF exists in two forms originating from an early divergence, one found in the phylum Chlorobi, including its paralogue BchV, and a second form that was ancestral to the enzyme found in the remaining anoxygenic phototrophic bacteria. The phylogeny of BchF is consistent with bacteriochlorophyll a evolving in an ancestral phototrophic bacterium that lived before the radiation event that gave rise to the phylum Chloroflexi, Chlorobi, Acidobacteria, Proteobacteria, and Gemmatimonadetes, but only after the divergence of Type I and Type II reaction centers. Consequently, it is suggested that the lack of phototrophy in many groups of extant bacteria is a derived trait. PMID:26953697

  11. Mechanical origins of rightward torsion in early chick brain development

    NASA Astrophysics Data System (ADS)

    Chen, Zi; Guo, Qiaohang; Dai, Eric; Taber, Larry

    2015-03-01

    During early development, the neural tube of the chick embryo undergoes a combination of progressive ventral bending and rightward torsion. This torsional deformation is one of the major organ-level left-right asymmetry events in development. Previous studies suggested that bending is mainly due to differential growth, however, the mechanism for torsion remains poorly understood. Since the heart almost always loops rightwards that the brain twists, researchers have speculated that heart looping affects the direction of brain torsion. However, direct evidence is lacking, nor is the mechanical origin of such torsion understood. In our study, experimental perturbations show that the bending and torsional deformations in the brain are coupled and that the vitelline membrane applies an external load necessary for torsion to occur. Moreover, the asymmetry of the looping heart gives rise to the chirality of the twisted brain. A computational model and a 3D printed physical model are employed to help interpret these findings. Our work clarifies the mechanical origins of brain torsion and the associated left-right asymmetry, and further reveals that the asymmetric development in one organ can induce the asymmetry of another developing organ through mechanics, reminiscent of D'Arcy Thompson's view of biological form as ``diagram of forces''. Z.C. is supported by the Society in Science - Branco Weiss fellowship, administered by ETH Zurich. L.A.T acknowledges the support from NIH Grants R01 GM075200 and R01 NS070918.

  12. Triassic origin and early radiation of multicellular volvocine algae

    PubMed Central

    Herron, Matthew D.; Hackett, Jeremiah D.; Aylward, Frank O.; Michod, Richard E.

    2009-01-01

    Evolutionary transitions in individuality (ETIs) underlie the watershed events in the history of life on Earth, including the origins of cells, eukaryotes, plants, animals, and fungi. Each of these events constitutes an increase in the level of complexity, as groups of individuals become individuals in their own right. Among the best-studied ETIs is the origin of multicellularity in the green alga Volvox, a model system for the evolution of multicellularity and cellular differentiation. Since its divergence from unicellular ancestors, Volvox has evolved into a highly integrated multicellular organism with cellular specialization, a complex developmental program, and a high degree of coordination among cells. Remarkably, all of these changes were previously thought to have occurred in the last 50–75 million years. Here we estimate divergence times using a multigene data set with multiple fossil calibrations and use these estimates to infer the times of developmental changes relevant to the evolution of multicellularity. Our results show that Volvox diverged from unicellular ancestors at least 200 million years ago. Two key innovations resulting from an early cycle of cooperation, conflict and conflict mediation led to a rapid integration and radiation of multicellular forms in this group. This is the only ETI for which a detailed timeline has been established, but multilevel selection theory predicts that similar changes must have occurred during other ETIs. PMID:19223580

  13. The Origin and Early Evolution of Membrane Channels

    NASA Astrophysics Data System (ADS)

    Pohorille, Andrew; Schweighofer, Karl; Wilson, Michael A.

    2005-02-01

    The origin and early evolution of ion channels are considered from the point of view that the transmembrane segments of membrane proteins are structurally quite simple and do not require specific sequences to fold. We argue that the transport of solute species, especially ions, required an early evolution of efficient transport mechanisms, and that the emergence of simple ion channels was protobiologically plausible. We also argue that, despite their simple structure, such channels could possess properties that, at the first sight, appear to require markedly greater complexity. These properties can be subtly modulated by local modifications to the sequence rather than global changes in molecular architecture. In order to address the evolution and development of ion channels, we focus on identifying those protein domains that are commonly associated with ion channel proteins and are conserved throughout the three main domains of life (Eukarya, Bacteria, and Archaea). We discuss the potassiumsodium- calcium superfamily of voltage-gated ion channels, mechanosensitive channels, porins, and ABC-transporters and argue that these families of membrane channels have sufficiently universal architectures that they can readily adapt to the diverse functional demands arising during evolution.

  14. The Origin and Early Evolution of Membrane Proteins

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Schweighofter, Karl; Wilson, Michael A.

    2006-01-01

    The origin and early evolution of membrane proteins, and in particular ion channels, are considered from the point of view that the transmembrane segments of membrane proteins are structurally quite simple and do not require specific sequences to fold. We argue that the transport of solute species, especially ions, required an early evolution of efficient transport mechanisms, and that the emergence of simple ion channels was protobiologically plausible. We also argue that, despite their simple structure, such channels could possess properties that, at the first sight, appear to require markedly larger complexity. These properties can be subtly modulated by local modifications to the sequence rather than global changes in molecular architecture. In order to address the evolution and development of ion channels, we focus on identifying those protein domains that are commonly associated with ion channel proteins and are conserved throughout the three main domains of life (Eukarya, Prokarya, and Archaea). We discuss the potassium-sodium-calcium superfamily of voltage-gated ion channels, mechanosensitive channels, porins, and ABC-transporters and argue that these families of membrane channels have sufficiently universal architectures that they can readily adapt to the diverse functional demands arising during evolution.

  15. The Origin and Early Evolution of Membrane Proteins

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Schweighofer, Karl; Wilson, Michael A.

    2005-01-01

    Membrane proteins mediate functions that are essential to all cells. These functions include transport of ions, nutrients and waste products across cell walls, capture of energy and its transduction into the form usable in chemical reactions, transmission of environmental signals to the interior of the cell, cellular growth and cell volume regulation. In the absence of membrane proteins, ancestors of cell (protocells), would have had only very limited capabilities to communicate with their environment. Thus, it is not surprising that membrane proteins are quite common even in simplest prokaryotic cells. Considering that contemporary membrane channels are large and complex, both structurally and functionally, a question arises how their presumably much simpler ancestors could have emerged, perform functions and diversify in early protobiological evolution. Remarkably, despite their overall complexity, structural motifs in membrane proteins are quite simple, with a-helices being most common. This suggests that these proteins might have evolved from simple building blocks. To explain how these blocks could have organized into functional structures, we performed large-scale, accurate computer simulations of folding peptides at a water-membrane interface, their insertion into the membrane, self-assembly into higher-order structures and function. The results of these simulations, combined with analysis of structural and functional experimental data led to the first integrated view of the origin and early evolution of membrane proteins.

  16. Cenozoic ice volume and margin erosion

    SciTech Connect

    Miller, K.C.; Fairbanks, R.G.; Mountain, G.S.

    1985-01-01

    Cenozoic benthic foraminiferal oxygen isotopic data indicates that the world was glaciated in the early Oligocene, middle Oligocene, latest Oligocene, and middle Miocene to Recent, but are insufficient to resolve if the world was ice free at other times. The authors relate Oligocene and younger intervals of ice growth to continental margin erosional events. Relationships between eustasy and continental margin sedimentation are controversial. Coastal onlap is indirectly linked with rising sea level, occurring either when subsidence exceeds the rate of sea level fall or during sea-level rise. Although chronostratigraphic breaks are often local in origin, inter-regional unconformities result from eustatic lowerings. Strong evidence for eustatic lowerings is provided by the incision of canyons on margins. Chronostratigraphic breaks and canyons have noted on the US and Irish margins near the lower/upper Oligocene and middle/upper Miocene boundaries. These periods of margin erosion are temporally linked with oxygen isotopic evidence for ice growth, with erosion correlating with the greatest rate of ice growth. If the Eocene was ice free, there may have been mechanistic differences between Eocene erosion and Oligocene to Recent glacio-eustatic erosion. The authors present seismic stratigraphic evidence from the New Jersey margin that indicates contrasting styles of margin erosion between the Lower Tertiary and Upper Tertiary.

  17. Major element, REE, and Pb, Nd and Sr isotopic geochemistry of Cenozoic volcanic rocks of eastern China: implications for their origin from suboceanic-type mantle reservoirs

    USGS Publications Warehouse

    Basu, A.R.; Wang, Junwen; Huang, Wankang; Xie, Guanghong; Tatsumoto, M.

    1991-01-01

    Major- and rare-earth-element (REE) concentrations and UThPb, SmNd, and RbSr isotope systematics are reported for Cenozoic volcanic rocks from northeastern and eastern China. These volcanic rocks, characteristically lacking the calc-alkaline suite of orogenic belts, were emplaced in a rift system which formed in response to the subduction of the western Pacific plate beneath the eastern Asiatic continental margin. The rocks sampled range from basanite and alkali olivine basalt, through olivine tholeiite and quartz tholeiite, to potassic basalts, alkali trachytes, pantellerite, and limburgite. These rock suites represent the volcanic centers of Datong, Hanobar, Kuandian, Changbaishan and Wudalianchi in northeastern China, and Mingxi in the Fujian Province of eastern China. The major-element and REE geochemistry is characteristic of each volcanic suite broadly evolving through cogenetic magmatic processes. Some of the outstanding features of the isotopic correlation arrays are as follows: (1) NdSr shows an anticorrelation within the field of ocean island basalts, extending from the MORB end-member to an enriched, time-averaged high Rb Sr and Nd Sr end-member (EM1), (2) SrPb also shows an anticorrelation, similar to that of Hawaiian and walvis Ridge basalts, (3) NdPb shows a positive correlation, and (4) the 207Pb 204Pb vs 206Pb 204Pb plot shows linear arrays parallel to the general trend (NHRL) for MORB on both sides of the geochron, although in the 208Pb 204Pb vs 206Pb 204Pb plot the linear array is significantly displaced above the NHRL in a pattern similar to that of the oceanic island basalts that show the Dupal signatures. In all isotope correlation patterns, the data arrays define two different mantle components-a MORB-like component and an enriched mantle component. The isotopic data presented here clearly demonstrate the existence of Dupal compositions in the sources of the continental volcanic rocks of eastern China. We suggest that the subcontinental mantle

  18. The origin of dwarf early-type galaxies

    NASA Astrophysics Data System (ADS)

    Toloba, E.

    2013-05-01

    We have conducted a spectrophotometric study of dwarf early-type galaxies (dEs) in the Virgo cluster and in regions of lower density. We have found that these galaxies show many properties in common with late-type galaxies but not with more massive early-types (E/S0). The properties of the dEs in Virgo show gradients within the cluster. dEs in the outer parts of the Virgo cluster are kinematically supported by rotation, while those in the center are supported by the random motions of their stars (i.e. pressure supported). The rotationally supported dEs have disky isophotes and faint underlying spiral/irregular substructures, they also show younger ages than those pressure supported, which have boxy isophotes and are smooth and regular, without any substructure. We compare the position of these dEs with massive early-type galaxies in the Faber-Jackson and Fundamental Plane relations, and we find that, although there is no difference between the position of rotationally and pressure supported dEs, both deviate from the relations of massive early-type galaxies in the direction of dwarf spheroidal systems (dSphs). We have used their offset with respect to the Fundamental Plane of E/S0 galaxies to estimate their dark matter fraction. All the properties studied in this work agree with a ram pressure stripping scenario, where late-type galaxies infall into the cluster, their interaction with the intergalactic medium blows away their gas and, as a result, they are quenched in a small amount of time. However, those dEs in the center of the cluster seem to have been fully transformed leaving no trace of their possible spiral origin, thus, if that is the case, they must have experienced a more violent mechanism in combination with ram pressure stripping, the open problem is that even galaxy harassment does not fully explain the observed properties for the pressure supported dEs in the center of the Virgo cluster.

  19. On the origin and early diagenesis of early Triassic carbonate mud (Dolomites, Italy)

    NASA Astrophysics Data System (ADS)

    Preto, Nereo; Westphal, Hildegard; Birgel, Daniel; Carampin, Raul; Dal Corso, Jacopo; Gattolin, Giovanni; Montinaro, Alice; Peckmann, Jörn

    2015-04-01

    The earliest Triassic (early Induan) deposits of the Italian Southern Alps are shallow water oolites, and lime-mudstone formed in an open shelf (mid to outer carbonate ramp) sedimentary environment, deposited after the end-Permian extinction that killed all carbonate producers. The origin of these lime-mudstones is thus enigmatic. We used a multidisciplinary petrographic and geochemical approach to identify the origin and early diagenesis of early Triassic lime-mudstones of the Dolomites (Northern Italy). This fine carbonate is made of pitted crystals of microsparite, ~ 25 μm in diameter, exhibiting zonation both in fluorescence and cathodoluminescence. Field and standard petrographic observations exclude an origin from fragmentation or abrasion of carbonate grains. Strontium content, measured in-situ with electron microprobe, has a bimodal distribution with values locally as high as > 4000 ppm. Lipid biomarker analysis revealed molecular fossils of bacteria (terminally-branched alkanes, hopanes, and scarce methylhopanes) along with compounds of low source specificity (n-alkanes), whereas biomarkers of algae (steranes) were not detected. This suggests that, differently from modern Caribbean shelfs, this fine carbonate did not originate from the disgregation of green algae. A Pristane to Phytane ratio < 1 also suggests deposition under anoxic conditions, in agreement with the known status of "superanoxia" of earliest Triassic oceans. Overall, our observations suggest an aragonitic mineralogy of the carbonate mud, followed by calcite replacement and cementation in the marine burial early diagenetic environment. Our data strongly suggest that the early Triassic carbonate mud of the Dolomites was precipitated in the water column, similarly to the modern whitings of the Bahamas, and then settled on a shelf bottom below wave base. Our study shows that these lime-mudstones contain aragonite replaced by calcite and calcite cement, in variable proportions. The δ13C of

  20. Marine ecosystem responses to Cenozoic global change.

    PubMed

    Norris, R D; Turner, S Kirtland; Hull, P M; Ridgwell, A

    2013-08-01

    The future impacts of anthropogenic global change on marine ecosystems are highly uncertain, but insights can be gained from past intervals of high atmospheric carbon dioxide partial pressure. The long-term geological record reveals an early Cenozoic warm climate that supported smaller polar ecosystems, few coral-algal reefs, expanded shallow-water platforms, longer food chains with less energy for top predators, and a less oxygenated ocean than today. The closest analogs for our likely future are climate transients, 10,000 to 200,000 years in duration, that occurred during the long early Cenozoic interval of elevated warmth. Although the future ocean will begin to resemble the past greenhouse world, it will retain elements of the present "icehouse" world long into the future. Changing temperatures and ocean acidification, together with rising sea level and shifts in ocean productivity, will keep marine ecosystems in a state of continuous change for 100,000 years. PMID:23908226

  1. Origin and early development of the chicken adenohypophysis

    PubMed Central

    Sánchez-Arrones, Luisa; Ferrán, José L.; Hidalgo-Sanchez, Matías; Puelles, Luis

    2015-01-01

    The adenohypophysis (ADH) is an important endocrine organ involved in the regulation of many physiological processes. The late morphogenesis of this organ at neural tube stages is well known: the epithelial ADH primordium is recognized as an invagination of the stomodeal roof (Rathke’s pouch), whose walls later thicken and differentiate as the primordium becomes pediculated, and then fully separated from the stomodeum. The primordium attaches to the pial surface of the basal hypothalamus, next to the neurohypophyseal field (NH; future posterior pituitary), from which it was previously separated by migrating prechordal plate (pp) cells. Once the NH evaginates, the ADH surrounds it and jointly forms with it the pituitary gland. In contrast, little is known about the precise origin of the ADH precursors at neural plate stages and how the primordium reaches the stomodeum. For that reason, we produced in the chicken a specific ADH fate map at early neural plate stages, which was amplified with gene markers. By means of experiments labeling the mapped presumptive ADH, we were able to follow the initial anlage into its transformation into Rathke’s pouch. The ADH origin was corroborated to be strictly extraneural, i.e., to lie at stage HH4/5 outside of the anterior neural plate (anp) within the pre-placodal field. The ADH primordium is fully segregated from the anterior neural border cells and the neighboring olfactory placodes both in terms of precursor cells and molecular profile from head fold stages onwards. The placode becomes visible as a molecularly characteristic ectodermal thickening from stage HH10 onwards. The onset of ADH genoarchitectonic regionalization into intermediate and anterior lobes occurs at closed neural tube stages. PMID:25741242

  2. The SSC dipole: Its conceptual origin and early design history

    SciTech Connect

    Dahl, P.F.

    1992-05-01

    The magnet system for the Superconducting Super Collider will likely remain the most ambitions-and challenging-application of superconducting technology for the foreseeable future. The centerpiece of the system is the behemoth collider dipole magnet. Its design, still evolving in its detailed features, dates from the mid-1980's when it emerged as the winter in an early technical showdown that occupied the fledgling SSC project. In the present report we chronicle the origins and chief milestones in the development of certain SSC dipole design concepts. Unfortunately, the chronicle must remain incomplete, with the design not yet frozen as we go to press and still subject to important modifications as the SSC Laboratory settles in near its future home in Ellis County, Texas, hard on the heels of a wide-ranging design review in the closing days of the SSC Central Design Group in (CDG) Berkeley. Be that as it may, in what follows we concentrate on the early years in an attempt to recapitulate the birth of the dipole, taking as our point of departure the SSC Reference Designs Study (RDS) of 1984. In Section 3 we touch on the background for the various RDS options, including ISABELLE/CBA and the Tevatron. In Section 4 the narrative focuses on the two final protagonists, a high-field cosine theta (cos {theta}) magnet and a low-field superferric magnet. Section 5 recounts the circumstances surrounding the selection of a particular magnet style'' for further development, and the ups and downs of the first model magnets. We conclude with a smattering of progress highlights in refining the design during the final push under the reign of the CDG. Beyond that, the ongoing chronicle must be left for others to amplify and complete.

  3. The SSC dipole: Its conceptual origin and early design history

    SciTech Connect

    Dahl, P.F.

    1990-06-01

    The magnet system for the Superconducting Super Collider will likely remain the most ambitious -- and challenging -- application of superconducting technology for the foreseeable future. The centerpiece of the system is the behemoth collider dipole magnet. Its design, still evolving in its detailed features, dates from the mid-1980's when it emerged as the winner in an early technical showdown that occupied the fledgling SSC project. However, some of its gross features can be traced back to three path-breaking superconducting accelerator initiatives under way a decade earlier -- on the East Coast, on the West Coast, and in the Midwest. Other features have a still earlier legacy. In the present report we chronicle the origins and chief milestones in the development of certain SSC dipole design concepts. Unfortunately, the chronicle must remain incomplete, with the design not yet frozen as we go to press and still subject to important modifications as the SSC Laboratory settles in near its future home in Ellis County, Texas, hard on the heels of a wide-ranging design review in the closing days of the SSC Central Design Group in (CDG) Berkeley. Be that as it may, in what follows we concentrate on the early years in an attempt to recapitulate the birth of the dipole, taking as our point of departure the SSC Reference Designs Study (RDS) of 1984. In Section 3 we touch on the background for the various RDS options, including ISABELLE/CBA and the Tevatron. In Section 4 the narrative focuses on the two final protagonists, a high-field cosine theta (cos {theta}) magnet and a low-field superferric magnet. Section 5 recounts the circumstances surrounding the selection of a particular magnet style'' for further development, and the ups and downs of the first model magnets. We conclude with a smattering of progress highlights in refining the design during the final push under the reign of the CDG.

  4. A study of uranium favorability of Cenozoic sedimentary rocks, Basin and Range Province, Arizona: Part I, General geology and chronology of pre-late Miocene Cenozoic sedimentary rocks

    USGS Publications Warehouse

    Scarborough, Robert Bryan; Wilt, Jan Carol

    1979-01-01

    This study focuses attention on Cenozoic sedimentary rocks in the Basin and Range Province of Arizona. The known occurrences of uranium and anomalous radioactivity in these rocks are associated with sediments that accumulated in a low energy environment characterized by fine-grained clastics, including important tuffaceous materials, and carbonate rocks. Most uranium occurrences, in these rocks appear to be stratabound. Emphasis was placed on those sedimentary materials that pre-date the late Cenozoic Basin and Range disturbance. They are deformed and crop out on pedimented range blocks and along the province interface with the Transition Zone. Three tentative age groups are recognized: Group I - Oligocene, pre-22 m.y., Group II - early Miocene - 22 m.y. - 16 m.y., and Group III - middle Miocene - 16 m.y. to 13--10 m.y. Regionally, these three groups contain both coarse to fine-grained red clastics and low energy lighter colored 'lacustrine' phases. Each of the three groups has been the object of uranium exploration. Group II, the early Miocene strata, embraces the Anderson Mine - Artillery region host rocks and also the New River - Cave Creek early Miocene beds-along the boundary with the Transition Zone. These three groups of rocks have been tectonically deformed to the extent that original basins of deposition cannot yet be reconstructed. However, they were considerably more extensive in size than the late Cenozoic basins the origin of which deformed the former. Group II rocks are judged to be of prime interest because of: (1) the development and preservation of organic matter in varying lithologies, (2) apparent contemporaneity with silicic volcanic centers, (3) influence of Precambrian crystalline rocks, and (4) relative outcrop continuity near the stable Transition Zone. The Transition Zone, especially along its boundary with the Basin and Range Province, needs additional geologic investigation, especially as regards the depositional continuity of Group II

  5. New aero-gravity results from the Arctic: Linking the latest Cretaceous-early Cenozoic plate kinematics of the North Atlantic and Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Døssing, A.; Hopper, J. R.; Olesen, A. V.; Rasmussen, T. M.; Halpenny, J.

    2013-10-01

    The tectonic history of the Arctic Ocean remains poorly resolved and highly controversial. Details regarding break up of the Lomonosov Ridge from the Barents-Kara shelf margins and the establishment of seafloor spreading in the Cenozoic Eurasia Basin are unresolved. Significantly, the plate tectonic evolution of the Mesozoic Amerasia Basin is essentially unknown. The Arctic Ocean north of Greenland is at a critical juncture that formed at the locus of a Mesozoic three-plate setting between the Lomonosov Ridge, Greenland, and North America. In addition, the area is close to the European plate, resulting in complicated interactions between all these areas that are difficult to resolve. In 2009, the 550,000 km2 LOMGRAV aero-geophysical survey produced the first collocated gravity and magnetic measurements over the area, significantly increasing the data coverage. We present an interpretation of a new free-air gravity compilation, which reveals a regionally consistent structural grain across the Lomonosov Ridge, the Ellesmere and Lincoln Sea shelves, and the Alpha Ridge. We interpret the grain as evidence of latest Cretaceous (˜80 Ma) regional extension in response to the northward propagation of Atlantic and Labrador Sea opening into the Arctic, west of Greenland. This interpretation is consistent with coincident alkaline volcanic activity evident in the borderlands of the Lincoln Sea. We further suggest that Eurekan crustal shortening contributed to the formation of the distinct Lomonosov Ridge plateau against an important fault zone north of Greenland. Our results provide new constraints for Cretaceous-Cenozoic plate reconstructions of the Arctic.

  6. Low-degree melting of a metasomatized lithospheric mantle for the origin of Cenozoic Yulong monzogranite-porphyry, east Tibet: Geochemical and Sr Nd Pb Hf isotopic constraints

    NASA Astrophysics Data System (ADS)

    Jiang, Yao-Hui; Jiang, Shao-Yong; Ling, Hong-Fei; Dai, Bao-Zhang

    2006-01-01

    understand the source and origin of diverse granites.

  7. Cenozoic climates: evidence from the North Atlantic

    SciTech Connect

    Berggren, W.A.

    1985-01-01

    Cenozoic biostratigraphy and climatology of the North Atlantic and adjacent land areas reflects the continuing fragmentation of Eurasia and concomitant changes on ocean-continent geometry. A latitudinal (zonal) Mesozoic circulation pattern evolved into a predominantly longitudinal (meridional) pattern during the Cenozoic in which the development of oceanic gateways and barriers gradually decreased the efficiency of poleward heat transfer resulting in the progressive climatic change which has taken place over the past 50 million years. Cenozoic distributional data from the North Atlantic and adjacent land areas will be reviewed from the following fields: a) terrestrial vertebrates and floras: b) marine calcareous microplankton and benthic foraminifera; c) other marine invertebrates. Available data suggests that the present climate in the northern hemisphere has resulted from a gradual, but inexorable, strengthening of latitudinal and vertical temperature gradients punctuated by several brief intervals of accelerated change. The absence of evidence for northern hemisphere polar glaciation prior to the late Neogene does not preclude seasonal cooling near the freezing point in post-Eocene time. Evidence for early Paleogene cold climates is not reflected in the fossil record.

  8. Cenozoic motion between East and West Antarctica

    PubMed

    Cande; Stock; Muller; Ishihara

    2000-03-01

    The West Antarctic rift system is the result of late Mesozoic and Cenozoic extension between East and West Antarctica, and represents one of the largest active continental rift systems on Earth. But the timing and magnitude of the plate motions leading to the development of this rift system remain poorly known, because of a lack of magnetic anomaly and fracture zone constraints on seafloor spreading. Here we report on magnetic data, gravity data and swath bathymetry collected in several areas of the south Tasman Sea and northern Ross Sea. These results enable us to calculate mid-Cenozoic rotation parameters for East and West Antarctica. These rotations show that there was roughly 180 km of separation in the western Ross Sea embayment in Eocene and Oligocene time. This episode of extension provides a tectonic setting for several significant Cenozoic tectonic events in the Ross Sea embayment including the uplift of the Transantarctic Mountains and the deposition of large thicknesses of Oligocene sediments. Inclusion of this East-West Antarctic motion in the plate circuit linking the Australia, Antarctic and Pacific plates removes a puzzling gap between the Lord Howe rise and Campbell plateau found in previous early Tertiary reconstructions of the New Zealand region. Determination of this East-West Antarctic motion also resolves a long standing controversy regarding the contribution of deformation in this region to the global plate circuit linking the Pacific to the rest of the world. PMID:10724159

  9. Early animal evolution and the origins of nervous systems

    PubMed Central

    Budd, Graham E.

    2015-01-01

    Understanding the evolution of early nervous systems is hazardous because we lack good criteria for determining homology between the systems of distant taxa; the timing of the evolutionary events is contested, and thus the relevant ecological and geological settings for them are also unclear. Here I argue that no simple approach will resolve the first issue, but that it remains likely that animals evolved relatively late, and that their nervous systems thus arose during the late Ediacaran, in a context provided by the changing planktonic and benthic environments of the time. The early trace fossil provides the most concrete evidence for early behavioural diversification, but it cannot simply be translated into increasing nervous system complexity: behavioural complexity does not map on a one-to-one basis onto nervous system complexity, both because of possible limitations to behaviour caused by the environment and because we know that even organisms without nervous systems are capable of relatively complex behaviour. PMID:26554037

  10. Early animal evolution and the origins of nervous systems.

    PubMed

    Budd, Graham E

    2015-12-19

    Understanding the evolution of early nervous systems is hazardous because we lack good criteria for determining homology between the systems of distant taxa; the timing of the evolutionary events is contested, and thus the relevant ecological and geological settings for them are also unclear. Here I argue that no simple approach will resolve the first issue, but that it remains likely that animals evolved relatively late, and that their nervous systems thus arose during the late Ediacaran, in a context provided by the changing planktonic and benthic environments of the time. The early trace fossil provides the most concrete evidence for early behavioural diversification, but it cannot simply be translated into increasing nervous system complexity: behavioural complexity does not map on a one-to-one basis onto nervous system complexity, both because of possible limitations to behaviour caused by the environment and because we know that even organisms without nervous systems are capable of relatively complex behaviour. PMID:26554037

  11. Early-Life Origins of the Race Gap in Men's Mortality

    ERIC Educational Resources Information Center

    Warner, David F.; Hayward, Mark D.

    2006-01-01

    Using a life course framework, we examine the early life origins of the race gap in men's all-cause mortality. Using the National Longitudinal Survey of Older Men (1966-1990), we evaluate major social pathways by which early life conditions differentiate the mortality experiences of blacks and whites. Our findings indicate that early life…

  12. Thresholds for Cenozoic bipolar glaciation.

    PubMed

    Deconto, Robert M; Pollard, David; Wilson, Paul A; Pälike, Heiko; Lear, Caroline H; Pagani, Mark

    2008-10-01

    The long-standing view of Earth's Cenozoic glacial history calls for the first continental-scale glaciation of Antarctica in the earliest Oligocene epoch ( approximately 33.6 million years ago), followed by the onset of northern-hemispheric glacial cycles in the late Pliocene epoch, about 31 million years later. The pivotal early Oligocene event is characterized by a rapid shift of 1.5 parts per thousand in deep-sea benthic oxygen-isotope values (Oi-1) within a few hundred thousand years, reflecting a combination of terrestrial ice growth and deep-sea cooling. The apparent absence of contemporaneous cooling in deep-sea Mg/Ca records, however, has been argued to reflect the growth of more ice than can be accommodated on Antarctica; this, combined with new evidence of continental cooling and ice-rafted debris in the Northern Hemisphere during this period, raises the possibility that Oi-1 represents a precursory bipolar glaciation. Here we test this hypothesis using an isotope-capable global climate/ice-sheet model that accommodates both the long-term decline of Cenozoic atmospheric CO(2) levels and the effects of orbital forcing. We show that the CO(2) threshold below which glaciation occurs in the Northern Hemisphere ( approximately 280 p.p.m.v.) is much lower than that for Antarctica ( approximately 750 p.p.m.v.). Therefore, the growth of ice sheets in the Northern Hemisphere immediately following Antarctic glaciation would have required rapid CO(2) drawdown within the Oi-1 timeframe, to levels lower than those estimated by geochemical proxies and carbon-cycle models. Instead of bipolar glaciation, we find that Oi-1 is best explained by Antarctic glaciation alone, combined with deep-sea cooling of up to 4 degrees C and Antarctic ice that is less isotopically depleted (-30 to -35 per thousand) than previously suggested. Proxy CO(2) estimates remain above our model's northern-hemispheric glaciation threshold of approximately 280 p.p.m.v. until approximately 25 Myr

  13. Variations in Cenozoic seawater uranium reconstructed from well preserved aragonitic fossil corals

    NASA Astrophysics Data System (ADS)

    Gothmann, A. O.; Higgins, J. A.; Bender, M. L.; Stolarski, J.; Adkins, J. F.; McKeon, R. E.; Farley, K. A.; Wang, X.; Planavsky, N.

    2015-12-01

    U/Ca ratios were measured in a subset (n ≈ 30) of well preserved scleractinian fossil corals previously described by Gothmann et al. (2015) in order to investigate Cenozoic changes in seawater [U]. He/U dating studies and measurements of 234U/238U and δ238/235U provide constraints on fossil coral U preservation. He/U ages also demonstrate the ability of well preserved coral aragonite to retain most of its radiogenic He over million year timescales. We find that fossil coral U/Ca has increased by a factor of ~4 between the Early Cenozoic and today. This number is calculated from the change in seawater [Ca2+] implied by brine inclusions and other proxies, and the assumption that the U/Ca in shallow water corals equals the seawater ratio. The change cannot be attributed to a dependence of coral U uptake on seawater pH or [CO32-] (e.g., Inoue et al., 2011), which would lead to a decrease in U/Ca going forward in time. Instead, we suggest that seawater [U] has increased since the Early Cenozoic. Possible explanations for the inferred change include: (1) a small decrease in uranium uptake in suboxic and anoxic sediments over the Cenozoic, (2) a decrease in the rate of low-temperature hydrothermal alteration, and associated U uptake, over the Cenozoic, and (3) a decrease in U removal from seawater resulting from an increase in UO2-CO3 complexation, as originally suggested by Broecker (1971). References: Broecker, W. S. (1971) A Kinetic Model for the Chemical Composition of Sea Water. Quaternary Research, 1, 188-207. Gothmann, A.M., Stolarski, J., Adkins, J.F., Dennis, K.J., Schrag, D.P., Schoene, B., Bender, M.L. (2015) Fossil corals as an archive of secular variations in seawater chemistry. Geochimica et Cosmochimica Acta, 160, 188-208. Inoue, M., Suwa, R., Suzuki, A., Sakai, K., and Kawahata, H., (2011) Effects of seawater pH on growth and skeletal U/Ca ratios of Acropora digitifera coral polyps. Geophysical Research Letters 38, 12801-12804.

  14. Cenozoic planktonic marine diatom diversity and correlation to climate change

    USGS Publications Warehouse

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂18O (climate) and carbon cycle records (∂13C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p2 were only moderately higher than today. Diversity is strongly correlated to both ∂13C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  15. Origin of uranium isotope variations in early solar nebula condensates

    PubMed Central

    Tissot, François L. H.; Dauphas, Nicolas; Grossman, Lawrence

    2016-01-01

    High-temperature condensates found in meteorites display uranium isotopic variations (235U/238U), which complicate dating the solar system’s formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide 247Cm (t1/2 = 15.6 My) into 235U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of 235U reaching ~+6% relative to average solar system composition, which can only be due to the decay of 247Cm. This allows us to constrain the 247Cm/235U ratio at solar system formation to (1.1 ± 0.3) × 10−4. This value provides new clues on the universality of the nucleosynthetic r-process of rapid neutron capture. PMID:26973874

  16. The Origin and Early Evolution of Roots1

    PubMed Central

    Kenrick, Paul; Strullu-Derrien, Christine

    2014-01-01

    Geological sites of exceptional fossil preservation are becoming a focus of research on root evolution because they retain edaphic and ecological context, and the remains of plant soft tissues are preserved in some. New information is emerging on the origins of rooting systems, their interactions with fungi, and their nature and diversity in the earliest forest ecosystems. Remarkably well-preserved fossils prove that mycorrhizal symbionts were diverse in simple rhizoid-based systems. Roots evolved in a piecemeal fashion and independently in several major clades through the Devonian Period (416 to 360 million years ago), rapidly extending functionality and complexity. Evidence from extinct arborescent clades indicates that polar auxin transport was recruited independently in several to regulate wood and root development. The broader impact of root evolution on the geochemical carbon cycle is a developing area and one in which the interests of the plant physiologist intersect with those of the geochemist. PMID:25187527

  17. Early Chordate Origins of the Vertebrate Second Heart Field

    PubMed Central

    Stolfi, Alberto; Gainous, T. Blair; Young, John J.; Mori, Alessandro; Levine, Michael; Christiaen, Lionel

    2016-01-01

    The vertebrate heart is formed from diverse embryonic territories, including the first and second heart fields. The second heart field (SHF) gives rise to the right ventricle and outflow tract, yet its evolutionary origins are unclear. We found that heart progenitor cells of the simple chordate Ciona intestinalis also generate precursors of the atrial siphon muscles (ASMs). These precursors express Islet and Tbx1/10, evocative of the splanchnic mesoderm that produces the lower jaw muscles and SHF of vertebrates. Evidence is presented that the transcription factor COE is a critical determinant of ASM fate. We propose that the last common ancestor of tunicates and vertebrates possessed multipotent cardiopharyngeal muscle precursors, and that their reallocation might have contributed to the emergence of the SHF. PMID:20671188

  18. Origin of uranium isotope variations in early solar nebula condensates.

    PubMed

    Tissot, François L H; Dauphas, Nicolas; Grossman, Lawrence

    2016-03-01

    High-temperature condensates found in meteorites display uranium isotopic variations ((235)U/(238)U), which complicate dating the solar system's formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide (247)Cm (t 1/2 = 15.6 My) into (235)U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of (235)U reaching ~+6% relative to average solar system composition, which can only be due to the decay of (247)Cm. This allows us to constrain the (247)Cm/(235)U ratio at solar system formation to (1.1 ± 0.3) × 10(-4). This value provides new clues on the universality of the nucleosynthetic r-process of rapid neutron capture. PMID:26973874

  19. Cardiovascular prevention: components, levels, early origins, and metrics.

    PubMed

    Kones, Richard; Rumana, Umme

    2014-08-01

    This article presents core epidemiological studies that establish the basis for cardiovascular prevention strategies. The results of the classic INTERHEART and INTERSTROKE studies that delineated population-attributed risk for myocardial infarction and stroke are described. Differences in the levels or types of prevention-primordial, primary, and secondary-lead to the concept that risk occurs on a continuum throughout life with great variability, beginning in infancy. Any meaningful and sustained reduction in cardiovascular risk must begin in childhood, as habits formed early in life have an impact for decades. Although it is never too late to improve unhealthy habits, interventions early in life are more likely to be effective in preventing disease from developing, in delaying manifestations, or in reversing pathology through evidence-based therapies that are applied later. There is compelling evidence that coronary atherosclerosis, heart disease related to diabetes, and hypertension begin with endothelial activation. Oxidative stress and reduced nitric oxide availability are also among the earliest of events, from which a self-amplifying web of events proceed. The American Heart Association, even prior to its now-validated and classic definition of risk metrics, developed a strategic plan to improve health habits in the population and at the community level for promoting and monitoring behavior change and patients' self-reported health status. Other initiatives for improving cardiovascular health are in place as well. Despite improvements in treatment of risk factors, there has been minimal, if any, success in reversing the dual epidemics of obesity and diabetes. These 2 factors continue to drive the high burden of cardiovascular risk, and now lead current public health issues. Because treatment alone cannot fully address this tsunami of risk, it has been suggested that all physicians assume an unprecedented and aggressive role as advocates for behavior change to

  20. Early Pleistocene origin of reefs around Lanai, Hawaii

    USGS Publications Warehouse

    Webster, Jody M.; Clague, David A.; Faichney, Iain D.E.; Fullagar, Paul D.; Hein, James R.; Moore, James G.; Paull, Charles K.

    2010-01-01

    A sequence of submerged terraces (L1–L12) offshore Lanai was previously interpreted as reefal, and correlated with a similar series of reef terraces offshore Hawaii island, whose ages are known to be <500 ka. We present bathymetric, observational, lithologic and 51 87Sr/86Sr isotopic measurements for the submerged Lanai terraces ranging from −300 to −1000 m (L3–L12) that indicate that these terraces are drowned reef systems that grew in shallow coral reef to intermediate and deeper fore-reef slope settings since the early Pleistocene. Age estimates based on 87Sr/86Sr isotopic measurements on corals, coralline algae, echinoids, and bulk sediments, although lacking the precision (∼±0.23 Ma) to distinguish the age–depth relationship and drowning times of individual reefs, indicate that the L12–L3 reefs range in age from ∼1.3–0.5 Ma and are therefore about 0.5–0.8 Ma older than the corresponding reefs around the flanks of Hawaii. These new age data, despite their lack of precision and the influence of later-stage submarine diagenesis on some analyzed corals, clearly revise the previous correlations between the reefs off Lanai and Hawaii. Soon after the end of major shield building (∼1.3–1.2 Ma), the Lanai reefs initiated growth and went through a period of rapid subsidence and reef drowning associated with glacial/interglacial cycles similar to that experienced by the Hawaii reefs. However, their early Pleistocene initiation means they experienced a longer, more complex growth history than their Hawaii counterparts.

  1. The origins and early history of the National Chiropractic Association

    PubMed Central

    Keating, Joseph C; Rehm, William S

    1993-01-01

    Early organization in chiropractic was prompted by the profession’s need to promote itself and to defend against the onslaught of political medicine and organized osteopathy. The first priorities were legal defense against prosecution for unlicensed practice and malpractice insurance. The Universal Chiropractors’ Association (UCA), organized at the Palmer School of Chiropractic (PSC) in 1906, sought to meet these needs by insuring its members and by developing a legal department under the supervision of attorney Tom Morris, one time lieutenant governor of Wisconsin. The public relations and marketing needs of chiropractors were largely served by the PSC and its legendary leader. However, as chiropractors increasingly sought to avoid prosecution by passage of chiropractic laws, Palmer’s efforts to direct this legislation so as to limit chiropractors’ scope of practice increasingly alienated many in the profession. The American Chiropractic Association (ACA) was founded in 1922 to provide a broadscope alternative to BJ’s UCA. With Palmer’s departure from the UCA following the neurocalometer debacle, ACA and UCA sought amalgamation. Simultaneously, organized medicine renewed its attack on the profession by introducing basic science legislation, which prompted chiropractors to try to upgrade and standardize chiropractic education. Early efforts to bring about the needed consensus were centered in the International Chiropractic Congress (ICC), particularly its division of state examining boards. In 1930 the ACA and UCA combined to form the National Chiropractic Association (NCA), and by 1934 the ICC had merged with the NCA to form part of its council structure. With this modicum of solidarity the NCA began the process of educational boot-strapping at its 1935 convention in Los Angeles, when its Committee on Education, a forerunner of today’s Council on Chiropractic Education, was proposed by C.O. Watkins of Montana. ImagesFigure 2Figure 3Figure 4Figure 5

  2. Origin of the Lyman excess in early-type stars

    NASA Astrophysics Data System (ADS)

    Cesaroni, R.; Sánchez-Monge, Á.; Beltrán, M. T.; Molinari, S.; Olmi, L.; Treviño-Morales, S. P.

    2016-04-01

    Context. Ionized regions around early-type stars are believed to be well-known objects, but until recently, our knowledge of the relation between the free-free radio emission and the IR emission has been observationally hindered by the limited angular resolution in the far-IR. The advent of Herschel has now made it possible to obtain a more precise comparison between the two regimes, and it has been found that about a third of the young H ii regions emit more Lyman continuum photons than expected, thus presenting a Lyman excess. Aims: With the present study we wish to distinguish between two scenarios that have been proposed to explain the existence of the Lyman excess: (i) underestimation of the bolometric luminosity, or (ii) additional emission of Lyman-continuum photons from an accretion shock. Methods: We observed an outflow (SiO) and an infall (HCO+) tracer toward a complete sample of 200 H ii regions, 67 of which present the Lyman excess. Our goal was to search for any systematic difference between sources with Lyman excess and those without. Results: While the outflow tracer does not reveal any significant difference between the two subsamples of H ii regions, the infall tracer indicates that the Lyman-excess sources are more associated with infall signposts than the other objects. Conclusions: Our findings indicate that the most plausible explanation for the Lyman excess is that in addition to the Lyman continuum emission from the early-type star, UV photons are emitted from accretion shocks in the stellar neighborhood. This result suggests that high-mass stars and/or stellar clusters containing young massive stars may continue to accrete for a long time, even after the development of a compact H ii region. Based on observations carried out with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  3. Origins and early development of human body knowledge.

    PubMed

    Slaughter, Virginia; Heron, Michelle

    2004-01-01

    As a knowable object, the human body is highly complex. Evidence from several converging lines of research, including psychological studies, neuroimaging and clinical neuropsychology, indicates that human body knowledge is widely distributed in the adult brain, and is instantiated in at least three partially independent levels of representation. Sensorimotor body knowledge is responsible for on-line control and movement of one's own body and may also contribute to the perception of others' moving bodies; visuo-spatial body knowledge specifies detailed structural descriptions of the spatial attributes of the human body; and lexical-semantic body knowledge contains language-based knowledge about the human body. In the first chapter of this Monograph, we outline the evidence for these three hypothesized levels of human body knowledge, then review relevant literature on infants' and young children's human body knowledge in terms of the three-level framework. In Chapters II and III, we report two complimentary series of studies that specifically investigate the emergence of visuo-spatial body knowledge in infancy. Our technique is to compare infants'responses to typical and scrambled human bodies, in order to evaluate when and how infants acquire knowledge about the canonical spatial layout of the human body. Data from a series of visual habituation studies indicate that infants first discriminate scrambled from typical human body picture sat 15 to 18 months of age. Data from object examination studies similarly indicate that infants are sensitive to violations of three-dimensional human body stimuli starting at 15-18 months of age. The overall pattern of data supports several conclusions about the early development of human body knowledge: (a) detailed visuo-spatial knowledge about the human body is first evident in the second year of life, (b) visuo-spatial knowledge of human faces and human bodies are at least partially independent in infancy and (c) infants' initial

  4. Early Miocene origin and cryptic diversification of South American salamanders

    PubMed Central

    2013-01-01

    Background The currently recognized species richness of South American salamanders is surprisingly low compared to North and Central America. In part, this low richness may be due to the salamanders being a recent arrival to South America. Additionally, the number of South American salamander species may be underestimated because of cryptic diversity. The aims of our present study were to infer evolutionary relationships, lineage diversity, and timing of divergence of the South American Bolitoglossa using mitochondrial and nuclear sequence data from specimens primarily from localities in the Andes and upper Amazon Basin. We also estimated time of colonization of South America to test whether it is consistent with arrival via the Panamanian Isthmus, or land bridge connection, at its traditionally assumed age of 3 million years. Results Divergence time estimates suggest that Bolitoglossa arrived in South America from Central America by at least the Early Miocene, ca. 23.6 MYA (95% HPD 15.9-30.3 MYA), and subsequently diversified. South American salamanders of the genus Bolitoglossa show strong phylogeographic structure at fine geographic scales and deep divergences at the mitochondrial gene cytochrome b (Cytb) and high diversity at the nuclear recombination activating gene-1 (Rag1). Species often contain multiple genetically divergent lineages that are occasionally geographically overlapping. Single specimens from two southeastern localities in Ecuador are sister to the equatoriana-peruviana clade and genetically distinct from all other species investigated to date. Another single exemplar from the Andes of northwestern Ecuador is highly divergent from all other specimens and is sister to all newly studied samples. Nevertheless, all sampled species of South American Bolitoglossa are members of a single clade that is one of several constituting the subgenus Eladinea, one of seven subgenera in this large genus. Conclusions The ancestors of South American salamanders

  5. The Origin of Dwarf Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Toloba, Elisa; Boselli, A.; Gorgas, J.

    2013-01-01

    The physical mechanisms involved in the formation and evolution of dwarf early-type galaxies (dEs) are not well understood yet. Whether these objects, that outnumber any other class of object in clusters, are the low luminosity extension of massive early-type galaxies, i.e. formed through similar processes, or are a different group of objects possibly formed through the transformation of low luminosity spiral galaxies, is still an open debate. Studying the kinematic properties of dEs is a powerful way to distinguish between these two scenarios. In my PhD, awarded with a Fulbright postdoctoral Fellowship and with the 2011 prize to the best Spanish PhD dissertation in Astronomy, we used this technique to make a spectrophotometric analysis of 18 dEs in the Virgo cluster. I found some differences for these dEs within the cluster. The dEs in the outer parts of Virgo have rotation curves with shapes and amplitudes similar to late-type galaxies of the same luminosity. They are rotationally supported, have disky isophotes, and younger ages than those dEs in the center of Virgo, which are pressure supported, often have boxy isophotes and are older. Ram pressure stripping, which removes the gas of galaxies leaving the stars untouched, explains the properties of the dEs located in the outskirts of Virgo. However, the dEs in the central cluster regions, which have lost their angular momentum, must have suffered a more violent transformation. A combination of ram pressure stripping and harassment is not enough to remove the rotation and the disky structures of these galaxies. I am conducting new analysis with 20 new dEs to throw some light in this direction. I also analysed the Faber-Jackson and the Fundamental Plane relations, and I found that dEs deviate from the trends of massive elliptical galaxies towards the position of dark matter dominated systems such as the dwarf spheroidal satellites of the Milky Way and M31. This indicates that dEs have a non-negligible dark matter

  6. Formal and Informal Early Education of Turkish-Origin Children in Germany

    ERIC Educational Resources Information Center

    Becker, Birgit; Boldin, Elena; Klein, Oliver

    2016-01-01

    A lack of adequate German language skills is often discussed as a major reason for the disadvantage of children of immigrants in the German educational system. This article analyses the access to formal and informal early education of Turkish-origin children in Germany and the influence of these early education contexts on the children's German…

  7. Early Roman military fortifications and the origin of Trieste, Italy

    PubMed Central

    Bernardini, Federico; Vinci, Giacomo; Horvat, Jana; De Min, Angelo; Forte, Emanuele; Furlani, Stefano; Lenaz, Davide; Pipan, Michele; Zhao, Wenke; Sgambati, Alessandro; Potleca, Michele; Micheli, Roberto; Fragiacomo, Andrea; Tuniz, Claudio

    2015-01-01

    An interdisciplinary study of the archaeological landscape of the Trieste area (northeastern Italy), mainly based on airborne light detection and ranging (LiDAR), ground penetrating radar (GPR), and archaeological surveys, has led to the discovery of an early Roman fortification system, composed of a big central camp (San Rocco) flanked by two minor forts. The most ancient archaeological findings, including a Greco–Italic amphora rim produced in Latium or Campania, provide a relative chronology for the first installation of the structures between the end of the third century B.C. and the first decades of the second century B.C. whereas other materials, such as Lamboglia 2 amphorae and a military footwear hobnail (type D of Alesia), indicate that they maintained a strategic role at least up to the mid first century B.C. According to archaeological data and literary sources, the sites were probably established in connection with the Roman conquest of the Istria peninsula in 178–177 B.C. They were in use, perhaps not continuously, at least until the foundation of Tergeste, the ancestor of Trieste, in the mid first century B.C. The San Rocco site, with its exceptional size and imposing fortifications, is the main known Roman evidence of the Trieste area during this phase and could correspond to the location of the first settlement of Tergeste preceding the colony foundation. This hypothesis would also be supported by literary sources that describe it as a phrourion (Strabo, V, 1, 9, C 215), a term used by ancient writers to designate the fortifications of the Roman army. PMID:25775558

  8. Early Roman military fortifications and the origin of Trieste, Italy.

    PubMed

    Bernardini, Federico; Vinci, Giacomo; Horvat, Jana; De Min, Angelo; Forte, Emanuele; Furlani, Stefano; Lenaz, Davide; Pipan, Michele; Zhao, Wenke; Sgambati, Alessandro; Potleca, Michele; Micheli, Roberto; Fragiacomo, Andrea; Tuniz, Claudio

    2015-03-31

    An interdisciplinary study of the archaeological landscape of the Trieste area (northeastern Italy), mainly based on airborne light detection and ranging (LiDAR), ground penetrating radar (GPR), and archaeological surveys, has led to the discovery of an early Roman fortification system, composed of a big central camp (San Rocco) flanked by two minor forts. The most ancient archaeological findings, including a Greco-Italic amphora rim produced in Latium or Campania, provide a relative chronology for the first installation of the structures between the end of the third century B.C. and the first decades of the second century B.C. whereas other materials, such as Lamboglia 2 amphorae and a military footwear hobnail (type D of Alesia), indicate that they maintained a strategic role at least up to the mid first century B.C. According to archaeological data and literary sources, the sites were probably established in connection with the Roman conquest of the Istria peninsula in 178-177 B.C. They were in use, perhaps not continuously, at least until the foundation of Tergeste, the ancestor of Trieste, in the mid first century B.C. The San Rocco site, with its exceptional size and imposing fortifications, is the main known Roman evidence of the Trieste area during this phase and could correspond to the location of the first settlement of Tergeste preceding the colony foundation. This hypothesis would also be supported by literary sources that describe it as a phrourion (Strabo, V, 1, 9, C 215), a term used by ancient writers to designate the fortifications of the Roman army. PMID:25775558

  9. Cenozoic stratigraphy of the Sahara, Northern Africa

    USGS Publications Warehouse

    Swezey, Christopher S.

    2009-01-01

    This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the

  10. Cenozoic intracontinental deformation of the Kopeh Dagh Belt, Northeastern Iran

    NASA Astrophysics Data System (ADS)

    Chu, Yang; Wan, Bo; Chen, Ling; Talebian, Morteza

    2016-04-01

    Compressional intracontinental orogens represent large tectonic zones far from plate boundaries. Since intracontinental mountain belts cannot be framed in the conventional plate tectonics theory, several hypotheses have been proposed to account for the formations of these mountain belts. The far-field effect of collision/subduction at plate margins is now well accepted for the origin and evolution of the intracontinental crust thickening, as exemplified by the Miocene tectonics of central Asia. In northern Iran, the Binalud-Alborz mountain belt witnessed the Triassic tectonothermal events (Cimmerian orogeny), which are interpreted as the result of the Paleotethys Ocean closure between the Eurasia and Central Iran blocks. The Kopeh Dagh Belt, located to the north of the Binalud-Alborz Belt, has experienced two significant tectonic phases: (1) Jurassic to Eocene rifting with more than 7 km of sediments; and (2) Late Eocene-Early Oligocene to Quaternary continuous compression. Due to the high seismicity, deformation associated with earthquakes has received more and more attention; however, the deformation pattern and architecture of this range remain poorly understood. Detailed field observations on the Cenozoic deformation indicate that the Kopeh Dagh Belt can be divided into a western zone and an eastern zone, separated by a series of dextral strike-slip faults, i.e. the Bakharden-Quchan Fault System. The eastern zone characterized by km-scale box-fold structures, associated with southwest-dipping reverse faults and top-to-the NE kinematics. In contrast, the western zone shows top-to-the SW kinematics, and the deformation intensifies from NE to SW. In the northern part of this zone, large-scale asymmetrical anticlines exhibit SW-directed vergence with subordinate thrusts and folds, whereas symmetrical anticlines are observed in the southern part. In regard to its tectonic feature, the Kopeh Dagh Belt is a typical Cenozoic intracontinental belt without ophiolites or

  11. The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic nontherian lineage into the late Cenozoic of South America.

    PubMed

    Rougier, Guillermo W; Wible, John R; Beck, Robin M D; Apesteguía, Sebastian

    2012-12-01

    The early Miocene mammal Necrolestes patagonensis from Patagonia, Argentina, was described in 1891 as the only known extinct placental "insectivore" from South America (SA). Since then, and despite the discovery of additional well-preserved material, the systematic status of Necrolestes has remained in flux, with earlier studies leaning toward placental affinities and more recent ones endorsing either therian or specifically metatherian relationships. We have further prepared the best-preserved specimens of Necrolestes and compared them with newly discovered nontribosphenic Mesozoic mammals from Argentina; based on this, we conclude that Necrolestes is related neither to marsupials nor placentals but is a late-surviving member of the recently recognized nontherian clade Meridiolestida, which is currently known only from SA. This conclusion is supported by a morphological phylogenetic analysis that includes a broad sampling of therian and nontherian taxa and that places Necrolestes within Meridiolestida. Thus, Necrolestes is a remnant of the highly endemic Mesozoic fauna of nontribosphenic mammals in SA and extends the known record of meridiolestidans by almost 45 million years. Together with other likely relictual mammals from earlier in the Cenozoic of SA and Antarctica, Necrolestes demonstrates the ecological diversity of mammals and the mosaic pattern of fauna replacement in SA during the Cenozoic. In contrast to northern continents, the Cenozoic faunal history of SA was characterized by a long period of interaction between endemic mammalian lineages of Mesozoic origin and metatherian and eutherian lineages that probably dispersed to SA during the latest Cretaceous or earliest Paleocene. PMID:23169652

  12. The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic nontherian lineage into the late Cenozoic of South America

    NASA Astrophysics Data System (ADS)

    Rougier, Guillermo W.; Wible, John R.; Beck, Robin M. D.; Apesteguía, Sebastian

    2012-12-01

    The early Miocene mammal Necrolestes patagonensis from Patagonia, Argentina, was described in 1891 as the only known extinct placental "insectivore" from South America (SA). Since then, and despite the discovery of additional well-preserved material, the systematic status of Necrolestes has remained in flux, with earlier studies leaning toward placental affinities and more recent ones endorsing either therian or specifically metatherian relationships. We have further prepared the best-preserved specimens of Necrolestes and compared them with newly discovered nontribosphenic Mesozoic mammals from Argentina; based on this, we conclude that Necrolestes is related neither to marsupials nor placentals but is a late-surviving member of the recently recognized nontherian clade Meridiolestida, which is currently known only from SA. This conclusion is supported by a morphological phylogenetic analysis that includes a broad sampling of therian and nontherian taxa and that places Necrolestes within Meridiolestida. Thus, Necrolestes is a remnant of the highly endemic Mesozoic fauna of nontribosphenic mammals in SA and extends the known record of meridiolestidans by almost 45 million years. Together with other likely relictual mammals from earlier in the Cenozoic of SA and Antarctica, Necrolestes demonstrates the ecological diversity of mammals and the mosaic pattern of fauna replacement in SA during the Cenozoic. In contrast to northern continents, the Cenozoic faunal history of SA was characterized by a long period of interaction between endemic mammalian lineages of Mesozoic origin and metatherian and eutherian lineages that probably dispersed to SA during the latest Cretaceous or earliest Paleocene.

  13. Cenozoic rift tectonics of the Japan Sea

    SciTech Connect

    Kimura, K.

    1988-08-01

    The Japan Sea is one of the back-arc basins in trench-arc systems bordering the western Pacific. Recent paleomagnetic works suggest the Japan Sea opened during early to middle Miocene. Radiometric and microfossil ages of the Cenozoic onland sequences in the Japanese Islands elucidate the rift tectonics of the Japan Sea. The rifting history is summarized as follows: nonmarine volcanic formations of prerift stage before 50 Ma, rift-onset unconformity at 40 Ma, nonmarine volcanic formations of synrift stage 20-33 Ma, breakup unconformity 19 Ma showing the opening of the Japan Sea, marine volcanic and sedimentary formations of synrift stage 14.5-18 Ma, beginning of regional subsidence 14.5 Ma corresponding to the end of the Japan Sea opening, marine sedimentary formations of postdrift stage after 14.5 Ma. Rifting is not limited to the synrift stage but is continued to the syndrift stage. Rifting led to a horst-and-graben structure. Thus, the Cenozoic onland sequences in the Japanese Islands are suited for a study of rift tectonics because the sequences were subaerially exposed by the late Miocene-Holocene island-arc tectonics. Rift tectonics cannot be studied as easily in most Atlantic-type passive margins.

  14. The Cenozoic palaeoenvironment of the Arctic Ocean

    USGS Publications Warehouse

    Moran, K.; Backman, J.; Brinkhuis, H.; Clemens, S.C.; Cronin, T.; Dickens, G.R.; Eynaud, F.; Gattacceca, J.; Jakobsson, M.; Jordan, R.W.; Kaminski, M.; King, J.; Koc, N.; Krylov, A.; Martinez, N.; Matthiessen, J.; McInroy, D.; Moore, T.C.; Onodera, J.; O'Regan, M.; Palike, H.; Rea, B.; Rio, D.; Sakamoto, T.; Smith, D.C.; Stein, R.; St, John K.; Suto, I.; Suzuki, N.; Takahashi, K.; Watanabe, M. E.; Yamamoto, M.; Farrell, J.; Frank, M.; Kubik, P.; Jokat, W.; Kristoffersen, Y.

    2006-01-01

    The history of the Arctic Ocean during the Cenozoic era (0-65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from >400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm 'greenhouse' world, during the late Palaeocene and early Eocene epochs, to a colder 'icehouse' world influenced by sea ice and icebergs from the middle Eocene epoch to the present. For the most recent ???14 Myr, we find sedimentation rates of 1-2 cm per thousand years, in stark contrast to the substantially lower rates proposed in earlier studies; this record of the Neogene reveals cooling of the Arctic that was synchronous with the expansion of Greenland ice (???3.2 Myr ago) and East Antarctic ice (???14 Myr ago). We find evidence for the first occurrence of ice-rafted debris in the middle Eocene epoch (???45 Myr ago), some 35 Myr earlier than previously thought; fresh surface waters were present at ???49 Myr ago, before the onset of ice-rafted debris. Also, the temperatures of surface waters during the Palaeocene/Eocene thermal maximum (???55 Myr ago) appear to have been substantially warmer than previously estimated. The revised timing of the earliest Arctic cooling events coincides with those from Antarctica, supporting arguments for bipolar symmetry in climate change. ?? 2006 Nature Publishing Group.

  15. Lower crustal high-velocity bodies along North Atlantic passive margins, and their link to Caledonian suture zone eclogites and Early Cenozoic magmatism

    NASA Astrophysics Data System (ADS)

    Mjelde, Rolf; Kvarven, Trond; Faleide, Jan Inge; Thybo, Hans

    2016-02-01

    In this study we use crustal-scale Ocean Bottom Seismic models to infer the presence of two types of lower crustal bodies at North Atlantic passive margins; Type I, primarily interpreted as Early Eocene magmatic intrusions, and Type II, interpreted as Caledonian eclogites. We discuss how these eclogites might be related to the main Caledonian Suture Zone and other tectonic features in a conjugate North Atlantic setting. Based on the first-order approximation that P-wave velocities can be related to rock strength, the narrower continental margin at the southern (Møre) transect may be explained by stronger lower crust there, compared with the northern (Vøring) transect. This difference in strength, possibly resulting in a steeper dip in the subducting Baltica Plate south of the proto-Jan Mayen Lineament, may explain the asymmetry in extensional style observed across this lineament. Our interpretation locates the main suture off mid-Norway close to the Møre Trøndelag Fault Zone on the Møre Margin, along the western boundary of the Trøndelag Platform on the Vøring Margin, and further northwards beneath the Lofoten Ridge. The Lower Crustal Body Type I is about 60% thicker on the Greenland side, for both transects, and its thickness along the northern transect is more than twice that of the southern transect. These differences are consistent with sub-lithospheric interaction between the Icelandic hotspot and the continental rift/oceanic accretion system around the time of continental break-up.

  16. The Cenozoic Cooling - continental signals from the Atlantic and Pacific side of Eurasia

    NASA Astrophysics Data System (ADS)

    Utescher, Torsten; Bondarenko, Olesya V.; Mosbrugger, Volker

    2015-04-01

    The evolution of Cenozoic continental climate signals from the Atlantic and Pacific side of Eurasia can be assessed for the first time by comparing climate records obtained for two mid-latitudinal regions. For the West, a detailed climate record over the past 45 Ma, based on palaeofloras from two Northern German Cenozoic basins (Mosbrugger et al., 2005) revealed major trends and shorter-term events throughout the Cenozoic Cooling, thus testifying the close correlation of continental and marine temperature evolution as derived from oxygen isotopes (Zachos et al., 2008). Using the same methodology, we analyze a total of 14 floral horizons originating from continental strata of Southern Primory'e (Russia) in order to study the evolution at the eastern side of the continent. The Primory'e record spans the middle Eocene to early Pleistocene. As the coeval record for the Atlantic side, it reflects major global signals of Cenozoic climate change such as the temperature decline throughout the late Eocene, coinciding with the growth of Antarctic Ice-sheets, warming during the Mid-Miocene Climatic Optimum, and step-wise cooling throughout the later Neogene. The comparison of both records reveals differing regional patterns. The considerable longitudinal temperature gradient, currently existing between both study areas, already began to evolve during the Aquitanian, and was very significant during the Mid-Miocene Climatic Optimum. The temperature offset between East and West is likely attributable to an effective North Atlantic Current, already operational from the late early Miocene onwards bringing about mild winters and low seasonality in Western Europe, while in Primory'e, seasonality steadily increased from the late Oligocene on. The strong late Pliocene decline of cold month mean temperatures recorded in Primory'e is supposed to coincide with the establishment of the Siberian High as semi-permanent structure of the Northern Hemisphere circulation pattern. When comparing

  17. Mexican-Origin Youth's Cultural Orientations and Adjustment: Changes from Early to Late Adolescence

    ERIC Educational Resources Information Center

    Updegraff, Kimberly A.; Umana-Taylor, Adriana J.; McHale, Susan M.; Wheeler, Lorey A.; Perez-Brena, Norma J.

    2012-01-01

    Drawing from developmental and cultural adaptation perspectives and using a longitudinal design, this study examined: (a) mean-level changes in Mexican-origin adolescents' cultural orientations and adjustment from early to late adolescence and (b) bidirectional associations between cultural orientations and adjustment using a cross-lag panel…

  18. The Genetic and Environmental Origins of Learning Abilities and Disabilities in the Early School Years

    ERIC Educational Resources Information Center

    Kovas, Yulia; Haworth, Claire M. A.; Dale, Philip S.; Plomin, Robert

    2007-01-01

    Despite the importance of learning abilities and disabilities in education and child development, little is known about their genetic and environmental origins in the early school years. We report results for English (which includes reading, writing, and speaking), mathematics, and science as well as general cognitive ability in a large and…

  19. Dropping Out of High School among Mexican-Origin Youths: Is Early Work Experience a Factor?

    ERIC Educational Resources Information Center

    Olatunji, Anane N.

    2005-01-01

    In this article, Anane Olatunji examines the effects of work experience on early high school attrition among Mexican-origin adolescents. He proposes a theoretical model that takes assimilation into account as a potential predictor of the consequences of work for this group. In order to estimate the effects of eighth-grade work experience on…

  20. The origin and early evolution of birds: discoveries, disputes, and perspectives from fossil evidence

    NASA Astrophysics Data System (ADS)

    Zhou, Zhonghe

    2004-10-01

    The study of the origin and early evolution of birds has never produced as much excitement and public attention as in the past decade. Well preserved and abundant new fossils of birds and dinosaurs have provided unprecedented new evidence on the dinosaurian origin of birds, the arboreal origin of avian flight, and the origin of feathers prior to flapping flight. The Mesozoic avian assemblage mainly comprises two major lineages: the prevalent extinct group Enantiornithes, and the Ornithurae, which gave rise to all modern birds, as well as several more basal taxa. Cretaceous birds radiated into various paleoecological niches that included fish- and seed-eating. Significant size and morphological differences and variation in flight capabilities, ranging from gliding to powerful flight among early birds, highlight the diversification of birds in the Early Cretaceous. There is little evidence, however, to support a Mesozoic origin of modern avian groups. Controversy and debate, nevertheless, surround many of these findings, and more details are needed to give a better appreciation of the significance of these new discoveries.

  1. Clues from Fe isotope variations on the origin of early Archean BIFs from Greenland.

    PubMed

    Dauphas, Nicolas; van Zuilen, Mark; Wadhwa, Meenakshi; Davis, Andrew M; Marty, Bernard; Janney, Philip E

    2004-12-17

    Archean rocks may provide a record of early Earth environments. However, such rocks have often been metamorphosed by high pressure and temperature, which can overprint the signatures of their original formation. Here, we show that the early Archean banded rocks from Isua, Akilia, and Innersuartuut, Greenland, are enriched in heavy iron isotopes by 0.1 to 0.5 per mil per atomic mass unit relative to igneous rocks worldwide. The observed enrichments are compatible with the transport, oxidation, and subsequent precipitation of ferrous iron emanating from hydrothermal vents and thus suggest that the original rocks were banded iron formations (BIFs). These variations therefore support a sedimentary origin for the Akilia banded rocks, which represent one of the oldest known occurrences of water-laid deposits on Earth. PMID:15604404

  2. Perinatal inflammation: a common factor in the early origins of cardiovascular disease?

    PubMed

    Nguyen, Maria U; Wallace, Megan J; Pepe, Salvatore; Menheniott, Trevelyan R; Moss, Timothy J; Burgner, David

    2015-10-01

    Cardiovascular disease continues to be the leading cause of global morbidity and mortality. Traditional risk factors account for only part of the attributable risk. The origins of atherosclerosis are in early life, a potential albeit largely unrecognized window of opportunity for early detection and treatment of subclinical cardiovascular disease. There are robust epidemiological data indicating that poor intrauterine growth and/or prematurity, and perinatal factors such as maternal hypercholesterolaemia, smoking, diabetes and obesity, are associated with adverse cardiovascular intermediate phenotypes in childhood and adulthood. Many of these early-life risk factors result in a heightened inflammatory state. Inflammation is a central mechanism in the development of atherosclerosis and cardiovascular disease, but few studies have investigated the role of overt perinatal infection and inflammation (chorioamnionitis) as a potential contributor to cardiovascular risk. Limited evidence from human and experimental models suggests an association between chorioamnionitis and cardiac and vascular dysfunction. Early life inflammatory events may be an important mechanism in the early development of cardiovascular risk and may provide insights into the associations between perinatal factors and adult cardiovascular disease. This review aims to summarise current data on the early life origins of atherosclerosis and cardiovascular disease, with particular focus on perinatal inflammation. PMID:26223841

  3. Early-life origins of the race gap in men's mortality.

    PubMed

    Warner, David F; Hayward, Mark D

    2006-09-01

    Using a life course framework, we examine the early life origins of the race gap in men's all-cause mortality. Using the National Longitudinal Survey of Older Men (1966-1990), we evaluate major social pathways by which early life conditions differentiate the mortality experiences of blacks and whites. Our findings indicate that early life socioeconomic conditions, particularly parental occupation and family structure, explain part of the race gap in mortality. Black men's higher rates of death are associated with lower socioeconomic standing in early life and living in homes lacking both biological parents. However these effects operate indirectly through adult socioeconomic achievement processes, as education, family income, wealth, and occupational complexity statistically account for the race gap in men's mortality. Our findings suggest that policy interventions to eliminate race disparities in mortality and health should address both childhood and adult socioeconomic conditions. PMID:17066773

  4. A quantitative review of the Cenozoic diatom deposition history

    NASA Astrophysics Data System (ADS)

    Renaudie, Johan; Lazarus, David B.

    2014-05-01

    Marine planktonic diatoms play an important role today as one of the world's main primary producers, as the main organic carbon exporter to the deep sea and also as the main silica exporter balancing global chemical weathering. They were however a very minor component of the plankton at the beginning of the Cenozoic. Studies to date have focussed mainly on the evolution of their taxonomic diversity. Studies of changes in their actual global abundance over the Cenozoic are few, qualitative, and based on limited amounts of data. Reviewing their depositional pattern during the Cenozoic is therefore of interest in order to understand the modality, the context and, eventually, the cause of their rise; and to understand how diatom evolution affected the Cenozoic functioning of the ocean pump. We present here, based on a review of the literature coupled with a new data analysis of the full global ODP-DSDP Initial Reports smear slides descriptions, a quantitative synthesis of the depositional history of marine diatoms for the last 60 Myr. We also place these data in their paleogeographical context in order to understand the changes in diatom biogeography and what it says about Cenozoic paleoceanography. Diatoms first became widespread during the Middle Eocene. Two temporary major high-abundance events, one at the Eocene-Oligocene transition, another during the Late Oligocene were followed by decreases in the Middle Oligocene and Early Miocene. Diatom abundance in sediments shifted in the Mid-Miocene to globally higher values which have largely persisted to the modern day. Despite appearing initially during the Late Oligocene, the Southern Ocean circumpolar diatom accumulation belt only became a stable feature in the Mid-Miocene. At this time the main diatom deposition loci switched from the Atlantic to the Pacific and Indian Oceans, and mid-latitude upwelling zones appeared. Our findings provide support for the idea that diatoms, through their ecological role in the ocean

  5. Early-life origins of chronic respiratory diseases: understanding and promoting healthy ageing.

    PubMed

    Carraro, Silvia; Scheltema, Nienke; Bont, Louis; Baraldi, Eugenio

    2014-12-01

    Chronic obstructive respiratory disorders such as asthma and chronic obstructive pulmonary disease often originate early in life. In addition to a genetic predisposition, prenatal and early-life environmental exposures have a persistent impact on respiratory health. Acting during a critical phase of lung development, these factors may change lung structure and metabolism, and may induce maladaptive responses to harmful agents, which will affect the whole lifespan. Some environmental factors, such as exposure to cigarette smoke, type of childbirth and diet, may be modifiable, but it is more difficult to influence other factors, such as preterm birth and early exposure to viruses or allergens. Here, we bring together recent literature to analyse the critical aspects involved in the early stages of lung development, going back to prenatal and perinatal events, and we discuss the mechanisms by which noxious factors encountered early on may have a lifelong impact on respiratory health. We briefly comment on the need for early disease biomarkers and on the possible role of "-omic" technologies in identifying risk profiles predictive of chronic respiratory conditions. Such profiles could guide the ideation of effective preventive strategies and/or targeted early lifestyle or therapeutic interventions. PMID:25323240

  6. Cenozoic evolution of San Joaquin basin, California

    SciTech Connect

    Bartow, J.A.

    1988-03-01

    The Neogene San Joaquin basin in the southern part of the 700-km long Great Valley of California is a successor to a late Mesozoic and earliest Tertiary forearc basin. The transition from forearc basin to the more restricted Neogene marine basin occurred principally during the Paleogene as the plate tectonic setting changed from oblique convergence to normal convergence, and finally to the initiation of tangential (transform) movement near the end of the Oligocene. Regional-scale tectonic events that affected the basin include: (1) clockwise rotation of the southernmost Sierra Nevada, and large-scale en echelon folding in the southern Diablo Range, both perhaps related to Late Cretaceous and early Tertiary right slip on the proto-San-Andreas fault; (2) regional uplift of southern California in the Oligocene that resulted from the subduction of the Pacific-Farallon spreading ridge: (3) extensional tectonism in the Basin and Range province, particularly in the Miocene; (4) wrench tectonism adjacent to the San Andreas fault in the Neogene; (5) northeastward emplacement of a wedge of the Franciscan complex at the west side of the Sierran block, with associated deep-seated thrusting in the late Cenozoic; and (6) the accelerated uplift of the Sierra Nevada beginning in the late Miocene. Neogene basin history was controlled principally by the tectonic effects of the northwestward migration of the Mendocino triple junction along the California continental margin and by the subsequent wrench tectonism associated with the San Andreas fault system. East-west compression in the basin, resulting from extension in the Basin and Range province was an important contributing factor to crustal shortening at the west side of the valley. Analysis of the sedimentary history of the basin, which was controlled to some extent by eustatic sea level change, enables reconstruction of the basin paleogeography through the Cenozoic.

  7. Early South Americans Cranial Morphological Variation and the Origin of American Biological Diversity

    PubMed Central

    Hubbe, Alex; Neves, Walter A.

    2015-01-01

    Recent South Americans have been described as presenting high regional cranial morphological diversity when compared to other regions of the world. This high diversity is in accordance with linguistic and some of the molecular data currently available for the continent, but the origin of this diversity has not been satisfactorily explained yet. Here we explore if this high morphological variation was already present among early groups in South America, in order to refine our knowledge about the timing and origins of the modern morphological diversity. Between-group (Fst estimates) and within-group variances (trace of within-group covariance matrix) of the only two early American population samples available to date (Lagoa Santa and Sabana de Bogotá) were estimated based on linear craniometric measurements and compared to modern human cranial series representing six regions of the world, including the Americas. The results show that early Americans present moderate within-group diversity, falling well within the range of modern human groups, despite representing almost three thousand years of human occupation. The between-group variance apportionment is very low between early Americans, but is high among recent South American groups, who show values similar to the ones observed on a global scale. Although limited to only two early South American series, these results suggest that the high morphological diversity of native South Americans was not present among the first human groups arriving in the continent and must have originated during the Middle Holocene, possibly due to the arrival of new morphological diversity coming from Asia during the Holocene. PMID:26465141

  8. Early South Americans Cranial Morphological Variation and the Origin of American Biological Diversity.

    PubMed

    Hubbe, Mark; Strauss, André; Hubbe, Alex; Neves, Walter A

    2015-01-01

    Recent South Americans have been described as presenting high regional cranial morphological diversity when compared to other regions of the world. This high diversity is in accordance with linguistic and some of the molecular data currently available for the continent, but the origin of this diversity has not been satisfactorily explained yet. Here we explore if this high morphological variation was already present among early groups in South America, in order to refine our knowledge about the timing and origins of the modern morphological diversity. Between-group (Fst estimates) and within-group variances (trace of within-group covariance matrix) of the only two early American population samples available to date (Lagoa Santa and Sabana de Bogotá) were estimated based on linear craniometric measurements and compared to modern human cranial series representing six regions of the world, including the Americas. The results show that early Americans present moderate within-group diversity, falling well within the range of modern human groups, despite representing almost three thousand years of human occupation. The between-group variance apportionment is very low between early Americans, but is high among recent South American groups, who show values similar to the ones observed on a global scale. Although limited to only two early South American series, these results suggest that the high morphological diversity of native South Americans was not present among the first human groups arriving in the continent and must have originated during the Middle Holocene, possibly due to the arrival of new morphological diversity coming from Asia during the Holocene. PMID:26465141

  9. Late Cenozoic tectonism of the Sacramento Valley, California

    SciTech Connect

    Harwood, D.S.; Helley, E.J.

    1987-01-01

    Structure contours drawn on top of the Cretaceous rocks in the Sacramento Valley define a large number of diversely oriented folds and faults that are expressed in topographic, hydrologic, and geologic features at the land surface. Although many of the structures in the valley have a protracted history of movement, some dating back to the late Mesozoic, a remarkable number of these structures show late Cenozoic deformation that can be accurately determined from folding and faulting of widespread, dated Pliocene and Pleistocene volcanic units. These time-stratigraphic units are used to define structural domains of essentially contemporaneous late Cenozoic deformation that was characterized by east-west compressive stress. The oldest structural domain is located in the southeastern part of the valley, where east-side-up reverse movement on the Willows fault ceased prior to deposition of continentally derived sediments of late Miocene and early Pliocene age. In the middle Pliocene to early Pleistocene, east-west compressive deformation progressed northward through the valley so that the youngest late Cenozoic deformation is recorded in east-northeast-trending folds and faults in the Battle Creek domain, at the northern-most part of the valley. The northward progression of east-west compressive deformation appears to be related to the northward eclipse of eastward subduction of the Juan de Fuca plate before the northwestward migration of the Mendocino triple junction along the continental margin west of the valley.

  10. Origin of Clothing Lice Indicates Early Clothing Use by Anatomically Modern Humans in Africa

    PubMed Central

    Toups, Melissa A.; Kitchen, Andrew; Light, Jessica E.; Reed, David L.

    2011-01-01

    Clothing use is an important modern behavior that contributed to the successful expansion of humans into higher latitudes and cold climates. Previous research suggests that clothing use originated anywhere between 40,000 and 3 Ma, though there is little direct archaeological, fossil, or genetic evidence to support more specific estimates. Since clothing lice evolved from head louse ancestors once humans adopted clothing, dating the emergence of clothing lice may provide more specific estimates of the origin of clothing use. Here, we use a Bayesian coalescent modeling approach to estimate that clothing lice diverged from head louse ancestors at least by 83,000 and possibly as early as 170,000 years ago. Our analysis suggests that the use of clothing likely originated with anatomically modern humans in Africa and reinforces a broad trend of modern human developments in Africa during the Middle to Late Pleistocene. PMID:20823373

  11. The ancient history of the structure of ribonuclease P and the early origins of Archaea

    PubMed Central

    2010-01-01

    Background Ribonuclease P is an ancient endonuclease that cleaves precursor tRNA and generally consists of a catalytic RNA subunit (RPR) and one or more proteins (RPPs). It represents an important macromolecular complex and model system that is universally distributed in life. Its putative origins have inspired fundamental hypotheses, including the proposal of an ancient RNA world. Results To study the evolution of this complex, we constructed rooted phylogenetic trees of RPR molecules and substructures and estimated RPP age using a cladistic method that embeds structure directly into phylogenetic analysis. The general approach was used previously to study the evolution of tRNA, SINE RNA and 5S rRNA, the origins of metabolism, and the evolution and complexity of the protein world, and revealed here remarkable evolutionary patterns. Trees of molecules uncovered the tripartite nature of life and the early origin of archaeal RPRs. Trees of substructures showed molecules originated in stem P12 and were accessorized with a catalytic P1-P4 core structure before the first substructure was lost in Archaea. This core currently interacts with RPPs and ancient segments of the tRNA molecule. Finally, a census of protein domain structure in hundreds of genomes established RPPs appeared after the rise of metabolic enzymes at the onset of the protein world. Conclusions The study provides a detailed account of the history and early diversification of a fundamental ribonucleoprotein and offers further evidence in support of the existence of a tripartite organismal world that originated by the segregation of archaeal lineages from an ancient community of primordial organisms. PMID:20334683

  12. Comparison of Early Maladaptive Schemas and Parenting Origins in Patients with Opioid Abuse and Non-Abusers

    PubMed Central

    Zargar, Mohammad; Salavati, Mojgan; Kakavand, Ali Reza

    2011-01-01

    Objective The aim of this study was to examine the difference of early maladaptive schemas and parenting origins in opioid abusers and non-opioid abusers. Method The early maladaptive schemas and parenting origins were compared in 56 opioid abusers and 56 non-opioids abusers. Schemas were assessed by the Young Schema Questionnaire 3rd (short form); and parenting origins were assessed by the Young Parenting Inventory. Results Data were analyzed by multivariate analysis of variance (MANOVA). The analysis showed that the means for schemas between opioid abusers and non-opioid abusers were different. Chi square test showed that parenting origins were significantly associated with their related schemas. Conclusion The early maladaptive schemas and parenting origins in opioid abusers were more than non-opioid abusers; and parenting origins were related to their Corresponding schemas. PMID:22952522

  13. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India.

    PubMed

    Rose, Kenneth D; Holbrook, Luke T; Rana, Rajendra S; Kumar, Kishor; Jones, Katrina E; Ahrens, Heather E; Missiaen, Pieter; Sahni, Ashok; Smith, Thierry

    2014-01-01

    Cambaytheres (Cambaytherium, Nakusia and Kalitherium) are recently discovered early Eocene placental mammals from the Indo-Pakistan region. They have been assigned to either Perissodactyla (the clade including horses, tapirs and rhinos, which is a member of the superorder Laurasiatheria) or Anthracobunidae, an obscure family that has been variously considered artiodactyls or perissodactyls, but most recently placed at the base of Proboscidea or of Tethytheria (Proboscidea+Sirenia, superorder Afrotheria). Here we report new dental, cranial and postcranial fossils of Cambaytherium, from the Cambay Shale Formation, Gujarat, India (~54.5 Myr). These fossils demonstrate that cambaytheres occupy a pivotal position as the sister taxon of Perissodactyla, thereby providing insight on the phylogenetic and biogeographic origin of Perissodactyla. The presence of the sister group of perissodactyls in western India near or before the time of collision suggests that Perissodactyla may have originated on the Indian Plate during its final drift toward Asia. PMID:25410701

  14. Mexican-Origin Youth's Cultural Orientations and Adjustment: Changes from Early to Late Adolescence

    PubMed Central

    Updegraff, Kimberly A.; Umaña-Taylor, Adriana J.; McHale, Susan M.; Wheeler, Lorey A.; Perez-Brena, Norma

    2013-01-01

    Drawing from developmental and cultural adaptation perspectives and using a longitudinal design, this study examined: (a) mean-level changes in Mexican-origin adolescents’ cultural orientations and adjustment from early to late adolescence; and (b) bidirectional associations between cultural orientations and adjustment using a cross-lag panel model. Participants included 246 Mexican-origin, predominantly immigrant families that participated in home interviews and a series of nightly phone calls when target adolescents were 12 years and 18 years of age. Girls exhibited more pronounced declines in traditional gender role attitudes than did boys, and all youth declined in familism values, time spent with family, and involvement in Mexican culture. Bidirectional relations between cultural orientations and adjustment emerged, and some associations were moderated by adolescent nativity and gender. PMID:22966929

  15. Early adolescent temperament, parental monitoring, and substance use in Mexican-origin adolescents.

    PubMed

    Clark, D Angus; Donnellan, M Brent; Robins, Richard W; Conger, Rand D

    2015-06-01

    Previous studies suggest that temperamental dispositions are associated with substance use. However, most research supporting this association has relied on European American samples (Stautz & Cooper, 2013). We addressed this gap by evaluating the prospective relations between 5th grade temperament and 9th grade substance use in a longitudinal sample of Mexican-origin youth (N = 674). Effortful control and trait aggressiveness predicted 9th grade substance use, intentions, and expectations, even after controlling for 5th grade substance use. Additionally, we found an interaction between temperament and parental monitoring such that monitoring is a protective factor for early substance use primarily for youth with temperamental tendencies associated with risk for substance use (e.g., low effortful control and aggression). Results add to the growing literature demonstrating that early manifestations of self-control are related to consequential life outcomes. PMID:25841175

  16. Structural phylogenomics uncovers the early and concurrent origins of cysteine biosynthesis and iron-sulfur proteins.

    PubMed

    Zhang, Hong-Yu; Qin, Tao; Jiang, Ying-Ying; Caetano-Anollés, Gustavo

    2012-01-01

    Cysteine (Cys) has unique chemical properties of catalysis, metal chelation, and protein stabilization. While Cys biosynthesis is assumed to be very ancient, the actual time of origin of these metabolic pathways remains unknown. Here, we use the molecular clocks of protein folds and fold superfamilies to time the origin of Cys biosynthesis. We find that the tRNA-dependent biosynthetic pathway appeared ~3.5 billion years ago while the tRNA-independent counterpart emerged ~500 million years later. A deep analysis of the origins of Cys biosynthesis in the context of emerging biochemistry uncovers some intriguing features of the planetary environment of early Earth. Results suggest that iron-sulfur (Fe-S) proteins that use cysteinyl sulfur to bind iron atoms were not the first to arise in evolution. Instead, their origin coincides with the appearance of the first Cys biosynthetic pathway. It is therefore likely that Cys did not play an important role in the make up of primordial protein molecules and that Fe-S clusters were not part of active sites at the beginning of biological history. PMID:22731683

  17. Origin of the Directed Movement of Protocells in the Early Stages of the Evolution of Life

    NASA Astrophysics Data System (ADS)

    Melkikh, Alexey V.; Chesnokova, Oksana I.

    2012-08-01

    The origin of the directed motion of protocells during the early stages of evolution was discussed. The expenditures for movement, space orientation, and reception of information about the environment were taken into consideration, and it was shown that directed movement is evolutionarily advantageous in the following cases: when opposite gradients of different resources (for example, matter and energy) are great enough and when there is a rapid change in environmental parameters. It was also shown that the advantage of directed movement strategies depends greatly on how information about the environment is obtained by a protocell.

  18. Origin of the directed movement of protocells in the early stages of the evolution of life.

    PubMed

    Melkikh, Alexey V; Chesnokova, Oksana I

    2012-08-01

    The origin of the directed motion of protocells during the early stages of evolution was discussed. The expenditures for movement, space orientation, and reception of information about the environment were taken into consideration, and it was shown that directed movement is evolutionarily advantageous in the following cases: when opposite gradients of different resources (for example, matter and energy) are great enough and when there is a rapid change in environmental parameters. It was also shown that the advantage of directed movement strategies depends greatly on how information about the environment is obtained by a protocell. PMID:22772806

  19. The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications.

    PubMed

    Crame, J Alistair; Beu, Alan G; Ineson, Jon R; Francis, Jane E; Whittle, Rowan J; Bowman, Vanessa C

    2014-01-01

    The extensive Late Cretaceous - Early Paleogene sedimentary succession of Seymour Island, N.E. Antarctic Peninsula offers an unparalleled opportunity to examine the evolutionary origins of a modern polar marine fauna. Some 38 modern Southern Ocean molluscan genera (26 gastropods and 12 bivalves), representing approximately 18% of the total modern benthic molluscan fauna, can now be traced back through at least part of this sequence. As noted elsewhere in the world, the balance of the molluscan fauna changes sharply across the Cretaceous - Paleogene (K/Pg) boundary, with gastropods subsequently becoming more diverse than bivalves. A major reason for this is a significant radiation of the Neogastropoda, which today forms one of the most diverse clades in the sea. Buccinoidea is the dominant neogastropod superfamily in both the Paleocene Sobral Formation (SF) (56% of neogastropod genera) and Early - Middle Eocene La Meseta Formation (LMF) (47%), with the Conoidea (25%) being prominent for the first time in the latter. This radiation of Neogastropoda is linked to a significant pulse of global warming that reached at least 65°S, and terminates abruptly in the upper LMF in an extinction event that most likely heralds the onset of global cooling. It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event. The radiation of this and other clades at ∼65°S indicates that Antarctica was not necessarily an evolutionary refugium, or sink, in the Early - Middle Eocene. Evolutionary source - sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds. PMID:25493546

  20. The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications

    PubMed Central

    Crame, J. Alistair; Beu, Alan G.; Ineson, Jon R.; Francis, Jane E.; Whittle, Rowan J.; Bowman, Vanessa C.

    2014-01-01

    The extensive Late Cretaceous – Early Paleogene sedimentary succession of Seymour Island, N.E. Antarctic Peninsula offers an unparalleled opportunity to examine the evolutionary origins of a modern polar marine fauna. Some 38 modern Southern Ocean molluscan genera (26 gastropods and 12 bivalves), representing approximately 18% of the total modern benthic molluscan fauna, can now be traced back through at least part of this sequence. As noted elsewhere in the world, the balance of the molluscan fauna changes sharply across the Cretaceous – Paleogene (K/Pg) boundary, with gastropods subsequently becoming more diverse than bivalves. A major reason for this is a significant radiation of the Neogastropoda, which today forms one of the most diverse clades in the sea. Buccinoidea is the dominant neogastropod superfamily in both the Paleocene Sobral Formation (SF) (56% of neogastropod genera) and Early - Middle Eocene La Meseta Formation (LMF) (47%), with the Conoidea (25%) being prominent for the first time in the latter. This radiation of Neogastropoda is linked to a significant pulse of global warming that reached at least 65°S, and terminates abruptly in the upper LMF in an extinction event that most likely heralds the onset of global cooling. It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event. The radiation of this and other clades at ∼65°S indicates that Antarctica was not necessarily an evolutionary refugium, or sink, in the Early – Middle Eocene. Evolutionary source – sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds. PMID:25493546

  1. Cenozoic reconstruction of southwest Pacific

    SciTech Connect

    Chun, Y.Y.; Kroenke, L.W.

    1986-07-01

    Poles of opening and spreading rates for some of the well-studied marginal basins in the southwest Pacific have been redetermined. Times of opening range from Late Cretaceous-Paleocene in the Tasman basin to middle Pliocene in the Bismarck Sea. The observed magnetic lineations in most of these basins show a relatively short duration of opening and relatively small area of total opening. Most of the smaller basins are bounded by troughs and arcuate island chains, some of which are inferred to be trenches and volcanic arcs situated along paleoconvergent boundaries. At least four successive paleoconvergent boundaries are believed to have formed between the Pacific and the Indian-Australian plates during the Cenozoic. Combining the newly determined poles of opening, spreading rates, and paleoplate boundary locations, a series of palinspastic maps of the southwest Pacific have been constructed for these times, relative to a fixed hot-spot frame of reference for both the Pacific and Indian-Australian plates.

  2. Evidence for Cenozoic uplift of the Appalachian Mountains in the southeastern United States

    SciTech Connect

    Prowell, D.C. ); Christopher, R.A. )

    1993-03-01

    The present height and shape of the (physiographic) Appalachian Mountains were traditionally attributed to Paleozoic and early Mesozoic tectonism and the resistance of the Precambrian and Paleozoic rocks to erosion. New evidence indicates that Cenozoic uplift is responsible for at least part of the present height of land as well as for the configuration of the inner margin of the Coastal Plain at the southern terminus of the mountains. Stratigraphic correlations from regional mapping and palynological analysis of Cretaceous non-marine and restricted marine strata in the southeastern Coastal Plain suggest that Cenozoic uplift has influence both the present height of the landmass and the outcrop pattern of the eastern Gulf Coastal Plain. In addition, Cenozoic uplift has raised Cretaceous marine deposits to 300 m (1,000 ft) above present sea level in south-central Tennessee, and subsequent erosion has modified the Coastal Plain section to expose the oldest strata at the point of maximum uplift in central Alabama. The magnitude of uplift appears to be greatest along the northeast-trending axis of the mountain chain, and it decreases with distance from the mountains. This uplift is thought to result from the compressive intraplate tectonism that produced numerous reverse faults on the Atlantic continental margin during the Cretaceous and Cenozoic. Most of the Cretaceous and early Cenozoic strata that once covered the Precambrian and Paleozoic rocks at the southern terminus of the Appalachians have been removed by late Cenozoic erosion, but remnants of the eroded Cenozoic beds are preserved at elevations up to +640 m (+2,100 ft) in numerous fault-bounded sediment traps as far inland as Chattanooga, Tenn. Palynological correlation of these inland deposits with geologic formations in the present Coastal Plain suggests the intriguing possibility that the Coastal Plain strata once may have extended hundreds of kilometers (miles) inland from their present inner margin.

  3. Origins.

    ERIC Educational Resources Information Center

    Online-Offline, 1999

    1999-01-01

    Provides an annotated list of resources dealing with the theme of origins of life, the universe, and traditions. Includes Web sites, videos, books, audio materials, and magazines with appropriate grade levels and/or subject disciplines indicated; professional resources; and learning activities. (LRW)

  4. Ocean acidification in the Meso- vs. Cenozoic: lessons from modeling about the geological expression of paleo-ocean acidification

    NASA Astrophysics Data System (ADS)

    Greene, S. E.; Ridgwell, A.; Kirtland Turner, S.

    2015-12-01

    Rapid climatic and biotic events putatively associated with ocean acidification are scattered throughout the Meso-Cenozoic. Many of these rapid perturbations, variably referred to as hyperthermals (Paleogene) and oceanic anoxic events or mass extinction events (Mesozoic), share a number of characteristic features, including some combination of negative carbon isotopic excursion, global warming, and a rise in atmospheric CO2 concentration. Comparisons between ocean acidification events over the last ~250 Ma are, however, problematic because the types of marine geological archives and carbon reservoirs that can be interrogated are fundamentally different for early Mesozoic vs. late Mesozoic-Cenozoic events. Many Mesozoic events are known primarily or exclusively from geological outcrops of relatively shallow water deposits, whereas the more recent Paleogene hyperthermal events have been chiefly identified from deep sea records. In addition, these earlier events are superimposed on an ocean with a fundamentally different carbonate buffering capacity, as calcifying plankton (which created the deep-sea carbonate sink) originate in the mid-Mesozoic. Here, we use both Earth system modeling and reaction transport sediment modeling to explore the ways in which comparable ocean acidification-inducing climate perturbations might manifest in the Mesozoic vs. the Cenozoic geological record. We examine the role of the deep-sea carbonate sink in the expression of ocean acidification, as well as the spatial heterogeneity of surface ocean pH and carbonate saturation state. These results critically inform interpretations of ocean acidification prior to the mid-Mesozoic advent of calcifying plankton and expectations about the recording of these events in geological outcrop.

  5. Terrestrial origin of viviparity in mesozoic marine reptiles indicated by early triassic embryonic fossils.

    PubMed

    Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

    2014-01-01

    Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction. PMID:24533127

  6. Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils

    PubMed Central

    Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

    2014-01-01

    Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction. PMID:24533127

  7. Source of oils in Gulf Coast Cenozoic reservoirs

    SciTech Connect

    Curtis, D.M. )

    1989-09-01

    Many Gulf Coast geologists have assumed that shales interbedded with or adjacent to the reservoir sandstones are source rocks for oils in Cenozoic reservoirs, but few source-rock quality shales have been identified in Cenozoic strata. Reservoirs and their associated shales are in thermally immature and organic-poor intervals. Based on geothermal gradient, age, and depth, it can be shown that thermally mature source rocks should be present in older slope shales beneath each producing trend. Assumptions regarding the source rock potential of the interbedded thermally immature shales derive from the fact that hydrocarbons migrated into traps soon after burial of the reservoir (early migration). Early migration from the source rock was therefore also assumed (shallow burial, early migration model). Review of the geochemical requirements for a source rock shows that geochemical constraints demand late migration from the source rock after many thousands of feet of burial (deep burial, late migration model). Geological and geochemical concepts are compatible, however, if migration out of the source rock was late (long after deposition and deep burial of the source rock) but migration into the reservoir was early (soon after shallow burial of the reservoir and trap system).

  8. Cenozoic diapiric traps in eastern China

    SciTech Connect

    Xie-Pei, W.; Qi, F.; Jia-Hua, Z.

    1985-12-01

    Diapiric traps, including diapirs of salt and mud or igneous intrusives, have recently been found in many places in the Cenozoic petroliferous basins in eastern China, and most of them produce oil and gas. During the Eocene-early Oligocene, salt-lake basins evolved extensively. Plastic source materials for diapirism were deposited in the basins in great thickness. We have found that the diapiric traps of salt and mud in eastern China are unpierced or slightly pierced structures. The diapiric materials are a mixture of salt, gypsum, and mudstone, but mudstone is the main component of the plastic bodies. Based on an analysis of the structural features of the diapirs and the regional tectonic setting, we believe that the diapiric traps are caused by a combination of horizontal stress due to regional tectonic movement and vertical stress due to gravitational instability. Some diabase diapirs are arranged in a series of small anticlinal traps along the regional faults in the Subei basin of Jiangsu province. Oil and gas have been found in certain of these diapirs. 16 figures.

  9. Relating Cenozoic North Sea sediments to topography in southern Norway: The interplay between tectonics and climate

    NASA Astrophysics Data System (ADS)

    Anell, Ingrid; Thybo, Hans; Stratford, Wanda

    2010-11-01

    About 482 000 km 3 of sediment (ca 24 m/Ma) accumulated in the North Sea during the Cenozoic. Early Cenozoic sedimentation was likely due to uplift of the circum North Atlantic landmasses related to continental break-up. Kilometre-scale transient uplift, and in some areas permanent uplift, generated sources for progradational influx of clastic sediments from Scotland, the Shetland platform and, to a lesser degree, southwestern Norway. The Eocene sedimentation pattern was similar to the Palaeocene, with lower rates of accumulation associated with flooding and tectonic quiescence. Sediment influx from the Shetland platform continued throughout the Cenozoic while supply from southern Norway increased markedly around the Eocene-Oligocene, coeval with the greenhouse-icehouse transition. Mass balance calculations of sediment and eroded rock volumes suggest that while some topography along the western margin of Norway may be pre-Cenozoic, significant uplift of the main Paleic surface in southern Norway occurred around the early Oligocene. Sedimentation rates were almost ten-fold higher than the Cenozoic average in the Plio-Pleistocene, slightly higher than the global average. Mass balance calculations indicate that Plio-Pleistocene erosion over-deepened a pre-existing topography.

  10. A stem batrachian from the Early Permian of Texas and the origin of frogs and salamanders.

    PubMed

    Anderson, Jason S; Reisz, Robert R; Scott, Diane; Fröbisch, Nadia B; Sumida, Stuart S

    2008-05-22

    The origin of extant amphibians (Lissamphibia: frogs, salamanders and caecilians) is one of the most controversial questions in vertebrate evolution, owing to large morphological and temporal gaps in the fossil record. Current discussions focus on three competing hypotheses: a monophyletic origin within either Temnospondyli or Lepospondyli, or a polyphyletic origin with frogs and salamanders arising among temnospondyls and caecilians among the lepospondyls. Recent molecular analyses are also controversial, with estimations for the batrachian (frog-salamander) divergence significantly older than the palaeontological evidence supports. Here we report the discovery of an amphibamid temnospondyl from the Early Permian of Texas that bridges the gap between other Palaeozoic amphibians and the earliest known salientians and caudatans from the Mesozoic. The presence of a mosaic of salientian and caudatan characters in this small fossil makes it a key taxon close to the batrachian (frog and salamander) divergence. Phylogenetic analysis suggests that the batrachian divergence occurred in the Middle Permian, rather than the late Carboniferous as recently estimated using molecular clocks, but the divergence with caecilians corresponds to the deep split between temnospondyls and lepospondyls, which is congruent with the molecular estimates. PMID:18497824

  11. Evidence for an Early Origin of Vernalization Responsiveness in Temperate Pooideae Grasses.

    PubMed

    McKeown, Meghan; Schubert, Marian; Marcussen, Thomas; Fjellheim, Siri; Preston, Jill C

    2016-09-01

    The ability of plants to match their reproductive output with favorable environmental conditions has major consequences both for lifetime fitness and geographic patterns of diversity. In temperate ecosystems, some plant species have evolved the ability to use winter nonfreezing cold (vernalization) as a cue to ready them for spring flowering. However, it is unknown how important the evolution of vernalization responsiveness has been for the colonization and subsequent diversification of taxa within the northern and southern temperate zones. Grasses of subfamily Pooideae, including several important crops, such as wheat (Triticum aestivum), barley (Hordeum vulgare), and oats (Avena sativa), predominate in the northern temperate zone, and it is hypothesized that their radiation was facilitated by the early evolution of vernalization responsiveness. Predictions of this early origin hypothesis are that a response to vernalization is widespread within the subfamily and that the genetic basis of this trait is conserved. To test these predictions, we determined and reconstructed vernalization responsiveness across Pooideae and compared expression of wheat vernalization gene orthologs VERNALIZATION1 (VRN1) and VRN3 in phylogenetically representative taxa under cold and control conditions. Our results demonstrate that vernalization responsive Pooideae species are widespread, suggesting that this trait evolved early in the lineage and that at least part of the vernalization gene network is conserved throughout the subfamily. These results are consistent with the hypothesis that the evolution of vernalization responsiveness was important for the initial transition of Pooideae out of the tropics and into the temperate zone. PMID:27474116

  12. Modern mammal origins: evolutionary grades in the Early Cretaceous of North America.

    PubMed

    Jacobs, L L; Winkler, D A; Murry, P A

    1989-07-01

    Major groups of modern mammals have their origins in the Mesozoic Era, yet the mammalian fossil record is generally poor for that time interval. Fundamental morphological changes that led to modern mammals are often represented by small samples of isolated teeth. Fortunately, functional wear facets on teeth allow prediction of the morphology of occluding teeth that may be unrepresented by fossils. A major step in mammalian evolution occurred in the Early Cretaceous with the evolution of tribosphenic molars, which characterize marsupials and placentals, the two most abundant and diverse extant groups of mammals. A tooth from the Early Cretaceous (110 million years before present) of Texas tests previous predictions (based on lower molars) of the morphology of upper molars in early tribosphenic dentitions. The lingual cusp (protocone) is primitively without shear facets, as expected, but the cheek side of the tooth is derived (advanced) in having distinctive cusps along the margin. The tooth, although distressingly inadequate to define many features of the organism, demonstrates unexpected morphological diversity at a strategic stage of mammalian evolution and falsifies previous claims of the earliest occurrence of true marsupials. PMID:2740336

  13. Modern mammal origins: evolutionary grades in the Early Cretaceous of North America.

    PubMed Central

    Jacobs, L L; Winkler, D A; Murry, P A

    1989-01-01

    Major groups of modern mammals have their origins in the Mesozoic Era, yet the mammalian fossil record is generally poor for that time interval. Fundamental morphological changes that led to modern mammals are often represented by small samples of isolated teeth. Fortunately, functional wear facets on teeth allow prediction of the morphology of occluding teeth that may be unrepresented by fossils. A major step in mammalian evolution occurred in the Early Cretaceous with the evolution of tribosphenic molars, which characterize marsupials and placentals, the two most abundant and diverse extant groups of mammals. A tooth from the Early Cretaceous (110 million years before present) of Texas tests previous predictions (based on lower molars) of the morphology of upper molars in early tribosphenic dentitions. The lingual cusp (protocone) is primitively without shear facets, as expected, but the cheek side of the tooth is derived (advanced) in having distinctive cusps along the margin. The tooth, although distressingly inadequate to define many features of the organism, demonstrates unexpected morphological diversity at a strategic stage of mammalian evolution and falsifies previous claims of the earliest occurrence of true marsupials. Images PMID:2740336

  14. Psychological Effects of Early versus Late Referral to the Vocational Rehabilitation Process: The Case of Mexican Origin Industrially Injured Workers.

    ERIC Educational Resources Information Center

    Fierro, Robert J.; Leal, Anita

    1988-01-01

    Sixty industrially injured workers of Mexican origin were examined to determine the psychological effects of early versus late referral to the California workers' compensation vocational rehabilitation system. Depression and dependency scores were significantly lower and self-esteem scores were higher for the early referral group compared to the…

  15. Cenozoic Motion of Greenland - Overlaps and Seaways

    NASA Astrophysics Data System (ADS)

    Lawver, L. A.; Norton, I. O.; Gahagan, L.

    2014-12-01

    Using the seafloor magnetic anomalies found in the Labrador Sea, North Atlantic and Eurasian basin to constrain the Cenozoic motion of Greenland, we have produced a new model for the tectonic evolution of the region. The aeromagnetic data collected by the Naval Research Lab [Brozena et al., 2003] in the Eurasian Basin and Canadian data from the Labrador Sea have been re-evaluated using new gridding algorithms and profile modeling using ModMag (Mendel et al., 2005). As a consequence, we have changed the published correlations, mostly prior to Chron C6 [19.05 Ma]. Presently published seafloor magnetic anomalies from the Labrador Sea assume that seafloor spreading ceased at C13 [33.06 Ma] but such an assumption produces an unacceptable overlap of Kronprins Christian Land of northeast Greenland with Svalbard, up to 140 km of overlap in some models. Our new model does not need any "unacceptable" overlap but does produce a slight amount of Eocene compression on Svalbard as is found on land there. Our model allows for an Early Eocene seaway between Ellesmere Island and northwest Greenland that may have connected the Labrador Sea through Baffin Bay and ultimately to the nascent Eurasian Basin, although its depth or even its essential existence is unknowable. During the Miocene, there is no room for a deepwater seaway in Fram Strait until at least the very end of the Early Miocene and perhaps not until Middle Miocene. Brozena, J. and six others, 2003. New aerogeophysical study of the Eurasia Basin and Lomonosov Ridge: Implications for basin development. Geology 31, 825-828. Mendel, V., M. Munschy and D.Sauter, 2005, MODMAG, a MATLAB program to model marine magnetic anomalies, Comp. Geosci., 31, .589-597

  16. Cenozoic erosion and flexural isostasy of Scandinavia

    NASA Astrophysics Data System (ADS)

    Gołędowski, Bartosz; Egholm, David L.; Nielsen, Søren B.; Clausen, Ole R.; McGregor, Eoin D.

    2013-10-01

    The presence of Cenozoic deposits along the Norwegian Atlantic margin required extensive erosion of the Scandinavian Mountains in a generally cooling climate from the Oligocene to the present. The volume of the deposits implies that the transfer of mass from the inland area to the offshore shelf induced isostatic displacements on a kilometer scale. However, except for glacial excavation of the deep fjords, little is known about the distribution of Cenozoic inland erosion. A long-lasting paradigm incorporates remnants of peneplains at high elevation and assumes very little Cenozoic erosion on these surfaces through time. This scenario has recently been challenged by quantitative geomorphological studies indicating that the matrix of Cenozoic sediments deposited offshore must have been sourced from these surfaces. An alternative explanation for the present-day high-elevation low-relief surfaces is therefore that they evolved throughout the Cenozoic because of glacial and periglacial erosion processes that are known to vary strongly with altitude. Here we explore the implications of the latter scenario by reconstructing a pre-Cenozoic fluvial landscape without elevated low-relief surfaces. We use the present-day offshore sediment volumes for constraining the total Cenozoic erosion, and we find that a likely pre-Cenozoic fluvial landscape is only in few places more than 1 km higher than today. The rock mass of the offshore sediments is generally used for filling the fjords created during the Quaternary glaciations and for restoring concave river profiles from sea level to the peaks. Our reconstruction is based on a fluvial landscape algorithm and considers the isostatic response to the transfer of rock mass - from the basins onto the onshore area. A comparison between the reconstructed and the present-day topography demonstrates that offshore tilting of pre-Cenozoic strata can be partly explained by flexural isostatic compensation in response to the Cenozoic erosion

  17. Early-type dwarf galaxies in clusters: A mixed bag with various origins?

    NASA Astrophysics Data System (ADS)

    Lisker, T.

    2009-12-01

    The formation of early-type dwarf (dE) galaxies, the most numerous objects in clusters, is believed to be closely connected to the physical processes that drive galaxy cluster evolution, like galaxy harassment and ram-pressure stripping. However, the actual significance of each mechanism for building the observed cluster dE population is yet unknown. Several distinct dE subclasses were identified, which show significant differences in their shape, stellar content, and distribution within the cluster. Does this diversity imply that dEs originate from various formation channels? Does ``cosmological'' formation play a role as well? I try to touch on these questions in this brief overview of dEs in galaxy clusters.

  18. The early origin of vertebral anomalies, as illustrated by a 'butterfly vertebra'.

    PubMed Central

    Müller, F; O'Rahilly, R; Benson, D R

    1986-01-01

    An anomalous (butterfly) eleventh thoracic vertebra in a fetus of 63 mm greatest length is described and graphic reconstructions (together with normal controls) are provided. The cartilaginous hemicentra are separated by disc-like material. Cartilaginous bars to adjacent vertebrae are present. The neural arch is complete. The notochord is not duplicated. Only one comparable case in the embryonic period has been described previously. After a discussion of cleft vertebrae in the human and in experimental animals, a developmental timetable of the appearance of several vertebral anomalies is provided. The sensitive period for butterfly vertebrae, depending on the mode of origin, seems to be 3-6 postovulatory weeks. More severe anomalies, such as the split notochord syndrome, appear earlier. It is concluded that most of the vertebral anomalies discussed arise during the embryonic period proper, although the timing of a few, such as spina bifida occulta, extends into the early fetal period. Images Fig. 1 Fig. 3 Fig. 5 PMID:3693103

  19. Cenozoic Methane-Seep Faunas of the Caribbean Region.

    PubMed

    Kiel, Steffen; Hansen, Bent T

    2015-01-01

    We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted 'Joes River fauna' consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted 'Bath Cliffs fauna' containing the vesicomyid Pleurophopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pegophysema). In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godineau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman's Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical 'Cenozoic' lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large lucinids because they

  20. Insulin use early in the course of type 2 diabetes mellitus: the ORIGIN trial.

    PubMed

    Hanefeld, Markolf; Bramlage, Peter

    2013-06-01

    There has been a recent shift from a uniform treatment targeting HbA1c to a patient centered approach due to disappointing results of intensified glucose control in mega-trials such as VADT, ADVANCE, and ACCORD. In addition, morbidity and mortality has been substantially reduced since the UKPDS leading to an overestimation of the absolute risk for cardiovascular complications in randomized controlled trials. With substantial progress in prevention of cardiovascular complications, patients with type 2 diabetes now survive long enough to face diabetes-related complications and cancer risk. This requires rethinking of antidiabetic treatment strategies as exemplified by a recent consensus statement of the EASD and ADA, calling for a more patient centered treatment. Within this context the value of early insulin initiation was reinforced, the clinical utility of which has been demonstrated in the recent ORIGIN trial. ORIGIN demonstrated neutral results for the primary endpoint, but reduced microangiopathy in patients with an HbA1c value of ≥6.4 % with basal insulin glargine. After 5 years of follow-up 77 % of the patients in the glargine arm and 66 % with standard care remained at an HbA1c <7 %. An ongoing long-term follow-up (ORIGINALE) will clarify whether this also translates into a reduction of macrovascular events and mortality. PMID:23397557

  1. The early life origin theory in the development of cardiovascular disease and type 2 diabetes.

    PubMed

    Lindblom, Runa; Ververis, Katherine; Tortorella, Stephanie M; Karagiannis, Tom C

    2015-04-01

    Life expectancy has been examined from a variety of perspectives in recent history. Epidemiology is one perspective which examines causes of morbidity and mortality at the population level. Over the past few 100 years there have been dramatic shifts in the major causes of death and expected life length. This change has suffered from inconsistency across time and space with vast inequalities observed between population groups. In current focus is the challenge of rising non-communicable diseases (NCD), such as cardiovascular disease and type 2 diabetes mellitus. In the search to discover methods to combat the rising incidence of these diseases, a number of new theories on the development of morbidity have arisen. A pertinent example is the hypothesis published by David Barker in 1995 which postulates the prenatal and early developmental origin of adult onset disease, and highlights the importance of the maternal environment. This theory has been subject to criticism however it has gradually gained acceptance. In addition, the relatively new field of epigenetics is contributing evidence in support of the theory. This review aims to explore the implication and limitations of the developmental origin hypothesis, via an historical perspective, in order to enhance understanding of the increasing incidence of NCDs, and facilitate an improvement in planning public health policy. PMID:25270249

  2. On the origin and early evolution of biological catalysis and other studies on chemical evolution

    NASA Technical Reports Server (NTRS)

    Oro, J.; Lazcano, A.

    1991-01-01

    One of the lines of research in molecular evolution which we have developed for the past three years is related to the experimental and theoretical study of the origin and early evolution of biological catalysis. In an attempt to understand the nature of the first peptidic catalysts and coenzymes, we have achieved the non-enzymatic synthesis of the coenzymes ADPG, GDPG, and CDP-ethanolamine, under conditions considered to have been prevalent on the primitive Earth. We have also accomplished the prebiotic synthesis of histidine, as well as histidyl-histidine, and we have measured the enhancing effects of this catalytic dipeptide on the dephosphorylation of deoxyribonucleotide monophosphates, the hydrolysis of oligo A, and the oligomerization 2', 3' cAMP. We reviewed and further developed the hypothesis that RNA preceded double stranded DNA molecules as a reservoir of cellular genetic information. This led us to undertake the study of extant RNA polymerases in an attempt to discover vestigial sequences preserved from early Archean times. In addition, we continued our studies of on the chemical evolution of organic compounds in the solar system and beyond.

  3. Antarctic Peninsula Ice Sheet evolution during the Cenozoic Era

    NASA Astrophysics Data System (ADS)

    Davies, Bethan J.; Hambrey, Michael J.; Smellie, John L.; Carrivick, Jonathan L.; Glasser, Neil F.

    2012-01-01

    The Antarctic Peninsula region is currently undergoing rapid environmental change, resulting in the thinning, acceleration and recession of glaciers and the sequential collapse of ice shelves. It is important to view these changes in the context of long-term palaeoenvironmental complexity and to understand the key processes controlling ice sheet growth and recession. In addition, numerical ice sheet models require detailed geological data for tuning and testing. Therefore, this paper systematically and holistically reviews published geological evidence for Antarctic Peninsula Ice Sheet variability for each key locality throughout the Cenozoic, and brings together the prevailing consensus of the extent, character and behaviour of the glaciations of the Antarctic Peninsula region. Major contributions include a downloadable database of 186 terrestrial and marine calibrated dates; an original reconstruction of the LGM ice sheet; and a new series of isochrones detailing ice sheet retreat following the LGM. Glaciation of Antarctica was initiated around the Eocene/Oligocene transition in East Antarctica. Palaeogene records of Antarctic Peninsula glaciation are primarily restricted to King George Island, where glacigenic sediments provide a record of early East Antarctic glaciations, but with modification of far-travelled erratics by local South Shetland Island ice caps. Evidence for Neogene glaciation is derived primarily from King George Island and James Ross Island, where glaciovolcanic strata indicate that ice thicknesses reached 500-850 m during glacials. This suggests that the Antarctic Peninsula Ice Sheet draped, rather than drowned, the topography. Marine geophysical investigations indicate multiple ice sheet advances during this time. Seismic profiling of continental shelf-slope deposits indicates up to ten large advances of the Antarctic Peninsula Ice Sheet during the Early Pleistocene, when the ice sheet was dominated by 40 kyr cycles. Glacials became more

  4. Mesozoic Cenozoic history of the Congo Basin

    NASA Astrophysics Data System (ADS)

    Giresse, Pierre

    2005-10-01

    Geophysical surveys and drilling of deep wells have recently led to the recognition of underlying Precambrian basement, and to an interpretation of the structural evolution of the Congo Basin. Deformation estimated as Late Cambrian to Early Ordovician corresponds to the late Pan-African event more accurately dated as end-early Cambrian in West Africa. Subsequently, Paleozoic deformation led to widespread erosion and the development of a marked regional unconformity. The 1000-m-thick mostly continental deposition during the Cretaceous and Tertiary did not involve a noticeable subsidence process. There was no volcanism during this deposition, except at the Early Cretaceous, with the advent of kimberlites that are distributed over the border of the Cuvette. As a consequence most of the diamonds were transported northward or southward from upstream sources. The Mesozoic sediments of the Congo Basin were formed in lacustrine or lagoonal basins close to the sea level as demonstrated by some intercalations with marine fossils. In the eastern part of the basin, a limited marine connection during the Kimmeridgian was only possible with a gulf belonging to the young Indian Ocean. In southern Kasai, the same Kimmeridgian transgression is observed. In the northern part of the basin, a probable Cenomanian marine connection was suggested between the Tethys and the South Atlantic, and the marine deposition at Kipala suggests a connection with the Trans-Saharan corridor during the Late Cretaceous. The geometry of the continental Mesozoic and Cenozoic deposits begins with beds overlying a widespread planation level unconformity and/or the presence of gravel or conglomerate in the lower portion. The Sables Ocres Series and the Grès Polymorphes Series rest on the planation levels of Late Cretaceous and mid-Tertiary ages respectively. Mechanical composition and morphoscopic characters argue for a dominant eolian transport for the Grès Polymorphes and for a fluvial deposition for the

  5. The origin and early evolution of metatherian mammals: the Cretaceous record

    PubMed Central

    Williamson, Thomas E.; Brusatte, Stephen L.; Wilson, Gregory P.

    2014-01-01

    Abstract Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new analytical tools. Here we provide a review of the phylogenetic relationships of metatherians with respect to other mammals, discuss the taxonomic definition and diagnosis of Metatheria, outline the Cretaceous history of major metatherian clades, describe the paleobiology, biogeography, and macroevolution of Cretaceous metatherians, and provide a physical and climatic background of Cretaceous metatherian faunas. Metatherians are a clade of boreosphendian mammals that must have originated by the Late Jurassic, but the first unequivocal metatherian fossil is from the Early Cretaceous of Asia. Metatherians have the distinctive tightly interlocking occlusal molar pattern of tribosphenic mammals, but differ from Eutheria in their dental formula and tooth replacement pattern, which may be related to the metatherian reproductive process which includes an extended period of lactation followed by birth of extremely altricial young. Metatherians were widespread over Laurasia during the Cretaceous, with members present in Asia, Europe, and North America by the early Late Cretaceous. In particular, they were taxonomically and morphologically diverse and relatively abundant in the Late Cretaceous of western North America, where they have been used to examine patterns of biogeography, macroevolution, diversification, and extinction through the Late Cretaceous and across the Cretaceous-Paleogene (K-Pg) boundary. Metatherian diversification patterns suggest that they were not strongly affected by a Cretaceous Terrestrial Revolution, but they clearly underwent a severe extinction across the K-Pg boundary. PMID:25589872

  6. The SSC dipole: Its conceptual origin and early design history. Revision 1

    SciTech Connect

    Dahl, P.F.

    1992-05-01

    The magnet system for the Superconducting Super Collider will likely remain the most ambitions-and challenging-application of superconducting technology for the foreseeable future. The centerpiece of the system is the behemoth collider dipole magnet. Its design, still evolving in its detailed features, dates from the mid-1980`s when it emerged as the winter in an early technical showdown that occupied the fledgling SSC project. In the present report we chronicle the origins and chief milestones in the development of certain SSC dipole design concepts. Unfortunately, the chronicle must remain incomplete, with the design not yet frozen as we go to press and still subject to important modifications as the SSC Laboratory settles in near its future home in Ellis County, Texas, hard on the heels of a wide-ranging design review in the closing days of the SSC Central Design Group in (CDG) Berkeley. Be that as it may, in what follows we concentrate on the early years in an attempt to recapitulate the birth of the dipole, taking as our point of departure the SSC Reference Designs Study (RDS) of 1984. In Section 3 we touch on the background for the various RDS options, including ISABELLE/CBA and the Tevatron. In Section 4 the narrative focuses on the two final protagonists, a high-field cosine theta (cos {theta}) magnet and a low-field superferric magnet. Section 5 recounts the circumstances surrounding the selection of a particular magnet ``style`` for further development, and the ups and downs of the first model magnets. We conclude with a smattering of progress highlights in refining the design during the final push under the reign of the CDG. Beyond that, the ongoing chronicle must be left for others to amplify and complete.

  7. The origin and early evolution of metatherian mammals: the Cretaceous record.

    PubMed

    Williamson, Thomas E; Brusatte, Stephen L; Wilson, Gregory P

    2014-01-01

    Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new analytical tools. Here we provide a review of the phylogenetic relationships of metatherians with respect to other mammals, discuss the taxonomic definition and diagnosis of Metatheria, outline the Cretaceous history of major metatherian clades, describe the paleobiology, biogeography, and macroevolution of Cretaceous metatherians, and provide a physical and climatic background of Cretaceous metatherian faunas. Metatherians are a clade of boreosphendian mammals that must have originated by the Late Jurassic, but the first unequivocal metatherian fossil is from the Early Cretaceous of Asia. Metatherians have the distinctive tightly interlocking occlusal molar pattern of tribosphenic mammals, but differ from Eutheria in their dental formula and tooth replacement pattern, which may be related to the metatherian reproductive process which includes an extended period of lactation followed by birth of extremely altricial young. Metatherians were widespread over Laurasia during the Cretaceous, with members present in Asia, Europe, and North America by the early Late Cretaceous. In particular, they were taxonomically and morphologically diverse and relatively abundant in the Late Cretaceous of western North America, where they have been used to examine patterns of biogeography, macroevolution, diversification, and extinction through the Late Cretaceous and across the Cretaceous-Paleogene (K-Pg) boundary. Metatherian diversification patterns suggest that they were not strongly affected by a Cretaceous Terrestrial Revolution, but they clearly underwent a severe extinction across the K-Pg boundary. PMID:25589872

  8. Cenozoic stratigraphic evolution, North Sea and Labrador Sea

    SciTech Connect

    Gradstein, F.M.; Grant, A.C.; Mudford, B.S. ); Berggren, W.A. ); Kaminski, M.A. ); D'Lorio, M.A. ); Cloetingh, S. ); Griffiths, C.M. )

    1990-05-01

    The authors are studying Cenozoic correlation patterns, burial trends, and subsidence history of the Central North Sea, Labrador, and Orphan basins. The authors objectives are (1) to detail intraregional mid-high latitude biozonations using noise filtering and probabilistic zonation techniques; (2) to detail paleobathymetric trends from basin margins to centers; (3) to apply this knowledge to model basin evolution, in the perspective of the evolving North Atlantic Ocean; (4) to evaluate causes for the occurrence of major hiatuses and rapid changes of subsidence; and (5) to relate rapid changes in sedimentation in the last few millions of years to model observed undercompaction trends. Cenozoic microfossil assemblages in these basins are similar, related to similarities in sedimentary and paleoeceanographic conditions. In more basinal wells, flysch-type agglutinated foraminiferal assemblages occur, also known from Carpathians, Trinidad, and Moroccan foredeeps. Over 90% of agglutinated taxa are common between these basins, although local stratigraphic ranges vary sufficiently to rely on the concept of average ranges, rather than total ones for correlations. Cenozoic stratigraphic resolution in the North Sea and Labrador basins generally is in 3-5-Ma units. and paleobathymetric zonations define a minimum of five niches, from inner shelf to middle slope regimes. Significant hiatuses occurred in the late Eocene through the Miocene, particularly in northern Labrador and northern North Sea. Subsidence in the Labrador/Grand Banks passive margin half grabens was strongly influenced by Labrador Sea opening between anomalies 34 (Campanian) and 13 (early Oligocene), when subsidence exceeded sedimentation and bathyal conditions prevailed along the margin. Thermally induced subsidence in the central North Sea grabens was considerable in the late Paleocene, when the Norwegian Sea started to open.

  9. Records of our Early Biosphere Illuminate our Origins and Guide our Search for Life Beyond Earth

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.

    2003-01-01

    A scientific "mission of exploration to early Earth" will help us chart the distribution of life elsewhere. We must discriminate between attributes of biospheres that are universal versus those attributes that represent principally the outcomes of long-term survival specifically on Earth. In addition to the basic physics and chemistry of matter, the geologic evolution of rocky habitable planets and their climates might be similar elsewhere in the Universe. Certain key agents that drive long-term environmental change (e.g., stellar evolution, impacts, geothermal heat flow, tectonics, etc.) can help us to reconstruct ancient climates and to compare their evolution among populations of Earth- like planets. Early Earth was tectonically more active than today and therefore it exhaled reduced chemical species into the more oxidized surface environment at greater rates. This tectonic activity thus sustained oxidation-reduction reactions that provided the basis for the development of biochemical pathways that harvest chemical energy ("bioenergetics"). Most examples of bioenergetics today that extract energy by reacting oxidized and reduced chemicals in the environment were likely more pervasive among our microbial ancestors than are the presently known examples of photosynthesis. The geologic rock record indicates that, as early as 3.5 billion years ago (3.5 Ga), microbial biofilms were widespread within the coastal environments of small continents and tectonically unstable volcanic islands. Non oxygen-producing (non-oxygenic) photosynthesis preceded oxygenic photosynthesis, but all types of photosynthesis contributed substantially to the long-term increase in global primary biological productivity. Evidence of photosynthesis is tentative by 3.5 Ga and compelling by 2.7 Ga. Evidence of oxygenic photosynthesis is strong by 2.7 Ga and compelling by 2.3 Ga. These successive innovations transformed life from local communities that survived principally by catalyzing chemical

  10. Records of our Early Biosphere Illuminate our Origins and Guide our Search for Life beyond Earth

    NASA Astrophysics Data System (ADS)

    Des Marais, D. J.

    2003-12-01

    A scientific "mission of exploration to early Earth" will help us chart the distribution of life elsewhere. We must discriminate between attributes of biospheres that are universal versus those attributes that represent principally the outcomes of long-term survival specifically on Earth. In addition to the basic physics and chemistry of matter, the geologic evolution of rocky habitable planets and their climates might be similar elsewhere in the Universe. Certain key agents that drive long-term environmental change (e.g., stellar evolution, impacts, geothermal heat flow, tectonics, etc.) can help us to reconstruct ancient climates and to compare their evolution among populations of Earth-like planets. Early Earth was tectonically more active than today and therefore it exhaled reduced chemical species into the more oxidized surface environment at greater rates. This tectonic activity thus sustained oxidation-reduction reactions that provided the basis for the development of biochemical pathways that harvest chemical energy ("bioenergetics"). Most examples of bioenergetics today that extract energy by reacting oxidized and reduced chemicals in the environment were likely more pervasive among our microbial ancestors than are the presently known examples of photosynthesis. The geologic rock record indicates that, as early as 3.5 billion years ago (3.5 Ga), microbial biofilms were widespread within the coastal environments of small continents and tectonically unstable volcanic islands. Non oxygen-producing (non-oxygenic) photosynthesis preceded oxygenic photosynthesis, but all types of photosynthesis contributed substantially to the long-term increase in global primary biological productivity. Evidence of photosynthesis is tentative by 3.5 Ga and compelling by 2.7 Ga. Evidence of oxygenic photosynthesis is strong by 2.7 Ga and compelling by 2.3 Ga. These successive innovations transformed life from local communities that survived principally by catalyzing chemical

  11. Early turbulent mixing as the origin of chemical homogeneity in open star clusters.

    PubMed

    Feng, Yi; Krumholz, Mark R

    2014-09-25

    The abundances of elements in stars are critical clues to stars' origins. Observed star-to-star variations in logarithmic abundance within an open star cluster--a gravitationally bound ensemble of stars in the Galactic plane--are typically only about 0.01 to 0.05 over many elements, which is noticeably smaller than the variation of about 0.06 to 0.3 seen in the interstellar medium from which the stars form. It is unknown why star clusters are so homogenous, and whether homogeneity should also prevail in regions of lower star formation efficiency that do not produce bound clusters. Here we report simulations that trace the mixing of chemical elements as star-forming clouds assemble and collapse. We show that turbulent mixing during cloud assembly naturally produces a stellar abundance scatter at least five times smaller than that in the gas, which is sufficient to explain the observed chemical homogeneity of stars. Moreover, mixing occurs very early, so that regions with star formation efficiencies of about 10 per cent are nearly as well mixed as those with formation efficiencies of about 50 per cent. This implies that even regions that do not form bound clusters are likely to be well mixed, and improves the prospects of using 'chemical tagging' to reconstruct (via their unique chemical signatures, or tags) star clusters whose constituent stars have become unbound from one another and spread across the Galactic disk. PMID:25174709

  12. Domestication and early agriculture in the Mediterranean Basin: Origins, diffusion, and impact

    PubMed Central

    Zeder, Melinda A.

    2008-01-01

    The past decade has witnessed a quantum leap in our understanding of the origins, diffusion, and impact of early agriculture in the Mediterranean Basin. In large measure these advances are attributable to new methods for documenting domestication in plants and animals. The initial steps toward plant and animal domestication in the Eastern Mediterranean can now be pushed back to the 12th millennium cal B.P. Evidence for herd management and crop cultivation appears at least 1,000 years earlier than the morphological changes traditionally used to document domestication. Different species seem to have been domesticated in different parts of the Fertile Crescent, with genetic analyses detecting multiple domestic lineages for each species. Recent evidence suggests that the expansion of domesticates and agricultural economies across the Mediterranean was accomplished by several waves of seafaring colonists who established coastal farming enclaves around the Mediterranean Basin. This process also involved the adoption of domesticates and domestic technologies by indigenous populations and the local domestication of some endemic species. Human environmental impacts are seen in the complete replacement of endemic island faunas by imported mainland fauna and in today's anthropogenic, but threatened, Mediterranean landscapes where sustainable agricultural practices have helped maintain high biodiversity since the Neolithic. PMID:18697943

  13. Early gas stripping as the origin of the darkest galaxies in the Universe.

    PubMed

    Mayer, L; Kazantzidis, S; Mastropietro, C; Wadsley, J

    2007-02-15

    The known galaxies most dominated by dark matter (Draco, Ursa Minor and Andromeda IX) are satellites of the Milky Way and the Andromeda galaxies. They are members of a class of faint galaxies, devoid of gas, known as dwarf spheroidals, and have by far the highest ratio of dark to luminous matter. None of the models proposed to unravel their origin can simultaneously explain their exceptional dark matter content and their proximity to a much larger galaxy. Here we report simulations showing that the progenitors of these galaxies were probably gas-dominated dwarf galaxies that became satellites of a larger galaxy earlier than the other dwarf spheroidals. We find that a combination of tidal shocks and ram pressure swept away the entire gas content of such progenitors about ten billion years ago because heating by the cosmic ultraviolet background kept the gas loosely bound: a tiny stellar component embedded in a relatively massive dark halo survived until today. All luminous galaxies should be surrounded by a few extremely dark-matter-dominated dwarf spheroidal satellites, and these should have the shortest orbital periods among dwarf spheroidals because they were accreted early. PMID:17301786

  14. Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

    PubMed Central

    Antonelli, Michael A.; Kim, Sang-Tae; Peters, Marc; Labidi, Jabrane; Cartigny, Pierre; Walker, Richard J.; Lyons, James R.; Hoek, Joost; Farquhar, James

    2014-01-01

    Achondrite meteorites have anomalous enrichments in 33S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying 33S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the 33S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous 33S depletions in IIIF iron meteorites (<−0.02 per mil), and 33S enrichments in other magmatic iron meteorite groups. The 33S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content. PMID:25453079

  15. Phylogeny of Dissimilatory Sulfite Reductases Supports an Early Origin of Sulfate Respiration

    PubMed Central

    Wagner, Michael; Roger, Andrew J.; Flax, Jodi L.; Brusseau, Gregory A.; Stahl, David A.

    1998-01-01

    Microorganisms that use sulfate as a terminal electron acceptor for anaerobic respiration play a central role in the global sulfur cycle. Here, we report the results of comparative sequence analysis of dissimilatory sulfite reductase (DSR) genes from closely and distantly related sulfate-reducing organisms to infer the evolutionary history of DSR. A 1.9-kb DNA region encoding most of the α and β subunits of DSR could be recovered only from organisms capable of dissimilatory sulfate reduction with a PCR primer set targeting highly conserved regions in these genes. All DNA sequences obtained were highly similar to one another (49 to 89% identity), and their inferred evolutionary relationships were nearly identical to those inferred on the basis of 16S rRNA. We conclude that the high similarity of bacterial and archaeal DSRs reflects their common origin from a conserved DSR. This ancestral DSR was either present before the split between the domains Bacteria, Archaea, and Eucarya or laterally transferred between Bacteria and Archaea soon after domain divergence. Thus, if the physiological role of the DSR was constant over time, then early ancestors of Bacteria and Archaea already possessed a key enzyme of sulfate and sulfite respiration. PMID:9603890

  16. Early Gas Stripping as the Origin of the Darkest Galaxies in the Universe

    SciTech Connect

    Mayer, Lucio; Kazantzidis, Stelios; Mastropietro, Chiara; Wadsley, James; /McMaster U.

    2007-02-28

    The known galaxies most dominated by dark matter (Draco, Ursa Minor and Andromeda IX) are satellites of the Milky Way and the Andromeda galaxies. They are members of a class of faint galaxies, devoid of gas, known as dwarf spheroidals, and have by far the highest ratio of dark to luminous matter. None of the models proposed to unravel their origin can simultaneously explain their exceptional dark matter content and their proximity to a much larger galaxy. Here we report simulations showing that the progenitors of these galaxies were probably gas-dominated dwarf galaxies that became satellites of a larger galaxy earlier than the other dwarf spheroidals. We find that a combination of tidal shocks and ram pressure swept away the entire gas content of such progenitors about ten billion years ago because heating by the cosmic ultraviolet background kept the gas loosely bound: a tiny stellar component embedded in a relatively massive dark halo survived until today. All luminous galaxies should be surrounded by a few extremely dark-matter-dominated dwarf spheroidal satellites, and these should have the shortest orbital periods among dwarf spheroidals because they were accreted early.

  17. Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets.

    PubMed

    Antonelli, Michael A; Kim, Sang-Tae; Peters, Marc; Labidi, Jabrane; Cartigny, Pierre; Walker, Richard J; Lyons, James R; Hoek, Joost; Farquhar, James

    2014-12-16

    Achondrite meteorites have anomalous enrichments in (33)S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying (33)S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the (33)S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous (33)S depletions in IIIF iron meteorites (<-0.02 per mil), and (33)S enrichments in other magmatic iron meteorite groups. The (33)S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content. PMID:25453079

  18. Ethnic Identity Trajectories among Mexican-Origin Girls during Early and Middle Adolescence: Predicting Future Psychosocial Adjustment

    ERIC Educational Resources Information Center

    Gonzales-Backen, Melinda A.; Bámaca-Colbert, Mayra Y.; Allen, Kimberly

    2016-01-01

    We examined trajectories of ethnic identity exploration, resolution, and affirmation and their associations with depressive symptoms and self-esteem 3.5 years later among early and middle adolescent Mexican-origin girls (N = 338). Findings indicated that exploration, resolution, and affirmation increased over time for both cohorts. Among early…

  19. Herbert T. Coutts and the Origins, Early Development, and Possible Future Directions of the Alberta Journal of Educational Research.

    ERIC Educational Resources Information Center

    Buck, George H.

    1994-01-01

    Herbert Coutts, dean of the University of Alberta faculty of education when the "Alberta Journal of Educational Research" was established in 1955, recalls the origins of the journal and early struggles to maintain its scholarly orientation. The journal filled a need for a Canadian-based scholarly journal devoted to educational research, and…

  20. Episodic Cenozoic volcanism and tectonism in the Andes of Peru

    USGS Publications Warehouse

    Noble, D.C.; McKee, E.H.; Farrar, E.; Petersen, U.

    1974-01-01

    Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise. ?? 1974.

  1. Cenozoic tectonic evolution of Asia: A preliminary synthesis

    NASA Astrophysics Data System (ADS)

    Yin, An

    2010-06-01

    Asia has been a major testing ground for various competing models of continental deformation due to its relatively well-understood plate boundary conditions in the Cenozoic, exceptional exposure of active structures, and strain distribution, and widespread syn-collisional igneous activity as a proxy for the thermal state of the mantle and crust. Two Cenozoic orogens dominate the continent: the Himalayan-Tibetan orogen in the east induced by the India-Asia collision and the Turkish-Iranian-Caucasus orogen in the west induced by the Arabia-Asia collision. The development of the two orogens was accomplished by shortening in the early stage followed by strike-slip faulting and extension in the late stage. In the Himalayan-Tibetan orogen, shortening across two discrete thrust belts at 55-30 Ma in southern and northern Tibet created a large intracontinental basin (the Paleo-Qaidam basin) in between. Subsequent crustal thickening and a possible thermal event in the mantle (e.g., convective removal of central Tibetan mantle lithosphere) may have raised the elevation of this early intra-plateau basin up to ~ 2-3 km to its current height. Collision between India and Asia also caused lateral extrusion of southeast Asia between 32 Ma and 17 Ma. The latest stage of the India-Asia collision was expressed by north-trending rifting and the development of trench-facing V-shaped conjugate strike-slip faults in central Mongolia, central Tibet, eastern Afghanistan and southeast Asia. In the Turkish-Iranian-Caucasus orogen, early crustal thickening in the orogenic interior began at or prior to 30-20 Ma. This style of deformation was replaced by strike-slip faulting at ~ 15-5 Ma associated with further northward penetration of Arabia into Asia, westward extrusion of the Anatolia/Turkey block, and rapid extension across the Sea of Crete and Sea of Aegean. The late stage extension in both orogens was locally related to extensional core-complex development. The continental-margin extension

  2. A Cenozoic record of the equatorial Pacific carbonate compensation depth.

    PubMed

    Pälike, Heiko; Lyle, Mitchell W; Nishi, Hiroshi; Raffi, Isabella; Ridgwell, Andy; Gamage, Kusali; Klaus, Adam; Acton, Gary; Anderson, Louise; Backman, Jan; Baldauf, Jack; Beltran, Catherine; Bohaty, Steven M; Bown, Paul; Busch, William; Channell, Jim E T; Chun, Cecily O J; Delaney, Margaret; Dewangan, Pawan; Dunkley Jones, Tom; Edgar, Kirsty M; Evans, Helen; Fitch, Peter; Foster, Gavin L; Gussone, Nikolaus; Hasegawa, Hitoshi; Hathorne, Ed C; Hayashi, Hiroki; Herrle, Jens O; Holbourn, Ann; Hovan, Steve; Hyeong, Kiseong; Iijima, Koichi; Ito, Takashi; Kamikuri, Shin-ichi; Kimoto, Katsunori; Kuroda, Junichiro; Leon-Rodriguez, Lizette; Malinverno, Alberto; Moore, Ted C; Murphy, Brandon H; Murphy, Daniel P; Nakamura, Hideto; Ogane, Kaoru; Ohneiser, Christian; Richter, Carl; Robinson, Rebecca; Rohling, Eelco J; Romero, Oscar; Sawada, Ken; Scher, Howie; Schneider, Leah; Sluijs, Appy; Takata, Hiroyuki; Tian, Jun; Tsujimoto, Akira; Wade, Bridget S; Westerhold, Thomas; Wilkens, Roy; Williams, Trevor; Wilson, Paul A; Yamamoto, Yuhji; Yamamoto, Shinya; Yamazaki, Toshitsugu; Zeebe, Richard E

    2012-08-30

    Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth. PMID:22932385

  3. Extracellular Vesicles Originate from the Conceptus and Uterus During Early Pregnancy in Sheep.

    PubMed

    Burns, Gregory W; Brooks, Kelsey E; Spencer, Thomas E

    2016-03-01

    Cells release diverse types of membrane-bound vesicles of endosomal and plasma membrane origin, termed exosomes and microvesicles, respectively. Extracellular vesicles (EVs) represent an important mode of intercellular communication by transferring select RNAs, proteins, and lipids between cells. The present studies tested the hypothesis that the elongating ovine conceptus and uterus produces EVs that mediate conceptus-maternal interactions during early pregnancy. In Study 1, EVs were purified from uterine luminal fluid of Day 14 cyclic sheep. The EVs were fluorescently labeled with PKH67 dye and infused into the uterine lumen of pregnant sheep for 6 days using an osmotic pump. On Day 14, labeled EVs were observed in the conceptus trophectoderm and uterine epithelia, but not in the uterine stroma or myometrium. In Study 2, Day 14 conceptuses were cultured ex vivo for 24 h and found to release EVs into the culture medium. Proteomics analysis of the Day 14 conceptus-derived EVs identified 231 proteins that were enriched for extracellular space and several protein classes, including proteases, protease inhibitors, chaperones and chaperonins. RNA sequencing of Day 14 conceptus-derived EVs detected expression of 512 mRNAs. The top-expressed genes were overrepresented in ribosomal functions and components. Isolated EVs from conceptuses were fluorescently labeled with PKH67 and infused into the uterine lumen of cyclic sheep for 6 days using an osmotic pump. On Day 14, labeled EVs were observed in the uterine epithelia, but not in the uterine stroma or myometrium. Labeled EVs were not observed in the ovary or in other maternal tissues. These studies support the ideas that EVs emanate from both the conceptus trophectoderm and uterine epithelia, and are involved in intercellular communication between those cells during the establishment of pregnancy in sheep. PMID:26819476

  4. Phylotranscriptomic analysis of the origin and early diversification of land plants.

    PubMed

    Wickett, Norman J; Mirarab, Siavash; Nguyen, Nam; Warnow, Tandy; Carpenter, Eric; Matasci, Naim; Ayyampalayam, Saravanaraj; Barker, Michael S; Burleigh, J Gordon; Gitzendanner, Matthew A; Ruhfel, Brad R; Wafula, Eric; Der, Joshua P; Graham, Sean W; Mathews, Sarah; Melkonian, Michael; Soltis, Douglas E; Soltis, Pamela S; Miles, Nicholas W; Rothfels, Carl J; Pokorny, Lisa; Shaw, A Jonathan; DeGironimo, Lisa; Stevenson, Dennis W; Surek, Barbara; Villarreal, Juan Carlos; Roure, Béatrice; Philippe, Hervé; dePamphilis, Claude W; Chen, Tao; Deyholos, Michael K; Baucom, Regina S; Kutchan, Toni M; Augustin, Megan M; Wang, Jun; Zhang, Yong; Tian, Zhijian; Yan, Zhixiang; Wu, Xiaolei; Sun, Xiao; Wong, Gane Ka-Shu; Leebens-Mack, James

    2014-11-11

    Reconstructing the origin and evolution of land plants and their algal relatives is a fundamental problem in plant phylogenetics, and is essential for understanding how critical adaptations arose, including the embryo, vascular tissue, seeds, and flowers. Despite advances in molecular systematics, some hypotheses of relationships remain weakly resolved. Inferring deep phylogenies with bouts of rapid diversification can be problematic; however, genome-scale data should significantly increase the number of informative characters for analyses. Recent phylogenomic reconstructions focused on the major divergences of plants have resulted in promising but inconsistent results. One limitation is sparse taxon sampling, likely resulting from the difficulty and cost of data generation. To address this limitation, transcriptome data for 92 streptophyte taxa were generated and analyzed along with 11 published plant genome sequences. Phylogenetic reconstructions were conducted using up to 852 nuclear genes and 1,701,170 aligned sites. Sixty-nine analyses were performed to test the robustness of phylogenetic inferences to permutations of the data matrix or to phylogenetic method, including supermatrix, supertree, and coalescent-based approaches, maximum-likelihood and Bayesian methods, partitioned and unpartitioned analyses, and amino acid versus DNA alignments. Among other results, we find robust support for a sister-group relationship between land plants and one group of streptophyte green algae, the Zygnematophyceae. Strong and robust support for a clade comprising liverworts and mosses is inconsistent with a widely accepted view of early land plant evolution, and suggests that phylogenetic hypotheses used to understand the evolution of fundamental plant traits should be reevaluated. PMID:25355905

  5. Phylotranscriptomic analysis of the origin and early diversification of land plants

    PubMed Central

    Wickett, Norman J.; Mirarab, Siavash; Nguyen, Nam; Warnow, Tandy; Carpenter, Eric; Matasci, Naim; Ayyampalayam, Saravanaraj; Barker, Michael S.; Burleigh, J. Gordon; Gitzendanner, Matthew A.; Ruhfel, Brad R.; Wafula, Eric; Graham, Sean W.; Mathews, Sarah; Melkonian, Michael; Soltis, Douglas E.; Soltis, Pamela S.; Miles, Nicholas W.; Rothfels, Carl J.; Pokorny, Lisa; Shaw, A. Jonathan; DeGironimo, Lisa; Stevenson, Dennis W.; Surek, Barbara; Villarreal, Juan Carlos; Roure, Béatrice; Philippe, Hervé; dePamphilis, Claude W.; Chen, Tao; Deyholos, Michael K.; Baucom, Regina S.; Kutchan, Toni M.; Augustin, Megan M.; Wang, Jun; Zhang, Yong; Tian, Zhijian; Yan, Zhixiang; Wu, Xiaolei; Sun, Xiao; Wong, Gane Ka-Shu; Leebens-Mack, James

    2014-01-01

    Reconstructing the origin and evolution of land plants and their algal relatives is a fundamental problem in plant phylogenetics, and is essential for understanding how critical adaptations arose, including the embryo, vascular tissue, seeds, and flowers. Despite advances in molecular systematics, some hypotheses of relationships remain weakly resolved. Inferring deep phylogenies with bouts of rapid diversification can be problematic; however, genome-scale data should significantly increase the number of informative characters for analyses. Recent phylogenomic reconstructions focused on the major divergences of plants have resulted in promising but inconsistent results. One limitation is sparse taxon sampling, likely resulting from the difficulty and cost of data generation. To address this limitation, transcriptome data for 92 streptophyte taxa were generated and analyzed along with 11 published plant genome sequences. Phylogenetic reconstructions were conducted using up to 852 nuclear genes and 1,701,170 aligned sites. Sixty-nine analyses were performed to test the robustness of phylogenetic inferences to permutations of the data matrix or to phylogenetic method, including supermatrix, supertree, and coalescent-based approaches, maximum-likelihood and Bayesian methods, partitioned and unpartitioned analyses, and amino acid versus DNA alignments. Among other results, we find robust support for a sister-group relationship between land plants and one group of streptophyte green algae, the Zygnematophyceae. Strong and robust support for a clade comprising liverworts and mosses is inconsistent with a widely accepted view of early land plant evolution, and suggests that phylogenetic hypotheses used to understand the evolution of fundamental plant traits should be reevaluated. PMID:25355905

  6. Cenozoic Tectonic Activity of the "Passive" North America Margin: Evidence for Cenozoic Activity on Mesozoic or Paleozoic Faults

    NASA Astrophysics Data System (ADS)

    Nedorub, O. I.; Knapp, C. C.

    2012-12-01

    The tectonic history of the Eastern North American Margin (ENAM) incorporates two cycles of continental assembly, multiple pulses of orogeny, rifting, and post-rift geodynamic evolution. This is reflected in the heterogeneous lithosphere of the ENAM which contains fault structures originated in Paleozoic to Mesozoic eras. The South Georgia Rift basin is probably the largest Mesozoic graben within its boundaries that is associated with the breakup of Pangea. It is composed of smaller sub-basins which appear to be bounded by high-angle normal faults, some of which may have been inverted in late Cretaceous and Cenozoic eras. Paleozoic structures may have been reactivated in Cenozoic time as well. The ENAM is characterized by N-NE maximum horizontal compressive stress direction. This maximum compressional stress field is sub-parallel to the strike of the Atlantic Coast province fault systems. Camden, Augusta, Allendale, and Pen Branch faults are four of the many such reactivated faults along the southern part of ENAM. These faults are now buried under the 0-400 m of loosely consolidated Cretaceous and Cenozoic age sediments and thus are either only partially mapped or currently not recognized. Some of the objectives of this study are to map the subsurface expression and geometry of these faults and to investigate the post Cretaceous deformation and possible causes of fault reactivation on a passive margin. This study employs an integrated geophysical approach to investigate the upper 200 m of identified locations of the above mentioned faults. 2-D high-resolution shallow seismic reflection and refraction methods, gravity surveys, GPR, 2-D electrical resistivity and well data are used for analyses and interpretation. Preliminary results suggest that Camden fault shows signs of Cenozoic reactivation through an approximately 30 m offset NW side up mainly along a steeply dipping fault zone in the basal contact of Coastal Plain sediments with the Carolina Piedmont. Drill

  7. Deciphering the coupled Paleozoic and Cenozoic tectonic history of the Qilian Shan, northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zuza, A. V.; Yin, A.; Li, J.

    2014-12-01

    The Cenozoic Qilian Shan--the widest thrust belt on the Tibetan Plateau--exposes a record of early Paleozoic subduction-accretion associated with closure of the Qilian Ocean as the Qaidam microcontinent converged with North China. Despite decades of intense research, there is little consensus regarding the nature of the Qilian orogen (e.g., subduction polarity or number of arcs). For example, are the scattered ophiolite-bearing mélange complexes in the Qilian Shan the result of multiple arcs colliding along several suture zones in the Paleozoic or Cenozoic thrust duplication of a single Paleozoic suture zone? A major problem is that existing hypotheses neglect Cenozoic reorganization of the earlier tectonic framework, and the coupling between Paleozoic and Cenozoic structures has yet to be systematically investigated. To address this issue, we examine the Paleozoic Qilian Shan in the context of Cenozoic deformation. We conducted detailed field mapping (~1:50,000), balanced cross-section construction and restoration, U-Pb-Th zircon geochronology, Th-Pb dating of monazite inclusions in garnet, thermobarometry, and whole-rock geochemistry across the central Qilian Shan and in the Hexi Corridor foreland near Jinchan, where the North China craton abuts directly against the Qilian orogen. Successions of juxtaposed amphibolite facies Proterozoic gneiss (T: 725 ± 53°C, P: 7.9 ± 0.9 kbar), Cambrian oceanic material (U-Pb zircon ages: 530-520 Ma), and Ordovician-Silurian arc-derived granite (U-Pb zircon ages: 475-445 Ma) are exposed in the hanging walls of south-directed Cenozoic thrusts that place this basement over younger strata. A regionally correlative unconformity at the base of Carboniferous-Triassic strata is duplicated by this deformation and is used as marker horizon in our restoration. Initial estimates indicate a minimum post-Triassic shortening strain of ~42-45% across the range. By removing this deformation on mapped faults and adhering to observed field

  8. Early origins of the Caribbean plate from deep seismic profiles across the Nicaraguan Rise

    NASA Astrophysics Data System (ADS)

    Ott, B.; Mann, W. P.

    2012-12-01

    The offshore Nicaraguan Rise in the maritime zones of Honduras, Jamaica, Nicaragua and Colombia covers a combined area of 500,000 km2, and is one of the least known equatorial Cretaceous-Cenozoic carbonate regions remaining on Earth. The purpose of this study is to describe the Cretaceous to Recent tectonic and stratigraphic history of the deep water Nicaraguan Rise, and to better understand how various types of crustal blocks underlying the Eocene to Recent carbonate cover fused into a single, larger Caribbean plate known today from GPS studies. We interpreted 8700 km of modern, deep-penetration 2D seismic data kindly provided by the oil industry, tied to five wells that penetrated Cretaceous igneous basement. Based on these data, and integration with gravity, magnetic and existing crustal refraction data, we define four crustal provinces for the offshore Nicaraguan Rise: 1) Thicker (15-18 km) Late Cretaceous Caribbean ocean plateau (COP) with rough, top basement surface; 2) normal (6-8 km) Late Cretaceous COP with smooth top basement surface (B") and correlative outcrops in southern Haiti and Jamaica; 3) Precambrian-Paleozoic continental crust (20-22 km thick) with correlative outcrops in northern Central America; and 4) Cretaceous arc crust (>18 km thick) with correlative outcrops in Jamaica. These strongly contrasting basement belts strike northeastward to eastward, and were juxtaposed by latest Cretaceous-Paleogene northward and northwestward thrusting of Caribbean arc over continental crust in Central America, and the western Nicaraguan Rise (84 to 85 degrees west). A large Paleogene to recent, CCW rotation of the Caribbean plate along the Cayman trough faults and into its present day location explains why terranes in Central America and beneath the Nicaraguan Rise have their present, anomalous north-east strike. Continuing, present-day activity on some of these crustal block boundaries is a likely result of intraplate stresses imposed by the surrounding

  9. Improved artificial origins for phage Φ29 terminal protein-primed replication. Insights into early replication events

    PubMed Central

    Gella, Pablo; Salas, Margarita; Mencía, Mario

    2014-01-01

    The replication machinery of bacteriophage Φ29 is a paradigm for protein-primed replication and it holds great potential for applied purposes. To better understand the early replication events and to find improved origins for DNA amplification based on the Φ29 system, we have studied the end-structure of a double-stranded DNA replication origin. We have observed that the strength of the origin is determined by a combination of factors. The strongest origin (30-fold respect to wt) has the sequence CCC at the 3′ end of the template strand, AAA at the 5′ end of the non-template strand and 6 nucleotides as optimal unpairing at the end of the origin. We also show that the presence of a correctly positioned displaced strand is important because origins with 5′ or 3′ ssDNA regions have very low activity. Most of the effect of the improved origins takes place at the passage between the terminal protein-primed and the DNA-primed modes of replication by the DNA polymerase suggesting the existence of a thermodynamic barrier at that point. We suggest that the template and non-template strands of the origin and the TP/DNA polymerase complex form series of interactions that control the critical start of terminal protein-primed replication. PMID:25081208

  10. Species duration and extinction patterns in Cenozoic non-marine Ostracoda, Western United States

    NASA Astrophysics Data System (ADS)

    Swain, Frederick M.

    About 260 species of non-marine Ostracoda appeared and, for the most part, became extinct during the approximately 65 million years of the Cenozoic Era in the western United States. Lacustrine rock sequences containing the ostracode faunas in the Colorado Plateau and Great Basin total as much as 10.000 m. Important new appearances occurred in the early Paleocene, late Paleocene?-early Eocene, late Eocene-Oligocene?, late Oligocene?-early Miocene, and late? Pliocene Epochs. Major extinctions took place in the middle and late Eocene, late Miocene, and Pliocene and early Pleistocene Epochs.

  11. Apatite fission track evidence for the Cretaceous-Cenozoic cooling history of the Qilian Shan (NW China) and for stepwise northeastward growth of the northeastern Tibetan Plateau since early Eocene

    NASA Astrophysics Data System (ADS)

    Qi, Bangshen; Hu, Daogong; Yang, Xiaoxiao; Zhang, Yaoling; Tan, Chengxuan; Zhang, Peng; Feng, Chengjun

    2016-07-01

    Apatite fission track (AFT) data from hinterland of the Qilian Shan at the northeastern margin of the Tibetan Plateau suggest this range has experienced northeastward propagation of surface uplift since early Eocene and that crustal shortening occurred in the Qilian Shan before the late Miocene. Thermochronometry data indicate that the Qilian Shan experienced a three-stage cooling history, including: (1) rapid initial cooling during Cretaceous; (2) a stage of slow cooling during late Cretaceous-early Eocene; and (3) rapid stepwise cooling in a southwestern-northeastern orientation since early Eocene. Cretaceous rapid cooling may be a record of the Lhasa block and Eurasian collision. Early Cretaceous denudation was followed by tectonic and quasi-isothermal quiescence that continued until early Eocene. Early Eocene rapid cooling in the South Qilian Shan may be the first far-field response in the Qilian Shan to the collision and convergence of the Indian and Eurasian continents. From late Eocene to middle Miocene, crustal shortening propagated into the Central Qilian Shan and North Qilian Shan and produced surface uplift of the entire Qilian Shan region before the late Miocene. This study provides a better understanding of the tectonic evolution of the Qilian Shan and when the far-field stress from the India-Eurasia collision into the northeastern Tibetan Plateau began.

  12. Expanding the Cenozoic paleoceanographic record in the Central Arctic Ocean: IODP Expedition 302 Synthesis

    NASA Astrophysics Data System (ADS)

    Backman, Jan; Moran, Kathryn

    2009-06-01

    The Arctic Coring Expedition (ACEX) proved to be one of the most transformational missions in almost 40 year of scientific ocean drilling. ACEX recovered the first Cenozoic sedimentary sequence from the Arctic Ocean and extended earlier piston core records from ≈1.5 Ma back to ≈56 Ma. The results have had a major impact in paleoceanography even though the recovered sediments represents only 29% of Cenozoic time. The missing time intervals were primarily the result of two unexpected hiatuses. This important Cenozoic paleoceanographic record was reconstructed from a total of 339 m sediments. The wide range of analyses conducted on the recovered material, along with studies that integrated regional tectonics and geophysical data, produced surprising results including high Arctic Ocean surface water temperatures and a hydrologically active climate during the Paleocene Eocene Thermal Maximum (PETM), the occurrence of a fresher water Arctic in the Eocene, ice-rafted debris as old as middle Eocene, a middle Eocene environment rife with organic carbon, and ventilation of the Arctic Ocean to the North Atlantic through the Fram Strait near the early-middle Miocene boundary. Taken together, these results have transformed our view of the Cenozoic Arctic Ocean and its role in the Earth climate system.

  13. Early-Life Origins of Life-Cycle Well-Being: Research and Policy Implications

    ERIC Educational Resources Information Center

    Currie, Janet; Rossin-Slater, Maya

    2015-01-01

    Mounting evidence across different disciplines suggests that early-life conditions can have consequences on individual outcomes throughout the life cycle. Relative to other developed countries, the United States fares poorly on standard indicators of early-life health, and this disadvantage may have profound consequences not only for population…

  14. Evaluating the Link between Self-Esteem and Temperament in Mexican Origin Early Adolescents

    ERIC Educational Resources Information Center

    Robins, Richard W.; Donnellan, M. Brent; Widaman, Keith F.; Conger, Rand D.

    2010-01-01

    The present study examined the relation between self-esteem and temperament in a sample of 646 Mexican-American early adolescents (mean age = 10.4). Findings show that (a) early adolescents with high self-esteem exhibit higher levels of Effortful Control but, contrary to findings in adult samples, do not differ from low self-esteem adolescents in…

  15. Early-life stress origins of gastrointestinal disease: animal models, intestinal pathophysiology, and translational implications.

    PubMed

    Pohl, Calvin S; Medland, Julia E; Moeser, Adam J

    2015-12-15

    Early-life stress and adversity are major risk factors in the onset and severity of gastrointestinal (GI) disease in humans later in life. The mechanisms by which early-life stress leads to increased GI disease susceptibility in adult life remain poorly understood. Animal models of early-life stress have provided a foundation from which to gain a more fundamental understanding of this important GI disease paradigm. This review focuses on animal models of early-life stress-induced GI disease, with a specific emphasis on translational aspects of each model to specific human GI disease states. Early postnatal development of major GI systems and the consequences of stress on their development are discussed in detail. Relevant translational differences between species and models are highlighted. PMID:26451004

  16. Fires in the Cenozoic: a late flowering of flammable ecosystems

    PubMed Central

    Bond, William J.

    2015-01-01

    Modern flammable ecosystems include tropical and subtropical savannas, steppe grasslands, boreal forests, and temperate sclerophyll shrublands. Despite the apparent fiery nature of much contemporary vegetation, terrestrial fossil evidence would suggest we live in a time of low fire activity relative to the deep past. The inertinite content of coal, fossil charcoal, is strikingly low from the Eocene to the Pleistocene and no charcoalified mesofossils have been reported for the Cenozoic. Marine cores have been analyzed for charcoal in the North Pacific, the north and south Atlantic off Africa, and the south China sea. These tell a different story with the oldest records indicating low levels of fire activity from the Eocene but a surge of fire from the late Miocene (~7 Ma). Phylogenetic studies of woody plants adapted to frequent savanna fires show them beginning to appear from the Late Miocene with peak origins in the late Pliocene in both South American and African lineages. Phylogenetic studies indicate ancient origins (60 Ma+) for clades characteristic of flammable sclerophyll vegetation from Australia and the Cape region of South Africa. However, as for savannas, there was a surge of speciation from the Late Miocene associated with the retreat of closed fire-intolerant forests. The wide geographic spread of increased fire activity in the last few million years suggests a global cause. However, none of the potential global factors (oxygen, rainfall seasonality, CO2, novel flammable growth forms) provides an adequate explanation as yet. The global patterns and processes of fire and flammable vegetation in the Cenozoic, especially since the Late Miocene, deserve much more attention to better understand fire in the earth system. PMID:25601873

  17. Fires in the Cenozoic: a late flowering of flammable ecosystems.

    PubMed

    Bond, William J

    2014-01-01

    Modern flammable ecosystems include tropical and subtropical savannas, steppe grasslands, boreal forests, and temperate sclerophyll shrublands. Despite the apparent fiery nature of much contemporary vegetation, terrestrial fossil evidence would suggest we live in a time of low fire activity relative to the deep past. The inertinite content of coal, fossil charcoal, is strikingly low from the Eocene to the Pleistocene and no charcoalified mesofossils have been reported for the Cenozoic. Marine cores have been analyzed for charcoal in the North Pacific, the north and south Atlantic off Africa, and the south China sea. These tell a different story with the oldest records indicating low levels of fire activity from the Eocene but a surge of fire from the late Miocene (~7 Ma). Phylogenetic studies of woody plants adapted to frequent savanna fires show them beginning to appear from the Late Miocene with peak origins in the late Pliocene in both South American and African lineages. Phylogenetic studies indicate ancient origins (60 Ma+) for clades characteristic of flammable sclerophyll vegetation from Australia and the Cape region of South Africa. However, as for savannas, there was a surge of speciation from the Late Miocene associated with the retreat of closed fire-intolerant forests. The wide geographic spread of increased fire activity in the last few million years suggests a global cause. However, none of the potential global factors (oxygen, rainfall seasonality, CO2, novel flammable growth forms) provides an adequate explanation as yet. The global patterns and processes of fire and flammable vegetation in the Cenozoic, especially since the Late Miocene, deserve much more attention to better understand fire in the earth system. PMID:25601873

  18. Cenozoic Methane-Seep Faunas of the Caribbean Region

    PubMed Central

    Kiel, Steffen; Hansen, Bent T.

    2015-01-01

    We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted ‘Joes River fauna’ consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted ‘Bath Cliffs fauna’ containing the vesicomyid Pleurophopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pegophysema). In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godineau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman’s Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical ‘Cenozoic’ lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large lucinids

  19. (Vitrinites of Mesozoic, Cenozoic, and Paleozoic coals)

    SciTech Connect

    Faizullina, E.M.; Lapo, A.V.

    1982-01-01

    In the reported experiment, the vitrinites of the coalification stages from B to A have been studied by IR spectrometry. A comparison of the intensities of the absorption bands of equally coalified vitrinites of different ages has shown that they differ mainly in their content of stretching vibrations of aliphatic CH and CH/sub 2/ groups (absorption bands at 2930 and 2860 cm/sup -1/) and the stretching vibrations of C.0 groups (band close to 1700 cm/sup -1/). A high absorption in the vitrinites of Mesozoic and Cenozoic coals due to aliphatic CH and CH/sub 2/ groups as compared with the vitrinities of Paleozoic coals has been found. The laws established previously in the coalification series for the vitrinites of Paleozoic coals have also been confirmed for the vitrinites of Meso-Cenozoic coals. 13 refs.

  20. Cenozoic climate change influences mammalian evolutionary dynamics

    PubMed Central

    Figueirido, Borja; Janis, Christine M.; Pérez-Claros, Juan A.; De Renzi, Miquel; Palmqvist, Paul

    2012-01-01

    Global climate change is having profound impacts on the natural world. However, climate influence on faunal dynamics at macroevolutionary scales remains poorly understood. In this paper we investigate the influence of climate over deep time on the diversity patterns of Cenozoic North American mammals. We use factor analysis to identify temporally correlated assemblages of taxa, or major evolutionary faunas that we can then study in relation to climatic change over the past 65 million years. These taxa can be grouped into six consecutive faunal associations that show some correspondence with the qualitative mammalian chronofaunas of previous workers. We also show that the diversity pattern of most of these chronofaunas can be correlated with the stacked deep-sea benthic foraminiferal oxygen isotope (δ18O) curve, which strongly suggests climatic forcing of faunal dynamics over a large macroevolutionary timescale. This study demonstrates the profound influence of climate on the diversity patterns of North American terrestrial mammals over the Cenozoic. PMID:22203974

  1. The Atmospheres of the Terrestrial Planets:Clues to the Origins and Early Evolution of Venus, Earth, and Mars

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; Atreya, Sushil K.; Bullock, Mark A.; Grinspoon, David H,; Mahaffy, Paul; Russell, Christopher T.; Schubert, Gerald; Zahnle, Kevin

    2015-01-01

    We review the current state of knowledge of the origin and early evolution of the three largest terrestrial planets - Venus, Earth, and Mars - setting the stage for the chapters on comparative climatological processes to follow. We summarize current models of planetary formation, as revealed by studies of solid materials from Earth and meteorites from Mars. For Venus, we emphasize the known differences and similarities in planetary bulk properties and composition with Earth and Mars, focusing on key properties indicative of planetary formation and early evolution, particularly of the atmospheres of all three planets. We review the need for future in situ measurements for improving our understanding of the origin and evolution of the atmospheres of our planetary neighbors and Earth, and suggest the accuracies required of such new in situ data. Finally, we discuss the role new measurements of Mars and Venus have in understanding the state and evolution of planets found in the habitable zones of other stars.

  2. Early-life origins of life-cycle well-being: research and policy implications.

    PubMed

    Currie, Janet; Rossin-Slater, Maya

    2015-01-01

    Mounting evidence across different disciplines suggests that early-life conditions can have consequences on individual outcomes throughout the life cycle. Relative to other developed countries, the United States fares poorly on standard indicators of early-life health, and this disadvantage may have profound consequences not only for population well-being, but also for economic growth and competitiveness in a global economy. In this paper, we first discuss the research on the strength of the link between early-life health and adult outcomes, and then provide an evidence-based review of the effectiveness of existing U.S. policies targeting the early-life environment. We conclude that there is a robust and economically meaningful relationship between early-life conditions and well-being throughout the life cycle, as measured by adult health, educational attainment, labor market attachment, and other indicators of socioeconomic status. However, there is some variation in the degree to which current policies in the United States are effective in improving early-life conditions. Among existing programs, some of the most effective are the Special Supplemental Program for Women, Infants, and Children (WIC), home visiting with nurse practitioners, and high-quality, center-based early-childhood care and education. In contrast, the evidence on other policies such as prenatal care and family leave is more mixed and limited. PMID:25558491

  3. Early-life Origins of Lifecycle Well-being: Research and Policy Implications

    PubMed Central

    Currie, Janet; Rossin-Slater, Maya

    2016-01-01

    Mounting evidence across different disciplines suggests that early-life conditions can have consequences on individual outcomes throughout the lifecycle. Relative to other developed countries, the United States fares poorly on standard indicators of early-life health, and this disadvantage may have profound consequences not only for population well-being, but also for economic growth and competitiveness in a global economy. In this paper, we first discuss the research on the strength of the link between early-life health and adult outcomes, and then provide an evidence-based review of the effectiveness of existing U.S. policies targeting the early-life environment. We conclude that there is a robust and economically meaningful relationship between early-life conditions and well-being throughout the lifecycle, as measured by adult health, educational attainment, labor market attachment, and other indicators of socio-economic status. However, there is some variation in the degree to which current policies in the U.S. are effective in improving early-life conditions. Among existing programs, some of the most effective are the Special Supplemental Program for Women, Infants, and Children (WIC), home visiting with nurse practitioners, and high-quality, center-based early childhood care and education. In contrast, the evidence on other policies such as prenatal care and family leave is more mixed and limited. PMID:25558491

  4. Comparative Genomics of Early-Diverging Mushroom-Forming Fungi Provides Insights into the Origins of Lignocellulose Decay Capabilities.

    PubMed

    Nagy, László G; Riley, Robert; Tritt, Andrew; Adam, Catherine; Daum, Chris; Floudas, Dimitrios; Sun, Hui; Yadav, Jagjit S; Pangilinan, Jasmyn; Larsson, Karl-Henrik; Matsuura, Kenji; Barry, Kerrie; Labutti, Kurt; Kuo, Rita; Ohm, Robin A; Bhattacharya, Sukanta S; Shirouzu, Takashi; Yoshinaga, Yuko; Martin, Francis M; Grigoriev, Igor V; Hibbett, David S

    2016-04-01

    Evolution of lignocellulose decomposition was one of the most ecologically important innovations in fungi. White-rot fungi in the Agaricomycetes (mushrooms and relatives) are the most effective microorganisms in degrading both cellulose and lignin components of woody plant cell walls (PCW). However, the precise evolutionary origins of lignocellulose decomposition are poorly understood, largely because certain early-diverging clades of Agaricomycetes and its sister group, the Dacrymycetes, have yet to be sampled, or have been undersampled, in comparative genomic studies. Here, we present new genome sequences of ten saprotrophic fungi, including members of the Dacrymycetes and early-diverging clades of Agaricomycetes (Cantharellales, Sebacinales, Auriculariales, and Trechisporales), which we use to refine the origins and evolutionary history of the enzymatic toolkit of lignocellulose decomposition. We reconstructed the origin of ligninolytic enzymes, focusing on class II peroxidases (AA2), as well as enzymes that attack crystalline cellulose. Despite previous reports of white rot appearing as early as the Dacrymycetes, our results suggest that white-rot fungi evolved later in the Agaricomycetes, with the first class II peroxidases reconstructed in the ancestor of the Auriculariales and residual Agaricomycetes. The exemplars of the most ancient clades of Agaricomycetes that we sampled all lack class II peroxidases, and are thus concluded to use a combination of plesiomorphic and derived PCW degrading enzymes that predate the evolution of white rot. PMID:26659563

  5. Circum-pacific late cenozoic structural rejuvenation: implications for sea floor spreading.

    PubMed

    Dott, R H

    1969-11-14

    The hypothesis of sea floor spreading and lithosphere plates seems to unify the origins of both oceanic ridges and volcanic arc-trench systems; therefore knowledge of well-known land areas should shed light upon sea floor tectonics. Impressive evidence of a major mid-Cenozoic discontinuity in the tectonic history of circum-Pacific land areas suggests a roughly synchronous change in sea floor development, more evidence for which may be anticipated in the future. PMID:17815749

  6. Medusae Fossae Formation, Mars: an Assessment of Possible Origins Utilizing Early Results from Mars Global Surveyor

    NASA Astrophysics Data System (ADS)

    Zimbelman, J.; Hooper, D.; Crown, D.; Grant, J.; Sakimoto, S.; Frey, H.

    1999-03-01

    The enigmatic MFF in the equatorial portion of Elysium-Amazonis Planitiae has numerous very different proposed hypotheses for its origin. Released MOC and MOLA data and Viking data are compared to predicted hypothesis-specific attributes.

  7. Antarctic Bottom Water: Major Change in Velocity during the Late Cenozoic between Australia and Antarctica.

    PubMed

    Watkins, N D; Kennett, J P

    1971-08-27

    Paleomagnetic and micropaleontological studies of deep-sea sedimentary cores between Australia and Antarctica define an extensive area centered in the south Tasman Basin, where sediment as old as Early Pliocene has been systematically eroded by bottom currents. This major sedimentary disconformity has been produced by a substantial increase in velocity of Antarctic bottom water, possibly associated with late Cenozoic climatic cooling and corresponding increased glaciation of Antarctica. PMID:17812192

  8. Late Cretaceous -Early Tertiary dyke swarm of North Greenland it's age, origins and tectonic significance

    NASA Astrophysics Data System (ADS)

    Manby, Geoffrey

    2014-05-01

    North Greenland is characterized by N-S, NW-SE and E-W trending swarms of mafic dykes which pre- and post date Kap Washington suite of bimodal lavas, ash flows and tuffs. Both rock groups are over-thrust by north vergent thrust sheets of Early Palaeozoic age rocks which record low grade Ellesmerian (Carboniferous) metamorphism and deformation. Laser ablation Ar/Ar ages of 58Ma and 62Ma obtained from thrust fault generated mylonites suggest that magmatism must have effectively ceased by then as no undeformed dykes have been found to cross the thrust planes. High resolution PMAP aeromagnetic surveys for 1989 and 1997-98 show that linear magnetic anomalies parallel to the dense N-S trending dyke swarm of Nansen Land can be traced out onto the Lincoln Sea platform suggesting the dykes are part of the predominantly offshore failed rift magmatic domain which lies central to the southern ends of Alpha ridge, the Lomonosov Ridge, the Markarov Basin, the Amundsen Basin and the Morris-Jessup Plateau. In addition the dykes to the SW of the Mascart Inlet appear to extend undisturbed by faulting 150km onto the Lincoln Sea platform north of Ellesmere Island. The curved ca EW deep negative anomaly which truncates the dyke swarm offshore to the north of the Kap Canon Fault zone together with a similar anomaly along the Harder fjord Fault Zone and its western continuation to the Kap Ramsey Fault appear to constitute the limits of Eurekan thrust belt of North Greenland. Stress tensor analyses of all Eurekan fault plane populations show a consistent N-S to NNW-SSE pure compression pattern orthogonal to the main thrust faults and near parallel to the main dyke trend. Rb/Sr, and Ar/Ar ages obtained from biotite separates, with U/Th ages from apatite-feldspar pairs suggest the dykes range in age from ca 103Ma to 69Ma. The peralkaline affinity of the dyke swarm is similar to that of many other rift generated basalts. Nd, Sr and a small number of Pb isotope ratios have been determined for

  9. Basal melting of snow on early Mars: A possible origin of some valley networks

    USGS Publications Warehouse

    Carr, M.H.; Head, J. W., III

    2003-01-01

    Valley networks appear to be cut by liquid water, yet simulations suggest that early Mars could not have been warmed enough by a CO2-H2O greenhouse to permit rainfall. The vulnerability of an early atmosphere to impact erosion, the likely rapid scavenging of CO2 from the atmosphere by weathering, and the lack of detection of weathering products all support a cold early Mars. We explore the hypothesis that valley networks could have formed as a result of basal melting of thick snow and ice deposits. Depending on the heat flow, an early snowpack a few hundred meters to a few kilometers thick could undergo basal melting, providing water to cut valley networks. Copyright 2003 by the American Geophysical Union.

  10. Early Origins of Child Obesity: Bridging Disciplines and Phases of Development - September 30–October 1, 2010

    PubMed Central

    Christoffel, Katherine Kaufer; Wang, Xiaobin; Binns, Helen J.

    2012-01-01

    This report summarizes a conference: “Early Origins of Child Obesity: Bridging Disciplines and Phases of Development”, held in Chicago on September 30–October 1, 2010. The conference was funded in part by the National Institutes of Health and the Williams Heart Foundation, to achieve the conference objective: forging a next-step research agenda related to the early origins of childhood obesity. This research agenda was to include working with an array of factors (from genetic determinants to societal ones) along a continuum from prenatal life to age 7, with an emphasis on how the developing child deals with the challenges presented by his/her environment (prenatal, parental, nutritional, etc.). The conference offered a unique opportunity to facilitate communication and planning of future work among a variety of researchers whose work separately addresses different periods in early life. Over the span of two days, speakers addressed existing, critical research topics within each of the most-studied age ranges. On the final day, workshops fostered the discussion needed to identify the highest priority research topics related to linking varied early factor domains. These are presented for use in planning future research and research funding. PMID:23443002

  11. Vertical-axis rotations determined from paleomagnetism of Mesozoic and Cenozoic strata of the Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Richards, David R.; Butler, Robert F.; Sempere, Thierry

    2004-07-01

    Thermal demagnetization and principal component analysis allowed determination of characteristic remanent magnetization (ChRM) directions from 256 sites at 22 localities in Mesozoic and Cenozoic sedimentary strata of the Bolivian Altiplano and Eastern Cordillera. An inclination-only fold test of site-mean ChRM directions from Cenozoic units (principally the Santa Lucía Formation) indicates optimum unfolding at 97.1% unfolding, consistent with a primary origin for the ChRM. For Mesozoic strata, optimum unfolding occurred at 89.2%, perhaps indicating secondary remagnetization at some locations. For Cenozoic units, comparison of locality-mean directions with expected paleomagnetic directions indicates vertical-axis rotations from 33° counterclockwise to 24° clockwise. Euler pole analysis of along-strike variation in crustal shortening within the Subandean and Interandean zones indicates 18° clockwise rotation south of the axis of curvature of the Bolivian Andes and 6° counterclockwise rotation northwest of the axis during the past 10 m.y. Along-strike variation of shortening within the Eastern Cordillera indicates 8° clockwise rotation south of the axis and 8° counterclockwise rotation northwest of the axis from 35 to 10 Ma. These vertical-axis rotations produced by along-strike variations in crustal shortening during development of the Bolivian fold-thrust belt agree well with observed rotations determined from paleomagnetism of Cenozoic rocks in the Eastern Cordillera and in the Subandean and Interandean zones. However, local rotations are required to account for complex rotations in the Cochabamba Basin and within the Altiplano. The curvature of the Bolivian Andes has been progressively enhanced during Cenozoic fold-thrust belt deformation.

  12. ACEX: A First Look at Arctic Ocean Cenozoic History

    NASA Astrophysics Data System (ADS)

    Moran, K.; Backman, J.

    2004-12-01

    The first Integrated Ocean Drilling Program mission specificplatform expedition (ACEX - Arctic Coring Expedition) drilled and recovered core from five holes at four sites through Cenozoic sediments draping the crest of the Lomonosov Ridge in the central Arctic Ocean. Coring continued into the underlying Cretaceous sedimentary bedrock. Sites are located only a few nautical miles apart along a single seismic line (AWI-91090), showing an identical and coherent Cenozoic seismostratigraphy. Preliminary results from shipboard investigations of core-catcher-based bio- and lithostratigraphy, pore water analyses and core logger data describe a thick (~160 m) middle Miocene through Pleistocene sequence that shows large amplitude, cyclic variability in the density, magnetic susceptibility and acoustic velocity of the sediments. Sediments are largely carbonate free. Pleistocene sedimentation rates are close to 3 cm/ka, whereas Pliocene sediments are by-and-large missing. A sharp change in physical properties at ~200 m defines the transition into a 200+ m thick Paleogene sequence that is initially dominated by large numbers of dinoflagellate cysts. The early Miocene, Oligocene and late Eocene appear to be largely missing in a hiatus. However, a 32 m thick interval separates the overlying middle Miocene from the underlying middle Eocene and presumably preserves some of the early Neogene and late Paleogene sections. Dinoflagellate cysts, diatoms, ebridians and silicoflagellates are common to abundant in the middle Eocene section, which bottoms in a spectacular layer showing massive occurrences of glochidia and massulae (megaspores) of the freshwater hydropterid fern Azolla (duckweed) at the early/middle Eocene boundary (~306 m), suggesting strongly reduced surface water salinity or perhaps even a brief episode of fresh water conditions at the surface. Biosilica is not present prior to the late early Eocene (~320 m). The (sub-) tropical dinoflagellate species Apectodinium augustum

  13. The Origin and Early Radiation of Archosauriforms: Integrating the Skeletal and Footprint Record

    PubMed Central

    Bernardi, Massimo; Klein, Hendrik; Petti, Fabio Massimo; Ezcurra, Martín D.

    2015-01-01

    We present a holistic approach to the study of early archosauriform evolution by integrating body and track records. The ichnological record supports a Late Permian–Early Triassic radiation of archosauriforms not well documented by skeletal material, and new footprints from the Upper Permian of the southern Alps (Italy) provide evidence for a diversity not yet sampled by body fossils. The integrative study of body fossil and footprint data supports the hypothesis that archosauriforms had already undergone substantial taxonomic diversification by the Late Permian and that by the Early Triassic archosauromorphs attained a broad geographical distribution over most parts of Pangea. Analysis of body size, as deduced from track size, suggests that archosauriform average body size did not change significantly from the Late Permian to the Early Triassic. A survey of facies yielding both skeletal and track record indicate an ecological preference for inland fluvial (lacustrine) environments for early archosauromorphs. Finally, although more data is needed, Late Permian chirotheriid imprints suggest a shift from sprawling to erect posture in archosauriforms before the end-Permian mass extinction event. We highlight the importance of approaching palaeobiological questions by using all available sources of data, specifically through integrating the body and track fossil record. PMID:26083612

  14. A multi-gene dataset reveals a tropical New World origin and Early Miocene diversification of croakers (Perciformes: Sciaenidae).

    PubMed

    Lo, Pei-Chun; Liu, Shu-Hui; Chao, Ning Labbish; Nunoo, Francis K E; Mok, Hin-Kiu; Chen, Wei-Jen

    2015-07-01

    Widely distributed groups of living animals, such as the predominantly marine fish family Sciaenidae, have always attracted the attention of biogeographers to document the origins and patterns of diversification in time and space. In this study, the historical biogeography of the global Sciaenidae is reconstructed within a molecular phylogenetic framework to investigate their origin and to test the hypotheses explaining the present-day biogeographic patterns. Our data matrix comprises six mitochondrial and nuclear genes in 93 globally sampled sciaenid species from 52 genera. Within the inferred phylogenetic tree of the Sciaenidae, we identify 15 main and well-supported lineages; some of which have not been recognized previously. Reconstruction of habitat preferences shows repeated habitat transitions between marine and euryhaline environments. This implies that sciaenids can easily adapt to some variations in salinity, possibly as the consequence of their nearshore habitats and migratory life history. Conversely, complete marine/euryhaline to freshwater transitions occurred only three times, in South America, North America and South Asia. Ancestral range reconstruction analysis concomitant with fossil evidence indicates that sciaenids first originated and diversified in the tropical America during the Oligocene to Early Miocene before undergoing two range expansions, to Eastern Atlantic and to the Indo-West Pacific where a maximum species richness is observed. The uncommon biogeographic pattern identified is discussed in relation to current knowledge on origin of gradients of marine biodiversity toward the center of origin hypothesis in the Indo-West Pacific. PMID:25848970

  15. The Centennial of Counselor Education: Origin and Early Development of a Discipline

    ERIC Educational Resources Information Center

    Savickas, Mark L.

    2011-01-01

    July 7, 2011, marks the centennial of counselor education as a formal discipline. In recognition of its 100th birthday, the author of this article describes the origins of the discipline, beginning with its prehistory in the work of Frank Parsons to establish the practice of vocational guidance, describing the 1st course in counselor education at…

  16. Origins of Early Adolescents' Hope: Personality, Parental Attachment, and Stressful Life Events

    ERIC Educational Resources Information Center

    Otis, Kristin L.; Huebner, E. Scott; Hills, Kimberly J.

    2016-01-01

    Psychology has recently increased attention to identifying psychological qualities in individuals that indicate positive mental health, such as hope. In an effort to understand further the origins of hope, we examined the relations among parental attachment, stressful life events, personality variables, and hope in a sample of 647 middle school…

  17. Microbes, Mineral Evolution, and the Rise of Microcontinents-Origin and Coevolution of Life with Early Earth.

    PubMed

    Grosch, Eugene G; Hazen, Robert M

    2015-10-01

    Earth is the most mineralogically diverse planet in our solar system, the direct consequence of a coevolving geosphere and biosphere. We consider the possibility that a microbial biosphere originated and thrived in the early Hadean-Archean Earth subseafloor environment, with fundamental consequences for the complex evolution and habitability of our planet. In this hypothesis paper, we explore possible venues for the origin of life and the direct consequences of microbially mediated, low-temperature hydrothermal alteration of the early oceanic lithosphere. We hypothesize that subsurface fluid-rock-microbe interactions resulted in more efficient hydration of the early oceanic crust, which in turn promoted bulk melting to produce the first evolved fragments of felsic crust. These evolved magmas most likely included sialic or tonalitic sheets, felsic volcaniclastics, and minor rhyolitic intrusions emplaced in an Iceland-type extensional setting as the earliest microcontinents. With the further development of proto-tectonic processes, these buoyant felsic crustal fragments formed the nucleus of intra-oceanic tonalite-trondhjemite-granitoid (TTG) island arcs. Thus microbes, by facilitating extensive hydrothermal alteration of the earliest oceanic crust through bioalteration, promoted mineral diversification and may have been early architects of surface environments and microcontinents on young Earth. We explore how the possible onset of subseafloor fluid-rock-microbe interactions on early Earth accelerated metavolcanic clay mineral formation, crustal melting, and subsequent metamorphic mineral evolution. We also consider environmental factors supporting this earliest step in geosphere-biosphere coevolution and the implications for habitability and mineral evolution on other rocky planets, such as Mars. PMID:26430911

  18. Early Cambrian origin of modern food webs: evidence from predator arrow worms

    PubMed Central

    Vannier, J; Steiner, M; Renvoisé, E; Hu, S.-X; Casanova, J.-P

    2006-01-01

    Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540–520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cambrian of China added to previous studies provide convincing evidence that protoconodont-bearing animals also belonged to chaetognaths. Chaetognaths were probably widespread and diverse in the earliest Cambrian. The obvious raptorial function of their circumoral apparatuses (grasping spines) places them among the earliest active predator metazoans. Morphology, body ratios and distribution suggest that the ancestral chaetognaths were planktonic with possible ecological preferences for hyperbenthic niches close to the sea bottom. Our results point to the early introduction of prey–predator relationships into the pelagic realm, and to the increase of trophic complexity (three-level structure) during the Precambrian–Cambrian transition, thus laying the foundations of present-day marine food chains. PMID:17254986

  19. The early origins of cardiovascular health and disease: who, when, and how.

    PubMed

    Rueda-Clausen, Christian F; Morton, Jude S; Davidge, Sandra T

    2011-05-01

    Almost 30 years ago, a series of epidemiological studies popularized the early programming theory that had resulted from observed associations between low birthweight and increased cardiovascular morbidity and mortality later in life. Since then, several clinical and experimental models have been created to understand the principles and mechanisms of this fascinating phenomenon and describe its relevance to the pathophysiology of cardiovascular and many other chronic diseases. Despite the growing body of published evidence, the specific mechanisms mediating early programming effects are still elusive. Moreover, many controversial issues have arisen regarding the characteristics of the most commonly used clinical and experimental models, the existence of potential windows of susceptibility for different organs, and the presence of sex differences in its pathophysiology. Therefore, this review synthesizes some of the antecedents behind the early programming theory and discusses some of the controversial issues surrounding it. Early programming has been extensively linked to several chronic diseases; however, for the purposes of this review we have concentrated on the potential role of this entity in the pathophysiology of chronic cardiovascular diseases. PMID:21710396

  20. Early Cambrian origin of modern food webs: evidence from predator arrow worms.

    PubMed

    Vannier, J; Steiner, M; Renvoisé, E; Hu, S-X; Casanova, J-P

    2007-03-01

    Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cambrian of China added to previous studies provide convincing evidence that protoconodont-bearing animals also belonged to chaetognaths. Chaetognaths were probably widespread and diverse in the earliest Cambrian. The obvious raptorial function of their circumoral apparatuses (grasping spines) places them among the earliest active predator metazoans. Morphology, body ratios and distribution suggest that the ancestral chaetognaths were planktonic with possible ecological preferences for hyperbenthic niches close to the sea bottom. Our results point to the early introduction of prey-predator relationships into the pelagic realm, and to the increase of trophic complexity (three-level structure) during the Precambrian-Cambrian transition, thus laying the foundations of present-day marine food chains. PMID:17254986

  1. Intrusions of mixed origin migmatising early Achaean crust in northern Labrador, Canada

    NASA Technical Reports Server (NTRS)

    Schiotte, L.; Bridgwater, D.

    1986-01-01

    Migmatization of Early Archean Uivak gneisses by Late Archean granitic and trondhjemitic injections are described. The rare earth element, major element, and isotopic geochemistry of the felsic sheets is interpreted to indicate both mantle and crustal components, and the sheets with associated fluids were the vehicle for element transport in the crustal column with attendant isotopic modification of the older gneisses.

  2. Mesozoic and Cenozoic structural trends under southern Bering Sea Shelf

    SciTech Connect

    Marlow, M.S.; Cooper, A.K.

    1980-12-01

    Mesozoic rocks exposed near the tip of the Alaska Peninsula form an antiformal structure that flanks the southern side of Bristol Bay basin and that can be traced with geophysical data about 700 km offshore to the vicinity of the Pribilof Islands. Upper Jurassic sandstone and Upper Cretaceous mudstone dredged from the top and flanks of this structure near the islands confirm that Mesozoic rocks extend from the Alaska Peninsula to the Bering sea margin. The southern part of the Bering Sea Shelf is underlain by several large structural basins. These filled basins encompass an offshore area of about 31,000 sq km. Reflection profiles show that the surface of the offshore antiformal structures is an angular unconformity overlain by Cenozoic beds. The downdip trace of the unconformity in Bristol Bay basin is underlain by reflectors paralleling the contact, a relation suggesting that the basin and perhaps other shelf basins may be underlain by ancient Mesozoic depocenters. The bulk of the thick sections in these basins is, however, thought to be mainly Cenozoic in age. Strata in the basins are cut by high-angle growth faults. The faults commonly offset the seafloor, which implies that basin subsidence and filling continue to the present. Shallow-water diatomaceous mudstone of Eocene and Oligocene age dredged from the continental slope near the Pribilof Islands indicates that collapse of the margin and outer shelf basins began by at least early Tertiary time. In Mesozoic time, the Bering margin between Siberia and the Alaska Peninsula (Beringian margin) may have been a zone of either oblique underthrusting or transform motion between the North American and Pacific lithosphere (Kula plate.). This motion may have rifted the edge of the North American plate, resulting in the formation of a series of elongate basins and ridges paralleling the plate edge.

  3. Mexican-origin Early Adolescents' Ethnic Socialization, Ethnic Identity, and Psychosocial Functioning.

    PubMed

    Umaña-Taylor, Adriana J; O'Donnell, Megan; Knight, George P; Roosa, Mark W; Berkel, Cady; Nair, Rajni

    2014-02-01

    The current study examined how parental ethnic socialization informed adolescents' ethnic identity development and, in turn, youths' psychosocial functioning (i.e., mental health, social competence, academic efficacy, externalizing behaviors) among 749 Mexican-origin families. In addition, school ethnic composition was examined as a moderator of these associations. Findings indicated that mothers' and fathers' ethnic socialization were significant longitudinal predictors of adolescents' ethnic identity, although fathers' ethnic socialization interacted significantly with youths' school ethnic composition in 5(th) grade to influence ethnic identity in 7(th) grade. Furthermore, adolescents' ethnic identity was significantly associated with increased academic self-efficacy and social competence, and decreased depressive symptoms and externalizing behaviors. Findings support theoretical predictions regarding the central role parents play in Mexican-origin adolescents' normative developmental processes and adjustment and, importantly, underscore the need to consider variability that is introduced into these processes by features of the social context such as school ethnic composition. PMID:24465033

  4. The origin of early age expansions induced in cementitious materials containing shrinkage reducing admixtures

    SciTech Connect

    Sant, Gaurav; Lothenbach, Barbara; Juilland, Patrick; Le Saout, Gwenn; Weiss, Jason; Scrivener, Karen

    2011-03-15

    Studies on the early-age shrinkage behavior of cement pastes, mortars, and concretes containing shrinkage reducing admixtures (SRAs) have indicated these mixtures frequently exhibit an expansion shortly after setting. While the magnitude of the expansion has been noted to be a function of the chemistry of the cement and the admixture dosage; the cause of the expansion is not clearly understood. This investigation uses measurements of autogenous deformation, X-ray diffraction, pore solution analysis, thermogravimetry, and scanning electron microscopy to study the early-age properties and describe the mechanism of the expansion in OPC pastes made with and without SRA. The composition of the pore solution indicates that the presence of the SRA increases the portlandite oversaturation level in solution which can result in higher crystallization stresses which could lead to an expansion. This observation is supported by deformation calculations for the systems examined.

  5. Impact melting of frozen oceans on the early Earth: implications for the origin of life

    NASA Technical Reports Server (NTRS)

    Bada, J. L.; Bigham, C.; Miller, S. L.

    1994-01-01

    Without sufficient greenhouse gases in the atmosphere, the early Earth would have become a permanently frozen planet because the young Sun was less luminous than it is today. Several resolutions to this faint young Sun-frozen Earth paradox have been proposed, with an atmosphere rich in CO2 being the one generally favored. However, these models assume that there were no mechanisms for melting a once frozen ocean. Here we show that bolide impacts between about 3.6 and 4.0 billion years ago could have episodically melted an ice-covered early ocean. Thaw-freeze cycles associated with bolide impacts could have been important for the initiation of abiotic reactions that gave rise to the first living organisms.

  6. The long-term impacts of Medicaid exposure in early childhood: Evidence from the program's origin.

    PubMed

    Boudreaux, Michel H; Golberstein, Ezra; McAlpine, Donna D

    2016-01-01

    This paper examines the long-term impact of exposure to Medicaid in early childhood on adult health and economic status. The staggered timing of Medicaid's adoption across the states created meaningful variation in cumulative exposure to Medicaid for birth cohorts that are now in adulthood. Analyses of the Panel Study of Income Dynamics suggest exposure to Medicaid in early childhood (age 0-5) is associated with statistically significant and meaningful improvements in adult health (age 25-54), and this effect is only seen in subgroups targeted by the program. Results for economic outcomes are imprecise and we are unable to come to definitive conclusions. Using separate data we find evidence of two mechanisms that could plausibly link Medicaid's introduction to long-term outcomes: contemporaneous increases in health services utilization for children and reductions in family medical debt. PMID:26763123

  7. Impact melting of frozen oceans on the early Earth: Implications for the origin of life

    PubMed Central

    Bada, J. L.; Bigham, C.; Miller, S. L.

    1994-01-01

    Without sufficient greenhouse gases in the atmosphere, the early Earth would have become a permanently frozen planet because the young Sun was less luminous than it is today. Several resolutions to this faint young Sun-frozen Earth paradox have been proposed, with an atmosphere rich in CO2 being the one generally favored. However, these models assume that there were no mechanisms for melting a once frozen ocean. Here we show that bolide impacts between about 3.6 and 4.0 billion years ago could have episodically melted an ice-covered early ocean. Thaw-freeze cycles associated with bolide impacts could have been important for the initiation of abiotic reactions that gave rise to the first living organisms. PMID:11539550

  8. Early archean spherule beds in the Barberton mountain land, South Africa: Impact or terrestrial origin?

    NASA Astrophysics Data System (ADS)

    Reimold, Wolf Uwe; Koeberl, Christian; Johnson, Steven; McDonald, Iain

    The origin of multiple spherule-rich layers of millimeter to meter width, all occurring within the transition from the Fig Tree to the Onverwacht Group of the Barberton Greenstone Belt in South Africa, has been strongly debated during the last decade. One school subscribes to an origin by large meteorite impact, whereas others have preferred terrestrial processes. In particular, strong enrichments in siderophile elements, especially Ir, and chondrite-like PGE patterns for spherule layer samples have been cited as evidence favoring an impact origin. Recently, Cr isotopic signatures obtained for samples from two spherule layers have provided further support for this hypothesis. In contrast, our group has emphasized that secondary hydrothermal processes have pervasively overprinted the whole stratigraphy at this transition. Ir concentrations up to 5 times chondritic are suspect as primary impact-produced signatures. Here, we report new petrographic and geochemical data for samples from spherulitic horizons marking the S2 layer and from interlayered BIF, chert, and mudstone strata. In contrast to earlier work, the new samples were obtained from outside of the gold-sulfide mineralized ore zone on Agnes Mine. Both spherule and country rock samples are enriched in siderophile elements, with up to >1500 ppb Ir. Some of the highest values are related to clearly secondary fault and shear zone deposits. Chrome-spinel in spherule layers is often zoned. A proton microprobe study identified in one case the mineral gersdorffite, of likely secondary origin, as a carrier phase for Ir, whereas in other samples Ir must be contained in matrix silicates. New PGE analyses for more or less sulfidemineralized samples yielded uniformly flat, near-chondritic patterns.

  9. The origins of the birth control movement in England in the early nineteenth century.

    PubMed

    Langer, W L

    1975-01-01

    The origins of the birth control movement in England in the 19th cen tury are discussed. The impact of Malthus's "Essay on the Principle of Population" and the activities of such thinkers and reformers as Jermy Bentham, James and John Stuart Mill, Francis Plance, Richard Carlile, Robert Dale Owen, and Charles Knowlton are discussed. The social debate that arose during the century is discussed. PMID:11619426

  10. Hospital for Special Surgery: Origin and Early History First Site 1863–1870

    PubMed Central

    2005-01-01

    Hospital for Special Surgery (HSS) originated as the Hospital for the Ruptured and Crippled (R&C) 142 years ago in New York City. As the first and only orthopaedic hospital of its kind in this country, it was located in the residence of its founder James Knight on Second Avenue, south of Sixth Street, and started with 28 inpatient beds for children but no operating facilities. The history of this institution has been documented in two books and occasionally published and unpublished papers. Many of these accounts have been limited by time, focus on a particular subject, or overall reviews. The emergence of such a specialized facility in the middle of the 19th century during a time of medicine in its infancy, our country at war and the city of New York racked in poverty, disease, civil riots, and political corruption is a story not necessarily appreciated in our day. The vision of one little-known physician and the cooperation and support of a small group of prominent New Yorkers and philanthropists were responsible for the origin of this hospital and particularly for its survival in such troubled times when most small hospitals of this period lasted only for a few years. Fortunately, almost all of the original Annual Reports of the Board of Managers, photographs, manuscripts, personal records, and newspaper clippings have been saved. They are now being collected, preserved, catalogued, and displayed in the newly formed HSS Archives from which this material has been taken. PMID:18751802