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  • 1
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    Late Paleocene – middle Eocene benthic foraminifera on a Pacific Seamount (Allison Guyot, ODP Site 865): Greenhouse Climate and superimposed hyperthermal events (2016)
    Wiley
    Details
    Publication Date: 2016-01-30
    Description: We investigated the response of late Paleocene-middle Eocene (~60-37.5 Ma) benthic foraminiferal assemblages to long term climate change and hyperthermal events including the Paleocene-Eocene Thermal Maximum (PETM) at ODP Site 865 on Allison Guyot, a seamount in the Mid-Pacific Mountains. Seamounts are isolated deep-sea environments where enhanced current systems interrupt bentho-pelagic coupling, and fossil assemblages from such settings have been little evaluated. Assemblages at Site 865 are diverse and dominated by cylindrical calcareous taxa with complex apertures, an extinct group which probably lived infaunally. Dominance of an infaunal morphogroup is unexpected in a highly oligotrophic setting, but these forms may have been shallow infaunal suspension feeders, which were ecologically successful on the current-swept seamount. The magnitude of the PETM extinction at Site 865 was similar to other sites globally, but lower diversity post-extinction faunas at this location were affected by ocean acidification as well as changes in current regime, which might have led to increased nutrient supply through trophic focusing. A minor hyperthermal (ETM3) saw less severe effects of changes in current regime, with no evidence for carbonate dissolution. Although the relative abundance of infaunal benthic foraminifera has been used as a proxy for surface productivity through bentho-pelagic coupling, we argue that this proxy can be used only in the absence of changes in carbonate saturation and current-driven biophysical linking.
    Print ISSN: 0883-8305
    Electronic ISSN: 1944-9186
    Topics: Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary (2010)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2010-03-06
    Description: The Cretaceous-Paleogene boundary approximately 65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulte, Peter -- Alegret, Laia -- Arenillas, Ignacio -- Arz, Jose A -- Barton, Penny J -- Bown, Paul R -- Bralower, Timothy J -- Christeson, Gail L -- Claeys, Philippe -- Cockell, Charles S -- Collins, Gareth S -- Deutsch, Alexander -- Goldin, Tamara J -- Goto, Kazuhisa -- Grajales-Nishimura, Jose M -- Grieve, Richard A F -- Gulick, Sean P S -- Johnson, Kirk R -- Kiessling, Wolfgang -- Koeberl, Christian -- Kring, David A -- MacLeod, Kenneth G -- Matsui, Takafumi -- Melosh, Jay -- Montanari, Alessandro -- Morgan, Joanna V -- Neal, Clive R -- Nichols, Douglas J -- Norris, Richard D -- Pierazzo, Elisabetta -- Ravizza, Greg -- Rebolledo-Vieyra, Mario -- Reimold, Wolf Uwe -- Robin, Eric -- Salge, Tobias -- Speijer, Robert P -- Sweet, Arthur R -- Urrutia-Fucugauchi, Jaime -- Vajda, Vivi -- Whalen, Michael T -- Willumsen, Pi S -- New York, N.Y. -- Science. 2010 Mar 5;327(5970):1214-8. doi: 10.1126/science.1177265.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉GeoZentrum Nordbayern, Universitat Erlangen-Nurnberg, Schlossgarten 5, D-91054 Erlangen, Germany. schulte@geol.uni-erlangen.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20203042" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Extinction, Biological ; *Fossils ; Geologic Sediments ; Mexico ; *Minor Planets
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Paleoenvironmental changes at ODP Site 702 (South Atlantic): anatomy of the Middle Eocene Climatic Optimum (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract The Middle Eocene Climatic Optimum (MECO) was an unusual global warming event that interrupted the long‐term Eocene cooling trend ca. 40 Ma. Here we present new high‐resolution bulk and benthic isotope records from South Atlantic ODP Site 702 to characterize the MECO at a high latitude setting. The MECO event, including early and peak warming as well as recovery to background levels had an estimated ~ 300 kyr duration (~40.51 to ~40.21 Ma). Cross‐plots (δ18O vs. δ13C) suggest that the mechanisms driving coupled changes in O and C isotope values across the MECO were weaker or absent before the event. The paleoecological response has been evaluated by quantitative analysis of calcareous nannofossils and benthic foraminifera assemblages. We document a shift in the biogeographical distribution of warm and temperate calcareous nannoplankton taxa, which migrated towards higher latitudes due to increased temperatures during the MECO. Conversely, changes in the organic matter flux to the seafloor appear to have controlled benthic foraminifera dynamics at Site 702. Benthic phytodetritus exploiting taxa (PET) increased in abundance coinciding with a positive δ13C excursion, ~150 kyr before the start of the δ18O negative excursion that marks the start of MECO warming. Our data suggest that paleoecological disturbance in the deep‐sea predates MECO δ18O excursion, and that it was driven by changes in the type and/or amount of organic matter reaching the seafloor rather than by increased temperature.
    Print ISSN: 0883-8305
    Electronic ISSN: 2572-4525
    Topics: Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Electronic Resource
    Electronic Resource
    The Cretaceous/Tertiary boundary: sedimentology and micropalaeontology at El Mulato section, NE Mexico (2002)
    Oxford, UK : Blackwell Science Ltd
    Terra nova 14 (2002), S. 0 
    Details
    ISSN: 1365-3121
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: In the El Mulato section (NE Mexico), the Upper Cretaceous marly Méndez and the Lower Palaeogene marly Velasco Formations are separated by a clastic unit. Benthic foraminifera from both marly formations indicate lower bathyal depths. The clastic unit, in contrast, contains platform sands, muddy pebbles and neritic (shallow) faunas mixed with microspherules, indicating that it was allochthonously deposited into the deep basin. The diversity and the variability in origin of the components in the clastic unit, and its sedimentological features, support a model of deposition by turbidity currents related to mass-wasting processes triggered by the Cretaceous/Tertiary (K/T) boundary impact. Planktic foraminifera were affected by a catastrophic extinction at the K/T boundary, whereas benthic foraminifera show reorganization of the community structure rather than significant extinction. The benthic faunal turnover may have resulted from the drop in primary productivity after the asteroid impact at the end of the Cretaceous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3121.2002.00425.x
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  • 5
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    End-Cretaceous marine mass extinction not caused by productivity collapse (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-12-29
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 6
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    Experimentos de disolución de CaCO 3 en foraminíferos bentónicos aglutinados del Paleoceno-Eoceno en Zumaya (Cuenca Vasco-Cantábrica, España) (2015)
    Consejo Superior de Investigaciones Científicas (CSIC)
    Details
    Publication Date: 2015-06-25
    Description: Durante el evento de calentamiento global conocido como Máximo Térmico del Paleoceno-Eoceno (PETM por sus siglas en inglés; hace ~55.8 Ma) tuvo lugar la mayor extinción de foraminíferos bentónicos de medios profundos de todo el Cenozoico. Mucho se ha especulado sobre las causas de dicha extinción, que incluyen cambios en la productividad y/o en la oxigenación de las aguas, cambios metabólicos y en la composición del aporte alimenticio al fondo marino, o la acidificación de los océanos relacionada con el aporte masivo de isótopos de carbono ligero al sistema océano-atmósfera, entre otros. En el presente estudio se analiza el potencial de la acidificación como agente desencadenante de las extinciones. En el corte de Zumaya (Cuenca Vasco-Cantábrica), el Eoceno inicial está marcado por un intervalo de 4 m con muy bajo contenido en CaCO 3 . Con el fin de analizar si la disolución del carbonato tuvo una incidencia directa sobre las extinciones del PETM, se han realizado experimentos de disolución en diversas especies de foraminíferos bentónicos aglutinados procedentes de Zumaya. En general, las especies aglutinadas que no desaparecen en el intervalo de máxima disolución en Zumaya son aquellas que fueron poco o nada afectadas por los experimentos de disolución, pues no presentan partículas y/o cemento calcáreo. No obstante, algunas especies que se extinguieron y/o desaparecieron localmente durante el Eoceno inicial, como Dorothia cylindracea, Spiroplectammina spectabilis y Haplophragmoides cf. walteri , resultaron ser resistentes a la disolución. Estos resultados sugieren que, además de la acidificación, debieron darse otros factores que contribuyeron a la desestabilización de las asociaciones de foraminíferos bentónicos.
    Print ISSN: 0367-0449
    Electronic ISSN: 1988-3250
    Topics: Geosciences
    Published by Consejo Superior de Investigaciones Científicas (CSIC)
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  • 7
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    Oligocene Benthic Foraminifera From the Fuente Caldera Section (Spain, Western Tethys): Taxonomy and Paleoenvironmental Inferences (2012)
    Cushman Foundation for Foraminiferal Research
    Details
    Publication Date: 2012-11-13
    Description: The effects of Oligocene paleoclimatic and paleoenvironmental events at lower latitudes have not been well defined, and the timing and extent of a proposed warming period in the late Oligocene are not clear. The study of benthic foraminifera from the upper bathyal Fuente Caldera section in southern Spain may help reconstruct the Oligocene paleoenvironmental turnover in the western Tethys. Rupelian and Chattian sediments from Fuente Caldera consist of hemipelagic marls intercalated with turbiditic sandstones. Based on a closely spaced sample collection, we present a quantitative analysis of benthic foraminiferal assemblage changes, and a detailed taxonomic study of 19 of the most abundant and paleoenvironmentally important species, belonging to the asterigerinids, rosalinids and bolivinids. The Fuente Caldera sediments contain abundant reworked neritic foraminifera (asterigerinids, rosalinids, Cibicides spp.), including epiphytes and species that commonly bear symbionts or kleptochloroplasts from the photic zone, that may have been transported downslope by turbidity currents or attached to floating plant material. The high relative abundance of bolivinid taxa in the autochthonous assemblages suggests a high food supply, probably at least in part consisting of refractory organic matter supplied by downslope turbidity currents. The benthic foraminifera indicate that water temperatures were several degrees warmer than today, as inferred from the common occurrence of warm-water taxa such as Nodobolivinella jhingrani, Rectobolivina costifera or Tubulogenerina vicksburgensis . Nevertheless, further paleotemperature studies are needed to test our conclusion that warm conditions prevailed in this part of the western Tethys during the Oligocene, even during colder intervals (Oi-events).
    Print ISSN: 0096-1191
    Topics: Geosciences
    Published by Cushman Foundation for Foraminiferal Research
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  • 8
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    Memorial To Eustoquio Molina (1950–2018) (2019)
    Cushman Foundation for Foraminiferal Research
    Details
    Publication Date: 2019
    Print ISSN: 0096-1191
    Electronic ISSN: 1943-264X
    Topics: Geosciences
    Published by Cushman Foundation for Foraminiferal Research
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  • 9
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    End-Cretaceous marine mass extinction not caused by productivity collapse [Geology] (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-01-18
    Description: An asteroid impact at the end of the Cretaceous caused mass extinction, but extinction mechanisms are not well-understood. The collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity (Strangelove Ocean) or export productivity (Living Ocean), which caused mass extinction higher in the marine food chain. Phytoplankton-dependent benthic foraminifera on the deep-sea floor, however, did not suffer significant extinction, suggesting that export productivity persisted at a level sufficient to support their populations. We compare benthic foraminiferal records with benthic and bulk stable carbon isotope records from the Pacific, Southeast Atlantic, and Southern Oceans. We conclude that end-Cretaceous decrease in export productivity was moderate, regional, and insufficient to explain marine mass extinction. A transient episode of surface ocean acidification may have been the main cause of extinction of calcifying plankton and ammonites, and recovery of productivity may have been as fast in the oceans as on land.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Diffraction Regimes of Single Holes (2012)
    American Physical Society (APS)
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    Publication Date: 2012-07-13
    Description: Author(s): J.-M. Yi, A. Cuche, F. de León-Pérez, A. Degiron, E. Laux, E. Devaux, C. Genet, J. Alegret, L. Martín-Moreno, and T. W. Ebbesen We investigate both experimentally and theoretically the far-field diffraction patterns of single circular apertures as a function of their diameters d and at a given illumination wavelength λ . We observe the transition between the well-known pseudoscalar regime of large holes ( d ≫ λ ) and the less-kno... [Phys. Rev. Lett. 109, 023901] Published Thu Jul 12, 2012
    Keywords: Nonlinear Dynamics, Fluid Dynamics, Classical Optics, etc.
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society (APS)
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