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Dennis V Kent - One of the best experts on this subject based on the ideXlab platform.

  • Chronostratigraphic terminology at the Paleocene/Eocene Boundary
    Causes and consequences of globally warm climates in the early Paleogene, 2020
    Co-Authors: Marie-pierre Aubry, Dennis V Kent, Henk Brinkhuis, Christian Dupuis, William A. Berggren, John A. Van Couvering, Benjamin S. Cramer, Carl C. Swisher, Philip D. Gingerich
    Abstract:

    Marie-Pierr e A ubryDepartment of Geolo gical Sciences, Rutg ers Univer sity, 610 Taylor Road, Piscataway , Ne w J ersey 08554, USAW illiam A. Ber ggr enDepartment of Geolo gy and Geophysics, W oods Hole Oceano gr aphic Institution, W oods Hole , Massac hussetts 02543, USA, and Department of Geolo gical Sciences, Rutg ers Univer sity, 610 Taylor Road, Piscataway , Ne w J ersey 08554, USAJohn A. V an Couv eringMicr opaleontolo gy Pr ess, American Museum of Natur al History , Ne w York, Ne w York 10024, USAJason AliDepartment of Earth Sciences, Univer sity of Hong K ong , Pokfulam Road, Hong K ong , ChinaHenk BrinkhuisLabor atory of P alaeobotany and P alynolo gy , Univer sity of Utr ec ht, Budapestlaan 4, 3584 CD, Utr ec ht, The NetherlandsBenjamin CramerDennis V K ent*Carl C. Swisher , IIIDepartment of Geolo gical Sciences, Rutg ers Univer sity, 610 Taylor Road, Piscataway , Ne w J ersey 08554, USAChristian DupuisGŽolo gie F ondamentale et AppliquŽe , Mons P olytec hnics, Rue de Houdain, 9 B-7000 Mons, BelgiumPhilip. D . GingerichDepartment of Geolo gical Sciences and Museum of P aleontolo gy , Univer sity of Mic higan, Ann Arbor , Mic higan 48109Ð1079, USAClaus Heilmann-ClausenGeolo gisk Institut, Aarhus Univer sitet, DK-8000 Aarhus C, DenmarkChris KingDa vid J . W ardDepartment of Earth Sciences, Univer sity of Gr eenwic h, Chatham, K ent, UKRobert W .OOB. KnoxBritish Geolo gical Surve y, K eyworth, Nottingham, NG12 5GG, UKKhaled OudaDepartment of Geolo gy , Univer sity of Assiut, Assiut, 71516 EgyptLo well D . StottDepartment of Geolo gy , Univer sity of Southern California, Los Ang eles, California 90089Ð0740, USAMedard ThiryEcole des Mines de P aris, 35, rue Saint Honor Ž, 77305 F ontainebleau, F rance1

  • enhanced magnetization of the marlboro clay as a product of soil pyrogenesis at the paleocene eocene Boundary
    Earth and Planetary Science Letters, 2017
    Co-Authors: Huapei Wang, Dennis V Kent, Luca Lanci, James D Wright
    Abstract:

    Abstract The kaolinite-rich Marlboro Clay was deposited on the inner shelf in the Salisbury Embayment of the U.S. Atlantic margin at the onset of the carbon isotope excursion marking the 56 Ma Paleocene–Eocene Boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization. Recent studies point to a magnetic assemblage that is dominated by single-domain magnetite particles that tend to be isolated rather than arranged in chains, the most distinguishing feature of magnetotactic bacteria fossils. On the other hand, it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter-scale thickness of the Marlboro Clay. We obtained new data from a landward proximal site at Wilson Lake on the New Jersey Coastal Plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the Marlboro Clay in the same core. Yet the high field magnetic susceptibility, a measure of total iron concentration, and strontium isotope values on bulk sediment, an indicator of sediment weathering provenance, are not different in the Marlboro Clay from the immediately underlying Vincentown Formation. We suggest that the distinctive magnetic properties of the Marlboro Clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area. The pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud-waves across the shelf, becoming the Marlboro Clay. A few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition. Disseminated wood ash stone entrained in the Marlboro Clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data. A plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range.

  • Enhanced magnetization of the Marlboro Clay as a product of soil pyrogenesis at the Paleocene–Eocene Boundary?
    Earth and Planetary Science Letters, 2017
    Co-Authors: Dennis V Kent, Huapei Wang, Luca Lanci, James D Wright
    Abstract:

    Abstract The kaolinite-rich Marlboro Clay was deposited on the inner shelf in the Salisbury Embayment of the U.S. Atlantic margin at the onset of the carbon isotope excursion marking the 56 Ma Paleocene–Eocene Boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization. Recent studies point to a magnetic assemblage that is dominated by single-domain magnetite particles that tend to be isolated rather than arranged in chains, the most distinguishing feature of magnetotactic bacteria fossils. On the other hand, it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter-scale thickness of the Marlboro Clay. We obtained new data from a landward proximal site at Wilson Lake on the New Jersey Coastal Plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the Marlboro Clay in the same core. Yet the high field magnetic susceptibility, a measure of total iron concentration, and strontium isotope values on bulk sediment, an indicator of sediment weathering provenance, are not different in the Marlboro Clay from the immediately underlying Vincentown Formation. We suggest that the distinctive magnetic properties of the Marlboro Clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area. The pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud-waves across the shelf, becoming the Marlboro Clay. A few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition. Disseminated wood ash stone entrained in the Marlboro Clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data. A plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range.

  • Impact ejecta at the Paleocene-Eocene Boundary
    Science, 2016
    Co-Authors: Morgan F. Schaller, James D Wright, Miriam E. Katz, Megan K. Fung, Dennis V Kent
    Abstract:

    Extraterrestrial impacts have left a substantial imprint on the climate and evolutionary history of Earth. A rapid carbon cycle perturbation and global warming event about 56 million years ago at the Paleocene-Eocene (P-E) Boundary (the Paleocene-Eocene Thermal Maximum) was accompanied by rapid expansions of mammals and terrestrial plants and extinctions of deep-sea benthic organisms. Here, we report the discovery of silicate glass spherules in a discrete stratigraphic layer from three marine P-E Boundary sections on the Atlantic margin. Distinct characteristics identify the spherules as microtektites and microkrystites, indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E Boundary.

  • Quantified abundance of magnetofossils at the Paleocene–Eocene Boundary from synchrotron-based transmission X-ray microscopy
    Proceedings of the National Academy of Sciences of the United States of America, 2015
    Co-Authors: Huapei Wang, Yu-chen Karen Chen-wiegart, Jun Wang, Dennis V Kent
    Abstract:

    Abstract The Paleocene–Eocene Boundary (∼55.8 million years ago) is marked by an abrupt negative carbon isotope excursion (CIE) that coincides with an oxygen isotope decrease interpreted as the Paleocene–Eocene thermal maximum. Biogenic magnetite (Fe3O4) in the form of giant (micron-sized) spearhead-like and spindle-like magnetofossils, as well as nano-sized magnetotactic bacteria magnetosome chains, have been reported in clay-rich sediments in the New Jersey Atlantic Coastal Plain and were thought to account for the distinctive single-domain magnetic properties of these sediments. Uncalibrated strong field magnet extraction techniques have been typically used to provide material for scanning and transmission electron microscopic imaging of these magnetic particles, whose concentration in the natural sediment is thus difficult to quantify. In this study, we use a recently developed ultrahigh-resolution, synchrotron-based, full-field transmission X-ray microscope to study the iron-rich minerals within the clay sediment in their bulk state. We are able to estimate the total magnetization concentration of the giant biogenic magnetofossils to be only ∼10% of whole sediment. Along with previous rock magnetic studies on the CIE clay, we suggest that most of the magnetite in the clay occurs as isolated, near-equidimensional nanoparticles, a suggestion that points to a nonbiogenic origin, such as comet impact plume condensates in what may be very rapidly deposited CIE clays.

Huapei Wang - One of the best experts on this subject based on the ideXlab platform.

  • enhanced magnetization of the marlboro clay as a product of soil pyrogenesis at the paleocene eocene Boundary
    Earth and Planetary Science Letters, 2017
    Co-Authors: Huapei Wang, Dennis V Kent, Luca Lanci, James D Wright
    Abstract:

    Abstract The kaolinite-rich Marlboro Clay was deposited on the inner shelf in the Salisbury Embayment of the U.S. Atlantic margin at the onset of the carbon isotope excursion marking the 56 Ma Paleocene–Eocene Boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization. Recent studies point to a magnetic assemblage that is dominated by single-domain magnetite particles that tend to be isolated rather than arranged in chains, the most distinguishing feature of magnetotactic bacteria fossils. On the other hand, it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter-scale thickness of the Marlboro Clay. We obtained new data from a landward proximal site at Wilson Lake on the New Jersey Coastal Plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the Marlboro Clay in the same core. Yet the high field magnetic susceptibility, a measure of total iron concentration, and strontium isotope values on bulk sediment, an indicator of sediment weathering provenance, are not different in the Marlboro Clay from the immediately underlying Vincentown Formation. We suggest that the distinctive magnetic properties of the Marlboro Clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area. The pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud-waves across the shelf, becoming the Marlboro Clay. A few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition. Disseminated wood ash stone entrained in the Marlboro Clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data. A plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range.

  • Enhanced magnetization of the Marlboro Clay as a product of soil pyrogenesis at the Paleocene–Eocene Boundary?
    Earth and Planetary Science Letters, 2017
    Co-Authors: Dennis V Kent, Huapei Wang, Luca Lanci, James D Wright
    Abstract:

    Abstract The kaolinite-rich Marlboro Clay was deposited on the inner shelf in the Salisbury Embayment of the U.S. Atlantic margin at the onset of the carbon isotope excursion marking the 56 Ma Paleocene–Eocene Boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization. Recent studies point to a magnetic assemblage that is dominated by single-domain magnetite particles that tend to be isolated rather than arranged in chains, the most distinguishing feature of magnetotactic bacteria fossils. On the other hand, it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter-scale thickness of the Marlboro Clay. We obtained new data from a landward proximal site at Wilson Lake on the New Jersey Coastal Plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the Marlboro Clay in the same core. Yet the high field magnetic susceptibility, a measure of total iron concentration, and strontium isotope values on bulk sediment, an indicator of sediment weathering provenance, are not different in the Marlboro Clay from the immediately underlying Vincentown Formation. We suggest that the distinctive magnetic properties of the Marlboro Clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area. The pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud-waves across the shelf, becoming the Marlboro Clay. A few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition. Disseminated wood ash stone entrained in the Marlboro Clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data. A plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range.

  • Quantified abundance of magnetofossils at the Paleocene–Eocene Boundary from synchrotron-based transmission X-ray microscopy
    Proceedings of the National Academy of Sciences of the United States of America, 2015
    Co-Authors: Huapei Wang, Yu-chen Karen Chen-wiegart, Jun Wang, Dennis V Kent
    Abstract:

    Abstract The Paleocene–Eocene Boundary (∼55.8 million years ago) is marked by an abrupt negative carbon isotope excursion (CIE) that coincides with an oxygen isotope decrease interpreted as the Paleocene–Eocene thermal maximum. Biogenic magnetite (Fe3O4) in the form of giant (micron-sized) spearhead-like and spindle-like magnetofossils, as well as nano-sized magnetotactic bacteria magnetosome chains, have been reported in clay-rich sediments in the New Jersey Atlantic Coastal Plain and were thought to account for the distinctive single-domain magnetic properties of these sediments. Uncalibrated strong field magnet extraction techniques have been typically used to provide material for scanning and transmission electron microscopic imaging of these magnetic particles, whose concentration in the natural sediment is thus difficult to quantify. In this study, we use a recently developed ultrahigh-resolution, synchrotron-based, full-field transmission X-ray microscope to study the iron-rich minerals within the clay sediment in their bulk state. We are able to estimate the total magnetization concentration of the giant biogenic magnetofossils to be only ∼10% of whole sediment. Along with previous rock magnetic studies on the CIE clay, we suggest that most of the magnetite in the clay occurs as isolated, near-equidimensional nanoparticles, a suggestion that points to a nonbiogenic origin, such as comet impact plume condensates in what may be very rapidly deposited CIE clays.

  • Quantified abundance of magnetofossils at the Paleocene–Eocene Boundary from synchrotron-based transmission X-ray microscopy
    Proceedings of the National Academy of Sciences, 2015
    Co-Authors: Huapei Wang, Yu-chen Karen Chen-wiegart, Jun Wang, Dennis V Kent
    Abstract:

    Significance: The Paleocene–Eocene thermal maximum (PETM) is an abrupt global warming event that occurred at about 55.8 Ma and is closely linked to a large carbon isotope excursion. What caused the PETM is unresolved. An unusual abundance of single-domain magnetite particles in PETM sediments on the Atlantic Coastal Plain might represent condensates from a comet impact. Alternatively, the magnetic nanoparticles may be of biogenic origin. We are now able to quantify the concentration of those magnetic grains that are distinctly of biogenic origin using synchrotron-based transmission X-ray microscopy. These and related findings allow us to exclude magnetofossils as a significant source of magnetization of the PETM sediments and point to an impact condensate origin of the magnetite particles. Abstract: The Paleocene–Eocene Boundary (∼55.8 million years ago) is marked by an abrupt negative carbon isotope excursion (CIE) that coincides with an oxygen isotope decrease interpreted as the Paleocene–Eocene thermal maximum. Biogenic magnetite (Fe3O4) in the form of giant (micron-sized) spearhead-like and spindle-like magnetofossils, as well as nano-sized magnetotactic bacteria magnetosome chains, have been reported in clay-rich sediments in the New Jersey Atlantic Coastal Plain and were thought to account for the distinctive single-domain magnetic properties of these sediments. Uncalibrated strong field magnet extraction techniques have been typically used to provide material for scanning and transmission electron microscopic imaging of these magnetic particles, whose concentration in the natural sediment is thus difficult to quantify. In this study, we use a recently developed ultrahigh-resolution, synchrotron-based, full-field transmission X-ray microscope to study the iron-rich minerals within the clay sediment in their bulk state. We are able to estimate the total magnetization concentration of the giant biogenic magnetofossils to be only ∼10% of whole sediment. Along with previous rock magnetic studies on the CIE clay, we suggest that most of the magnetite in the clay occurs as isolated, near-equidimensional nanoparticles, a suggestion that points to a nonbiogenic origin, such as comet impact plume condensates in what may be very rapidly deposited CIE clays.

  • Evidence for abundant isolated magnetic nanoparticles at the Paleocene-Eocene Boundary.
    Proceedings of the National Academy of Sciences of the United States of America, 2012
    Co-Authors: Huapei Wang, Dennis V Kent, Michael J Jackson
    Abstract:

    New rock magnetic results (thermal fluctuation tomography, high-resolution first-order reversal curves and low temperature measurements) for samples from the Paleocene–Eocene thermal maximum and carbon isotope excursion in cored sections at Ancora and Wilson Lake on the Atlantic Coastal Plain of New Jersey indicate the presence of predominantly isolated, near-equidimensional single-domain magnetic particles rather than the chain patterns observed in a cultured magnetotactic bacteria sample or magnetofossils in extracts. The various published results can be reconciled with the recognition that chain magnetosomes tend to be preferentially extracted in the magnetic separation process but, as we show, may represent only a small fraction of the overall magnetic assemblage that accounts for the greatly enhanced magnetization of the carbon isotope excursion sediment but whose origin is thus unclear.

James D Wright - One of the best experts on this subject based on the ideXlab platform.

  • enhanced magnetization of the marlboro clay as a product of soil pyrogenesis at the paleocene eocene Boundary
    Earth and Planetary Science Letters, 2017
    Co-Authors: Huapei Wang, Dennis V Kent, Luca Lanci, James D Wright
    Abstract:

    Abstract The kaolinite-rich Marlboro Clay was deposited on the inner shelf in the Salisbury Embayment of the U.S. Atlantic margin at the onset of the carbon isotope excursion marking the 56 Ma Paleocene–Eocene Boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization. Recent studies point to a magnetic assemblage that is dominated by single-domain magnetite particles that tend to be isolated rather than arranged in chains, the most distinguishing feature of magnetotactic bacteria fossils. On the other hand, it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter-scale thickness of the Marlboro Clay. We obtained new data from a landward proximal site at Wilson Lake on the New Jersey Coastal Plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the Marlboro Clay in the same core. Yet the high field magnetic susceptibility, a measure of total iron concentration, and strontium isotope values on bulk sediment, an indicator of sediment weathering provenance, are not different in the Marlboro Clay from the immediately underlying Vincentown Formation. We suggest that the distinctive magnetic properties of the Marlboro Clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area. The pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud-waves across the shelf, becoming the Marlboro Clay. A few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition. Disseminated wood ash stone entrained in the Marlboro Clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data. A plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range.

  • Enhanced magnetization of the Marlboro Clay as a product of soil pyrogenesis at the Paleocene–Eocene Boundary?
    Earth and Planetary Science Letters, 2017
    Co-Authors: Dennis V Kent, Huapei Wang, Luca Lanci, James D Wright
    Abstract:

    Abstract The kaolinite-rich Marlboro Clay was deposited on the inner shelf in the Salisbury Embayment of the U.S. Atlantic margin at the onset of the carbon isotope excursion marking the 56 Ma Paleocene–Eocene Boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization. Recent studies point to a magnetic assemblage that is dominated by single-domain magnetite particles that tend to be isolated rather than arranged in chains, the most distinguishing feature of magnetotactic bacteria fossils. On the other hand, it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter-scale thickness of the Marlboro Clay. We obtained new data from a landward proximal site at Wilson Lake on the New Jersey Coastal Plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the Marlboro Clay in the same core. Yet the high field magnetic susceptibility, a measure of total iron concentration, and strontium isotope values on bulk sediment, an indicator of sediment weathering provenance, are not different in the Marlboro Clay from the immediately underlying Vincentown Formation. We suggest that the distinctive magnetic properties of the Marlboro Clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area. The pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud-waves across the shelf, becoming the Marlboro Clay. A few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition. Disseminated wood ash stone entrained in the Marlboro Clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data. A plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range.

  • Impact ejecta at the Paleocene-Eocene Boundary
    Science, 2016
    Co-Authors: Morgan F. Schaller, James D Wright, Miriam E. Katz, Megan K. Fung, Dennis V Kent
    Abstract:

    Extraterrestrial impacts have left a substantial imprint on the climate and evolutionary history of Earth. A rapid carbon cycle perturbation and global warming event about 56 million years ago at the Paleocene-Eocene (P-E) Boundary (the Paleocene-Eocene Thermal Maximum) was accompanied by rapid expansions of mammals and terrestrial plants and extinctions of deep-sea benthic organisms. Here, we report the discovery of silicate glass spherules in a discrete stratigraphic layer from three marine P-E Boundary sections on the Atlantic margin. Distinct characteristics identify the spherules as microtektites and microkrystites, indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E Boundary.

  • A continental shelf perspective of ocean acidification and temperature evolution during the Paleocene-Eocene Thermal Maximum
    Geology, 2016
    Co-Authors: Tali L. Babila, James D Wright, Yair Rosenthal, Kenneth G. Miller
    Abstract:

    A rapid and large injection of isotopically light carbon into the ocean-atmosphere reservoirs is signaled by a negative carbon isotope excursion (CIE) at the Paleocene-Eocene Boundary ∼56 m.y. ago. To better understand the extent of ocean warming and acidification associated with the carbon injection we generated elemental and isotopic records of surface and thermocline planktonic foraminifera across the Paleocene-Eocene Boundary from an expanded section along the Mid-Atlantic coastal plain, New Jersey (USA). Ocean temperatures (derived from magnesium/calcium paleothermometer) document a lag in thermocline warming relative to surface waters, implying a progressive deepening of the mixed layer in addition to global warming. A similar magnitude of acidification (as recorded by boron/calcium, B/Ca) on the shelf compared with open ocean sites confirms widespread acidification of the surface ocean. An increase in seawater alkalinity after the CIE, as recorded by B/Ca in planktonic foraminifera, likely played an important role in neutralizing the added carbon, possibly minimizing benthic extinction along the shelf.

Robert P. Speijer - One of the best experts on this subject based on the ideXlab platform.

  • DISSOLUTION SUSCEPTIBILITY OF SOME PALEOGENE PLANKTONIC FORAMINIFERA FROM ODP SITE 1209 (SHATSKY RISE, PACIFIC OCEAN)
    Journal of Foraminiferal Research, 2008
    Co-Authors: Maria Rose Petrizzo, Robert P. Speijer, Greta Leoni, Bianca De Bernardi, Fabrizio Felletti
    Abstract:

    A detailed, quantitative analysis of planktonic foraminiferal composition and shell fragmentation is presented for samples from Ocean Drilling Program Site 1209 (Leg 198, Shatsky Rise, Pacific Ocean) in a stratigraphic interval from the Paleocene/Eocene Boundary, which is characterized by enhanced carbonate dissolution, to the base of the middle Eocene where no distinct dissolution layers are recorded. The aims are to evaluate whether the composition of the fossil Paleogene assemblage is representative of the original assemblage and to what extent it is influenced by carbonate dissolution. By comparing the absolute abundances of whole specimens and fragments of the three most common Paleogene genera ( Morozovella , Acarinina and Subbotina ), it is demonstrated that the percentage of foraminiferal fragments, identified to genus, is helpful in interpreting the paleoenvironment of fossil planktonic foraminiferal assemblages affected by marked carbonate dissolution. In addition, the absolute abundance of whole specimens and fragments of the three Paleogene genera collected at the Paleocene/Eocene Boundary and in the Eocene reveal that, contrary to earlier suggestions, the spinose, asymbiotic, deep-dweller Subbotina is less resistant to dissolution than the muricate, symbiont-bearing, surface-dwellers Morozovella and Acarinina . Distinguishing between primary and taphonomic signals in Paleogene planktonic foraminiferal assemblages will be an important challenge to overcome in order to better constrain paleoecologic and paleoclimatic signals of global significance.

  • Environmental perturbation in the southern Tethys across the Paleocene/Eocene Boundary (Dababiya, Egypt): Foraminiferal and clay mineral records
    Marine Micropaleontology, 2006
    Co-Authors: Sander R. Ernst, Christian Dupuis, Elisa Guasti, Robert P. Speijer
    Abstract:

    Foraminiferal and clay mineral records were studied in the upper Paleocene to lower Eocene Dababiya section (Egypt). This section hosts the GSSP for the Paleocene/Eocene Boundary and as such provides an expanded and relatively continuous record across the Paleocene/Eocene Thermal Maximum (PETM). Deposition of illite–smectite clay minerals is interpreted as a result of warm and arid conditions in the southern Tethys during the latest Paleocene. Benthic foraminiferal assemblages are indicative of seasonal variation of oxygen and food levels at the seafloor. A sea-level fall occurred in the latest Paleocene, followed by a rise in the earliest Eocene. Foraminiferal diversity and densities decreased strongly at the P/E Boundary, coinciding with the level of global extinction of benthic foraminifera (BEE) and start of the Carbon Isotope Excursion (CIE) and PETM. In the lower CIE, the seafloor of the stratified basin remained (nearly) permanently anoxic and azoic. A sudden increase in mixed clay minerals (kaolinite and others) suggests that warm and perennial humid conditions prevailed on the continent. High levels of TOC and phosphathic concretions in the middle CIE are evidence for increased organic fluxes to the sea floor, related to upwelling and to augmented continental runoff. Low densities of opportunistic taxa appeared, indicating occasional ephemeral oxygenation and repopulation of the benthic environment. The planktic community diversified, although conditions remained poor for deep-dwelling taxa. An increase in illite–smectite dominated clay association is considered to mark the return of a seasonal signature on climatic conditions. During the late CIE environmental conditions changed to seasonally fluctuating mesotrophic conditions and diverse and rich benthic and planktic foraminiferal communities developed. Post-CIE planktic faunas consisted of both deep and shallow-dwelling taxa and buliminid-dominated benthic assemblages reflect fluctuating mesotrophic conditions. The frequent environmental perturbations during the CIE/PETM at Dababiya provided a rather specialized group of foraminiferal taxa (i.e., Anomalinoides aegyptiacus) the opportunity to repopulate, survive and subsequently dominate by a hypothesized capacity to switch to an alternative life strategy (population dynamics, habitat shift) or different metabolic pathway. The faunal record of Dababiya provides insight into the cause and development of the BEE: various severe global changes during the PETM (e.g., ocean circulation, CaCO3-dissolution, productivity and temperature changes) disturbed a wide range of environments on a geologically brief timescale, explaining together the geographically and temporally variable character of the BEE. This allowed a number of specific but different foraminiferal assemblages composed of stress-tolerant and opportunistic taxa to be successful during and after the periods of environmental perturbations associated with the PETM.

  • High-resolution ostracode records of the paleocene/eocene transition in the South Eastern Desert of Egypt — Taxonomy, biostratigraphy, paleoecology and paleobiogeography
    Senckenbergiana Lethaea, 2003
    Co-Authors: Abdel-mohsen M. Morsi, Robert P. Speijer
    Abstract:

    Two high-resolution records (Gebel Duwi and Gebel Aweina, southern part of the Eastern Desert, Egypt) across the Paleocene/Eocene Boundary were investigated for their ostracode contents. We particularly focused on the taxonomy, biostratigraphy, paleoecology and paleobiogeography of the ostracode assemblages and on the question whether there was a relationship between faunal and environmental changes associated with the Paleocene/Eocene thermal maximum (PETM). The two sections yielded a total of 29 different taxa, 19 in Duwi and 17 in Aweina, respectively. Four species,Cytherella aegyptopunctata, “Bairdia” malzi, Alocopocythere schmitzi andAegyptiana duwiensis are newly described. The ostracode fauna recorded in Aweina reflects outer neritic deposition, whereas the fauna at Duwi represents a middle neritic environment. Among the many taxa first appearing close to the Paleocene/Eocene Boundary in Aweina and/or Duwi, onlyLeguminocythereis lokossaensis, Dahomeya alata anteroglabrata, Buntonia jordanica subjordanica, Nigeroloxoconcha aegyptiaca punctata andCytherella aegyptopunctata were not observed below the interval of the PETM in Egyptian sediments. During the latest Paleocene, some of these taxa migrated from West African basins, possibly through the Trans-Saharan Seaway. Just a few taxa disappeared during the PETM:Reticulina lamellata, Alocopocythere schmitzi andAegyptiana duwiensis. The Paleocene/Eocene Boundary interval is also marked by enhanced aggradation and degradation inParacosta species, possibly resulting from lowered oxygen and/or enhanced food levels. These faunal and environmental shifts were controlled by a complex interplay between oceanographic, climatic, and sea-level changes.

  • High-resolution ostracode records of the paleocene/eocene transition in the South Eastern Desert of Egypt — Taxonomy, biostratigraphy, paleoecology and paleobiogeography
    Senckenbergiana Lethaea, 2003
    Co-Authors: Abdel-mohsen M. Morsi, Robert P. Speijer
    Abstract:

    Two high-resolution records (Gebel Duwi and Gebel Aweina, southern part of the Eastern Desert, Egypt) across the Paleocene/Eocene Boundary were investigated for their ostracode contents. We particularly focused on the taxonomy, biostratigraphy, paleoecology and paleobiogeography of the ostracode assemblages and on the question whether there was a relationship between faunal and environmental changes associated with the Paleocene/Eocene thermal maximum (PETM). The two sections yielded a total of 29 different taxa, 19 in Duwi and 17 in Aweina, respectively. Four species, Cytherella aegyptopunctata, “Bairdia” malzi, Alocopocythere schmitzi and Aegyptiana duwiensis are newly described. The ostracode fauna recorded in Aweina reflects outer neritic deposition, whereas the fauna at Duwi represents a middle neritic environment. Among the many taxa first appearing close to the Paleocene/Eocene Boundary in Aweina and/or Duwi, only Leguminocythereis lokossaensis, Dahomeya alata anteroglabrata, Buntonia jordanica subjordanica, Nigeroloxoconcha aegyptiaca punctata and Cytherella aegyptopunctata were not observed below the interval of the PETM in Egyptian sediments. During the latest Paleocene, some of these taxa migrated from West African basins, possibly through the Trans-Saharan Seaway. Just a few taxa disappeared during the PETM: Reticulina lamellata, Alocopocythere schmitzi and Aegyptiana duwiensis . The Paleocene/Eocene Boundary interval is also marked by enhanced aggradation and degradation in Paracosta species, possibly resulting from lowered oxygen and/or enhanced food levels. These faunal and environmental shifts were controlled by a complex interplay between oceanographic, climatic, and sea-level changes. Die Ostrakoden zweier hochauflösender Profile (Gebel Duwi und Gebel Aweina, im südlichen Teil der Östlichen Wüste, Ägypten), die dem Bereich der Paleozän/Eozän-Grenze abdecken, wurden untersucht. Die Schwerpunkte waren die Taxonomie, Biostratigraphie, Palökologie und Paläobiogeographie der Ostrakodenvergesellschaftungen und die Frage, ob es einen Bezug zwischen Faunen- und Umweltveränderungen im Zusammenhang mit dem Paleozän/Eozän Thermalen Maximum (PETM) gab. Die zwei Profile enthielten insgesamt 29 unterschiedliche Taxa, bzw. 19 in Duwi und 17 in Aweina. Vier Arten werden neu beschrieben: Cytherella aegyptopunctata, „Bairdia“ malzi, Alocopocythere schmitzi und Aegyptiana duwiensis . Die Ostrakoden-Fauna von Aweina zeigt Ablagerung auf dem äußeren Schelf an, während die Fauna von Duwi Sedimentation auf dem mittleren Schelf belegt. Unter den vielen Arten, die in Aweina und/oder Duwi nahe der Paleozän/Eozän-Grenze zum ersten Mal erschienen, wurden nur Leguminocythereis lokossaensis, Dahomeya alata anteroglabrata, Buntonia jordanica subjordanica, Nigeroloxoconcha aegyptiaca punctata und Cytherella aegyptopunctata nicht unter dem PETM Bereich in Sedimenten Ägyptens beobachtet. Während des späten Paleozäns emigrierten einige dieser Taxa aus westafrikanischen Becken in die Tethys hinein, möglicherweise durch die transsaharische Meeresstraße. Nur wenige Taxa verschwanden gleichzeitig: Reticulina lamellata, Alocopocythere schmitzi und Aegyptiana duwiensis . Der Bereich der Paleozän/Eozän-Grenze wird auch von erhöhter Aggradation und Degradation in Paracosta Arten gekennzeichnet, was möglicherweise mit geringen Sauerstoff- und/oder erhöhten Nährstoffgehalten in Verbindung steht. Diese Fauna- und Umweltverschiebungen wurden von einem komplexen Zusammenspiel von ozeanographischen, klimatischen und Meeresspiegeländerungen verursacht.

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  • Foraminiferal turnover across the Paleocene/Eocene Boundary at the Zumaya section, Spain: record of a bathyal gradual mass extinction
    Revista Mexicana De Ciencias Geologicas, 2009
    Co-Authors: Lamia Zili, Ignacio Arenillas, Dalila Zaghbib-turki, Laia Alegret, Eustoquio Molina
    Abstract:

    An integrated study of benthic and planktonic foraminiferal assemblages across the Paleocene/Eocene Boundary at the Zumaya section (Spain) has been carried out in order to analyse the short period that is commonly known as the Initial Eocene Thermal Maximum, and its impact on the foraminiferal assemblages. Benthic foraminiferal assemblages from uppermost Paleocene and lowermost Eocene sediments at the Zumaya section contain abundant representatives of the calcareous Velasco-type fauna and of the agglutinated fl ysch-type fauna, indicating a lower bathyal depth of deposition. The onset of the carbon isotope excursion, which marks the Paleocene/Eocene Boundary, is recorded at the base of a 40-cm thick grey marly interval (unit U2), and it coincides with the beginning of a Benthic Foraminiferal Gradual Extinction. The pattern of extinction is adjusted more to a gradual and rapid episode rather than to a catastrophic sudden event as was proposed initially. The Paleocene/Eocene benthic foraminiferal extinction is followed by an acme of acarininids (among planktonic foraminifers) and of agglutinated benthic foraminifers, referred here as Agglutinated-Acarinina peak, which is interpreted as the result of global warming, carbonate corrosivity and environmental stress during the Initial Eocene Thermal Maximum. The occurrence of a dissolution interval above the extinction event, where agglutinated benthic foraminifers are abundant and calcareous foraminifers are scarce to absent, is compatible with the global rise of the lysocline and Calcite Compensation Depth in the lower Eocene, due to the increase in partial pressure of oceanic CO2 and therefore, in the deep ocean water corrosiveness.

  • Correlation between the Paleocene/Eocene Boundary and the Ilerdian at Campo, Spain
    Revue de Micropaléontologie, 2003
    Co-Authors: Eustoquio Molina, Eugenia Angori, Ignacio Arenillas, Henk Brinkhuis, Erica M. Crouch, Hanspeter Luterbacher, Simonetta Monechi, Birger Schmitz
    Abstract:

    Abstract The Ilerdian is a well-established Tethyan marine stage, which corresponds to an important phase in the evolution of larger foraminifera not represented in the type-area of the classical Northwest-European stages. This biostratigraphic restudy of its parastratotype in the Campo Section (northeastern Spain) based on planktic foraminifera, calcareous nannofossils, dinoflagellate cysts and the distribution of the stable isotopes ∂13C and ∂18O is an attempt to correlate the Paleocene/Eocene Boundary based on a characteristic carbon isotope excursion (CIE) marking the onset of the Initial Eocene Thermal Maximum (IETM) and the Ilerdian stage. The base of this ∂13C excursion has been chosen as the criterion for the recent proposal of the Global Stratotype Section and Point (GSSP) of the base of the Eocene (= base of the Ypresian) in the Dababiya Section (Egypt) to which an age of 54.9 Ma has been attributed. This level is also characterized by a marked extinction among the deep-water benthic foraminifera (Benthic Foraminifera Extinction Event, BFEE), a flood of representatives of the planktic foraminiferal genus Acarinina and the acme of dinoflagellate cysts of the genus Apectodinium. In the Campo Section, detailed biozonations (planktic foraminifera, calcareous nannofossils, dinoflagellate cysts) are recognized in the Lower and Middle Ilerdian. The correlation with the Ypresian stratotype is based on dinoflagellate cysts and calcareous nannofossils. The base of the Ilerdian is poor in planktic microfossils and its precise correlation with the redefined Paleocene/Eocene Boundary remains uncertain.

  • Planktic foraminiferal and 13C isotopic changes across the Paleocene/Eocene Boundary at Possagno (Italy)
    International Journal of Earth Sciences, 1999
    Co-Authors: Ignacio Arenillas, Eustoquio Molina, Birger Schmitz
    Abstract:

    The interval spanning the Paleocene–Eocene (P/E) transition in the Possagno section consists of 1 m of red marls, including a 4-cm-thick, dark-red "dissolution" clay, which represents the Paleocene/Eocene Boundary event. The Possagno section is much more condensed than other Tethyan and North Atlantic sections previously studied; however, in this section the most significant biotic, isotopic and sedimentological events across the P/E Boundary can be recognized. The Possagno section spans the following planktic foraminiferal subzones: upper part of M. gracilis Subzone, A. berggreni Subzone, A. sibaiyaensis Subzone and probably lowermost part of P. wilcoxensis Subzone. The quantitative analysis indicates a major increase of low-latitude acarininids, including compressed tropical acarininids just above the Boundary clay. This acarininid incursion begins just below the Boundary clay but reaches its maximum just above the clay. The planktic foraminiferal faunal turnover is gradual except for the acarininid incursion. The isotopic results show a negative excursion in ∂13C values at the small benthic foraminifera mass extinction event. The acarininid maximum diversity coincides with this isotopic excursion, and reflects an increase in surface seawater temperature. Despite being very condensed, the Possagno section allows us to further confirm that the different biotic, isotopic and sedimentological events recognized in the Spanish sections (Alamedilla, Campo, Caravaca, Zumaya) are not local in nature and allows the establishment of a detailed chronostratigraphic framework to define the P/E Boundary stratotype.

  • Field trip guide to the Paleocene and Early Eocene of Zumaya section
    1996
    Co-Authors: Eustoquio Molina, Ignacio Arenillas
    Abstract:

    The stratigraphic section chosen for the field trip is easily accesible since exposure occurs along San Telmo beach, just north of the township of Zumaya (Guipuzcoa province, northern Spain). (Fig. 1). Lithologically the lower Paleocene consist of about 50 metres of limestones with intercalated thin marl layers, the upper Paleocene is composed of about 120 metres of marls with interbedded limestones and calcarenite strata, and marls in the uppermost part. Turbidite strata are rare across the Paleocene stage boundaries and Paleocene/Eocene Boundary, but beco me common in the upper part of the section from the M. subbotinae Biozone (Early Eocene) and in the upper Cretaceous. The Paleocene and Early Eocene sedimentation in the Pyrenean Basin appears relatively continuous although there are differences between the sections. The Zumaya section was deposited in the deep part of a basin which outcrops along the beaches at the northern coast range of the iberian peninsula. The lithology and geologic setting of the Zumaya section was described in detail by Hillebrandt (1965) and Pujalte et al., (1989). The depositional sequences have been established by Pujalte et al. (1993; 1994; 1995). Orue-Etxebarria and Lamolda (1985) studied the paleogeography of the Basque-Cantabrian basin by means of planktic foraminifera from the Paleocene to Middle Eocene and they concluded that deposition ocurred in a tropical to temperate province during the Paleogene. Futhermore, Orue-Etxebarria et al. (1996) have published an integrated biostratigraphy in other sections of the Basque Country (Ermua and Trabakua Pass), which are reference sections for the Paleocene/Eocene Boundary. Excellent reference sections are also the Campo and Tremp sections in the area of the Ilerdian stratotype (Molina, 1994; 1996; Molina et al., 1992; 1995; 1996). Hillebrandt (1965) first published a significant biostratigraphic analysis of the planktic foraminiferal fauna from the Zumaya section but did not discuss details across the Paleocene stage boundaries and Paleocene/Eocene Boundary. Planktic foraminifera and calcareous nannofossils are the major fossil components in the sediments across the Paleocene-Eocene Boundary at Zumaya section. Benthic foraminifera and ostracodes occur in low percentage (

  • Integrated stratigraphy across the Paleocene/Eocene Boundary at Caravaca, southern Spain
    Eclogae Geologicae Helvetiae, 1994
    Co-Authors: Eustoquio Molina, José Ignacio Canudo, F. Martinez-ruiz, Nieves Ortiz
    Abstract:

    La coupe de Caravaca est evaluee comme stratotype potentiel de la limite Paleocene/Eocene a partir d'une etude stratigraphique integree et de haute resolution. L'evenement de la limite P/E est caracterise biostratigraphiquement et geochimiquement. L'horizon de l'extinction massive des petits foraminiferes bentiques coincide avec un grand changement negatif de ∂ 13 C et ∂ 18 O, un niveau noir anoxique, un intervalle de dissolution de carbonates et une importante augmentation du contenu en quartz. Il coincide aussi avec de grandes variations dans d'autres groupes de microfossiles et des changements significatifs dans la concentration de TiO 2 , MnO, Cr, Cu, Zn et REE. Cet horizon est considere comme le plus approprie pour definir la limite P/E