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Ralf Schiebel - One of the best experts on this subject based on the ideXlab platform.
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A robust calibration of the clumped isotopes to temperature relationship for Foraminifers
Geochimica et Cosmochimica Acta, 2020Co-Authors: Niklas Meinicke, Ralf Schiebel, Bjarte Hannisdal, Dirk Nürnberg, Aradhna Tripati, Anna Nele MecklerAbstract:Abstract The clumped isotope (Δ47) proxy is a promising geochemical tool to reconstruct past ocean temperatures far back in time and in unknown settings, due to its unique thermodynamic basis that renders it independent from other environmental factors like seawater composition. Although previously hampered by large sample-size requirements, recent methodological advances have made the paleoceanographic application of Δ47 on small ( Previous studies show a reasonable match between Δ47 calibrations based on synthetic carbonate and various species of planktonic Foraminifers. However, studies performed before recent methodological advances were based on relatively few species and data treatment that is now outdated. To overcome these limitations and elucidate species-specific effects, we analyzed 14 species of planktonic Foraminifers in sediment surface samples from 13 sites, covering a growth temperature range of ∼0–28 °C. We selected mixed layer-dwelling and deep-dwelling species from a wide range of ocean settings to evaluate the feasibility of temperature reconstructions for different water depths. Various techniques to estimate Foraminifer calcification temperatures were tested in order to assess their effects on the calibration and to find the most suitable approach. Results from this study generally confirm previous findings that there are no species-specific effects on the Δ47-temperature relationship in planktonic Foraminifers, with one possible exception. Various morphotypes of Globigerinoides ruber were found to often deviate from the general trend determined for planktonic Foraminifers. Our data are in excellent agreement with a recent Foraminifer calibration study that was performed with a different analytical setup, as well as with a calibration based exclusively on benthic Foraminifers. A combined, methodologically homogenized dataset also reveals very good agreement with an inorganic calibration based on travertines. Our findings highlight the potential of the Δ47 paleothermometer to be applied to recent and extinct species alike to study surface ocean temperatures as well as thermocline variability for a multitude of settings and time scales.
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ground truthing the planktic Foraminifer bound nitrogen isotope paleo proxy in the sargasso sea
Geochimica et Cosmochimica Acta, 2018Co-Authors: Sandi M. Smart, Ralf Schiebel, Haojia Ren, Sarah E Fawcett, Maureen H Conte, Patrick A Rafter, Karen K Ellis, M A Weigand, Sergey Oleynik, Gerald H HaugAbstract:Abstract We report the nitrogen (N) isotope ratios (δ15N) of planktic Foraminifera collected from upper-ocean net tows (surface to 200 m), moored sediment traps, and core-top sediments at the Bermuda Time-series Site in the northern Sargasso Sea between 2009 and 2013. Consistent with previous measurements from low-latitude core-top sediments, the annually-averaged δ15N of organic matter bound within the shells of euphotic zone-dwelling, dinoflagellate symbiont-bearing Foraminifera collected in net tows (2.3‰ on average) approximates that of shallow thermocline (∼200 m) nitrate (2.6‰), the dominant source of new N to Sargasso Sea surface waters. Deeper-dwelling Foraminifer species without dinoflagellate symbionts tend to have a higher δ15N (3.6‰ on average). We observe no systematic difference between the bulk tissue and shell-bound δ15N in net tow-collected Foraminifera. A decline in shell N content is observed from net tows (6.8 nmol/mg) to sediment traps (5.4 nmol/mg) and surface sediment (3.0 nmol/mg). On average, shell-bound δ15N rises from net tows (3.1‰) to sediment traps (3.7‰) but does not change further upon incorporation into the sediments (3.7‰). Together, these observations are consistent with preferential loss of shells or shell portions with lower δ15N and higher N content during sinking through the upper 500 m, followed by a non-isotope fractionating decrease in N content between sinking and burial. Time-series data from sediment traps (and to a lesser extent, surface net tows) exhibit seasonal δ15N variations, with a minimum in early spring, a maximum in late spring and a decline from summer to fall. These variations appear to arise from seasonal changes in the δ15N of total upper-ocean biomass, which are, in turn, driven by early springtime nitrate supply, subsequent nitrate drawdown, and an increase in the relative importance of ammonium recycling into the late summer and early fall. The δ15N connection between total upper ocean biomass and Foraminifera indicates that Foraminifer-bound δ15N records the δ15N of the annual nitrate supply in oligotrophic (e.g., subtropical) environments but will also be sensitive to the degree of nitrate consumption in high-nutrient regions and possibly to changes in upper-ocean ammonium recycling under some conditions.
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Factors Influencing Porosity in Planktonic Foraminifera
2018Co-Authors: Janet E. Burke, Leanne E. Elder, Willem Renema, Michael J. Henehan, Catherine V. Davis, Amy E. Maas, Gavin L. Foster, Ralf Schiebel, Pincelli M. HullAbstract:Abstract. The clustering of mitochondria near pores in the test walls of Foraminifera suggests that these perforations play a critical role in metabolic gas exchange. As such, pore measurements could provide a novel means of tracking changes in metabolic rate in the fossil record. However, in planktonic Foraminifera, variation in pore size, density, and porosity have been variously attributed to environmental, biological, and taxonomic drivers, complicating such an interpretation. Here we examine the environmental, biological, and evolutionary determinants of porosity in 718 individuals representing 17 morphospecies of planktonic Foraminifera from 6 core tops in the North Atlantic. Using random forest models, we find that porosity is primarily correlated to size and habitat temperature, two key factors in determining metabolic rates. In order to test if this correlation arose spuriously through the association of cryptic species with distinct biomes, we cultured Globigerinoides ruber in three different temperature conditions, and found that porosity increased with temperature. Crucially, these results show that porosity can be plastic: changing in response to environmental drivers within the lifetime of an individual Foraminifer. This demonstrates the potential of porosity as a proxy for Foraminiferal metabolic rates, with significance for interpreting geochemical data and the physiology of Foraminifera in non-analog environments. It also highlights the importance of phenotypic plasticity (i.e., ecophenotypy) in accounting for some aspects of morphological variation in the modern and fossil record.
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Advances in planktonic Foraminifer research: New perspectives for paleoceanography
Revue de Micropaléontologie, 2018Co-Authors: Ralf Schiebel, Pincelli M. Hull, Julie Meilland, Sandi M. Smart, Anna Jentzen, Lukas Jonkers, Raphael Morard, Elisabeth Michel, Helen K. Coxall, Thibault De Garidel-thoronAbstract:Abstract Planktonic Foraminifer tests are major archives of environmental change and provide a multitude of proxies in paleoceanography and paleoclimatology. The application of such proxies is contingent upon a collaborative effort to better understand how the living organisms record the properties of their environment and how the resulting signals are recorded in marine sediments. In this contribution, we provide a review of the rapidly developing sub-fields of research, where new advances have been made possible by technological developments, and by cross-disciplinary work of the scientific community. Following brief historical overviews of the sub-fields, we discuss the latest advances in planktonic Foraminifer research and highlight the resulting new perspectives in ocean and climate research. Natural classification based on consistent species concepts forms the basis for analysis of any Foraminifer-derived proxy. New approaches in taxonomy and phylogeny of Cenozoic planktonic Foraminifers (Section 2) are presented, highlighting new perspectives on sensitivity and response of planktonic Foraminifers to the changing climate and environment (Section 4). Calibration of Foraminifer-specific data and environmental parameters is improving along with the technical development of probes and the access to samples from the natural environment (Section 3), enhancing our understanding of the ever-changing climate and ocean system. Comprehension of sedimentation and flux dynamics facilitates maximum gain of information from fossil assemblages (Section 5). Subtle changes in the physical (e.g., temperature), chemical (e.g., pH), and biological (e.g., food) conditions of ambient seawater affect the abundance of species and composition of assemblages as well as the chemical composition of the Foraminifer shell and provide increasingly-detailed proxy data on paleoenvironments (Section 6).
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individual planktic Foraminifer protein biomass affected by trophic conditions in the southwest indian ocean 30 s 60 s
Marine Micropaleontology, 2016Co-Authors: Julie Meilland, Hélène Howa, Lo C Monaco, Ralf SchiebelAbstract:Abstract Planktic Foraminifers are ubiquitous marine mesozooplankton, and contribute to the biological carbon pump by generating organic and inorganic carbon flux. We have analyzed the morphometry and quantified the protein-biomass of the test (i.e. shell) of 1441 living planktic Foraminifers from 19 stations sampled during three consecutive years (2012–2014) in the Southwest Indian Ocean (30°S–60°S, 50°E–80°E). Transects were sampled across three main hydrographic fronts, the Subtropical Front (STF), Sub-Antarctic Front (SAF), and Polar Front (PF), including water bodies of different primary productivity and interannual variability. Differences in size-normalized planktic Foraminifer protein-biomass between the years, species, and water bodies indicate that environmental parameters affect the production of planktic Foraminifer organic (cytoplasm) carbon to varying degrees. Among the environmental parameters, trophic conditions (i.e., chlorophyll concentration) are best related to, and assumed most important for, the ontogenetic development of species and their individual biomass. We conclude that the contribution of planktic Foraminifers to the biological carbon pump depends on ecological conditions and biological prerequisites at the species level, whereas the qualitative effect of prey (i.e., diatom species) remains to be determined. The applicability of planktic Foraminifers as a proxy of the past biological carbon pump in mid to high latitudes would hence critically depend on the effect exerted by changing ecological conditions, and the presence of different species of both prey and planktic Foraminifers on the regional scale.
Pierre E. Biscaye - One of the best experts on this subject based on the ideXlab platform.
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Production and resuspension of planktonic Foraminifers at the shelf break of the Southern Middle Atlantic Bight
Deep Sea Research Part I: Oceanographic Research Papers, 2003Co-Authors: Charlotte A. Brunner, Pierre E. BiscayeAbstract:Abstract Mesoscale hydrographic events that characterize circulation at the shelf break of the US East Coast enhance Foraminifer production to levels comparable to that in regions of oceanic upwelling, including subpolar waters, equatorial zones, and coastal upwelling areas. In this work, we quantify the magnitude of shelf break production events and attempt to constrain the response of Foraminifers to high frequency, hydrographic forcing. Specifically, we examined production and resuspension of planktonic Foraminifers on the shelf break and upper slope of the Middle Atlantic Bight using trap samples, temperature data, and ancillary data collected as part of the SEEP II experiment offshore from the Delmarva Peninsula. We examined a time series of 30 sediment trap samples with an average trapping period of 13 days from February 1988 to May 1989 and cross-shelf transects of trap samples taken during three selected trapping periods (snapshots). Hydrography during the time series and snapshots was interpreted from 395 daily temperature sections. Planktonic Foraminifer fluxes exceeded 6000 tests/m2/d in nine trapping periods of the time series. The largest flux event exceeded 40,000 tests/m2/d and resulted from storm-driven resuspension and transport of particles from the shelf to the upper slope. Two other events were clearly associated with resuspension. In contrast, other peaks in Foraminifer flux were due to production that was 1.5–7 times higher than that in gyre-center ecosystems and comparable to production in oceanic upwelling locales. Peaks in Foraminifer production were associated with specific hydrographic events that lifted nutrient-rich, deep water into the euphotic zone near the shelf break. These events stimulated phytoplankton blooms, which nourished rapid growth and reproduction of planktonic Foraminifers. The trophic events lasted a minimum of ∼6 days and occurred with greater frequency than those of typical open-ocean ecosystems. The shelf break, in general, may be a region of significant planktonic Foraminifer production despite its proximity to unfavorable conditions that limit the range of planktonic Foraminifers on the shelf.
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Storm-driven transport of Foraminifers from the shelf to the upper slope, southern Middle Atlantic Bight
Continental Shelf Research, 1997Co-Authors: Charlotte A. Brunner, Pierre E. BiscayeAbstract:Storms play an important role in the delivery of benthonic Foraminifers to the continental slope, as observed in a study of Foraminifer fluxes through the upper slope water column. The authors studied 30 sediment-trap samples with a 13-day average period from the 1988–1989 SEEP II experiment offshore from the Delmarva Peninsula. The traps were suspended at about 125 m water depth on a mooring in 400 m of water. Benthonic and planktonic Foraminifers from 10-ml subsamples were measured, identified by taxa and growth stage, and counted. Number fluxes of benthonic Foraminifers averaged 155 test/m2/d during periods of relative calm during the spring and summer, when mass fluxes of aluminosilicates were also minimal. In contrast, number fluxes of benthonic Foraminifers peaked during a mid-April 1988 storm and ranged from about 300 to 50,000 tests/m2/d from mid-December 1988 to the end of April 1989, when mass fluxes of aluminosilicates also were highly elevated. Highest Foraminifer fluxes (29,000 and 50,000 tests/m2/d) coincided with a late February storm. Taxa observed included Bolivina, Nonionella, Trochammina, Rosalina, and other taxa typical of the continental shelf of this region. Number fluxes of planktonic Foraminifers peaked during the spring and summer due to production. The peaks from 6000 to 11,000 tests/m2/d were due to peaks in productivity of Globigerinita glutinata in early March and late April, Turborotalita quinqueloba in mid-July, and Globigerinita uvula and Globigerinoides ruber in latest September. Planktonic Foraminifer fluxes did not crest during the mid-April or mid-December 1988 storms, but fluxes reached peaks of 38,000 and 41,000 tests/m2/d in late February and early March 1989 when fluxes of benthonic Foraminifers and aluminosilicate material also were highest. Storms dominated the delivery of both benthonic and planktonic Foraminifers to the slope. The single storm in late February 1989 delivered more Foraminifers through the water column to the slope (120 × 104 benthonic and 130 × 104 planktonic tests/m2 in 32 days) than during all the preceding calm days in 1988 (1.9 × 104 benthonic and 72 × 104 planktonic tests/m2 in 217 days). Mid-water advection of benthonic Foraminifers from the continental shelf to the slope is an important mechanism of delivery that exceeds by an order of magnitude the numbers of planktonic Foraminifers produced in slope waters during periods of relative calm weather.
Charlotte A. Brunner - One of the best experts on this subject based on the ideXlab platform.
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Production and resuspension of planktonic Foraminifers at the shelf break of the Southern Middle Atlantic Bight
Deep Sea Research Part I: Oceanographic Research Papers, 2003Co-Authors: Charlotte A. Brunner, Pierre E. BiscayeAbstract:Abstract Mesoscale hydrographic events that characterize circulation at the shelf break of the US East Coast enhance Foraminifer production to levels comparable to that in regions of oceanic upwelling, including subpolar waters, equatorial zones, and coastal upwelling areas. In this work, we quantify the magnitude of shelf break production events and attempt to constrain the response of Foraminifers to high frequency, hydrographic forcing. Specifically, we examined production and resuspension of planktonic Foraminifers on the shelf break and upper slope of the Middle Atlantic Bight using trap samples, temperature data, and ancillary data collected as part of the SEEP II experiment offshore from the Delmarva Peninsula. We examined a time series of 30 sediment trap samples with an average trapping period of 13 days from February 1988 to May 1989 and cross-shelf transects of trap samples taken during three selected trapping periods (snapshots). Hydrography during the time series and snapshots was interpreted from 395 daily temperature sections. Planktonic Foraminifer fluxes exceeded 6000 tests/m2/d in nine trapping periods of the time series. The largest flux event exceeded 40,000 tests/m2/d and resulted from storm-driven resuspension and transport of particles from the shelf to the upper slope. Two other events were clearly associated with resuspension. In contrast, other peaks in Foraminifer flux were due to production that was 1.5–7 times higher than that in gyre-center ecosystems and comparable to production in oceanic upwelling locales. Peaks in Foraminifer production were associated with specific hydrographic events that lifted nutrient-rich, deep water into the euphotic zone near the shelf break. These events stimulated phytoplankton blooms, which nourished rapid growth and reproduction of planktonic Foraminifers. The trophic events lasted a minimum of ∼6 days and occurred with greater frequency than those of typical open-ocean ecosystems. The shelf break, in general, may be a region of significant planktonic Foraminifer production despite its proximity to unfavorable conditions that limit the range of planktonic Foraminifers on the shelf.
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Storm-driven transport of Foraminifers from the shelf to the upper slope, southern Middle Atlantic Bight
Continental Shelf Research, 1997Co-Authors: Charlotte A. Brunner, Pierre E. BiscayeAbstract:Storms play an important role in the delivery of benthonic Foraminifers to the continental slope, as observed in a study of Foraminifer fluxes through the upper slope water column. The authors studied 30 sediment-trap samples with a 13-day average period from the 1988–1989 SEEP II experiment offshore from the Delmarva Peninsula. The traps were suspended at about 125 m water depth on a mooring in 400 m of water. Benthonic and planktonic Foraminifers from 10-ml subsamples were measured, identified by taxa and growth stage, and counted. Number fluxes of benthonic Foraminifers averaged 155 test/m2/d during periods of relative calm during the spring and summer, when mass fluxes of aluminosilicates were also minimal. In contrast, number fluxes of benthonic Foraminifers peaked during a mid-April 1988 storm and ranged from about 300 to 50,000 tests/m2/d from mid-December 1988 to the end of April 1989, when mass fluxes of aluminosilicates also were highly elevated. Highest Foraminifer fluxes (29,000 and 50,000 tests/m2/d) coincided with a late February storm. Taxa observed included Bolivina, Nonionella, Trochammina, Rosalina, and other taxa typical of the continental shelf of this region. Number fluxes of planktonic Foraminifers peaked during the spring and summer due to production. The peaks from 6000 to 11,000 tests/m2/d were due to peaks in productivity of Globigerinita glutinata in early March and late April, Turborotalita quinqueloba in mid-July, and Globigerinita uvula and Globigerinoides ruber in latest September. Planktonic Foraminifer fluxes did not crest during the mid-April or mid-December 1988 storms, but fluxes reached peaks of 38,000 and 41,000 tests/m2/d in late February and early March 1989 when fluxes of benthonic Foraminifers and aluminosilicate material also were highest. Storms dominated the delivery of both benthonic and planktonic Foraminifers to the slope. The single storm in late February 1989 delivered more Foraminifers through the water column to the slope (120 × 104 benthonic and 130 × 104 planktonic tests/m2 in 32 days) than during all the preceding calm days in 1988 (1.9 × 104 benthonic and 72 × 104 planktonic tests/m2 in 217 days). Mid-water advection of benthonic Foraminifers from the continental shelf to the slope is an important mechanism of delivery that exceeds by an order of magnitude the numbers of planktonic Foraminifers produced in slope waters during periods of relative calm weather.
Esmeralda Caus - One of the best experts on this subject based on the ideXlab platform.
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larger Foraminifera distribution and strontium isotope stratigraphy of the la cova limestones coniacian santonian serra del montsec pyrenees ne spain
Cretaceous Research, 2011Co-Authors: Carme Boix, Gianluca Frijia, Vicent Vicedo, Josep María Bernaus, Matteo Di Lucia, Mariano Parente, Esmeralda CausAbstract:Abstract The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger Foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian–Turonian boundary. The stratigraphic distribution of the main taxa of larger Foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids (Pseudolacazina loeblichi) and meandropsinids (Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids (Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis. A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic Foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger Foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province. By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger Foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic Foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger Foraminifera standard biozonation for Upper Cretaceous carbonate platform facies.
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Larger Foraminifera distribution and strontium isotope stratigraphy of the La Cova limestones (Coniacian–Santonian, “Serra del Montsec”, Pyrenees, NE Spain)
Cretaceous Research, 2011Co-Authors: Carme Boix, Gianluca Frijia, Vicent Vicedo, Josep María Bernaus, Matteo Di Lucia, Mariano Parente, Esmeralda CausAbstract:The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger Foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian-Turonian boundary.The stratigraphic distribution of the main taxa of larger Foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids (Pseudolacazina loeblichi) and meandropsinids (Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids (Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis.A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic Foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger Foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province.By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger Foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic Foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger Foraminifera standard biozonation for Upper Cretaceous carbonate platform facies. © 2011 Elsevier Ltd
Carme Boix - One of the best experts on this subject based on the ideXlab platform.
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larger Foraminifera distribution and strontium isotope stratigraphy of the la cova limestones coniacian santonian serra del montsec pyrenees ne spain
Cretaceous Research, 2011Co-Authors: Carme Boix, Gianluca Frijia, Vicent Vicedo, Josep María Bernaus, Matteo Di Lucia, Mariano Parente, Esmeralda CausAbstract:Abstract The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger Foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian–Turonian boundary. The stratigraphic distribution of the main taxa of larger Foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids (Pseudolacazina loeblichi) and meandropsinids (Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids (Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis. A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic Foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger Foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province. By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger Foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic Foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger Foraminifera standard biozonation for Upper Cretaceous carbonate platform facies.
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Larger Foraminifera distribution and strontium isotope stratigraphy of the La Cova limestones (Coniacian–Santonian, “Serra del Montsec”, Pyrenees, NE Spain)
Cretaceous Research, 2011Co-Authors: Carme Boix, Gianluca Frijia, Vicent Vicedo, Josep María Bernaus, Matteo Di Lucia, Mariano Parente, Esmeralda CausAbstract:The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger Foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian-Turonian boundary.The stratigraphic distribution of the main taxa of larger Foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids (Pseudolacazina loeblichi) and meandropsinids (Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids (Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis.A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic Foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger Foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province.By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger Foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic Foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger Foraminifera standard biozonation for Upper Cretaceous carbonate platform facies. © 2011 Elsevier Ltd
