Benthic foraminiferal stable isotope record of the early Paleogene in the Southern Ocean
ODP Leg 114 recovered sections at four sites east of the Falkland Plateau that cover a wide range of paleodepths and provide the opportunity to evaluate the response of benthic foraminifers to late Paleocene and Eocene Oceanographic changes. Early Paleogene paleodepth estimates were obtained by &quo...
| Main Authors: | , |
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| Format: | Dataset |
| Language: | English |
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PANGAEA
1991
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| Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.754016 https://doi.org/10.1594/PANGAEA.754016 |
| Summary: | ODP Leg 114 recovered sections at four sites east of the Falkland Plateau that cover a wide range of paleodepths and provide the opportunity to evaluate the response of benthic foraminifers to late Paleocene and Eocene Oceanographic changes. Early Paleogene paleodepth estimates were obtained by "backtracking" assuming simple thermal subsidence (Site 698, -900 m; Site 702, -2000 m; Site 700, -2400 m; and Site 699, -2800 m). These estimates agree with paleodepths determined by comparing our quantitative benthic foraminiferal assemblages to previously published assemblages associated with known paleodepths. Previous studies document that a major benthic foraminiferal crisis occurred in the latest Paleocene in the Atlantic, Caribbean, and Pacific; a similar faunal turnover occurred in the latest Paleocene throughout the Atlantic sector of the Southern Ocean. At the Leg 114 sites, Stensioina beccariiformis-dominated assemblages were replaced by Nuttallides tryempyi-dominated assemblages just prior to the Paleocene/Eocene boundary. A preponderance of benthic foraminiferal taxa last appeared immediately prior to the Paleocene/Eocene boundary, as recognized at these high latitudes by the last appearance of the calcareous nannofossil F?sciculithus spp. and the first appearance of the planktonic foraminifer Pseudohastigerina spp. Recovery and biostratigraphic control at the Leg 114 sites is insufficient to constrain precisely the timing of the extinction event, although studies of material from the Maud Rise (Weddell Sea) suggest that it occurred in the latest Paleocene. The benthic foraminiferal crisis may have been caused by deep-water warming, a drop in food supply, or changing deep-water source regions. Oxygen isotope data show that there is no clear correlation between d18O changes and extinctions. Similarly, most of the extinctions occurred well after the start of the drop in global d13C values, which may, in part, reflect a decrease in productivity. Interbasinal carbon isotope comparisons suggest that the Southern ... |
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