Biogeography of the late Paleocene benthic foraminiferal extinction

Author(s): Thomas, Ellen
Author Affiliation(s): Primary:
Wesleyan University, Earth and Environmental Sciences, Middletown, CT, United States
New Mexico Museum of Natural History, United States
Woods Hole Oceanographic Institution, United States
Volume Title: Late Paleocene-early Eocene climatic and biotic events in the marine and terrestrial records
Volume Author(s): Aubry, Marie-Pierre, editor; Lucas, Spencer G.; Berggren, William A.
Source: Late Paleocene-early Eocene climatic and biotic events in the marine and terrestrial records, edited by Marie-Pierre Aubry, Spencer G. Lucas and William A. Berggren, p.214-243. Publisher: Columbia University Press, New York, NY, United States. ISBN: 0-231-10238-0
Note: In English. Includes appendices. 194 refs.; illus., incl. sketch map
Summary: During the Late Paleocene Thermal Maximum (LPTM) benthic foraminifera at middle bathyal and greater depths suffered extinction of 30-50% of species during a few thousand years. Extinction was less severe at neritic to upper bathyal depths, where temporary changes in faunal composition prevailed. Preextinction deep-sea faunas were cosmopolitan and diverse, and contained heavily calcified species. Immediate postextinction faunas were more variable geographically, exhibited low diversity, and were dominated by thin-walled calcareous or agglutinated taxa, possibly because CaCO3 dissolution increased globally from neritic to abyssal depths just before the extinction. These assemblages were dominated either by long-lived taxa such as Nuttallides truempyi or by buliminid taxa, the latter accompanied by agglutinants in some areas. Faunas dominated by N. truempyi were common in the South Atlantic and at lower bathyal through upper abyssal depth in the Indian Ocean, and might indicate oligotrophic conditions as well as increased corrosiveness. Buliminid-dominated faunas might indicate high rates of deposition of organic matter or low-oxygen conditions. Such faunas were common globally along continental margins, and locally co-occurred with sedimento-logic or planktonic faunal indicators of high productivity. In the bathyal central Pacific, however, buliminid-dominated faunas co-occurred with planktonic faunas suggesting oligotrophy, and they could reflect low-oxygen conditions resulting from sluggish ocean circulation, oxidation of dissociated methane hydrates, or warming of bathyal-abyssal waters caused by a change in deep-sea circulation. Alternatively, they could indicate that the fraction of organic matter reaching the seafloor increased as a result of decreased oceanic oxygenation. The latest Paleocene benthic extinction thus was complex, and factors such as changes in deep-sea circulation, increased CaCO3 corrosiveness, increased temperatures, decreased oxygenation, and changes in the patterns of high productivity may have contributed to its severity.
Year of Publication: 1998
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 10 Paleontology, Invertebrate; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Benthic taxa; Biogeography; Calcium carbonate; Cenozoic; DSDP Site 525; Deep Sea Drilling Project; Extinction; Foraminifera; IPOD; Indian Ocean; Invertebrata; Leg 113; Leg 143; Leg 74; Microfossils; ODP Site 689; ODP Site 865; Ocean Drilling Program; Ocean circulation; Ocean floors; Oxidation; Paleo-oceanography; Paleocene; Paleoclimatology; Paleogene; Paleogeography; Planktonic taxa; Protista; South Atlantic; Tertiary; Upper Paleocene
Coordinates: S290415 S290414 E0025908 E0025907
S643101 S643100 E0030600 E0030559
N182624 N182626 W1793320 W1793321
Record ID: 2000031864
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute.