Palaeoceanographic change in the Pacific at the Eocene-Oligocene boundary

Author(s): Keigwin, L. D., Jr.
Author Affiliation(s): Primary:
Univ. R.I., Grad. Sch. Oceanogr., Kingston, RI, United States
Volume Title: Nature (London)
Source: Nature (London), 287(5784), p.722-725. Publisher: Macmillan Journals, London, United Kingdom. ISSN: 0028-0836 CODEN: NATUAS
Note: In English. 39 refs.; illus. incl. tables
Summary: Oxygen isotopic studies both of benthic foraminifera and shallow-marine carbonates have provided a useful monitor of marine palaeotemperatures. The Deep Sea Drilling Project (DSDP) has provided cores from many ocean basins to conduct detailed stable isotopic and palaeoceanographic studies of the Cenozoic and late Mesozoic. DSDP Sites 277 and 292, separated by about 60 degrees latitude in Palaeogene times, each record an 18O enrichment in benthic foraminifera of nearly 1% beginning at the Eocene-Oligocene boundary. Planktonic foraminiferal trends are similar to benthic trends in the high latitude south-west Pacific Ocean, but tropical planktonics show only a minor (-O.3%) increase which may reflect a change in seawater composition. These results suggest a sudden cooling of Pacific deep waters and high latitude surface waters forms a useful stratigraphic marker for the Eocene-Oligocene boundary. This boundary is particularly important because of its association with several worldwide palaeo-oceanographic and biogeographic changes. These include a sudden drop in the calcite compensation depth of 1-2 km; a decrease in planktonic microfossils diversity; a change in planktonic biogeographic patterns; and increased erosion of deep-sea sediments over wide areas.
Year of Publication: 1980
Research Program: DSDP Deep Sea Drilling Project
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Abundance; Benham Rise; Benthic taxa; Biochemistry; Biostratigraphy; C-13/C-12; Campbell Plateau; Carbon; Cenozoic; Deep Sea Drilling Project; Eocene; Foraminifera; Invertebrata; Isotopes; Lower Oligocene; Microfossils; North Pacific; Northwest Pacific; O-18/O-16; Oligocene; Oxygen; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleoecology; Paleogene; Philippine Sea; Planktonic taxa; Protista; Ratios; Site 277; Site 292; South Pacific; Southwest Pacific; Stable isotopes; Stratigraphic boundary; Stratigraphy; Temperature; Tertiary; Upper Eocene; West Pacific
Coordinates: S521330 S521300 E1661200 E1661130
N154900 N154930 E1243906 E1243900
Record ID: 1981021264
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Institute of Geological and Nuclear Sciences Limited (GNS Science), Lower Hutt, New Zealand