The Paleocene-Eocene transition in the Antarctic Indian Ocean; inference from planktic foraminifera

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doi: 10.1016/0377-8398(93)90012-M
Author(s): Lu, Gangyi; Keller, Gerta
Author Affiliation(s): Primary:
Princeton University, Department of Geological and Geophysical Sciences, Princeton, NJ, United States
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, 21(1-3), p.101-142. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. 80 refs.; illus. incl. 2 tables
Summary: Isotopic depth stratification and relative abundance studies of planktic foraminifera at ODP Site 738 reveal three major faunal turnovers during the latest Paleocene and early Eocene, reflecting the climatic and structural changes in the Antarctic surface ocean. Faunal Event 1 occurred near the Paleocene/Eocene boundary and is characterized by a faunal turnover in deep dwellers, decreased relative abundance in intermediate dwellers and increased relative abundance in surface dwellers. This event marks a temporary elimination of the vertical structure in the surface ocean over a period of more than 63,000 years that is apparently associated with the sudden shutdown of the "Antarctic Intermediate Water" production. The appearance of morozovellids before this event suggests that polar warming is the cause for the shutdown in the production of this water mass. At this time warm saline deep water may have formed at low latitudes. Faunal Event 2 occurred near the AP5a/AP5b Subzonal boundary and is characterized by a faunal turnover in deep dwellers with no apparent change in surface and intermediate dwellers. Increased individual size, wall-thickness and relative abundance in deep dwelling chiloguembelinids suggests the formation of a deep oxygen minima in the Antarctic Oceans during the maximum polar warming possibly as a result of upwelling of nutrient-rich deep water. Faunal Event 3 occurred in Subzone AP6 and is characterized by a faunal turnover in surface dwellers and a delayed diversification in deep dwellers. This event marks the onset of Antarctic cooling. A drastic decrease in the δ13C/δ18O values of the deep assemblage in Zone AP7 suggests an intensified thermocline and reduced upwelling following the polar cooling.
Year of Publication: 1993
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctic Ocean; Biostratigraphy; C-13/C-12; Carbon; Cenozoic; Eocene; Faunal studies; Foraminifera; Geochemistry; Indian Ocean; Invertebrata; Isotope ratios; Isotopes; Kerguelen Plateau; Leg 119; Lower Eocene; Microfossils; O-18/O-16; ODP Site 738; Ocean Drilling Program; Oxygen; Paleocene; Paleoclimatology; Paleoenvironment; Paleogene; Planktonic taxa; Protista; Stable isotopes; Tertiary; Upper Paleocene
Coordinates: S624233 S624232 E0824715 E0824714
Record ID: 1993010303
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands