Census of calcareous nannofossil taxa expressed as percent of total number of individuals counted, ODP Legs 113, 114, 119, 120

Quantitative analysis of upper Eocene-upper Oligocene calcareous nannofossil assemblages from five Ocean Drilling Program sites in the Atlantic and Indian Ocean sectors of the Southern Ocean reveals an abrupt increase in cool-water taxa at the top of magnetic Subchron C13R ca. 35.9 Ma, coincident wi...

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Bibliographic Details
Main Author: Wei, Wuchang
Format: Other/Unknown Material
Language:English
Published: PANGAEA 1991
Subjects:
113-689
114-699
114-703
119-744
120-748
COMPCORE
Composite Core
Indian Ocean
Joides Resolution
Leg113
Leg114
Leg119
Leg120
Ocean Drilling Program
ODP
South Atlantic Ocean
South Indian Ridge
South Indian Ocean
Southern Ocean
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.712626
https://doi.org/10.1594/PANGAEA.712626
Description
Summary:Quantitative analysis of upper Eocene-upper Oligocene calcareous nannofossil assemblages from five Ocean Drilling Program sites in the Atlantic and Indian Ocean sectors of the Southern Ocean reveals an abrupt increase in cool-water taxa at the top of magnetic Subchron C13R ca. 35.9 Ma, coincident with an enrichment of ~1‰ d18O in the planktonic foraminifers at these sites. The synchrony of the abrupt increase in cool-water taxa in the Southern Ocean renders this event a useful biostratigraphic datum at southern high latitudes. This earliest Oligocene cool-water taxa increase was the sharpest and largest during the late Eocene-late Oligocene interval and indicates a drop in surface-water temperature of more than 3°C in the Southern Ocean. This suggests that the earliest Oligocene d18O shift represents primarily a temperature signal; a small portion (~0.2‰) is attributable to a global ice-volume increase.

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