Calculation of paleoproductivity during the Eocene-Oligocene transition of ODP Site 113-689

DOI

High-resolution records of carbon and oxygen isotopes and benthic foraminiferal accumulation rates for the Eocene-Oligocene section at Ocean Drilling Program Site 689 (Maud Rise, Weddell Sea; paleodepth about 1500 m) were used to infer variations in paleoproductivity in relation to changes in climate and ventilation of the deeper-water column. The benthic foraminiferal abundance and isotope records show short-term fluctuations at periodicities of 100 and 400 ka, implying orbitally driven climatic variations. Both records suggest that intermediate-depth water chemistry and primary productivity changed in response to climate. During the Eocene, productivity increased during cold periods and during cold-to-warm transitions, possibly as a result of increased upwelling of nutrient-rich waters. In the Oligocene, in contrast, productivity maxima occurred during intervals of low delta18O values (presumably warmer periods), when a proto–polar front moved to the south of the location of Site 689. This profound transition in climate-productivity patterns occurred around 37 Ma, coeval with rapid changes toward increasing variability of the oxygen and carbon isotope and benthic abundance records and toward larger-amplitude delta18O fluctuations. Therefore, we infer that, at this time, temperature fluctuations increased and a proto–polar front formed in conjunction with the first distinct pulsations in size of the Antarctic ice sheet. We speculate that this major change might have resulted from an initial opening of the Drake Passage at 37 Ma, at least for surface- and intermediate-water circulation.

Supplement to: Diester-Haass, Lieselotte; Zahn, Rainer (1996): Eocene-Oligocene transition in the Southern Ocean: History of water mass circulation and biological productivity. Geology, 24(2), 163-166

Identifier
DOI https://doi.org/10.1594/PANGAEA.712516
Related Identifier https://doi.org/10.1130/0091-7613(1996)024<0163:EOTITS>2.3.CO
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.712516
Provenance
Creator Diester-Haass, Lieselotte; Zahn, Rainer
Publisher PANGAEA
Publication Year 1996
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 1748 data points
Discipline Earth System Research
Spatial Coverage (3.100 LON, -64.517 LAT); South Atlantic Ocean
Temporal Coverage Begin 1987-01-15T00:00:00Z
Temporal Coverage End 1987-01-19T00:00:00Z