Eocene-Oligocene transition in the Southern Ocean: History of water mass circulation and biological productivity

Abstract

Research Article| February 01, 1996 Eocene-Oligocene transition in the Southern Ocean: History of water mass circulation and biological productivity Liselotte Diester-Haass; Liselotte Diester-Haass 1Universität des Saarlandes, Fachrichtung Geographie, D-66041 Saarbrücken, Germany Search for other works by this author on: GSW Google Scholar Rainer Zahn Rainer Zahn 2GEOMAR, Research Center for Marine Geosciences Wischhofstraße 1-3, D-24148 Kiel, Germany Search for other works by this author on: GSW Google Scholar Geology (1996) 24 (2): 163–166. https://doi.org/10.1130/0091-7613(1996)024<0163:EOTITS>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Liselotte Diester-Haass, Rainer Zahn; Eocene-Oligocene transition in the Southern Ocean: History of water mass circulation and biological productivity. Geology 1996;; 24 (2): 163–166. doi: https://doi.org/10.1130/0091-7613(1996)024<0163:EOTITS>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract 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 δ18O 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 δ18O 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. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.