2. MID- TO LATE-QUATERNARY VARIATIONS IN THE OXYGEN ISOTOPE SIGNATURE OF GLOBIGERINOIDES RUBER AT SITE 1006 IN THE WESTERN SUBTROPICAL ATLANTIC¹

ABSTRACT

The 1.4-m.y.-long stable oxygen isotope record of Site 1006 in the low-latitude North Atlantic Ocean shows large glacial/interglacial amplitude changes caused by a combination of temperature and salinity fluctuations. A trend of increased sea-surface temperatures during the interglacial periods is present in the record beginning at isotopic Stage 11 and ultimately leading to the lightest ¹⁸O values in isotopic Stages 9, 5, and 1. Maximum ¹⁸O values are recorded during glacial isotopic Stages 6 and 8. Stable isotopic variability increased during the Brunhes Chron at the 100-ka time scale. The large amplitude changes can best be explained by global and regional ocean circulation changes. Increased strengthened return flow of warm salty water from the Pacific may have occurred during interglacial periods since isotopic Stage 11, which was largely reduced during glacial periods. The large climate fluctuations had a profound effect on the shallow-water carbonate production of the Great Bahama Bank. The aragonite content of the sediments shows fluctuations that follow the ¹⁸O record. The leeward side of the Great Bahama Bank received increased input of platform material during sea-level highstands when the sea-surface waters were warm.

¹ Swart, P.K., Eberli, G.P., Malone, M.J., and Sarg, J.F. (Eds.), 2000. Proc. ODP, Sci. Results, 166 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/166_SR/166TOC.HTM>. [Cited YYYY-MM-DD]
² Department of Geology and Geophysics, University of Edinburgh, Grant Institute, West Mains Road, Edinburgh EH9 3JW, Scotland. dkroon@glg.ed.ac.uk
³ GEOMAR Research Center for Marine Geosciences, Christian-Albrechts-Universität zu Kiel, Wischhofstrasse 1-3, Gebäude 4, D-24148 Kiel, Federal Republic of Germany.

Date of initial receipt: 17 August 1998
Date of acceptance: 2 June 1999
Ms 166SR-104