Connotea
CiteULike
del.ico.us
BibSonomyAbstract
Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean
Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA
Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA
Geosciences Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA
Geosciences Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA
We demonstrate that the carbon isotopic signal of mid-depth waters evolved differently from deep waters in the South Atlantic sector of the Southern Ocean during the Pleistocene. Deep sites (>3700 m) exhibit large glacial-to-interglacial variations in benthic δ13C, whereas the amplitude of the δ13C signal at Site 1088 (∼2100 m water depth) is small. Unlike the deep sites, at no time during the Pleistocene were benthic δ13C values at Site 1088 lower than those of the deep Pacific. Reconstruction of intermediate-to-deep δ13C gradients (Δ13CI-D) supports the existence of a sharp chemocline between 2100 and 2700 m during most glacial stages of the last 1.1 myr. This chemical divide in the glacial Southern Ocean separated well-ventilated water above ∼2500 m from poorly ventilated water below. The Δ13CI-D signal parallels the Vostok atmospheric pCO2 record for the last 400 kyr, lending support to physical models that invoke changes in Southern Ocean deep water ventilation as a mechanism for changing atmospheric pCO2. The emergence of a strong 100-kyr cycle in Δ13CI-D during the mid-Pleistocene supports a change in vertical fractionation and deep-water ventilation rates in the Southern Ocean, and is consistent with possible CO2-forcing of this climate transition.
Received 19 April 2002; accepted 1 August 2002; published 10 January 2003.
Citation: (2003), Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean, Geochem. Geophys. Geosyst., 4(1), 1004, doi:10.1029/2002GC000367.
Cited By
Cortese, G., A. Abelmann, and R. Gersonde (2007), The last five glacial-interglacial transitions: A high-resolution 450,000-year record from the subantarctic Atlantic, Paleoceanogr, 22, PA4203, doi:10.1029/2007PA001457.
Hall, Ian R., and Julia Becker (2007), Deep Western Boundary Current variability in the subtropical northwest Atlantic Ocean during marine isotope stages 12–10, Geochem Geophys Geosyst, 8, Q06013, doi:10.1029/2006GC001518.
Hayward, Bruce W., Shungo Kawagata, Hugh R. Grenfell, Ashwaq T. Sabaa, and Tanya O'Neill (2007), Last global extinction in the deep sea during the mid-Pleistocene climate transition, Paleoceanogr, 22, PA3103, doi:10.1029/2007PA001424.
Hemming, S. R., T. van de Flierdt, S. L. Goldstein, A. M. Franzese, M. Roy, G. Gastineau, and G. Landrot (2007), Strontium isotope tracing of terrigenous sediment dispersal in the Antarctic Circumpolar Current: Implications for constraining frontal positions, Geochem Geophys Geosyst, 8, Q06N13, doi:10.1029/2006GC001441.
Hodell, David A., and Kathryn A. Venz-Curtis (2006), Late Neogene history of deepwater ventilation in the Southern Ocean, Geochem Geophys Geosyst, 7, Q09001, doi:10.1029/2005GC001211.
Hogg, Andrew McC. (2008), Glacial cycles and carbon dioxide: A conceptual model, Geophys Res Lett, 35, L01701, doi:10.1029/2007GL032071.
Köhler, Peter, Hubertus Fischer, Guy Munhoven, and Richard E. Zeebe (2005), Quantitative interpretation of atmospheric carbon records over the last glacial termination, Global Biogeochem Cycles, 19, GB4020, doi:10.1029/2004GB002345.
Köhler, Peter, Raimund Muscheler, and Hubertus Fischer (2006), A model-based interpretation of low-frequency changes in the carbon cycle during the last 120,000 years and its implications for the reconstruction of atmospheric Î14C, Geochem Geophys Geosyst, 7, Q11N06, doi:10.1029/2005GC001228.
Molyneux, Elizabeth G., Ian R. Hall, Rainer Zahn, and Paula Diz (2007), Deep water variability on the southern Agulhas Plateau: Interhemispheric links over the past 170 ka, Paleoceanogr, 22, PA4209, doi:10.1029/2006PA001407.
O'NEILL, TANYA A., BRUCE W. HAYWARD, SHUNGO KAWAGATA, ASHWAQ T. SABAA, and HUGH R. GRENFELL (2007), PLEISTOCENE EXTINCTIONS OF DEEP-SEA BENTHIC FORAMINIFERA: THE SOUTH ATLANTIC RECORD, Palaeontology, 50(5), 1073, doi:10.1111/j.1475-4983.2007.00702.x.
Rutberg, Randye L., and Synte L. Peacock (2006), High-latitude forcing of interior ocean ?13C, Paleoceanogr, 21, PA2012, doi:10.1029/2005PA001226.
Toggweiler, J. R., Joellen L. Russell, and S. R. Carson (2006), Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages, Paleoceanogr, 21, PA2005, doi:10.1029/2005PA001154.
Toggweiler, J. R. (2008), Origin of the 100,000-year timescale in Antarctic temperatures and atmospheric CO2, Paleoceanogr, 23, PA2211, doi:10.1029/2006PA001405.
Tschumi, T., F. Joos, and P. Parekh (2008), How important are Southern Hemisphere wind changes for low glacial carbon dioxide? A model study, Paleoceanogr, 23, PA4208, doi:10.1029/2008PA001592.