FastFind »   Lastname: doi:10.1029/ Year: | Advanced Search  

G-Cubed: Geochemistry, Geophysics, Geosystems

 

Keywords

  • Mg-calcite preservation state
  • Mg/Ca in Mg-calcite
  • Caribbean Sea
  • mid-Pleistocene

Index Terms

  • Biogeosciences: Paleoclimatology and paleoceanography
  • Geochemistry: Major and trace element geochemistry
Abstract
Cited By (1)
 

Abstract

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 10, Q11013, 15 PP., 2009
doi:10.1029/2009GC002779 [Citation]

Preservation state of metastable magnesian calcite in periplatform sediments from the Caribbean Sea over the last million years

Sophie Sepulcre

CEREGE, UMR 6635, Aix-Marseille Université, Collège de France, CNRS, Europôle de l'Arbois, BP80, F-13545 Aix-en-Provence, France

Kazuyo Tachikawa

CEREGE, UMR 6635, Aix-Marseille Université, Collège de France, CNRS, Europôle de l'Arbois, BP80, F-13545 Aix-en-Provence, France

Laurence Vidal

CEREGE, UMR 6635, Aix-Marseille Université, Collège de France, CNRS, Europôle de l'Arbois, BP80, F-13545 Aix-en-Provence, France

Nicolas Thouveny

CEREGE, UMR 6635, Aix-Marseille Université, Collège de France, CNRS, Europôle de l'Arbois, BP80, F-13545 Aix-en-Provence, France

Edouard Bard

CEREGE, UMR 6635, Aix-Marseille Université, Collège de France, CNRS, Europôle de l'Arbois, BP80, F-13545 Aix-en-Provence, France

Carbonate-rich periplatform sediments represent an active carbon reservoir containing metastable aragonite and magnesian calcite (Mg-calcite, > 4 mol % MgCO3). Since Mg-calcite is highly soluble, the preservation state of this mineral provides information on past carbonate systems at water depths shallower than the lysocline. The mineralogy and geochemistry of the carbonate-rich fine fraction (<63 μm) was determined for the last 940 ka in a sediment core collected from the Walton Basin (Northern Caribbean Sea, 846 m water depth). Mg/Ca ratios for Mg-calcite showed clear glacial-interglacial cycles with high values (12 mol % MgCO3) during interglacials. Glacial Mg/Ca ratios were approximately 8 mol % MgCO3 for the period from 940 ka to 400 ka, and approximately 10 mol % MgCO3 for the last 400 ka. The Mg/Ca shift is concomitant with a preferential loss of Mg-calcite relative to aragonite. The preservation state of Mg-calcite revealed that the bottom water mass of the studied site was slightly more corrosive for the earlier period, possibly relating to a composition change in intermediate water and/or to the ventilation rate in the Atlantic Ocean.

Received 13 August 2009; accepted 28 September 2009; published 21 November 2009.

Citation: Sepulcre, S., K. Tachikawa, L. Vidal, N. Thouveny, and E. Bard (2009), Preservation state of metastable magnesian calcite in periplatform sediments from the Caribbean Sea over the last million years, Geochem. Geophys. Geosyst., 10, Q11013, doi:10.1029/2009GC002779.

Cited By

Please wait one moment ...