Data/hora: 01/06/2024 11:21:23

Provedor de dados: | 5
País: | France
Título: | Preservation state of metastable magnesian calcite in periplatform sediments from the Caribbean Sea over the last million years
Autores: | Sepulcre, Sophie; Tachikawa, Kazuyo; Vidal, Laurence; Thouveny, Nicolas; Bard, Edouard.
Data: | 2009-11-21
Ano: | 2009
Palavras-chave: | Mg-calcite preservation state; Mg/Ca in Mg-calcite; Caribbean Sea; Mid-Pleistocene.
Resumo: | Carbonate-rich periplatform sediments represent an active carbon reservoir containing metastable aragonite and magnesian calcite (Mg-calcite, &gt; 4 mol % MgCO(3)). 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 (&lt; 63 mu m) 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 % MgCO(3)) during interglacials. Glacial Mg/Ca ratios were approximately 8 mol % MgCO(3) for the period from 940 ka to 400 ka, and approximately 10 mol % MgCO(3) 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.
Tipo: | Text
Idioma: | Inglês

Identificador:

https://archimer.ifremer.fr/doc/00218/32908/31417.pdf

DOI:10.1029/2009GC002779

https://archimer.ifremer.fr/doc/00218/32908/

Editor: | Amer Geophysical Union
Formato: | application/pdf
Fonte: | Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2009-11-21 , Vol. 10 , N. 11 , P. 1-15

Fonte:

Copyright 2009 by the American Geophysical Union

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