| Type |
Article |
| Date |
2009-11-21 |
| Language |
English |
| Author(s) |
Sepulcre Sophie1, Tachikawa Kazuyo1, Vidal Laurence1, Thouveny Nicolas1, Bard Edouard1 |
| Affiliation(s) |
1 : Aix Marseille Univ, CNRS, Coll France, CEREGE,UMR 6635, F-13545 Aix En Provence, France. |
| Source |
Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2009-11-21 , Vol. 10 , N. 11 , P. 1-15 |
| DOI |
10.1029/2009GC002779 |
| WOS© Times Cited |
8 |
| Keyword(s) |
Mg-calcite preservation state, Mg/Ca in Mg-calcite, Caribbean Sea, mid-Pleistocene |
| Abstract |
Carbonate-rich periplatform sediments represent an active carbon reservoir containing metastable aragonite and magnesian calcite (Mg-calcite, > 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 (< 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. |
| Full Text |
| File |
Pages |
Size |
Access |
| Publisher's official version |
15 |
3 MB |
Open access |
|
