Mg/Ca paleothermometry in high salinity environments

Hoogakker, B. A. A. and Klinkhammer, G. P. and Elderfield, H. and Rohling, E. J. and Hayward, C. (2009) Mg/Ca paleothermometry in high salinity environments. Earth and Planetary Science Letters, 284 (3-4). pp. 583-589. DOI

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Planktonic foraminiferal Mg/Ca ratios have become a fundamental temperature proxy in past climate reconstructions. However, in the highly evaporative seas of the tropics and subtropics, anomalously high planktonic foraminiferal Mg/Ca ratios arise, possibly linked to high salinities. The extent to which salinity affects Mg uptake into foraminiferal calcite remains disputed. Some studies suggest only minor salinity effects, whereas others suggest a dominant role. Here, we present new data from the highly saline (> 40) Red Sea, which separate pure foraminiferal calcite from other phases. The results show that high Mg/Ca ratios (7 to 13 mmol/mol), found by conventional analysis of planktonic foraminifera from a Red Sea sediment core, are not caused by increased Mg uptake into foraminiferal calcite in a high salinity setting (e.g. beyond those predicted by culturing studies), but instead result from secondary high Mg-calcite overgrowths. The overgrowths likely formed near the sediment-seawater interface, from CaCO3 supersaturated interstitial seawater.

Item Type: Article
Uncontrolled Keywords: 09AREP; IA58;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 284
Page Range: pp. 583-589
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 23 Jul 2009 14:35
Last Modified: 23 Jul 2013 09:55

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