Mg/Ca paleothermometry in high salinity environments
Hoogakker, Babette A.A., Klinkhammer, Gary P., Elderfield, Harry, Rohling, Eelco J. and Hayward, Chris (2009) Mg/Ca paleothermometry in high salinity environments. Earth and Planetary Science Letters, 284, (3-4), 583-589. (doi:10.1016/j.epsl.2009.05.027).
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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.
|Keywords:||Mg/Ca paleothermometry; Red Sea; salinity; high Mg-calcite overgrowths; conventional ICP-AES; electron microprobe analysis; scanning electron microscopy; flow-through time resolved analysis; CaCO3 supersaturation; Globigerinoides ruber|
|Subjects:||Q Science > QE Geology
Q Science > QD Chemistry
G Geography. Anthropology. Recreation > GC Oceanography
|Divisions:||University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
|Date Deposited:||17 Aug 2009|
|Last Modified:||01 Jun 2011 15:04|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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