Mg/Ca paleothermometry in high salinity environments
Mg/Ca paleothermometry in high salinity environments
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DOI：
10.1016/j.epsl.2009.05.027
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发表时间：
2009-07-15
影响因子：
5.3
通讯作者：
Hayward, Chris
中科院分区：
文献类型：
--
作者：
Hoogakker, Babette A. A.;Klinkhammer, Gary P.;Hayward, Chris
浮游有孔虫镁/钙比已成为过去气候重建中的基本温度指标。然而，在热带和亚热带高度蒸发的海洋中，出现异常高的浮游有孔虫镁/钙比，这可能与高盐度有关。盐度对有孔虫方解石吸收镁的影响程度仍存在争议。一些研究表明盐度的影响很小，而另一些研究则表明盐度的影响占主导地位。在这里，我们提供了来自高盐度 (>40) 红海的新数据，这些数据将纯有孔虫方解石与其他相分开。结果表明，通过对红海沉积物核心的浮游有孔虫进行常规分析发现，高 Mg/Ca 比率（7 至 13 mmol/mol）并不是由于高盐度环境下有孔虫方解石吸收镁增加所致（例如超出培养研究预测的值），而是由次生高镁方解石过度生长造成的。这些过度生长可能是在沉积物-海水界面附近形成的，由碳酸钙过饱和间隙海水形成。 (C) 2009 Elsevier B.V. 保留所有权利。
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 byconventional 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. (C) 2009 Elsevier B.V. All rights reserved.