Coupled Mg/Ca and clumped isotope analyses of foraminifera provide consistent water temperatures
Coupled Mg/Ca and clumped isotope analyses of foraminifera provide consistent water temperatures
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DOI：
10.1016/j.gca.2018.03.010
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发表时间：
2018-09-01
影响因子：
5
通讯作者：
Hodell, David A.
中科院分区：
文献类型：
--
作者：
Breitenbach, Sebastian F. M.;Mleneck-Vautravers, Maryline J.;Hodell, David A.
过去海水温度的可靠测定是古气候研究的基础。我们在相同的岩心顶端浮游有孔虫标本上，通过结合镁/钙和簇状同位素(Delta(47))来测试两个古温度替代指标的稳健性。这种方法的优点是，在相同的有孔虫标本上测量了镁/钙和Delta(47)，从而提供了两个独立的温度估计。这种复制构成了对单个方法的严格测试，其优点是相同的方法可以应用于化石标本。在对用于微量元素和同位素分析的有孔虫进行改进的清洁程序之后，以相同的方式处理用于镁/钙分析和成团分析的等分。我们分析了岩心顶部样品中8种浮游有孔虫，温度范围从2摄氏度到29摄氏度。我们提供了一种新的使用水下洞穴碳酸盐进行块状同位素温度校准的方法，这与最近的研究一致。串联的Mg/Ca-Delta(47)结果符合温度校准方程所预测的指数曲线。观测到的与预测的镁/钙-三角洲(47)关系的偏差归因于铁-锰氧化物涂层、污染或有孔虫测试的溶解的影响。当Mg/Ca和Delta(47)得到一致的结果时，这种耦合方法在温度估计中提供了高度的置信度，并可用于推断过去海水的Delta O-18(Delta O-18(Sw))，用于古气候研究。(C)爱思唯尔有限公司出版的2018年。
The reliable determination of past seawater temperature is fundamental to paleoclimate studies. We test the robustness of two paleotemperature proxies by combining Mg/Ca and clumped isotopes (Delta(47)) on the same specimens of core top planktonic foraminifera. The strength of this approach is that Mg/Ca and Delta(47) are measured on the same specimens of foraminifera, thereby providing two independent estimates of temperature. This replication constitutes a rigorous test of individual methods with the advantage that the same approach can be applied to fossil specimens. Aliquots for Mg/Ca and clumped analyses are treated in the same manner following a modified cleaning procedure of foraminifera for trace element and isotopic analyses. We analysed eight species of planktonic foraminifera from coretop samples over a wide range of temperatures from 2 to 29 degrees C. We provide a new clumped isotope temperature calibrations using subaqueous cave carbonates, which is consistent with recent studies. Tandem Mg/Ca-Delta(47) results follow an exponential curve as predicted by temperature calibration equations. Observed deviations from the predicted Mg/Ca-Delta(47) relationship are attributed to the effects of Fe-Mn oxide coatings, contamination, or dissolution of foraminiferal tests. This coupled approach provides a high degree of confidence in temperature estimates when Mg/Ca and Delta(47) yield concordant results, and can be used to infer the past delta O-18 of seawater (delta O-18(sw)) for paleoclimate studies. (C) 2018 Published by Elsevier Ltd.