Coral Sr-U thermometry
Coral Sr-U thermometry
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DOI：
10.1002/2015pa002908
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发表时间：
2016-06-01
期刊：
影响因子：
--
通讯作者：
Stewart, Joseph A.
中科院分区：
文献类型：
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作者：
DeCarlo, Thomas M.;Gaetani, Glenn A.;Stewart, Joseph A.
珊瑚骨骼以无与伦比的时间分辨率记录了过去的气候变化。然而，从珊瑚骨骼提取准确的温度信息受到生命效应的限制，这混淆了，有时覆盖了地球化学代理的温度依赖性。我们提出了一种新的方法来珊瑚古温度的基础上解释的珊瑚生物矿化过程的定量模型提供的框架内的非生物成因的降水实验的结果。DeCarlo等人（2015 a）研究了温度和碳酸盐化学对文石和海水之间Sr/Ca和U/Ca非生物分配的控制，并模拟了骨骼成分对钙化部位发生的过程的敏感性。该模型预测，温度可以准确地重建从珊瑚骨骼相结合的Sr/Ca和U/Ca比率到一个新的代理，我们称之为Sr-U温度计。在这里，我们测试的模型预测与测量的Sr/Ca和U/Ca比的14个滨珊瑚种。珊瑚收集从热带太平洋和红海，与一个子集也分析了使用硼同位素（B-11）pH值代理。观察到的Sr/Ca，U/Ca，和B-11之间的关系同意模型的预测，表明该模型占珊瑚生物矿化过程的关键特征。通过校准仪器温度记录，我们表明，Sr-U捕获93%的平均年温度变化（26-30摄氏度），并具有0.5摄氏度的预测标准偏差，相比之下，1摄氏度单独使用Sr/Ca。锶铀温度计可以提供显着改善的可靠性重建过去的海洋温度从珊瑚骨骼。
Coral skeletons archive past climate variability with unrivaled temporal resolution. However, extraction of accurate temperature information from coral skeletons has been limited by vital effects, which confound, and sometimes override, the temperature dependence of geochemical proxies. We present a new approach to coral paleothermometry based on results of abiogenic precipitation experiments interpreted within a framework provided by a quantitative model of the coral biomineralization process. DeCarlo et al. (2015a) investigated temperature and carbonate chemistry controls on abiogenic partitioning of Sr/Ca and U/Ca between aragonite and seawater and modeled the sensitivity of skeletal composition to processes occurring at the site of calcification. The model predicts that temperature can be accurately reconstructed from coral skeleton by combining Sr/Ca and U/Ca ratios into a new proxy, which we refer to hereafter as the Sr-U thermometer. Here we test the model predictions with measured Sr/Ca and U/Ca ratios of 14 Porites sp. corals collected from the tropical Pacific Ocean and the Red Sea, with a subset also analyzed using the boron isotope (B-11) pH proxy. Observed relationships among Sr/Ca, U/Ca, and B-11 agree with model predictions, indicating that the model accounts for the key features of the coral biomineralization process. By calibrating to instrumental temperature records, we show that Sr-U captures 93% of mean annual temperature variability (26-30 degrees C) and has a standard deviation of prediction of 0.5 degrees C, compared to 1 degrees C using Sr/Ca alone. The Sr-U thermometer may offer significantly improved reliability for reconstructing past ocean temperatures from coral skeletons.