Calibration and application of the 'clumped isotope' thermometer to foraminifera for high-resolution climate reconstructions
Calibration and application of the 'clumped isotope' thermometer to foraminifera for high-resolution climate reconstructions
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DOI：
10.1016/j.gca.2012.12.049
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发表时间：
2013-05-01
影响因子：
5
通讯作者：
Bernasconi, Stefano M.
中科院分区：
文献类型：
--
作者：
Grauel, Anna-Lena;Schmid, Thomas W.;Bernasconi, Stefano M.
重建过去的海洋温度是研究过去气候变化的基础，因此，在开发海水温度代理方面投入了大量努力。最新和最有前途的新代理之一是碳酸盐的“凝聚同位素”测温法，特别是因为它是基于热力学平衡，而不是地球化学代理。在这里，我们提出了一个新的校准的'成团同位素'温度计有孔虫的基础上，7种浮游和底栖有孔虫跨越生长温度范围类似于2-28摄氏度。我们使用了一种新开发的小样本测量技术，以提高这种方法的古海洋学的适用性。我们的数据具有相当的精度（类似于0.005-0.013千分之一），并证实了以前的校准研究的基础上生物和无机方解石。我们讨论了可能的不确定性来源，如过度/低估的钙化温度，物种特异性的生命效应，为了验证我们的校准研究和测试我们的测量技术在古气候和古海洋学研究中的适用性，我们测量了Globigerinoides ruber（白色），在高分辨率的沉积物核心覆盖了过去700年在塔兰托湾（地中海）。结果表明，它是必要的平均相对大量的分析，以实现一致的温度信号的检测小的海面温度变化。虽然在现有的分析系统中，“聚集同位素”测温法仅适用于分析海洋沉积物中相对较大的SST变化，但进一步的技术改进可能使其成为古海洋学研究的一种非常强大的技术。(C)2013爱思唯尔有限公司保留所有权利。
The reconstruction of past ocean temperatures is fundamental to the study of past climate changes, therefore considerable effort has been invested in developing proxies for seawater temperatures. One of the most recent and promising new proxy is carbonate 'clumped isotope' thermometry, in particular because it is based on thermodynamic equilibrium and not on biogeochemical proxies. Here, we present a new calibration of the 'clumped isotope' thermometer to foraminifera based on seven species of planktic and benthic foraminifera spanning a growth temperature range of similar to 2-28 degrees C. We used a newly developed technique for the measurements of small samples to improve the applicability of this method to paleoceanography. Our data have a comparable precision (similar to 0.005-0.013 parts per thousand) and confirm previous calibration studies based on biogenic and inorganic calcite. We discuss possible sources of uncertainty such as over-/underestimation of the calcification temperatures, species-specific vital effects, pH variations between the seawater and the vacuole water of the species and possible kinetic effects on the 'clumped isotope' calibration.To validate our calibration study and test the applicability of our measuring technique to paleoclimate and paleoceanographic studies we measured the isotope composition of Globigerinoides ruber (white) at high-resolution in a sediment core covering the last 700 years in the Gulf of Taranto (Mediterranean Sea). The results show that it is necessary to average a relatively large number of analyses to achieve a consistent temperature signal for the detection of small sea surface temperature changes. Although with the current analytical system, 'clumped isotope' thermometry is only applicable to the analysis of relatively large SST changes in marine sediments, further technical improvements may make this a very powerful technique for paleoceanographic studies. (C) 2013 Elsevier Ltd. All rights reserved.