Empirical calibration of the clumped isotope paleothermometer using calcites of various origins
Empirical calibration of the clumped isotope paleothermometer using calcites of various origins
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DOI：
10.1016/j.gca.2014.06.004
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发表时间：
2014-09
影响因子：
5
通讯作者：
U. Wacker;J. Fiebig;J. Tödter;B. Schöne;A. Bahr;O. Friedrich;T. Tütken;E. Gischler;M. Joachimski
中科院分区：
文献类型：
--
作者：
U. Wacker;J. Fiebig;J. Tödter;B. Schöne;A. Bahr;O. Friedrich;T. Tütken;E. Gischler;M. Joachimski
我们提出了第一个通用的校准的块状同位素温度计的各种矿化类型的方解石。这些是鸵鸟的蛋壳，热带双壳类，腕足动物壳，冷泉碳酸盐和三个在9到38° C之间生长的有孔虫样本。CaCO 3在90° C下使用普通酸浴消化。考虑到在25 ° C和90° C下反应之间的磷酸分馏因子的差异为0.069‰（Guo等人，结果表明，生长温度T与析出CO2中13 C-18 O键的过剩量之间的关系可用1/T2与Δ 47绝对值之间的线性回归表示（R2 = 0.9915）：Δ 47= 0.0327（±0.0026）× 106/T2 + 0.3030（±0.0308）（Δ 47以‰表示，T以K表示）。我们的回归线的斜率和截距均显著偏离基于在25° C下消化的合成方解石的第一实验校准（Ghosh等人，2006 a）和其他几项研究证实了这一开创性的校准（即，Came等人，2007; Tripati等人，2010; Thiagarajan等人，2011; Grauel等人，2012; Saenger等人，2012; Zaarur等人，2013年）的报告。然而，我们的温度和绝对Δ 47值之间的关系与Henkes等人确定的关系无法区分。（2013），如果将25 ° C和90° C之间的磷酸分馏因子的相同差异应用于两个数据集。我们的研究和Henkes等人的研究。（2013）的共同点是，数据主要预测到丹尼斯等人提出的绝对规模。（2011年）-一个参考框架，允许比较在不同实验室测量的聚集同位素数据。此外，在任何温度下，我们的回归线都在Guo等人的理论方解石校准值的0.006‰以内。（2009年）。两种经验校准彼此无法区分的观察结果意味着，如果（1）磷酸消化温度设置为90° C，并且（2）原始数据主要投影到绝对标度，则可以在实验室之间直接比较聚集的同位素数据并参考独特的温度校准。
We present the first universal calibration of the clumped isotope thermometer for calcites of various mineralizing types. These are an eggshell of an ostrich, a tropical bivalve, a brachiopod shell, cold seep carbonate, and three foraminifera samples that grew between 9 and 38° C. CaCO 3 was digested at 90° C using a common acid bath. Considering a difference in phosphoric acid fractionation factors between reaction at 25 and 90° C of 0.069‰(Guo et al., 2009), the function between growth temperature T and the excess of 13 C–18 O bonds in the evolved CO 2 is expressed by a linear regression between 1/T 2 and absolute Δ 47 (R 2= 0.9915): Δ 47= 0.0327 (±0.0026)× 10 6/T 2+ 0.3030 (±0.0308)(with Δ 47 in‰ and T in K). Both the slope and intercept of our regression line deviate significantly from the first experimental calibration based on synthetic calcites digested at 25° C (Ghosh et al., 2006a) and from several other studies having confirmed this pioneering calibration (ie, Came et al., 2007; Tripati et al., 2010; Thiagarajan et al., 2011; Grauel et al., 2012; Saenger et al., 2012; Zaarur et al., 2013). However, our relationship between temperature and absolute Δ 47 values is indistinguishable from that determined by Henkes et al.(2013) if the same difference in phosphoric acid fractionation factors between 25 and 90° C is applied to both datasets. Our study and that of Henkes et al.(2013) have in common that data were primarily projected onto the absolute scale proposed by Dennis et al.(2011)–a reference frame that allows comparison of clumped isotope data measured in different laboratories. Furthermore, at any T, our regression line lies within 0.006‰ of the theoretical calcite calibration of Guo et al.(2009). The observation that both empirical calibrations are indistinguishable from each other implies that clumped isotope data can be directly compared between laboratories and referenced to a unique temperature calibration if (1) the phosphoric acid digestion temperature is set to 90° C, and (2) raw data are primarily projected to the absolute scale.