Experimental constraints on siderite clumped isotope thermometry
Experimental constraints on siderite clumped isotope thermometry
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菱铁矿团块同位素测温的实验限制
DOI：
10.1016/j.gca.2022.12.012
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发表时间：
2023
影响因子：
5
通讯作者：
Hurowitz, Joel A.
中科院分区：
文献类型：
--
作者：
Holme, Ella A.;Henkes, Gregory A.;Tosca, Nicholas J.;Rasbury, E. Troy;Young, Jordan M.;Schaub, D.R.;Nekvasil, Hanna;Hurowitz, Joel A.
我们介绍了在15 ° C至75° C之间使用改进的恒定组成方法进行的化学稳定菱铁矿沉淀实验的结果，并将这些结果与以前的温度关系进行比较，以获得菱铁矿聚集同位素比（Δ 47）在8.5 ° C至75° C之间的复合低温关系：Δ 47= 0.0 36 4 ± 0.0 0 4 × 10 6 T2 + 0.16 72 ± 0.0 46 ±95% CL，R2 = 0.70 8该线的斜率与文石、方解石和白云石的团聚同位素的斜率在统计上无差别，但截距不同。为了测试这种差异是否是由于菱铁矿和钙镁碳酸盐之间磷酸分馏因子（AFF）的矿物学差异造成的，我们在1 GPa下将菱铁矿加热到625° C，这产生了一个统计学上无法区分的Δ 47值，该值与已发表的由较高温度下的钙和镁碳酸盐数据填充的聚集同位素校准预测的值相同。因此，菱铁矿成团同位素行为与其他碳酸盐矿物之间的明显差异可能不能很好地解释AFF的差异。尽管沉淀方法存在差异，但我们的结果与已发表的无机和微生物介导的实验菱铁矿团块同位素数据完全一致，表明菱铁矿Δ 47-温度依赖性与Ca-Mg碳酸盐不同，原因与沉淀方法无关。我们的同位素结果也与已发表的天然菱铁矿在已知环境温度下沉淀的同位素测量结果一致。我们的分析使我们得出这样的结论，过饱和相关的动力学效应可能发挥重要作用，在天然和实验沉淀菱铁矿的聚集同位素分馏。
We present results from chemostatic siderite precipitation experiments conducted using a modified constant composition method at temperatures between 15 and 75° C and compare these results with previous temperature relationships to obtain a composite low temperature relationship for siderite clumped isotope ratios (Δ 47) from 8.5 to 75° C: Δ 47= 0.0364±0.004∗ 10 6 T 2+ 0.1672±0.046±95% C L, R 2= 0.708 The slope of this line is statistically indistinguishable from those reported for aragonite, calcite, and dolomite clumped isotopes, but differs in its intercept. To test whether this difference results from mineralogical differences in phosphoric acid fractionation factors (AFF) between siderite and Ca-Mg carbonates, we heated siderite to 625° C at 1 GPa, which yielded a statistically indistinguishable Δ 47 value from that predicted by published clumped isotope calibrations populated by Ca-and Mg-carbonate data at higher temperatures. Thus, the apparent difference between siderite clumped isotope behavior and that of other carbonate minerals may not be well explained by differences in AFF. Despite differences in precipitation methods, our results are entirely consistent with published inorganic and microbially-mediated experimental siderite clumped isotope data, suggesting that siderite Δ 47-temperature dependence differs from Ca-Mg carbonates for reasons unrelated to precipitation methods. Our isotopic results are also consistent with published isotopic measurements on natural siderites precipitated at known environmental temperatures. Our analysis leads us to conclude that supersaturation-related kinetic effects likely play an important role in clumped isotope fractionation in natural and experimentally precipitated siderite.
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DOI：
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发表时间：
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期刊：
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影响因子：
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