Iron isotopes in hot springs along the Juan de Fuca Ridge
Iron isotopes in hot springs along the Juan de Fuca Ridge
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DOI：
10.1016/s0012-821x(01)00538-6
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发表时间：
2001-12
影响因子：
5.3
通讯作者：
Mukul Sharma;M. Polizzotto;A. Anbar
中科院分区：
文献类型：
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作者：
Mukul Sharma;M. Polizzotto;A. Anbar
我们提供了Juan de Fuca Ridge、USGS标准玄武岩BCR-2和峡谷暗黑铁矿陨石中高温热液流体、硫化物和玄武岩的Fe同位素数据。所有样品的Fe同位素组成均在∼1‰范围内。然而，在热液流体中溶解的铁与峡谷暗黑岩中的铁之间存在着微小但具有统计学意义的同位素差异。具体地说，与峡谷暗黑火山相比，热液流体更轻，产生δ56Fe(=[(56Fe/54Fe)Sample/(56Fe/54Fe)Canyon Diablo−1]×1000)值，范围从−0.30‰到−0.77‰。相比之下，BCR-2玄武岩和峡谷暗黑岩在同位素上是难以区分的。胡安德富卡山脊玄武岩和硫化物中δ_(56)Fe的测量结果表明，热液系统中的Fe同位素是分馏的。然而，这些数据并不排除流体铁来源的岩石与其他火成岩Fe之间存在δ56Fe小差异的可能性，在这种情况下，火成岩系统中存在分馏作用。无论如何，这些结果都是自然界中铁同位素非生物质量分馏的证据。此外，热液流体向上覆水柱喷发，可为深海提供同位素轻铁的来源，有助于在深海沉积物中观察到铁的同位素变化。
We present Fe isotope data for high temperature hydrothermal fluids, sulfides, and basalts from the Juan de Fuca Ridge, USGS basalt standard BCR-2 and the Canyon Diablo iron meteorite. The Fe isotopic compositions of all samples fall within a range of ∼1‰. However, there is a small but statistically significant isotopic variation between Fe dissolved in hydrothermal fluids and Fe in Canyon Diablo. Specifically, the hydrothermal fluids are lighter compared to Canyon Diablo, yielding δ56Fe (=[(56Fe/54Fe)sample/(56Fe/54Fe)Canyon Diablo−1]×1000) values from −0.30‰ to −0.77‰. In contrast, the BCR-2 basalt and Canyon Diablo are isotopically indistinguishable. Measurements of δ56Fe in Juan de Fuca Ridge basalts and sulfides suggest that Fe isotopes are fractionated in hydrothermal systems. However, the data do not exclude the possibility of small δ56Fe differences between the rocks from which fluid Fe is derived and other igneous Fe, in which case fractionation in igneous systems is indicated. Regardless, these results are evidence of non-biological mass fractionation of Fe isotopes in nature. Further, venting of hydrothermal fluids into the overlying water column could provide a source of isotopically light Fe to the deep oceans, contributing to Fe isotopic variations observed in deep-sea sediments.