Mercury isotopic composition of hydrothermal systems in the Yellowstone Plateau volcanic field and Guaymas Basin sea-floor rift
Mercury isotopic composition of hydrothermal systems in the Yellowstone Plateau volcanic field and Guaymas Basin sea-floor rift
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DOI：
10.1016/j.epsl.2008.12.032
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发表时间：
2009-03
影响因子：
5.3
通讯作者：
L. Sherman;J. Blum;D. Nordstrom;R. McCleskey;T. Barkay;C. Vetriani
中科院分区：
文献类型：
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作者：
L. Sherman;J. Blum;D. Nordstrom;R. McCleskey;T. Barkay;C. Vetriani
为了表征热液系统中的汞（Hg）同位素和同位素分馏，我们分析了黄石高原火山区温泉中的流体和沉淀物样品以及瓜伊马斯盆地海底裂谷中的排气烟囱样品。这些样品提供了一个初步的指示汞同位素组成的变化之间的海洋和大陆热液系统，主要是由幔源岩浆控制。黄石公园Ojo Caliente温泉的流体样品的δ 202 Hg范围为−1.02‰至0.58‰（±0.11‰，2SD），瓜伊马斯盆地的固体沉淀样品的δ 202 Hg范围为−0.37‰至−0.01‰（±0.14‰，2SD）。Ojo Caliente的流体样品显示汞从喷口（δ 202 Hg =0.10‰±0.11‰，2SD）到流出通道末端（δ 202 Hg =0.58‰±0.11 ‰，2SD）的质量分馏（Hg），以及汞浓度从46.6 pg/g下降到20.0 pg/g。尽管由于与硅质烧结物的共沉淀，少量Hg从流体中损失，但我们推断，Ojo Caliente沃茨中观测到的Hg和Hg损失的大部分是由于Hg 0（aq）挥发为Hg 0（g）以及具有较低δ 202 Hg值的Hg优先损失到大气中。Ojo Caliente的所有样品中均观察到少量的质量无关分馏（MIF）（Δ 199 Hg =0.13‰±10.06‰，2SD），而瓜伊马斯盆地的海底裂谷样品中没有测量到明显的MIF。这项研究表明，几种不同的热液过程fractionated汞同位素和汞同位素可以用来更好地了解这些过程。
To characterize mercury (Hg) isotopes and isotopic fractionation in hydrothermal systems we analyzed fluid and precipitate samples from hot springs in the Yellowstone Plateau volcanic field and vent chimney samples from the Guaymas Basin sea-floor rift. These samples provide an initial indication of the variability in Hg isotopic composition among marine and continental hydrothermal systems that are controlled predominantly by mantle-derived magmas. Fluid samples from Ojo Caliente hot spring in Yellowstone range in δ202Hg from −1.02‰ to 0.58‰ (±0.11‰, 2SD) and solid precipitate samples from Guaymas Basin range in δ202Hg from −0.37‰ to −0.01‰ (±0.14‰, 2SD). Fluid samples from Ojo Caliente display mass-dependent fractionation (MDF) of Hg from the vent (δ202Hg=0.10‰±0.11‰, 2SD) to the end of the outflow channel (δ202Hg=0.58‰±0.11‰, 2SD) in conjunction with a decrease in Hg concentration from 46.6 pg/g to 20.0 pg/g. Although a small amount of Hg is lost from the fluids due to co-precipitation with siliceous sinter, we infer that the majority of the observed MDF and Hg loss from waters in Ojo Caliente is due to volatilization of Hg0(aq)to Hg0(g)and the preferential loss of Hg with a lower δ202Hg value to the atmosphere. A small amount of mass-independent fractionation (MIF) was observed in all samples from Ojo Caliente (Δ199Hg=0.13‰±10.06‰, 2SD) but no significant MIF was measured in the sea-floor rift samples from Guaymas Basin. This study demonstrates that several different hydrothermal processes fractionate Hg isotopes and that Hg isotopes may be used to better understand these processes.