Chlorine isotope constraints on fluid‐rock interactions during subduction and exhumation of the Zermatt‐Saas ophiolite
Chlorine isotope constraints on fluid‐rock interactions during subduction and exhumation of the Zermatt‐Saas ophiolite
复制标题
氯同位素对采尔马特-萨斯蛇绿岩俯冲和折返过程中流体-岩石相互作用的限制
DOI：
10.1002/ggge.20269
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Z. Sharp
中科院分区：
文献类型：
--
作者：
J. Selverstone;Z. Sharp
意大利奥斯塔地区高压（~ 2.3 GPa）蛇纹岩、罗纹岩和热液蚀变海洋地壳（AOC）的氯同位素组成与高压和超高压（> 3.2 GPa）变质沉积岩有显著差异。在结构上，早期蛇纹岩、绿纹岩和AOC的δ37Cl值与现代海底类似物的δ37Cl值（δ37Cl = - 1.0 ~ +1.0‰）难以区分。相比之下，在发掘过程中重结晶的蛇纹岩和AOC样品δ37Cl值较低（−2.7 ~−0.5‰）；cl的耗竭与体化学的逐渐变化有关。高压/超高压沉积δ37Cl值较低（中值= - 2.5‰），与现代海相沉积δ37Cl值（中值= - 0.6‰）有统计学差异。变质沉积岩中的Cl在结构上主要集中在早期矿物中，表明在俯冲史早期海底成分发生了改变。研究结果表明：①俯冲板块顶部的海相沉积物可能在俯冲早期与来自增生楔体的轻质孔隙流体相互作用；(2)在随后的俯冲至最大埋藏深度的过程中，没有发生与外部衍生流体的普遍相互作用。(3)在俯冲通道的挖掘过程中，蛇纹岩与先前同位素修饰的变质沉积物释放的流体发生了局部混合。然而，大多数样品在俯冲至近弧深度期间保留了原岩特征。
Chlorine isotope compositions of high‐pressure (∼2.3 GPa) serpentinite, rodingite, and hydrothermally altered oceanic crust (AOC) differ significantly from high‐ and ultrahigh‐pressure (> 3.2 GPa) metasedimentary rocks in the Aosta region, Italy. Texturally early serpentinites, rodingites, and AOC have bulk δ37Cl values indistinguishable from those of modern seafloor analogues (δ37Cl = −1.0 to +1.0‰). In contrast, serpentinites and AOC samples that recrystallized during exhumation have low δ37Cl values (−2.7 to −0.5‰); 37Cl depletion correlates with progressive changes in bulk chemistry. HP/UHP metasediments have low δ37Cl values (median = −2.5‰) that differ statistically from modern marine sediments (median = −0.6‰). Cl in metasedimentary rocks is concentrated in texturally early minerals, indicating modification of seafloor compositions early in the subduction history. The data constrain fluid sources during both subduction and exhumation‐related phases of fluid‐rock interaction: (1) marine sediments at the top of the downgoing plate likely interacted with isotopically light pore fluids from the accretionary wedge in the early stages of subduction. (2) No pervasive interaction with externally derived fluid occurred during subsequent subduction to the maximum depths of burial. (3) Localized mixing between serpentinites and fluids released by previously isotopically modified metasediments occurred during exhumation in the subduction channel. Most samples, however, preserved protolith signatures during subduction to near‐arc depths.
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影响因子：
5.8
作者：
McCaig, Andrew M.;Cliff, Robert A.;MacLeod, Christopher J.
通讯作者：
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影响因子：
3.9
作者：
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通讯作者：
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影响因子：
5
作者：
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通讯作者：
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影响因子：
18.3
作者：
John, Timm;Gussone, Nikolaus;Seitz, Hans-Michael
通讯作者：
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