Primary aqueous fluids in rhyolitic magmas: Melt inclusion evidence for pre- and post-trapping exsolution
Primary aqueous fluids in rhyolitic magmas: Melt inclusion evidence for pre- and post-trapping exsolution
复制标题
流纹质岩浆中的原生水性流体：捕获前和捕获后溶出的熔融包裹体证据
DOI：
10.1016/j.chemgeo.2006.07.009
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发表时间：
2007
期刊：
影响因子：
3.9
通讯作者：
Vadim Kamenetsky
中科院分区：
文献类型：
--
作者：
P. Davidson;Vadim Kamenetsky
本文研究了新西兰Okataina火山中心和智利Río布兰科Cu-Mo存款的流纹中含有水流体气泡（L、V和L + V）的熔融包裹体。我们证明，这些含水流体与硅酸盐熔体（岩浆）共存，并代表后捕获出溶（在Okataina的情况下），或共同捕获的阶段已经共存于岩浆（在里奥布兰科的情况下）。显微测温证明，一些气泡是单相的水溶液，并通过PIXE分析显示所有的是富含金属的盐溶液。因此，这些含水流体提供了最接近的直接测试的命题，冷却岩浆exsolve富含金属的含水流体。在Río布兰科的预捕获出溶的情况下，我们表明，一些包裹体记录和保存的岩浆乳液（熔体+含水流体），这是热液流体演化的第一阶段。我们证明，富含挥发分的熔融包裹体的加热实验可以产生原位出溶的超盐度的富含金属的水溶液的流体气泡，可能允许岩浆室的过程进行实验建模。
This study examines melt inclusions containing bubbles of aqueous fluid (L, V, and L + V), occurring in rhyolites from the Okataina Volcanic Centre, New Zealand, and the Río Blanco Cu–Mo deposit, Chile. We demonstrate that these aqueous fluids coexisted with silicate melts (magmas) and represent either post-trapping exsolution (in the case of Okataina), or co-trapping of phases already coexisting in the magma (in the case of Río Blanco). Microthermometry proves that some of the bubbles are a single-phase aqueous liquid, and all are shown by PIXE analysis to be metal rich saline solutions. As such, these aqueous fluids provide the closest approximation to direct testing of the proposition that cooling magmas exsolve metal-rich aqueous fluid. In the case of pre-trapping exsolution at Río Blanco we show that some inclusions record and preserve magmatic emulsions (melt + aqueous fluid) that are the first stage in the evolution of hydrothermal fluids. We demonstrate that heating experiments on volatile-rich melt inclusions can produce in-situ exsolution of hypersaline metal-rich aqueous fluid bubbles, potentially permitting magma-chamber processes to be experimentally modelled.