Water in Nominally Anhydrous Crustal Minerals: Speciation, Concentration, and Geologic Significance
Water in Nominally Anhydrous Crustal Minerals: Speciation, Concentration, and Geologic Significance
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DOI：
10.2138/rmg.2006.62.6
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发表时间：
2006
影响因子：
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通讯作者：
E. A. Johnson
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文献类型：
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作者：
E. A. Johnson
### 地壳中名义无水矿物的重要性 为什么我们应该对地壳名义无水矿物中的微量含水物质感兴趣？毕竟，含水矿物在土壤圈中占主导地位，并且在许多变质岩和火成地壳岩石中含量丰富，甚至是相当常见的微量矿物。另一方面，地壳中最丰富的矿物——长石、石英、辉石和石榴石——名义上都是无水的。它们甚至存在于总挥发物或液体含量较低的系统中，或含水矿物不稳定的水活度较低的环境中。这些名义上无水的矿物提供了一个机会来扩大我们对流体成分和水活度以及水对岩石物理性质和地球化学特征的影响的了解。研究岩石圈地壳成分的优点之一是地壳的许多部分（特别是大陆地壳）可用于在地球表面露头中直接研究。这使得名义上的无水矿物及其含水物质能够被置于手工样品、露头甚至区域地质的背景中。 ### 本章的范围和目标 试图在本章中涵盖地壳中的所有含水矿物是不现实的。我的讨论仅限于不需要含水物质来完成其化学计量的矿物，以及那些已经在天然地壳样本上完成研究的矿物。这些矿物是：石英、长石、霞石、辉石、石榴石（镁铝榴石除外）、蓝晶石、红柱石、硅线石、金红石、锡石、锆石、钛矿、堇青石和绿柱石。这种矿物选择将讨论主要限制在约 3 公里深度以下的大陆地壳。为了完整起见，其中包括一些对榴辉岩和地幔楔矿物的参考。这是一个相当新的研究领域，因此，本章的目标是概述……
### Importance of nominally anhydrous minerals in the crust Why should we be interested in trace hydrous species in nominally anhydrous minerals in the Earth’s crust? After all, hydrous minerals dominate the pedosphere and are abundant to fairly common trace minerals in many metamorphic and igneous crustal rocks. On the other hand, the most abundant minerals in the crust—feldspars, quartz, pyroxenes, and garnet—are all nominally anhydrous. They are present even in systems with low total volatiles or fluid contents, or environments with low water activities where hydrous minerals are unstable. These nominally anhydrous minerals provide an opportunity to expand the extent of our knowledge of fluid composition and water activity, as well as the influence of water on physical properties and geochemical signatures of rocks. One advantage to investigations of the crustal component of the lithosphere is that many parts of the crust (especially the continental crust) are available for direct study in outcrops at the surface of the Earth. This allows the nominally anhydrous mineral and its hydrous species to be placed into the context of the hand sample, the outcrop, and even the regional geology. ### Scope and goals of this chapter It would be unrealistic to try to cover every water-bearing mineral in the Earth’s crust in this chapter. I have limited my discussion to minerals that do not require hydrous species to complete their stoichiometry, and those for which research has been completed on natural crustal samples. These minerals are: quartz, the feldspars, nepheline, pyroxenes, garnets (except pyrope), kyanite, andalusite, sillimanite, rutile, cassiterite, zircon, titanite, cordierite, and beryl. This selection of minerals restricts the discussion primarily to the continental crust below about 3 km depth. Some references to eclogitic and mantle-wedge minerals are included for completeness. This is a fairly new field of study, and as such, the goal of this chapter is to give an overview of the work that has …