Hydrous alkali-silicate liquids at the magmatic-hydrothermal transition

岩浆-热液转变时的含水碱金属硅酸盐液体

• 批准号: 5449983
• 负责人: Professor Dr. Wilhelm Heinrich
• 金额: --
• 依托单位: Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5449983?language=en
• 关键词: Hydrous; alkali; silicate; liquids; magmatic

This proposal focuses on alkali-silicate liquids with the highest solubility of H2O and the lowest solidus temperatures. The nature of these liquids is contentious. They are considered either as melts, or concentrated aqueous solutions, or colloidal gels. However, they are able to crystallise common rock-forming silicates, such as feldspars and quartz, and thus can be regarded as plausible magmatic liquids. Natural alkali silicate liquids are likely to play an important role at the final stages of magma crystallisation in felsic intrusions, during anatectic melting of the crust and they may also form in subduction zone magmatism. The project includes comprehensive experimental studies in synthetic systems, and involves experimental and analytical methods (hydrothermal diamond anvil cells, in situ Raman spectroscopy, laser ablation ICP-MS), some of which, such as ultrasonic spectroscopy, were never applied, as far as we know, to water-rich alkali-silicate liquids before. By using new tools, we expect to resolve the controversy regarding the nature of the amorphous silicate phases and particularly examine their role in geologic systems at the magmatic-hydrothermal transition. The project aims at a major breakthrough in understanding pegmatite formation from alkali silicate liquids and has broader implications for fluid-induced melting in continental crust and lithospheric mantle. Amorphous silicate materials (liquid, glassy or colloidal) with large contents of water may shed new light on solubility mechanisms of volatiles in silicate melts and are also of great interest to material science.

这一提议的重点是具有最高溶解度的水和最低的固相温度的碱硅酸盐液体。这些液体的性质尚有争议。它们要么被认为是熔体，要么被认为是浓缩水溶液，要么被认为是胶体。然而，它们能够使常见的形成岩石的硅酸盐结晶，如长石和石英，因此可以被视为似是而非的岩浆液体。天然碱硅酸盐液体可能在长英质侵入体岩浆结晶的最后阶段、地壳的熔净熔融过程中起重要作用，它们也可能在俯冲带岩浆作用中形成。该项目包括合成系统的综合实验研究，涉及实验和分析方法（热液金刚石砧细胞、原位拉曼光谱、激光烧蚀ICP-MS），其中一些方法，如超声波光谱，据我们所知，以前从未应用于富含水的碱硅酸盐液体。通过使用新的工具，我们期望解决关于无定形硅酸盐相性质的争议，特别是研究它们在岩浆-热液转变的地质系统中的作用。该项目旨在在理解碱硅酸盐液体伟晶岩形成方面取得重大突破，并对大陆地壳和岩石圈地幔的流体诱导熔融具有更广泛的意义。含有大量水分的无定形硅酸盐材料（液态、玻璃状或胶体状）可能为研究硅酸盐熔体中挥发物的溶解机制提供新的思路，也是材料科学研究的热点。