Aqueous Aluminosilicate Polymers: Transport Agents in Crustal and Mantle Fluids?

水性铝硅酸盐聚合物：地壳和地幔流体中的传输剂？

• 批准号: 1049901
• 负责人: Craig Manning
• 金额: $ 39.84万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-15 至 2015-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1049901&HistoricalAwards=false
• 关键词: Aqueous; Aluminosilicate; Polymers; Transport; Agents

The movement of fluids in the Earth's crust and mantle changes rock composition. Geologists see evidence for these changes on a variety of scales, ranging from mineral-filled microcracks to volcanoes such as Mount St. Helens. However, it is extremely difficult to assess how much flow is required to produce the observed changes, chiefly because we know little about how the rock-forming minerals dissolve in geofluids at high pressures and temperatures. This project will quantify the solubility of minerals in geofluids using novel experimental approaches.Key to the completion of the work is the recent recognition that aqueous silica is a dominant solute in geofluids, and that dissolved silica polymerizes significantly at high pressures and temperatures. Aluminum is readily incorporated in these structures, dramatically raising its solubility. Titanium exhibits similar behavior. Evidently, dissolution of these elements is aided by the availability of structural environments in the polymeric species that are more energetically favorable than those offered by pure H2O. These observations suggest the simple hypothesis that the aluminosilicate polymeric solutes may hold the key to understanding element mobility in deep metasomatic settings. The experiments to be carried out by the research team target three components of this hypothesis. The first will address the evolution of such structures, and their transport capacity, when they encounter new chemical environments by studying dissolution of mantle minerals (enstatite + forsterite) in Na2O-Al2O3-SiO2-H2O fluids. A second line of investigation will explore the solubility rare-earth elements in polymer-bearing fluid, using the minerals monazite and xenotime. Finally, the team will investigate the role played by polymeric solutes in Earth's volatile cycling by focusing on calcite. When complete, the experimental research will offer a test of a new mechanism for controlling element transfer in Earth's deep metasomatic environments.

地壳和地幔中的流体运动改变了岩石的成分。地质学家在各种尺度上看到了这些变化的证据，从充满矿物质的微裂缝到圣海伦火山等火山。然而，要评估产生所观察到的变化需要多少流量是非常困难的，主要是因为我们对造岩矿物如何在高压和高温下溶解在地质流体中知之甚少。该项目将使用新型实验方法量化矿物在地质流体中的溶解度。完成这项工作的关键是最近认识到含水二氧化硅是地质流体中的主要溶质，并且溶解的二氧化硅在高压和高温下会显着聚合。铝很容易结合在这些结构中，大大提高了它的溶解度。钛表现出类似的行为。显然，这些元素的溶解是由聚合物物种中的结构环境的可用性所帮助的，所述结构环境比纯H2O所提供的结构环境在能量上更有利。这些观察结果表明，简单的假设，铝硅酸盐聚合物溶质可能持有的关键，了解元素的流动性在深交代设置。研究小组将进行的实验针对这一假设的三个组成部分。第一个将解决这样的结构的演变，和他们的运输能力，当他们遇到新的化学环境，通过研究溶解的地幔矿物（顽火辉石+镁橄榄石）在Na 2 O-Al 2 O3-SiO2-H2O流体。第二条调查路线将利用独居石和磷钇矿来探索稀土元素在含聚合物流体中的溶解度。最后，研究小组将通过关注方解石来研究聚合溶质在地球挥发性循环中所起的作用。完成后，实验研究将提供一个新的机制，控制地球深部交代环境中的元素转移的测试。