Collaborative Research: Water Concentration and Distribution in the Oceanic Lithosphere

合作研究：海洋岩石圈中的水浓度和分布

• 批准号: 1624315
• 负责人: Michael Bizimis
• 金额: $ 28.22万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-15 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1624315&HistoricalAwards=false
• 关键词: Collaborative; Research; Water; Concentration; Distribution

The chemical compound H2O, which in its liquid state is called water, when it occurs bound in minerals and other solids, influences melting, rheology and plastic behavior of the mineral or material, and the material's thermal and electrical properties. In the case where H2O is bound in minerals deep in the ocean crust, this can result in enhanced generation of magmas, hence volcanic eruptions, and changes in the plasticity, deformation of the lithosphere. In areas where magmas rise to the surface, this H2O is released and forms an important part of the global cycle of H2O. Because most of the H2O on Earth is locked up in minerals in the crust and mantle, the concentration and distribution of H2O in various mantle and lithospheric reservoirs have been inferred primarily from analyses of undegassed glasses and melt inclusions in oceanic basalts through a comparison of their H2O content with incompatible rare earth elements like Cerium. This only provides a rough estimate of the H2O content of the Earth. This research builds off the results of a pilot study and uses a novel new approach to determine how much H2O is stored in minerals in the oceanic mantle and lithosphere, the mechanisms that fractionate H2O from other geochemical tracers in mantle lithologies, and the fate of the H2O and how it impacts the electrical conductivity and rheology of the oceanic lithosphere. Broader impacts of the work include support of a faculty member at an institution in South Carolina, an EPSCoR state (i.e., a state that does not receive significant federal funding), support of a researcher whose gender is under-represented in the sciences, and student training who will get trained on cutting-edge analytical instrumentation at NASA at the Johnson Space Center in Houston, TX. Impacts also include international collaboration with Belgian and Japanese scientists and making the data accessible to the public.Questions to be addressed by this research include seeing if H2O varies independently from lithophile elements in the lithosphere and if diffusion is responsible if decoupling is observed; looking to see if pyroxenes are typically a high-H2O, low-solidus reservoir; examine if H2O solubility in minerals under lithospheric pressures and temperatures put an upper limit on how much structurally bound H2O is held in the unaltered lithosphere; whether H2O concentrations are reflected in the H2O systematics of lithospheric samples; and whether there are systematic correlations between H2O distribution in the lithosphere and the degree of melting, depth, and lithology and metasomatic agents. To address these issues, Fourier Transform Infrared Spectroscopy (FTIR) will be used to determine the H2O concentrations in well-characterized, fresh (i.e., unaltered) peridotites and pyroxenites from a suite of locations and tectonic settings that include the Canary Islands in the Atlantic Ocean; the Kerguelen Plateau in the South Indian Ocean; the Hawaiian and Samoan Islands and the Ontong Java Plateau in the Pacific Ocean; and the Lena Trough in the Arctic Ocean. Additional geochemical indicators, such as trace element compositions of minerals and radiogenic isotopes of Sr, Hf, Nd, and Pb in minerals and rocks will be used to help determine if there is a link between process, mineralogy, and H2O content/behavior.

化合物H2O在其液态状态下称为水时，当它发生在矿物质和其他固体结合时，会影响矿物或材料的融化，流变和塑性行为，以及材料的热和电性能。 如果H2O结合在海角深处的矿物质中，这可能导致岩浆的产生增强，因此火山喷发以及可塑性的变化，岩石圈的变形。在岩浆上升到表面的地区，该H2O被释放并构成H2O全球周期的重要组成部分。 Because most of the H2O on Earth is locked up in minerals in the crust and mantle, the concentration and distribution of H2O in various mantle and lithospheric reservoirs have been inferred primarily from analyses of undegassed glasses and melt inclusions in oceanic basalts through a comparison of their H2O content with incompatible rare earth elements like Cerium. 这仅提供对地球H2O含量的粗略估计。 This research builds off the results of a pilot study and uses a novel new approach to determine how much H2O is stored in minerals in the oceanic mantle and lithosphere, the mechanisms that fractionate H2O from other geochemical tracers in mantle lithologies, and the fate of the H2O and how it impacts the electrical conductivity and rheology of the oceanic lithosphere. 这项工作的更广泛的影响包括在南卡罗来纳州的一家机构，EPSCOR州的一名教职员工（即未获得大量联邦资金的州）的支持，支持科学中性别不足的研究人员的支持，以及学生培训的性别不足，他们的性别培训将在NASA的NASA上受过培训的培训。影响还包括与比利时和日本科学家的国际合作以及使公众可以访问的数据。该研究应解决的问题包括查看H2O是否与岩石圈中的岩石噬菌元素不同，以及如果观察到解耦合，是否造成扩散；希望查看辉石是否通常是高H2O，低螺球库；检查在岩石圈压力和温度下矿物质中的H2O溶解度是否对未更改的岩石圈中的结构结合的H2O持有多少限制； H2O浓度是否反映在岩石圈样品的H2O系统学中；以及岩石圈中的H2O分布与熔化，深度和岩性和岩性剂的程度之间存在系统的相关性。为了解决这些问题，将使用傅立叶变换红外光谱（FTIR）来确定来自一系列位置和构造场所的特征良好，新鲜，新鲜（即未改变的橄榄岩）和pyroxenites的H2O浓度；南印度洋的Kerguelen高原；夏威夷和萨摩亚群岛以及太平洋的宽大爪哇高原；和北极海洋中的莉娜（Lena）槽。其他地球化学指标，例如矿物质和岩石中SR，HF，ND和PB的痕量元素组成以及将使用矿物质和岩石中的PB的痕量元素组成，以帮助确定是否存在过程，矿物质学和H2O含量/行为之间的联系。