CAREER: Partitioning of Rare Earth Elements (REE) Between Minerals and Aqueous Fluids in Ore Deposits

职业：矿床中的矿物和水流体之间的稀土元素 (REE) 分配

• 批准号: 1845258
• 负责人: Alexander Gysi
• 金额: $ 57.75万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1845258&HistoricalAwards=false
• 关键词: CAREER; Partitioning; Rare; Earth; Elements

The rare earth elements (REE) have similar but slightly different ionic radii and atomic masses, which permits studying the fundamental behavior of chemical elements and their incorporation in mineral structures in natural systems. Their magnetic properties make them important components in permanent magnets used in wind turbines, batteries of hybrid cars, and phosphors in energy efficient light. The REE composition of minerals is also used in geosciences to trace geological processes in the Earth's crust. Ore deposits commonly form at depth through the mobilization of metals in aqueous fluids and the mineralization in hydrothermal veins. The properties of both, the fluid and the minerals, will affect how the different REE are fractionated. Currently, we have much to discover about how to quantify systematically the trace element signatures of minerals with regards to fluid-rock interaction and ore-forming processes. This CAREER proposal explores how REE fractionate between aqueous fluids and minerals in ore deposits using laboratory experiments, numerical modeling and fluid inclusions trapped in natural minerals. The THERMO fluids project will be initiated with the preparation of a Fluids & Minerals summer school for undergraduate students, an open access booklet, and a dedicated hands-on thermodynamics tutorial webpage. A major aim of this project will be to provide an education platform and demonstrate the broader significance of thermodynamics in geosciences. Calcite, fluorite and apatite are common gangue minerals associated to REE and other mineral deposits. These minerals record geochemical signatures that may be used to determine temperature, fluid chemistry and potentially fluid pathways associated to ore-forming processes. This research involves a comprehensive series of hydrothermal experiments at 100 to 350 degrees C for determining the partitioning of REE between aqueous fluid-calcite, -apatite and -fluorite as a function of temperature and fluid composition (i.e., salinity, pH and ligand activity). The experimental data will be used to develop a new thermodynamic model for predicting and quantifying REE signatures in these hydrothermal minerals. To test the model, a set of mineral trace element compositions and fluid inclusions will be studied in peralkaline, carbonatite, and iron oxide-apatite hosted ore deposits in North America. The objective of the proposed research is to provide a framework for simulating the partitioning of trace metals associated to fluid-rock reactions in ore deposits and advance our capabilities of modeling and interpreting ore-forming processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

稀土元素 (REE) 具有相似但略有不同的离子半径和原子质量，这使得研究化学元素的基本行为及其在自然系统矿物结构中的结合成为可能。它们的磁性使其成为风力涡轮机中使用的永磁体、混合动力汽车电池以及节能灯中荧光粉的重要组成部分。矿物的稀土成分也用于地球科学，以追踪地壳的地质过程。矿床通常通过含水流体中金属的流动和热液脉中的矿化而在深处形成。流体和矿物质的特性将影响不同稀土元素的分馏方式。目前，关于如何系统地量化矿物在流体-岩石相互作用和成矿过程方面的微量元素特征，我们还有很多有待发现。该职业提案利用实验室实验、数值模拟和天然矿物中捕获的流体包裹体，探讨了稀土元素如何在矿床中的水性流体和矿物之间进行分馏。 THERMO 流体项目将通过为本科生准备流体与矿物暑期学校、开放获取小册子和专门的热力学实践教程网页来启动。该项目的主要目标是提供一个教育平台并展示热力学在地球科学中更广泛的意义。方解石、萤石和磷灰石是与稀土元素和其他矿床相关的常见脉石矿物。这些矿物记录了地球化学特征，可用于确定与成矿过程相关的温度、流体化学和潜在的流体路径。这项研究涉及在 100 至 350 摄氏度下进行一系列全面的水热实验，以确定 REE 在水性流体-方解石、-磷灰石和-萤石之间的分配，作为温度和流体成分（即盐度、pH 和配体活性）的函数。实验数据将用于开发新的热力学模型，用于预测和量化这些热液矿物中的稀土元素特征。为了测试该模型，将在北美的过碱性、碳酸岩和氧化铁-磷灰石矿床中研究一组矿物微量元素成分和流体包裹体。拟议研究的目的是提供一个框架来模拟与矿床中流体-岩石反应相关的痕量金属的分配，并提高我们建模和解释成矿过程的能力。该奖项反映了 NSF 的法定使命，并被视为值得通过使用基金会的智力优点和更广泛的影响审查标准进行评估来支持。