Scandium transport in hydrothermal systems: New insight from experimental, theoretical and field-based studies

热液系统中的钪输运：实验、理论和现场研究的新见解

• 批准号: 420479856
• 负责人: Professor Dr. Thomas Wagner
• 金额: --
• 依托单位: Arbeitsbereich Mineralogie-Petrologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/420479856?language=en
• 关键词: Scandium; transport; hydrothermal; systems; New

Quantitative data for the transport of ore metals in hydrothermal fluids are essential for understanding fluid flow and formation of economic mineral deposits in the Earthʼs crust. Experimental and theoretical first-principles studies of the solubility and complexation of metals at elevated P-T conditions are critical for developing quantitative process models for hydrothermal ore-forming systems. Experimental research has provided quantitative data for the hydrothermal behavior of common base and precious metals, but many economically important rare-metals have not been adequately studied. Scandium is a rare-metal that is becoming increasingly important for emerging green climate-neutral technologies, but the processes that drive hydrothermal mobilization, transport and enrichment of Sc in ore-forming systems are poorly understood. Scandium shares chemical similarities with Al but also with the REE and Y, which makes it a promising proxy for elemental fractionation in magmatic and hydrothermal systems. Key unresolved questions are the relative importance of chloride and fluoride as ligands for Sc complexation, the differences in solubility and speciation between Sc and the REE and Y, and the relative role of magmatic and hydrothermal processes that lead up to Sc enrichment in mineralized systems. The proposed project will address the hydrothermal transport of Sc through an integrated approach that links high-temperature solubility experiments and first-principles simulation of Sc complexation with fluid inclusion studies of the Sc concentration in magmatic-hydrothermal systems and geochemical modeling of hydrothermal Sc transport. The project is organized as four work packages, which will jointly result in fundamentally new understanding of the hydrothermal geochemistry of Sc. Work package A will study the solubility of Sc in aqueous chloride and fluoride solutions through batch solubility experiments at temperatures of 100-300 ºC. Work package B will investigate the Sc complexation in hydrothermal chloride and fluoride solutions using first-principles simulation. The experimental and first-principles results will be used to develop a consistent thermodynamic model for Sc solubility and speciation in hydrothermal fluids. Work package C will provide fluid inclusion constraints on the chemical composition of Sc transporting magmatic-hydrothermal fluids, including Sc concentrations in natural fluids. Work package D will address the impact of key system parameters (temperature, pressure, salinity, fluorine concentration, pH) on transport of Sc in magmatic-hydrothermal systems through geochemical-thermodynamic modeling, and will also look at the differences in solubility and speciation behavior between Sc, the REE and Y.

成矿物质在热液流体中迁移的定量数据对于了解地壳中流体流动和经济矿床的形成是必不可少的。高温高压条件下金属的溶解度和络合作用的实验和理论第一性原理研究对于建立热液成矿系统的定量过程模型至关重要。实验研究为普通贱金属和贵金属的水热行为提供了定量数据，但许多具有重要经济价值的稀有金属尚未得到充分研究。钪是一种稀有金属，对于新兴的绿色气候中性技术越来越重要，但人们对驱动成矿系统中热液活动、运输和富集钪的过程知之甚少。钪与铝的化学相似性，但也与稀土元素和Y，这使得它成为一个有前途的代理元素分馏在岩浆和热液系统。关键的未解决的问题是氯化物和氟化物作为配体Sc络合的相对重要性，Sc和REE和Y之间的溶解度和形态的差异，以及岩浆和热液过程的相对作用，导致Sc富集在矿化系统。拟议的项目将通过一种综合办法解决钪的热液迁移问题，这种办法将高温溶解度实验和钪络合作用的第一性原理模拟与岩浆热液系统中钪浓度的流体包裹体研究和热液钪迁移的地球化学建模联系起来。工作包A将通过在100-300 ºC温度下进行批量溶解度实验，研究钪在氯化物和氟化物水溶液中的溶解度。工作包B将使用第一性原理模拟研究水热氯化物和氟化物溶液中的Sc络合。实验和第一性原理的结果将被用来开发一个一致的热力学模型Sc的溶解度和形态在热液流体。工作包C将提供流体包裹体对运送岩浆热液流体的钪的化学成分的限制，包括天然流体中的钪浓度。工作包D将通过地球化学-热力学建模解决关键系统参数（温度、压力、盐度、氟浓度、pH值）对岩浆-热液系统中Sc迁移的影响，还将研究Sc、REE和Y之间溶解度和形态行为的差异。