Enrichment of critical elements in granites: melting process or protolith?

花岗岩中关键元素的富集：熔化过程还是原岩？

• 批准号: 2285343
• 金额: --
• 依托单位: The Open University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2285343
• 关键词: Enrichment; critical; elements; granites; melting

The rise of electric vehicles is driving demand for critical elements (http://tinyurl.com/z77y4v7) such as Li, Nb, Ta, and Be. These elements are currently produced in relatively few countries, raising the spectre of disruption to their supply. They are commonly hosted in Sn-W bearing granites and pegmatites, but little is known about which minerals carry and concentrate these elements from the crustal protolith, via metamorphism and partial melting (anatexis), to the granitic magma. This project will track these trace elements from their original source to the host granite. A recent study1 proposes a critical role for both the composition of the starting materials and the melting conditions in determining whether granites are enriched in critical elements or not. Unmineralised Himalayan leucogranites represent a rare example of granites formed from a known, accessible single source: pelitic metasediments2. This situation offers an opportunity to investigate the partitioning of critical elements by key mineral phases (e.g. feldspar, micas, tourmaline, titanite, magnetite, rutile) through metamorphism and low temperature (<750 Degrees C) anatexis by muscovite breakdown. By contrast, studies of mineralised granites suggest that critical elements may only be released into the melt as their host minerals break down at the higher temperatures of biotite dehydration melting (>750 Degrees C)1,3.

电动汽车的兴起正在推动对锂、铌、钽和铍等关键元素 (http://tinyurl.com/z77y4v7) 的需求。这些元素目前在相对较少的国家生产，引发了供应中断的担忧。它们通常存在于含 Sn-W 的花岗岩和伟晶岩中，但人们对哪些矿物将这些元素从地壳原岩通过变质作用和部分熔融（深熔）携带和浓缩到花岗岩岩浆中知之甚少。该项目将跟踪这些微量元素从其原始来源到主体花岗岩。最近的一项研究提出，原材料的成分和熔化条件在确定花岗岩是否富含关键元素方面起着关键作用。未矿化的喜马拉雅淡色花岗岩是由已知的、可获取的单一来源形成的花岗岩的罕见例子：泥质变质沉积岩2。这种情况提供了一个机会来研究关键矿物相（例如长石、云母、电气石、钛矿、磁铁矿、金红石）通过变质作用和白云母分解的低温（<750 摄氏度）深熔作用对关键元素的分配。相比之下，对矿化花岗岩的研究表明，关键元素只有在黑云母脱水熔化的较高温度（> 750 摄氏度）下分解时，才会释放到熔体中1,3。