Processes Influencing Critical Element Enrichment in Alkaline Magmatic Systems

地壳中关键元素的分布受到不同地质环境中许多过程的影响。稀土元素在我们日常生活的许多方面都是重要的组成部分，例如永磁体、许多电子产品和混合动力汽车的电池。铂族元素是催化剂的重要组成部分，在许多工业和电子应用中得到了广泛的应用。尽管在许多碱性岩浆系统中都有关键元素的富集区，但我们对影响其富集度和分布的火成岩过程的了解是有限的。更好地了解控制碱性系统中关键元素浓度的火成岩过程有助于指导重点进行关键元素勘探。该项目旨在评估可能影响怀俄明州Rattlesnake Hills碱性杂岩中PGE和REE的富集度和分布的火成过程。该项目的更广泛影响包括研究生培训、本科生的研究经验，以及开发3D岩石模型和相关作业，以便分发给教育工作者。该项目由岩石学和地球化学计划和已建立的促进竞争性研究计划(EPSCoR)共同资助。碱性系统在关键元素(如REE、PGES、Te、V、W、BA和F)和Au含量上表现出极大的差异。拟议的项目将评估对响尾蛇山碱性复合体(RHAC)关键元素浓缩的潜在控制。关于关键元素富集的端员假说包括：1)围岩控制，可能是地壳同化或热液清除和重新分配围岩中的关键元素；2)液体不混溶；3)碱性岩浆的初始成分。该项目将记录RHAC的火成岩历史，区分火成岩单位的时间和来源及其与矿化的关系。将收集地球化学和同位素数据，以评估来自围岩的关键元素的输入。将通过使用地球化学和熔体包裹体数据来研究液体不混溶的作用。尽管认识到100多年来碱性系统的经济浓缩，但控制这些矿床内关键元素浓缩的过程尚不清楚。了解这些控制将更好地阐明浅层侵位、地幔来源的熔体的演化、上地壳中关键矿物的循环，并为关键矿物的定向勘探提供信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The distribution of critical elements in the Earth’s crust is influenced by many processes across distinct geologic settings. The rare earth elements (REEs) are important components in many facets of our day-to-day life, for example, in permanent magnets, many electronics, and batteries in hybrid cars. Platinum group elements (PGEs) are important components in catalytic agents and are utilized in many industrial and electronic applications. Despite critical element enrichment in many alkaline magmatic systems, our understanding of the igneous processes that influence their enrichment and distribution is limited. A better understanding of the igneous processes that control critical element concentrations in alkaline systems can aid in informing focused critical element exploration. This project aims to evaluate igneous processes that may influence the enrichment and distribution of PGEs and REEs within the alkaline magmatic system at the Rattlesnake Hills Alkaline Complex, Wyoming. Broader impacts of this project include graduate student training, research experience for undergraduate students, and the development of 3D rock models and associated assignments for distribution to educators. This project is jointly funded by the Petrology and Geochemistry program and the Established Program to Stimulate Competitive Research (EPSCoR).Alkaline systems show extreme variation in critical element enrichment (e.g., REEs, PGEs, Te, V, W, Ba, and F) and Au contents. The proposed project will evaluate potential controls on critical element enrichment at the Rattlesnake Hills alkaline complex (RHAC). End-member hypotheses for critical element enrichment include: 1) country rock control, potentially as crustal assimilation or hydrothermal scavenging and redistribution of critical elements from country rock, 2) liquid immiscibility, and 3) initial composition of alkaline magmas. The project will document the igneous history of the RHAC, distinguishing timing and sources of igneous units and their relationship to mineralization. Geochemical and isotopic data will be collected to evaluate the input of critical elements from country rock. The role of liquid immiscibility will be investigated through the use of geochemical and melt inclusion data. Despite recognition of economic enrichment in alkaline systems for over 100 years, the processes that control critical element enrichment within these deposits are unclear. Understanding these controls will better elucidate the evolution of shallowly-emplaced, mantle-derived melts, the cycling of critical minerals in the upper-crust, and inform targeted exploration for critical minerals.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.