Ore Systems, Tectonics and the Geochemical Cycles of Metals

全球地球化学循环使地球处于或多或少的稳定状态。流体-岩石相互作用是维持这些地球化学循环的主要过程，也是近地表环境(如铀矿床)和地壳较深层(如造山带金矿床)中物质(如元素)迁移的主要原因。虽然我们对某些地球化学循环，如碳循环和硫循环有相当多的了解，但我们对金属的地球化学循环及其与构造和矿石系统的关系的理解存在差距。找出全球金属地球化学平衡中的这些差距或不一致之处，可能会指出我们对潜在资源的知识也存在类似的差距。我的研究旨在通过了解金属的提取、运输和浓缩过程，以及大规模(地壳)流体事件与区域、地方和原子层面的质量运输之间的关系来解决这些差距。通过这样做，我计划为科学做出根本性的贡献，这些科学将在环境科学和矿产勘探中得到应用。*大多数经济价值元素(例如，金、铀)以百万分之几(Ppm)或更低的浓度存在于地壳中。为了使这些金属在经济上是可提取的，它们必须在地壳中以足够的浓度积累。因此，几个过程必须在适当的时间发生。同位素可以提供有关这些过程的信息，这些过程在自然系统中分布和浓缩金属。传统的光稳定同位素(H、C、O、N和S)和铅的分馏作为流固相互作用、地温、质量传输和污染物的示踪剂已经得到了很好的应用，而放射性同位素(如U-Pb)是有用的流体事件计时器。然而，B和Li等非传统轻同位素以及过渡金属(如Fe)和其他重金属同位素(如U)的使用还处于初级阶段。因此，在这一资助期间，我和我的学生计划将传统和非传统的同位素系统结合起来，以解决与铀矿系统相关的一些关键问题。我们计划将实地观察和对自然样本的分析结合起来，以验证我们的观察和解释。这项工作的新奇之处在于，多种矿物学和同位素技术相结合，为矿藏的成因提供了见解。这项建议涉及以研究生和本科生的形式广泛培训高素质人员，并与来自其他大学和政府机构的来访科学家合作。特别是，提出的合作工作将为学生提供异常广泛和多样化的科学背景，为他们发展未来的研究做好准备。

Global geochemical cycles maintain the Earth in a more-or-less steady state. Fluid-rock interaction is a major process which helps maintain these geochemical cycles and is responsible for mass (e.g., elemental) transport in near-surface environments (e.g., U deposits) as well as the deeper crust (e.g., Orogenic Au deposits). Although we know a considerable amount about certain geochemical cycles such as the carbon and sulfur cycles, there are gaps in our understanding of geochemical cycles of metals and their relation to tectonics and ore systems. Identifying these gaps or inconsistencies in the global metal geochemical balance may point to similar gaps in our knowledge of potential resources. My research aims to address these gaps by understanding the processes that extract, transport and concentrate metals, and the relationship between large-scale (crustal) fluid events and mass transport at the regional, local and atomic levels. In so doing, I plan to make fundamental contributions to science that will find application in the environmental sciences and mineral exploration. ******Most elements of economic value (e.g., Au, U) occur in the Earth's crust in concentrations of a few parts per million (ppm) or lower. For these metals to be economically extractible they must accumulate in the Earth's crust in sufficient concentrations. Therefore, several processes must occur at the appropriate time. Isotopes can provide information on these processes that distribute and concentrate metals in natural systems. The utility of using the fractionation of traditional light stable isotopes (H, C, O, N, and S) and Pb as tracers of fluid-solid interactions, geothermometers, mass transport and contaminants is well established, and radiogenic isotopes (e.g., U-Pb) are useful chronometers of fluid events. However, the use of non-traditional light isotopes such as B and Li, and transition- (e.g., Fe) and other heavy-metal isotopes (e.g., U), is in its infancy. Therefore, during this funding period my students and I plan to combine traditional and non-traditional isotope systems to address some key questions related to uranium ore systems. We plan to combine field observations and analysis of natural samples to verify our observations and interpretations. The novelty of the work is that diverse mineralogical and isotopic techniques are combined to provide insights into the genesis of mineral deposits. This proposal involves extensive training of Highly Qualified Personnel in the form of graduate and undergraduate students, and collaborative work with visiting scientists from other Universities and government institutions. In particular, the collaborative work proposed will give students an unusually wide and diverse background in science, preparing them to develop the research of the future.