Radionuclide and mass transport in surface and in near-surface environments

全球地球化学循环使地球处于或多或少的稳定状态。流固相互作用是帮助维持这些地球化学循环的一个主要过程，也是近地表环境（如盆地铀矿床）以及较深地壳（如太古宙矿脉金矿床）中物质（化学、元素、营养物质）运输的原因。流固相互作用的重要性和潜在影响不仅限于自然地球化学循环，如矿床的形成，而且还适用于可以影响环境的人为系统。例如，评价流固相互作用对在地质储存库和尾矿场址处置高放射性废物的潜在影响是全球关注的问题，许多国家正在积极进行调查。虽然流体-固体相互作用的特征可以在地质尺度上监测到影响到1000立方千米岩石的特征（例如，沉积盆地、岩基周围的变质晕），但这些相互作用最终是由发生在原子尺度上的过程控制的。这项工作的长期目标是确定这些过程的性质以及大尺度（地壳）流体事件与区域、地方和原子一级的质量运输之间的关系，这对环境科学和矿物勘探都有影响。这个问题是通过使用各种技术对与矿床和尾矿地点有关的矿物的化学和同位素组成、共生作用和时间（地质年代学）的详细研究来解决的。这项工作的新颖之处在于，不同的矿物学和同位素技术相结合，提供了对矿床成因和从尾矿场地释放到环境中的潜在有毒元素的见解。这一提议包括以研究生和本科生的形式广泛培训高素质人才，并与来自其他大学和政府机构的访问科学家合作。特别地，提出的合作工作将给学生一个不同寻常的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-solid interaction is a major process which helps maintain these geochemical cycles and is responsible for mass (chemical, elemental, nutrient) transport in near-surface environments (e.g., basin-hosted uranium deposits) as well as the deeper crust (e.g., Archean lode-gold deposits). The importance and potential impact of fluid-solid interaction is not only limited to natural geochemical cycles such as the formation of ore deposits, but also applies to man-made systems that can impact the environment. For example, evaluating the potential impact of fluid-solid interaction on the disposal of high-level radioactive waste in geological repositories and at tailing sites is of global concern and is being actively investigated in many countries. Although the signatures of fluid-solid interactions can be monitored at geologic scales up to those affecting 1000s of km3 of rock (e.g., sedimentary basins, metamorphic haloes around batholiths), these interactions are ultimately governed by processes occurring at the atomic scale. The long term objective of the work is to determine the nature of these processes and the relationship between large-scale (crustal) fluid events and mass transport at the regional, local and atomic level, with implications for both environmental science and mineral exploration. This problem is addressed by detailed studies of the chemical and isotopic composition, paragenesis, and timing (geochronology) of the minerals associated with both mineral deposits and tailing sites using a variety of techniques. The novelty of the work is that diverse mineralogical, and isotopic techniques are combined to provide insights into the genesis of mineral deposits and the release of potentially toxic elements from tailing sites into the environment. 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.