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。流体-固体相互作用是帮助维持这些地球化学循环的一个主要过程，并负责在近地表环境(如盆地容矿)和地壳深层(如太古宙矿脉-金矿)中进行物质(化学、元素、营养)运输。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，而且还适用于可能影响环境的人造系统。例如，评价流固相互作用对在地质储存库和尾矿场处置高放射性废物的潜在影响是全球关注的问题，许多国家正在积极调查这一问题。尽管可以在地质尺度上监测到影响到数千千米的岩石(例如沉积盆地、岩层周围的变质晕)的流体-固体相互作用的特征，但这些相互作用最终是由原子尺度上发生的过程控制的。这项工作的长期目标是确定这些过程的性质以及大规模(地壳)流体事件与区域、地方和原子一级的物质传输之间的关系，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藏和尾矿场相关的矿物的化学和同位素组成、共生作用和时间(年代学)进行详细研究来解决的。这项工作的新颖性在于，结合了各种矿物学和同位素技术，为深入了解矿藏的成因以及尾矿场向环境释放潜在有毒元素提供了见解。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-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.