A Theoretical Analysis of SEDEX-type Ore Formation McArthur Basin, Australia

9909292加文沉积盆地提供了地球上大约四分之三的贱金属资源。铅锌矿化主要有三种类型：1）SEDEX型页岩型矿床，2）MVT型石灰岩和辉铜矿型矿床，3）爱尔兰型石灰岩和辉铜矿型矿床。已知所有这三种类型的矿石都是由沉积盆地中含金属卤水的深迁移形成的，在沉积盆地中，锌和铅从较老的砂岩和断裂的结晶基底中浸出。主要故障似乎发挥了重要作用，引导运输的含金属盐水在SEDEX和爱尔兰的矿石，这是在裂谷构造环境中发现的。关于这些铅锌矿床的成因，尚未解决的问题包括流体流动的时间、速率和模式，流体混合和矿床沉积的地球化学和热方面，以及断层对矿床成因的影响。到目前为止，还没有一个小组解决了SEDEX型矿石的这些问题，因此这个主题构成了我的项目的基础。 澳大利亚北方的麦克阿瑟盆地拥有世界上最大的SEDEX型矿石之一，HYC存款。为了了解断层和断陷盆地地质对成矿的影响，我们计划开发一系列的数值实验，其中热液流体流动，传热和地球化学反应的过程中模拟HYC使用数学建模。断层渗透率、锌浓度等基本参数对于麦克阿瑟盆地等古裂谷环境的约束很差，因此基于计算机的模拟使我们能够探索参数效应，并将化学反应等复杂过程与地下水文耦合起来。我计划与澳大利亚霍巴特矿石存款研究中心的专家合作，他们在过去十年中一直在研究麦克阿瑟盆地金属矿床的地球化学和地质属性。我们希望共同更好地了解这些巨型矿床是如何形成的，这反过来将有助于为澳大利亚、美国和加拿大的裂谷盆地建立更好的勘探模型。我也希望，这项研究的一些成果将有助于美国地质调查局对阿拉斯加红狗存款的新研究，这是另一个巨大的SEDEX型矿石系统。

9909292GarvenSedimentary basins provide about three-quarters of the Earth's base-metal resources. Three major types of lead-zinc mineralization are observed: 1) shale-hosted ore deposits of the SEDEX type, 2) limestone and dolomite-hosted ore deposits of the MVT type, and 3) limestone and dolomite-hosted ores of the Irish type. All three types of ores are known to have formed by the deep migration of metal-bearing brines in sedimentary basins where zinc and lead was leached from older sandstone and fractured crystalline basement. Major faults appear to have played an important role in guiding the transport of metal-bearing brines in both SEDEX and Irish ores, which are found in rifted tectonic environments. Unresolved issues regarding the origin of these lead-zinc deposits include the timing, rates and patterns of fluid flow, the geochemical and thermal aspects of fluid mixing and ore deposition, and the effects of faults on ore genesis. Until now, no group has tackled these issues for SEDEX-type ores so this topic forms the foundation of my project. The McArthur Basin in northern Australia hosts one of the world's largest SEDEX-type ores, the HYC deposit. To understand the effects of faults and rift-basin geology on ore formation, we plan to develop a series of numerical experiments wherein processes of hydrothermal fluid flow, heat transfer, and geochemical reactions are simulated for HYC using mathematical modeling. Basic parameters such as fault permeability, zinc concentration, etc. are poorly constrained for ancient rift settings like the McArthur Basin and so computer-based simulations allow us to explore parameter effects and couple complex processes like chemical reactions with the subsurface hydrology. I plan to collaborate with experts at the Centre for Ore Deposit Research in Hobart, Australia, who have been studying the geochemical and geological attributes of metal deposits in the McArthur Basin over the past decade. Together we hope to develop a better understanding of how these giant ore deposits form, and this in turn will help build better exploration models for rift basins in Australia, the USA, and Canada. I also hope that some of this research will benefit new studies by the US Geological Survey of the Red Dog deposit, Alaska, another giant SEDEX-type ore system.