Sedimentary rock-hosted ore-forming systems: structural setting and paleohydrology

沉积在陆内和被动边缘盆地的沉积岩承载着各种各样的热液矿床，这些矿床含有全球金属资源的很大一部分，特别是铅、锌、铜和金。这些矿床形成于不同的成矿系统中，这些成矿系统在不同的时期运行，因为盆地经历了裂陷、沉积、碰撞、变形、侵蚀和挖掘的顺序阶段。成矿系统在任何阶段产生矿床的潜力在很大程度上取决于盆地的整体水文地质格架，这在很大程度上受盆地几何形状、沉积层的渗透率以及横切构造的密度、几何形状和渗透率的控制。我提出的研究计划的长期目标是评估沉积盆地及其组成沉积物的物理和化学演化如何影响产生不同类型沉积岩矿床的潜力。这将通过比较被动边缘沉积物在生命周期的三个不同阶段（从沉积到发掘）的成矿系统来完成：(1)沉积喷淋（SEDEX）铅锌矿系统在广泛岩化作用之前的盆地沉积期间活跃；(2)在变形和低变质作用期间活跃的造山带金系，并伴有被动边缘沉积物向前陆褶皱和冲断带的合并；(3)卡林型金系在寄主被动边缘沉积并入褶皱冲断带后近3亿年活跃。我提出的研究计划将为了解被动边缘沉积盆地的演化如何影响将形成的沉积岩含矿矿床类型提供新的约束条件。该项目包括育空地区和西北地区的下古生代Selwyn盆地，以及内华达州中部和东部的横向等效盆地。将利用微观分析技术和地球化学成像方面的最新进展，综合广泛的地质实地观测、仔细的构造测绘、地质年代学和地球化学，对形成矿床的水文地质框架进行一级限制。热液流体对寄主岩的原始沉积学特征和后期成岩构造演化的控制程度，以及后期碰撞和盆地变形对早期矿床的改造程度。研究结果将用于提出沉积岩承载矿床的形成及其与沉积盆地生命周期的联系的概念模型，对勘探和发现对社会至关重要的金属具有影响。

Sedimentary rocks deposited in intracontinental and passive margin basins host a wide variety of hydrothermal ore-deposits that contain a significant percentage of global metal resources, especially lead, zinc, copper, and gold. These deposits form in a variety of ore-forming systems that operate at different periods of time as the basins progress through sequential stages of rifting, sedimentation, collision, deformation, erosion, and exhumation. The potential for ore-forming systems to generate deposits at any stage is strongly dependent on the overall hydrogeological framework of the basin, which is largely controlled by basin geometry, the permeability of sedimentary layers, and the density, geometry and permeability of cross-cutting structures. The long-term goal of my proposed research program is to evaluate how the physical and chemical evolution of sedimentary basins and their constituent sediments affects the potential for generating different types of sedimentary rock-hosted ore-deposits. This will be accomplished by comparing ore-forming systems operating at three different stages in the life cycle, from deposition to exhumation, of passive margin sediments: (1) sedimentary exhalative (SEDEX) Pb-Zn ore systems active during basin sedimentation prior to extensive lithification; (2) orogenic Au-systems active during deformation and low-grade metamorphism accompanying the incorporation of passive margin sediments into a foreland fold and thrust belt; and (3) Carlin-type Au-systems active nearly 300 million years after the host passive margin sediments were incorporated into a fold and thrust belt. My proposed research program will provide new constraints in understanding how the evolution of passive margin sedimentary basins influences the type of sedimentary rock-hosted ore-deposit that will form. The program encompasses field sites in the lower Paleozoic Selwyn Basin of the Yukon and Northwest Territories, and the laterally equivalent basin of central and eastern Nevada. First-order constraints on the hydrogeological framework under which the deposits formed will be provided by integrating extensive geological field observations, careful structural mapping, geochronology and geochemistry, taking advantage of recent advances in micro-analytical techniques and geochemical imaging. The extent to which the primary sedimentological character and subsequent diagenetic and structural evolution of host rocks is controlled by hydrothermal fluid flow and how early formed ore-deposits are modified by subsequent stages of collision and basin deformation will also be evaluated. The results will be used to advance conceptual models for the formation of sedimentary rock-hosted ore-deposits and their link to the life cycle of sedimentary basins, with implications for the exploration and discovery of metals vital to society.