SusChEM: Exploring Links Among U, Fe, and Hydrocarbon Movement in the Paradox Basin, Colorado Plateau

Paradox盆地和科罗拉多高原的其他沉积盆地拥有许多重要的矿物和碳氢化合物资源，包括铁、铜、钴、锰、银和石油和天然气，并以拥有世界上最大的铀生产省份之一而闻名。Paradox盆地新的勘查地质研究揭示了铀矿化、碳氢化合物运移以及铁和其他元素的流动性之间出人意料的空间和地层联系。这些联系表明，需要一种新的铀沉积模式：在这种模式中，石油，可能还有天然气，导致铀的局部捕获，可能是在混合区，而不是目前流行的模式，即铀被寄主岩石原生的有机物质捕获。这一新的假设并不排除其他选择，但它预测，较大的矿床可能具有更高的品位，具有明显的和更局部化的分布。铁和其他元素同时重新分布的证据表明，相同的流体移动了许多元素；这种元素重新分布为流体地球化学和运动提供了线索。该项目将促进对Paradox和其他沉积盆地中金属运动和物质运移的基本地球化学理解，并可能为在拥有世界级矿产资源的地区发现矿产提供新的途径。在Paradox盆地长达100多公里的里斯本谷盐墙沿线选择了5个重点地点进行野外测绘、岩心测井、岩石学、流体包裹体以及元素和同位素分析。焦点地点代表了不同的地层和构造环境，范围从盆地中央深处到边缘，但都显示出铀矿化、铁的流动性和漂白或其他碳氢化合物的证据。蚀变矿物填图、岩相学和全岩分析将被用来记录铁、碱和贱金属在从单个矿床到次区域的尺度上的分布和共生。研究人员将把这些观察结果与铀及其相关(钒、铜)矿化的分布、演化和时间序列以及油气藏和运移路径的位置相关联。结合蚀变矿物的流体包裹体和同位素分析以及用于评价流体特征和来源的地球化学模拟，这些数据将使系统地测试含金属盆地卤水、烃类与局部构造和岩石类型之间的相互作用-例如，U、Fe和烃的移动和沉积是代表单个短期系统的不同方面，代表单个系统在很长一段时间内的演化，还是由多个无关的叠加事件产生。这是朝着研究Paradox盆地质量传输现象之间联系的综合方法迈出的第一步，这种方法可应用于科罗拉多高原和世界各地，以了解重要资源省的地质和地球化学演化，并探索和管理其中的资源开发。

The Paradox basin and other sedimentary basins of the Colorado Plateau host many significant mineral and hydrocarbon resources, including iron, copper, cobalt, manganese, silver, and oil and gas, and are best known for hosting one of the world's great uranium-producing provinces. New reconnaissance geological studies in the Paradox basin revealed unexpected spatial and stratigraphic connections between uranium mineralization, hydrocarbon migration, and mobility of iron and other elements. These connections suggest that a new model for uranium deposition is required: one where oil, and possibly natural gas, leads to localized trapping of uranium perhaps in mixing zones, in contrast to the prevailing model where uranium is trapped by organic matter that is indigenous to the host rock. This new hypothesis does not preclude the alternatives, but it predicts that the larger deposits may have higher grades and have a distinct and more localized distribution. Evidence for concurrent redistribution of iron and other elements suggests that the same fluids move many elements; such element redistribution gives clues to fluid geochemistry and movement. This project will advance the fundamental geochemical understanding of metal movement and mass transport in the Paradox and other sedimentary basins and it may provide novel approaches to mineral discovery in a region with world-class mineral resources. Five focus sites along the 100+ km-long Lisbon Valley salt wall in the Paradox Basin have been selected for field mapping, core logging, petrographic, fluid inclusion, and elemental and isotopic analyses. The focus sites represent diverse stratigraphic and structural settings and range from the deep central part of the basin to the fringes, but all show uranium mineralization, iron mobility, and bleaching or other evidence of hydrocarbons. The mapping of alteration minerals, petrography, and whole-rock analyses will be used to document the distribution and paragenesis of iron, alkali, and base metal enrichment and depletion at scales from the single deposit to the sub-region. The investigators will correlate these observations with the distribution, evolution, and temporal sequence of uranium and related (vanadium, copper) mineralization and the loci of hydrocarbon reservoirs and migration paths. Coupled with fluid inclusion and isotopic analyses of alteration minerals and geochemical modeling to evaluate fluid characteristics and sources, these data will enable a systematic test of the interplay between metal-bearing basinal brines, hydrocarbons, and local structures and rock types - e.g. whether the movement and deposition of U, Fe, and hydrocarbons represent different facets of a single short-lived system, represent the evolution of a single system over a long time, or were produced by multiple unrelated superimposed events. This is a first step toward an integrated approach to studying linkages among mass transport phenomena in the Paradox Basin, which can be applied on the Colorado Plateau and worldwide both to understanding the geological and geochemical evolution of important resource provinces and to exploring and managing resource development therein.