Geochemical and Isotopic Evolution of the Pore Waters of theCreede Formation, Colorado

该研究将验证Creede组沉积物（Colorado）是Creede矿区成矿流体主要来源的假设，并将定量评价Creede组孔隙水的地球化学和同位素演化。克里德组沉积物经历了一个复杂的历史，似乎包括有争议的盐度流体的低温蚀变和后来的热液蚀变。该项目将包括观测和计算相结合的研究，以表征Creede组的沉积物和孔隙水。作为大陆科学钻探计划的一部分，将研究先前从两个计划钻孔中收集的露头样品和岩心样品。将对化学沉积物和自生矿物（包括沸石、钾长石、粘土、碳酸盐和盐酸盐矿物）的矿物学、结构、化学和稳定同位素组成以及年龄进行表征。分析技术将包括XRD，岩石学，SEM，电子探针，稳定同位素地球化学，激光39Ar/40Ar和K/Ar年龄测定。主要研究人员将与Robert Rye（美国地质勘探局，丹佛）和Marvin Lansphere（美国地质勘探局，门洛帕克）密切合作，收集和解释稳定和放射性同位素数据。他们还将利用地球化学和同位素传质计算机程序开发克里德沉积物成岩蚀变的定量模型。他们还希望通过将广泛的矿物学和地球化学方法与最先进的地球化学和同位素建模相结合，来建立一个综合的克里德组沉积、成岩和热液历史模型，从而获得对这个系统和其他类似系统的新见解。

The proposed study will test the hypothesis that Creede Formation sediments (Colorado) were a major source of mineralizing fluids for the Creede ore district and will quantitatively evaluate the geochemical and isotopic evolution of pore waters in the Creede Formation. The Creede Formation sediments have undergone a complicated history that appears to include low temperature alteration by fluids of controversial salinity and later hydrothermal alteration. The project will involve a combined observational and computational study to characterize the sediments and porewaters of the Creede Formation. Previously collected outcrop samples and core samples from two planned drill holes undertaken as part of the Continental Scientific Drilling Program will be studied. The mineralogy, texture, chemical and stable isotopic composition, and age of chemical sediments and authigenic minerals, including zeolites, K-feldspar, clays, carbonates, and saline minerals will be characterized. Analytical techniques will include XRD, petrography, SEM, electron microprobe, stable isotope geochemistry, and laser 39Ar/40Ar and K/Ar age dating. The principal investigators will work closely with Robert Rye (USGS, Denver) and Marvin Lansphere (USGS, Menlo Park) in the collection and interpretation of stable and radiogenic isotope data. They will also develop quantitative models of the diagenetic alteration of Creede sediments using a geochemical and isotopic mass transfer computer program. They also hope to gain new insights into this and other similar systems by incorporating a broad spectrum of mineralogical and geochemical methods with state-of-the-art geochemical and isotopic modeling to develop and integrated model of the depositional, diagenetic, and hydrothermal history of the Creede Formation.