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Oxygen, Sulfur and Carbon Isotopic Study of Pore Fluid Evolution in the Creede Formation

Creede地层孔隙流体演化的氧、硫和碳同位素研究

基本信息

批准号：
9115965
负责人：
J. Palin
金额：
$ 14.65万
依托单位：
Carnegie Institution of Washington
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1992
资助国家：
美国
起止时间：
1992-04-15 至 1994-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9115965&HistoricalAwards=false
关键词：
Oxygen Sulfur Carbon Isotopic Study

项目摘要

This project involves an integrated petrographic and stable isotopic study of samples selected from core obtained during drilling in the Creede Formation of southwestern Colorado for the purpose of documenting progressive changes in the oxygen, sulfur and carbon isotopic compositions of secondary minerals which precipitated from pore fluids during the course of diagenesis and hydrothermal activity in the Creede hydrothermal system. The textural relationships and mineral compositions of pore-filling, fracture-filling, and wall rock alteration minerals will be examined in order to establish the relative timing of secondary mineral precipitation. Laser-based in situ extraction techniques will be employed whenever possible to measure oxygen and sulfur isotopes in fine-grained minerals and test for isotopic variation within minerals. Oxygen (and to a lesser extent sulfur and carbon) isotopic partitioning between appropriate minerals will be measured and combined with experimentally and theoretically derived fractionation factors in order to constrain temperatures of precipitation. The measured isotopic compositions of oxygen, sulfur, and carbon in secondary mineral minerals will be combined with temperature constraints and mineral-fluid fractionation factors to calculate the stable isotopic compositions of the solutions from which the minerals precipitated. The sequence of stable isotopoic variation reconstructed from data for the secondary minerals will be used to assess the relative importance of closed-system processes (e.g. local fluid-rock reaction) and open-system processes (e.g. groundwater or hydrothermal fluid influx) in controlling the isotopic compositions of oxygen, sulfur, and carbon in the pore fluids.

该项目涉及一个综合的岩相和稳定的对1998年以来获得的岩心样品进行了同位素研究，在科罗拉多西南部的克里德地层钻探，目的是记录氧气、硫和次生矿物的碳同位素组成，在成岩作用过程中从孔隙流体中沉淀出来，克里德热液系统中的热液活动。的孔隙充填的结构关系和矿物组成，充填物、围岩蚀变矿物为了确定次要的相对时间，矿物沉淀激光原位萃取技术将尽可能地用于测量氧和硫细粒矿物中的同位素及其变异检验在矿物中。氧（以及较小程度的硫和碳）将测量适当矿物之间的同位素分配结合实验和理论推导，分馏因子，以限制降水测得的氧同位素组成，次生矿物中的硫和碳将结合温度限制和矿物流体分馏计算稳定同位素组成的因素沉淀出矿物质的溶液。的序列稳定的同位素变化重建的数据，次生矿物将被用来评估相对重要性封闭系统过程（如局部流体-岩石反应），开放系统过程（例如地下水或热液流入）在控制氧，硫，孔隙流体中的碳。