海相页岩油气成藏改造的Re-Os年代学约束研究

成藏年代学是石油地质学的重要分支学科，其研究焦点一直是常规油气藏，而页岩油气成藏改造年代学研究几乎处于空白状态。围绕这一薄弱环节，基于海相页岩黄铁矿广泛发育且与油气成藏改造密切相关的地质实际，本项目将成矿年代学领域已经成熟的黄铁矿Re-Os同位素测年技术引入海相页岩油气成藏改造年代学研究。通过对湘中-湘西北地区寒武系页岩中黄铁矿开展矿物岩石学与地球化学分析，在成因鉴别基础上，利用ICP-MS测定晚期成岩及热液黄铁矿Re-Os同位素年龄，结合流体包裹体年代学、页岩有机-无机相互作用分析以及页岩构造-热演化地质背景，揭示黄铁矿Re-Os年代学对海相页岩油气成藏改造的约束。研究结果不仅能为研究区寒武系页岩油气成藏改造过程恢复提供准确的时间限定，助力其页岩气资源勘探评价；还可为海相页岩油气成藏年代学研究提供新的技术思路，丰富和完善油气成藏年代学研究的方法体系。

Geochronology of oil and gas accumulation is an important branch of petroleum geology, and its focus has always been the conventional reservoirs, while the research on the geochronology of shale oil and gas accumulation and transformation is almost in a blank state. Focusing on the weak link, and based on the geological reality that pyrite is widely developed and closely related to oil and gas accumulation and transformation in marine shale, this project will introduce the mature Re-Os isotopic dating technology of pyrite in the field of metallogenic geochronology into the geochronological study on hydrocarbon accumulation and transformation of marine shale. On the basis of genetic identification of pyrites in the Cambrian shales in central and northwest regions of Hunan province through mineral petrology and geochemical analyses, carry out the Re-Os isotopic dating of late diagenetic and hydrothermal pyrites by ICP-MS. Then combined with fluid inclusion geochronology, organic-inorganic interaction analysis and tectonic-thermal evolution background of shales, reveal the pyrite Re-Os geochronological constraints on hydrocarbon accumulation and transformation of marine shale. The research results can not only provide an accurate time limit for the recovery of hydrocarbon accumulation and transformation, helping the exploration and evaluation of shale gas resources, but also provide a new technical idea for the study on oil and gas accumulation geochronology of marine shale, enriching and improving the method system of oil and gas accumulation geochronology.