四川盆地西缘栖霞组白云岩形成过程及其与二叠纪末火山活动的成因联系

近年来，中二叠统白云岩因其良好的油气储集性成为研究关注的焦点，但对白云岩形成过程及其与二叠纪末火山活动的成因联系存在诸多争议。本项目以四川盆地西缘栖霞组白云岩为研究对象，通过岩相学、元素（主、微量包括稀土）、同位素（C-O-Sr-Mg、团簇）地球化学和流体包裹体显微测温的综合研究，分析白云化流体的性质、Mg2+来源及演化，剖析白云化流体-岩石相互作用过程，评估火山活动所携带的深部物质组分参与白云化作用的强度。同时选择典型的白云石和方解石尝试进行激光原位U-Pb同位素定年，为白云化流体提供精确的年代约束，结合区域构造演化，揭示二叠纪末火山活动对白云化过程的影响与制约，建立四川盆地西缘栖霞组白云岩成因地质模式。本项研究不仅对丰富白云岩成因研究的理论体系具有重要的科学意义，还可为盆地未来油气及相关热液型矿床的勘探提供地质理论依据。

The Middle Permian dolomite as favourable hydrocarbon reservoir in recent years has drawn much more attentions than ever before. However, the origin of dolomite and its causal link to the end-Permian volcanic activity still remain a matter of debate. This project will focus on the Chihsia dolomite of Middle Permian in the Western Sichuan Basin, and aims to determine the nature, Mg2+ sources and evolution of the dolomitizing fluids, and to elucidate the processes of fluid-rock interaction as well as to evaluate the intensity of deeply-derived components during dolomitization, based on integrated studies on petrology, element and isotopic geochemistry (C, O, Sr, Mg, △47) and fluid inclusion microthermometry. In addition, the project further intends to reveal the constraints of the end-Permian volcanic activity on the dolomitization, and finally to establish a conceptual dolomitization model in terms of U-Pb dating of dolomite/calcite and the regional tectonic evolution. This study is not only of significance for the theoretical improvement of the mechanism of dolomite, but also provide geological evidence for the exploration of hydrocarbon and related hydrothermal mineral deposits in the future.