中二叠统茅口组热液交代硅质岩成因——来自贵州桑树湾剖面角砾状硅质岩元素及硅同位素的证据  

Genesis of hydrothermal replaced cherts in the Middle Permian Maokou Formation:evidences from elements and silicon isotopes of brecciated cherts in Sangshuwan section,Guizhou province

作　　者：许涛 韦恒叶[1,2] 张璇 耿梓傲 汪建国 Xu Tao;Wei Hengye;Zhang Xuan;Geng Zi’ao;Wang Jianguo(School of Earth Sciences,East China University of Technology,Jiangxi Nanchang 330013,China;School of Geoscience and Technology,Southwest Petroleum University,Sichuan Chengdu 610500,China;Chinese Petroleum Society,Beijing 100724,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]西南石油大学地球科学与技术学院,四川成都610500 [3]中国石油学会,北京100724

出　　处：《石油学报》2020年第4期446-456,共11页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.41762003)资助。

摘　　要：华南地区贵州省茅口组上部发育一套灰白色角砾状硅质岩,其特征与华南地区孤峰组的黑色层状硅质岩明显不同,这套特殊的角砾状硅质岩的成因尚不清楚。选择贵州省仁怀市桑树湾剖面中二叠统茅口组角砾状硅质岩作为研究对象,对其进行岩相、主量、微量和稀土元素以及硅同位素组成分析。研究结果表明,角砾状硅质岩形成于大陆边缘环境;茅口组角砾状硅质岩的形成主要与热液活动密切相关,是由热液交代碳酸盐岩形成的;热液受峨眉山地幔柱的活动的影响,从海底喷出后,对其上的碳酸盐岩沉积物破坏为角砾状,并对其自上而下进行硅化交代,从而形成热液交代成因角砾状硅质岩。A set of gray-white brecciated cherts were developed in the upper part of the Maokou Formation in Guizhou,South China,whose characteristics are significantly different from those of the black bedded cherts from the Gufeng Formation in South China.However,the genesis of this special cherts is still unknown.Taking the Permian Maokou Formation brecciated cherts from the Sangshuwan section of Renhuai City in Guizhou as the research object,this paper analyzes its lithofacies,major and minor elements,rare earth elements,and composition of silicon isotopes.The research results show that the brecciated cherts were formed in the continental marginal environment.The formation of the brecciated cherts in the Maokou Formation is closely related to hydrothermal activity,and is formed by hydrothermal replacement of carbonate rocks.Impacted by the Emeishan mantle plume activity,hydrothermal fluids from the ocean floor broke the carbonate deposits above into brecciated rocks.The carbonate deposits were silicified from top to bottom to form brecciated cherts through hydrothermal replacement.

关 键 词：角砾状硅质岩 茅口组 热液交代 峨眉山地幔柱 元素地球化学 硅同位素 

分 类 号：TE122.2[石油与天然气工程—油气勘探]