摘要
通过对塔里木盆地西北缘下寒武统玉尔吐斯组沉积地层特征及地球化学分析,研究了玉尔吐斯组沉积时期水体氧化-还原环境及初级生产力的变化特征,探讨了玉尔吐斯组黑色岩系有机质富集机制及烃源岩分布的主要控制因素。塔里木盆地西北缘玉尔吐斯组可分为5段:底部黑色含磷硅质岩段,下部黑色泥岩段,中部灰色白云岩段,上部黑色页岩与灰色微晶灰岩互层段,顶部浅灰色粉晶白云岩段。它们构成一个完整的海侵-海退沉积旋回。氧化-还原指标及热液示踪参数显示玉尔吐斯组黑色岩系不同层段的形成环境存在差异:底部硅质岩形成于缺氧环境,热液活动显著;下部黑色泥岩形成于强缺氧硫化环境,热液活动较强;上部黑色页岩形成于贫氧-氧化环境,热液活动较弱。综合研究表明:玉尔吐斯组黑色岩系沉积时期,水体先变深后变浅,氧逸度先降低后升高,古生产力逐渐减弱,在缺氧的水体条件和热液作用主导的高生产力综合控制下形成了以玉尔吐斯组下部黑色泥岩为代表的优质烃源岩。
Based on the sedimentary and geochemical characteristics of the Lower Cambrian Yuertusi Formation in the northwestern margin of the Tarim Basin,the variation of seawater redox condition and primary productivity during sediment deposition and its control on organic enrichment in the black rock series and source rock distribution in the Yuertusi Formation were investigated.The Yuertusi Formation in the northwestern Tarim Basin can be divided into five members:black phosphorus-bearing siliceous rock at bottom;black mudstone in the lower part;gray dolomite in the middle part;interbedded black shale and gray microcrystalline limestone in the upper part;and gray crystal dolomite near top;this vertical lithofacies sequence incorporates a complete transgression-regression sedimentary cycle.The redox index and hydrothermal tracing parameters revealed the details of paleoenvironmental variation:the bottom siliceous rock is formed in an anoxic environment with strong hydrothermal activity;the lower black mudstone in an euxinic environment with slight hydrothermal activity;and the upper black shale in a sub-anoxic to anoxic environment with weak hydrothermal activity.Comprehensive studies have shown that during the deposition of the black rock series sea level first rises then falls,oxygen fugacity first decreases then increases,and paleo-productivity gradually weakens.The anoxic condition and high productivity influenced by hydrothermal activity jointly control the distribution of ancient,high-quality source rocks represented by the black mudstone in the lower part of the Yuertusi Formation.
作者
陈践发
许锦
王杰
刘鹏
陈斐然
黎茂稳
CHEN Jianfa;XU Jin;WANG Jie;LIU Peng;CHEN Feiran;LI Maowen(State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China;Key Laboratory of Petroleum Accumulation Mechanisms,SINOPEC,Wuxi 214126,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Exploration Company,SINOPEC,Chengdu 610041,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2023年第6期150-161,共12页
Earth Science Frontiers
基金
国家自然科学基金企业创新发展联合基金项目(U19B6003)
中国石化油气成藏重点实验室基金项目“塔里木盆地下古生界海相烃源岩微量元素组成特征及其在烃源岩判识中的应用(G5800-19-ZS-KFZC003)”。
