摘要
通过野外露头地质剖面实测、岩心描述、薄片鉴定、氩离子抛光-场发射扫描电镜、能谱分析、X衍射、总有机碳含量及主量、微量元素测试等手段,对四川盆地东部地区中二叠统茅口组一段(简称茅一段)含海泡石层系内的有机质赋存类型及主控因素进行研究,建立海泡石共生吸附有机质富集模式。研究结果表明:(1)茅一段含海泡石层系为泥岩-泥质灰岩-灰岩韵律层,纵向上发育5个结构段,有机质多富集于下部的3个结构段的泥岩和泥质灰岩内。宏观-中观尺度上有机质主要以层状或瘤状产出,镜下微观特征以块状-脉状为主,介观尺度下呈分散状、填隙状和吸附状。(2)茅一段含海泡石层系经历低盐度向高盐度、贫氧-缺氧还原向贫氧-局部富氧的古环境演化过程。(3)茅一段沉积初期的第1和第2结构段为泥岩-泥质灰岩-灰岩韵律层,在通江—长寿凹陷内沉积大量的纤维状-羽状海泡石,海泡石吸附藻类体于其晶间、层面及层间孔隙,形成连片状有机质;沉积中期的第3和第4结构段主要为泥岩-泥质灰岩韵律层,藻类体见于纤维状-羽状-片状海泡石的晶体表面及晶间孔隙内,有机质呈连片状或环带状富集;沉积晚期的第5结构段由厚层状灰岩-极薄层状泥质灰岩韵律层构成,纤维状海泡石沉积于泥质灰岩层内,有机质呈不规则状零星分布于海泡石周缘。有机质与海泡石呈现出共生吸附的特征,有效提升了有机质的保存效率与茅一段的烃源岩品质,丰富了对沉积有机质富集模式的认识。
The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in Eastern Sichuan Basin have been investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing-field scanning electron microscope,energy spectrum analysis,X-ray diffraction,total organic carbon content(TOC),major and trace elements analysis.And finally the symbiotic adsorption model of sepiolite for organic matter enrichment has been established.The results show that the sepiolite-containing successions of Mao-1 Member are composed of the cyclothems of mudstone,argillaceous limestone and limestone,with five depositional intervals vertically and the organic matter mostly developed in the mudstone and argillaceous limestone layers within the lower three intervals.The organic matter occurrence types are mostly layered or nodular in macro to meso-scale,blocky-vein-like under a microscope,but scattered,intersertal or adsorbed at a mesoscopic scale.It underwent transition processes from lower to higher salinity,from oxygen-poor and anoxic reduction to oxygen-poor and localized oxygen enrichment on the palaeo-environment of the Mao-1 Member.The first two intervals of the early depositional phase of Mao-1 Member constitute the cyclothems of mudstone,argillaceous limestone and limestone and quantities of fibrous-feathered sepiolite settle down within the Tongjiang-Changshou sag with continuous patchy organic matter from adsorption of alginate by sepiolite in intercrystalline,bedding surfaces and interlayer pores.The third and fourth intervals in the mid-depositional phase are mostly composed of the mudstone and argillaceous limestone alternations with the continuous patchy or banded organic matter in the surface and inter-crystalline pores of fibrous,feathered and flaky sepiolite.And the fifth interval in the late depositional phase of the Mao-1 Member comprises the cyclothems of extremely thin layered argillaceous limestone and thick-layered limestone with the fibrous sepiolite depositing in the argillaceous limestone and irregular organic matter dispersing around the sepiolite.Therefore,the symbiotic adsorption between organic matter and sepiolite effectively enhances the preservation efficiency of organic matter and improves the source rock quality of the Mao-1 Member,which enhances our understanding on the enrichment model of the depositional organic matter.
作者
宋金民
王俊轲
刘树根
文龙
叶玥豪
罗冰
李智武
张本健
金鑫
杨迪
张玺华
王佳蕊
周刚
郭嘉欣
张钊益
罗平
SONG Jinmin;WANG Junke;LIU Shugen;WEN Long;YE Yuehao;LUO Bing;LI Zhiwu;ZHANG Benjian;JIN Xin;YANG Di;ZHANG Xihua;WANG Jiarui;ZHOU Gang;GUO Jiaxin;ZHANG Zhaoyi;LUO Ping(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;Xihua University,Chengdu 610039,China;PetroChina Southwest Oil&Gasfield Company,Chengdu 610051,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)
出处
《石油勘探与开发》
北大核心
2025年第5期1054-1067,共14页
Petroleum Exploration and Development
基金
国家自然科学基金面上项目(42572132,41872150)
国家自然科学基金重点项目(42230310)
国家自然科学基金联合基金(U24B6001,U2344209)。
关键词
四川盆地
川东地区
中二叠统茅一段
含海泡石层系
有机质赋存类型
共生吸附富集模式
Sichuan Basin
Eastern Sichuan Basin
Mid-Permian Mao-1 Member
sepiolite-containing succession
organic matter occurrence types
symbiotic adsorption enrichment model
