湘中及周缘奥陶纪岩相古地理演化与原型盆地研究  

Paleogeographic evolution and prototype basins of Ordovician in central Hunan and its surrounding areas

作　　者：谭慧 秦明阳 李杰[2] 郭建华[2] 吴诗情[2] 边瑞康 TAN Hui;QIN Mingyang;LI Jie;GUO Jianhua;WU Shiqing;BIAN Ruikang(State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 100083,China;School of Geosciences and Info-Physics Engineering,Central South University,Changsha 410083,China)

机构地区：[1]页岩油气富集机理与有效开发国家重点实验室,北京100083 [2]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2020年第12期3430-3443,共14页Journal of Central South University:Science and Technology

基　　金：湖南省重点研发计划项目(2017GK2233)。

摘　　要：为了恢复湘中地区奥陶纪沉积演化过程,分析原型盆地类型,从沉积学的角度论证,通过野外地质调查与室内分析,在研究区奥陶系识别出4种岩石类型、3种沉积体系和6种沉积相组合,自西北向东南可将奥陶纪划分为扬子型、江南型以及华南型3种沉积类型,其中奥陶纪扬子区以碳酸盐岩台地相为主,江南区以陆棚相为主,华南区以深水盆地相为主,相带分布位置不同,但分区明显,呈连续变化,无明显间断或突变接触。研究结果表明:湘中及周缘地区奥陶纪的原型盆地类型不是一个洋盆,而是一个完整的内陆海盆;沉积体系模式呈3层阶梯式构造,湘西北地区碳酸盐台地边缘为第1层,湘中区地区斜坡—陆棚为第2层,在海平面下降期与盆地相区分开,湘南区的盆地相为第3层。其中深水陆棚和盆地相是富有机质页岩发育的有利相带,中奥陶统烟溪组以生物成因为主,是潜在的勘探有利层位。The perspective of sedimentology was employed to recover sedimentary evolution of Ordovician in central Hunan and its surrounding areas and analyze the type of prototype basin,through field geological survey and laboratory test.Four rock types,three sedimentary systems and six sedimentary facies associations were identified in the Ordovician period in the study area.From northwest to southeast,the Ordovician can be divided into three sedimentary types,i.e.Yangtze type,Jiangnan type and South China type.Yangtze area is carbonate platform facies,the Jiangnan area is shelf facies,and the South China area is deep-water basin facies.The distribution of facies belts is different,but the zoning is obvious and continuous without obvious discontinuity or abrupt contact.The results show that the archetypal basin type in central Hunan and surrounding areas is not an ocean basin,but a complete inland sea basin.The sedimentary system model is a three-layer stepped structure,the carbonate platform margin in northwestern Hunan is the 1st layer,the slope-shelf in central Hunan in central Hunan is the 2nd layer,and it is separated from the basin facies during the period of sea-level decline,while the basin facies in southern Hunan is the 3rd layer.The deep-water continental shelf and basin facies are favorable facies belts for the development of organic shale,the Yanxi formation of the Middle Ordovician is mainly biogenic and is a potential favorable bed for exploration.

关 键 词：湘中 烟溪组 原型盆地 岩相古地理 

分 类 号：P595[天文地球—地球化学]