鄂尔多斯盆地西缘早中奥陶世岩相古地理研究  

Lithofacies and Palaeogeography of the Early-Middle Ordovician in the Western Ordos Basin

作　　者：吴东旭 周进高[1] 吴兴宁 丁振纯 于洲 王少依 李维岭 王淑敏 WU Dongxu;ZHOU Jingao;WU Xingning;DING Zhenchun;YU Zhou;WANG Shaoyi;LI Weiling;WANG Shumin(Petrochina Hangzhou Research Institute of Geology,Hangzhou 310023,China;CNPC,Key Laboratory of Carbonate Reservoirs,Hangzhou 310023,China;China University of Petroleum(Beijing),Beijing 100083,China)

机构地区：[1]中国石油杭州地质研究院,杭州310023 [2]中国石油天然气集团公司碳酸盐岩储层重点实验室,杭州310023 [3]中国石油大学(北京),北京100083

出　　处：《高校地质学报》2018年第5期747-760,共14页Geological Journal of China Universities

基　　金：国家科技重大专项(2016ZX05004-002);中国石油集团科技重大专项(2014E-32-02)联合资助

摘　　要：通过多口探井的分层对比、岩心和薄片观察,结合多条野外露头剖面的实测,借鉴单因素分析多因素综合作图法,对盆地西部早中奥陶世岩相古地理进行了恢复。地层厚度刻画表明,盆地西部早中奥陶世整体为三陆一洼一槽古地理格局,分别为阿拉善古陆、伊盟古陆、庆阳古陆、定北洼地以及贺兰海槽。野外剖面岩性实测以及钻井资料对比表明,随着贺兰海槽的拉张并向东与华北板块挤压,盆地西部先后经历了三道坎期和桌子山期的碳酸盐岩缓坡沉积、克里摩里期弱镶边台地沉积以及乌拉力克期斜坡和盆地沉积,且发育以桌子山组为代表的台内颗粒滩储层,以克里摩里组为代表的弱镶边台地边缘滩储层,储层普遍云化。研究区早中奥陶世发育大量深海浊流沉积,形成了巨厚的类复理石建造,但普遍不具生烃能力,只在晚奥陶统乌拉力克组、平凉组等发育一定规模的含笔石泥页岩,具备生烃能力。The lithofacies and paleogeography of the Early-Middle Ordovician in the western Ordos Basin were reconstructed based on the stratigraphic comparison and core and thin section observation of many exploration wells,combined with measurements of multiple outcrops.The methodology is the single factor analysis and multifactor comprehensive mapping.Results of characterization of stratigraphic thickness show that the Early-Middle Ordovician in the western basin has a palaeogeographic pattern of three oldlands,one depression and one trough,i.e.,the Alxa oldland,Iran oldland,Qingyang oldland,Dingbei depression and Helan sea trough.Field measurement of lithologic profiles and comparison with drilling data show that along with the extension of the Helan Trough and the extrusion to the North China plate eastward,the western basin experienced multiple tectono-sedimentary stages.These include the successively sedimentation of carbonate rocks in the Sandaokan and Zhuozishan periods,weakly striped platform deposition in the Kelimoli period,the slope and basin sediments in the Wulalike period.Accordingly,carbonate reservoirs were developed,including the platform shoal reservoirs represented by the Zhuozishan Group,the reef shoal reservoirs in the weakly striped platform margin represented by the Kelimoli Group.They are generally dolomitized.In the Early-Middle Ordovician,large amounts of deep-sea turbidites were developed in the study area,forming on extremely thick flyschoid sedimentary formation,which has few hydrocarbon generation abilities.Only the graptolite-bearing shales that formed in the Upper Ordovician Wulalike and Pingliang formations have some hydrocarbon generation abilities.

关 键 词：奥陶纪 古地理格局 缓坡 弱镶边台地 颗粒滩 浊流 

分 类 号：P618.13[天文地球—矿床学]