【摘要】 在层序地层学理论指导下,运用单因素分析综合岩相古地理作图方法,通过野外露头、岩心、测井和地震资料研究,编制了三级层序格架下的鄂尔多斯盆地寒武纪层序-体系域岩相古地理图7张。研究区寒武纪总体表现为由清水与浑水交替出现的碳酸盐缓坡(黔东世—武陵世台江期)向清水碳酸盐镶边台地(武陵世王村期—芙蓉世)演变的过程,古气候表现为由干旱向相对潮湿演变的特点。寒武纪早期(黔东世)即辛集组、朱砂洞组及馒头组下段沉积期表现为典型的南海北陆特征,因海侵作用的不断进行,寒武纪中期(武陵世台江期)即馒头组中段及上段沉积期原鄂尔多斯古陆被海水分割为3个相互分离的古陆(伊盟古陆、吕梁古陆及镇原古陆),至寒武纪武陵世王村期即张夏组沉积期海侵达到最大范围并形成了鄂尔多斯盆地"中央古隆起"的雏形和东西分异的古地理格局,寒武纪晚期(武陵世古丈期—芙蓉世)即三山子组中下部沉积期发生海退并形成了近SN向展布的"伊盟—中央古陆"。寒武纪早中期(黔东世—武陵世台江期),潮坪相是鄂尔多斯盆地的优势相带;寒武纪晚期(武陵世王村期—芙蓉世),局限台地相则是分布面积最大的相带。馒头组上段、张夏组鲕粒滩具有环绕内缓坡及开阔台地分布即主要分布于中缓坡及台地边缘的特点,三山子组多孔白云岩具有全区分布的特点。更多还原

【Abstract】 Based on the study of field outcrops,core,logging and seismic data,seven lithofacies palaeogeography maps were prepared for the Cambrian sequences and system tracts in Ordos Basin in a 3rd-order sequence stratigraphic framework using the single factor analysis and comprehensive mapping method in accord with the theory of sequence stratigraphy.Overall,the sequence lithofacies palaeogeography of the Cambrian evolved from carbonate ramps with alternative occurrence of clear water and muddy water(Qiandong Epoch to Taijiang Age of Wuling Epoch) to rimmed carbonate platforms with clear water(Wangcun Age of Wuling Epoch to Furong Epoch),and the palaeoclimate changed from an arid type to a relatively humid type.In the Early Cambrian(Qiandong Epoch),i.e.,deposition period of Xinji Formation,Zhushadong Formation and the lower Member of Mantou Formation,there were typical characteristics of south sea-north continent.In the Middle Cambrian(Taijiang Age of Wuling Epoch),i.e.,deposition period of the middle and upper Member of Mantou Formation,the original Ordos oldland was separated into 3 oldlands due to continuous transgression,including Yimeng oldland,Lüliang oldland and Zhenyuan oldland.In the Wangcun Age of Wuling Epoch(Cambrian),i.e.,deposition period of Zhangxia Formation,the transgression occurred on the largest scale,thus developing the rudiment of central paleouplift and the palaeogeographic framework of east-west differentiation in Ordos Basin.In the Late Cambrian(Guzhang Age of Wuling Epoch to Furong Epoch),i.e.,deposition period of the middle and lower Member of Sanshanzi Formation,the marine regression occurred and led to the formation of Yimeng-central oldland in a south-north direction.In the Early and Middle Cambrian(Qiandong Epoch to Taijiang Age of Wuling Epoch),tidal flat facies was dominant in Ordos Basin,whereas in the Late Cambrian(Wangcun Age of Wuling Epoch to Furong Epoch),restricted platform facies occurred in the largest area.In Zhangxia Formation and the upper Member of Mantou Formation,oolitic shoals were mainly distributed around the inner ramps and open platforms,i.e.,within the middle ramp and platform margin;whereas in Sanshanzi Formation,porous dolomites were widely distributed in the strata.更多还原