下扬子鄂东南地区寒武纪岩相古地理基本格局与沉积作用研究

Research of Lithofacies Paleogeography and Sedimentation in Cambrian of Lower Yangtze in Southeast Hubei

下扬子鄂东南地区寒武纪于通山—崇阳一带南北两侧,存在两种明显不同的沉积地层体,通过对它们沉积特征、古生态面貌和沉积作用的系统研究,可分为三个不同的沉积相区,以北的下扬子地层区为台地相碳酸盐岩沉积,以南的江南地层区为盆地相泥质岩沉积,沿此界线为斜坡带沉积,可划分二种斜坡类型,早期主要为缓斜坡型碳酸盐岩软泥滑动流动,晚期为陡斜坡型碳酸盐岩重力滑塌之角砾岩楔,这种陡坡沉积特征一直延至早奥陶世。这种台、盆、斜坡沉积格局由早至晚受海平面升降作用影响,明显具南北摆动迁移特点。

There are two different sedimentary formation bodies on both sides of Tongshan-Chongyang region in Cambrian, in southeast Hubei. Through systematic research for sedimentary characteristics, paleoecology visage and sedimentation of the two sedimentary formation bodies, the authors think there are three different sedimentary facies in southeast Hubei： the sedimentary facies in the northern of Tongshan-Chongyang where belongs to lower Yangtze is carbonate platform, in the southern belongs to Jiangnan stratigraphic zone is basin facies, the sedimentary facies along Tongshan-Chongyang re- gion is slope. And the slope belt can be divided into two types ： the belt in the early stage the sedimentary facies is flat gradient carbonate platform, and develop slip-type or flow-type sedimentary structures, and in the late stage is sharp gradi- ent carbonate platform, and develop breccia which is a kind of gravity sliding structure, and the sharp gradient carbonate platform continued to Ordovician. The pattern of carbonate platform, basin and slope is influenced by the sea level fluctuation from early to late, and the Tongshan-Chongyang region has a north-south swing characteristic.