上扬子区震旦系层序地层格架及其形成的古地理背景  

Sequence stratigraphic framework and its palaeogeographical background for the Sinian of Upper Yangtze Region

作　　者：梅冥相[1,2] 周鹏[1,2] 张海[1,2] 陈永红[1,2] 聂瑞贞[1,2] 

机构地区：[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《古地理学报》2006年第2期219-231,共13页Journal of Palaeogeography：Chinese Edition

基　　金：中国石油化工股份有限公司科技工程重点项目(QZ-2005-06)的研究成果之一

摘　　要：上扬子区的震旦系包括陡山沱组和灯影组,前者包含较多的黑色页岩,而后者则以发育大套白云岩为特征。从岩相序列到米级旋回,从沉积相序列到三级层序,可将浅水台地背景的震旦系划分为5个三级层序。这些三级层序可以进一步归为一个二级层序。以各个主要剖面的层序划分为基础,依据地层记录中的两种相变面和两种穿时性,可以建立研究区震旦系的层序地层格架。其中包含较多的深水黑色页岩系的陡山沱组,反映了大冰期之后海侵作用的特点;与寒武系的变化特征不同,自北西而南东沉积环境由浅变深,该背景中沉积了原生沉积组构保存较为完好的灯影组白云岩,这种变化可能反映了前寒武纪末期特殊的白云石化作用特征,同时也代表了许多有待于进一步研究的沉积学问题。从陡山沱组黑色页岩系到灯影组白云岩,不但构成了一个更大级别的总体向上变浅的沉积相序列,还反映了一个与三级和二级海平面变化过程相响应的缓坡型碳酸盐台地的生长发育过程,该过程较为清楚地显示在系列层序地层格架栅状图和岩相古地理图之中。The Sinian in the Upper Yangtze Region contains the Doushantuo Formation and the Dengying Formation, the former includes more black shales and the latter is marked by a set of dolomites. From lithofacies succession to meter-scale cycle and from sedimentary facies succession to third-order sequence, the Sinian in the shallow-water setting can be divided into five third-order sequences that can be grouped into one second-order sequence. According to two types of facies-changing surfaces and two types of diachronisms in the stratigraphic records, sequence stratigraphic divisions at each main logging section become the basis to establish the sequence stratigraphic framework of the Sinian in the study area. This sequence stratigraphic framework indicates several features.The Doushantuo Formation with more deep-water black shales represents a transgression process after the great glaciation period. Different from the changing feature in the Cambrian, the dolomites of the Dengying Formation with well-preserved primary sedimentary fabrics are also characterized by a set of dolomites in the deeper depositional background. This changing feature may reflect a particular dolomitization in the Sinian and a problem that need to be researched in the future. The stratigraphic succession from the Doushantuo Formation to the Dengying Formation, both makes up of a largerscale upward-shoaling succession of sedimentary facies and demonstrates a growth process of the ramp carbonate-platform which responds to the third and the second-order sea-level changes. This process is clearly illustrated in a series of the panel sequence stratigraphic framework diagrams and the corresponding palaeogeographical maps.

关 键 词：上扬子区 震旦系 层序地层格架 岩相古地理 

分 类 号：P539.2[天文地球—古生物学与地层学]