湘西北慈利大庸地区上震旦统—下寒武统沉积特征及层序地层划分

通过对各类层序界面的识别,以沉积特征、副层序和体系域与结构转换面等层序分析,进行露头层序地层学研究,将湘西北慈利大庸地区台缘斜坡相区上震旦统-下寒武统划分为11个Ⅲ级层序,其中上震旦统7个、下寒武统4个,主要是Ⅱ型层序。在区域层序地层对比、分析的基础上初步讨论了露头层序地层分析中存在的问题。

Sequence stratigraphic division of the Upper Sinian-Lower Cambrian strata in the Cili-Dayong region, northwestern Hunan

The Cili-Dayong region in northwestern Hunan lay on the passive continental margin of the southeastern Yangtze landmass during the Late Sinian to Cambrian. The bulk of the Upper Sinian strata are represented by the carbonate rocks, while the Lower Cambrian strata consist dominantly of a variety of shales and limestones. The above-mentioned strata within the platform-margin to slope facies zones are divided in this study, on the basis of sequence boundary, depositional characteristics, parasequences, systems tracts and transitional surfaces and outcrop sequence stratigraphy, into eleven third-order type 2 sequences, including seven for the Upper Sinian strata and four for the Lower Cambrian strata. Other aspects of outcrop sequence stratigraphic analysis are dealt with as well.