皖西南地区泥盆纪─三叠纪层序地层

Sequence stratigraphy of the Devonian-Triassic strata in Southwest Anhui,China

通过1∶25万区域地质调查,运用层序地层学的理论和研究方法,对皖西南地区的宿松-东至一带泥盆-三叠系露头剖面进行了层序地层研究,划分了沉积层序和沉积体系域,探讨了界面性质、层序类型及层序特征,并对其相应的沉积环境、沉积相进行了分析。根据生物地层、岩石地层和年代地层等成果,将泥盆-三叠系划分为1个一级层序、5个二级层序和29个三级层序。一级和二级层序在沉积相序上总的趋势表现为由浅到深再到浅的变化,且与海平面变化曲线相吻合;三级沉积层序海平面上升和下降往往受区域构造作用、海平面变化和冰川事件等影响。

This paper studies the stratigraphic sections of the Devonian-Triassic stratigraphic outcrops and their sedimentary environments and facies in the Susong-Dongzhi zone of Anhui by using the theory and research approach of sequence stratigraphy on the basis of the 1 ： 250 000 regional geological survey. It also divides the depositional sequences and system tracts and discusses the nature of the boundary, type, and characteristics sequences. The Devonian-Triassic strata can be divided into one first-order sequence, five second-order sequences and twenty-nine third-order sequence sets. The former two show a general trend of change in facies succession from shallow to deep and back to shallow up-section, coincident with the curve of sea-level fluctuation. The sea-level fluctuation of the last one is commonly controlled by tectonism, sea-level change and glaciation.