塔里木盆地北部震旦系古生界层序地层特征

塔里木盆地北部由于古构造运动、构造应力场转换或海平面下降事件,形成了许多不同级别的不整合面。其中Ⅰ级不整合有前震旦系顶界面、下奥陶统顶界面、前石炭系顶界面、古生界顶界面。依据不整合面序列,在震旦系-古生界中可识别出3个巨层序、9个超层序组和39个三级层序。3个巨层序虽有着不同的沉积背景、体系域构成特征和展布规律,但其内部的三级层序间的叠置方式有4种基本型式:即加积、进积、退积和上超组合。根据年代地层格架,震旦系-古生界可划分为3个大的沉积旋回,旋回间的不整合面控制着沉积格局的转换。

SEQUENCE STRATIGRAPHIC FEATURES OF SINIAN-PALEOZOIC IN NORTH TARIM BASIN

Different orders of unconformities in North Tarim Basin are resulted from tectonic movement,stress field transformation and sea level changes.According to multi order unconformities in stratigraphic record,the sequences of Sinian Paleozoic in the study area could be distingushed into 3 megasequences,9 supersequence sets and 39 third order sequences.Though the sedimentary environment,typical featrues of system tracts and distribution regularities of the 3 megasequences are different,the superposition patterns of the third order suquences are basically the same,that is,aggradation,transgression,regression and onlap associations.Based on chronostratigraphic framework,the Sinian Paleozoic could be divided into 3 mega cycles of sedimention.The unconformities between the mega cycles controlled the transformation of depositional pattern.