新疆塔里木盆地白垩纪—第三纪层序地层学研究

通过对塔里木盆地西南坳陷区和东北坳陷区白垩纪－第三系典型剖面的层序地层学研究，结合地震和钻井资料的分析，划分出西南坳陷区30个三级层序，东北坳陷区24个三级层序，因其所处的构造位置和沉积环境不同，两坳陷区形成的三级层序并非一一对应，不能进行大区域的直接对比。而三级层序的有序叠置构成了二级超序及其体系域，基叠置方式包括进积组合、退积组织和加积组合。通过二级超层序的研究发现，两坳陷区白垩系－第三系（中新统）可划分为4个二组超层序（SS1－SS4），并可以等时对比，所反映的相对海平面变化周期也基本相同，并且与同受特提斯海水影响的西藏南部地区白垩－早第三纪沉积层序有海平面变化基本一致，即西藏西南地区和塔里木盆地受特提斯构造和全球海平面变化的共同影响。从中新世开始，青藏高原快速隆升，塔里木盆地相对下降，造成了两地区层序类型及海平面变化速率的不同。

A Study of the Cretaceous-Tertiary Sequence Stratigraphy of Tarim Basin, Xinjiang

According to the comprehensive analyses of the depositional sequence of the Cretaceous Tertiary outcrop sections in Tarim basin, combined with the seismic sequence and drilling information, the authors hold that the Cretaceous Tertiary strata can be divi ded into 30 depositional sequences in the southwestern depression and 24 depositional sequences in the northwestern depression. This suggests that, due to their different tectonic settings and sedimentary environments, the 3rd order sequences in these two depressions cannot be correlated directly one by one. Ordered stacking of several 3rd order sequences forms 2nd order supersequence and the system tracts of the supersequences. The ordered stacking has three types, namely progradation association, retrogradation association and aggradation association. Each supersequence is formed by different types of 3rd order sequence group. On the basis of the study of 2nd order sequences, the Cretaceous Tertiary strata may be subdivided into 4 supersequences, which can be correlated synchronously in Tarim basin, and the cycles of relative sea level reflected by them are basically the same. The Cretaceous Tertiary strata in south Tibet were also influenced by seawater of the Tethys. The depositional sequences and sea level changes in Tarim basin are consistent with those in south Tibet. This proves that these two areas are both influenced by Tethyan tectonic movement and eustatic change. The rapid uplifting of the Qinghai Tibet plateau and the relative subsidence of the Tarim basin since Miocene have resulted in the difference between these two areas in sequence types and rates of sea level change.