羌塘盆地基底构造特征

Structural Characteristics of the Basement of the Qiangtang Basin

羌塘盆地是叠置于元古宙基底之上,中、新生代发育起来的大型沉积盆地,基底为元古宙变质岩系,具双层结构,其下为结晶“硬基底”,其上为变质“软基底”。基底构造具两坳夹一隆特征。坳陷和隆起内部为若干次级凸起和凹陷复杂化,具断凸断凹特征。ENE、WNW两组共轭基底断裂发育,将基底切割成菱形块体。基底构造明显控制盖层构造。

The Qiangtang basin is a huge sedimentary basin which is superposed over the Proterozoic basement and developed from the Meso-Cenozoic. The basement of the basin consists of Proterozoic metamorphic rock series, which have the feature of a two-layer structure. The lower part of the basement is the crystallized 'hard basement' , while the upper part is the metamorphic 'soft basement'. The structure of the basement is characterized by two depressions with an uplift in-between. Within the depressions and uplift are a number of secondary fault convexes and concaves. There have developed in the basin two groups of conjugate basement faults trending ENE and WNW respectively, which cut the basement into rhombohedron blocks. The cover structures are obviously controlled by the basement structures.