西藏措勤盆地构造特征与地壳缩短

措勤盆地为青藏高原仅次于羌塘盆地的第二大海相盆地,笔者通过对盆地基底和盖层变形特征分析,将措勤盆地基底划分为北部拗陷、北部隆起、中部拗陷和南部隆起4个一级构造单元;盖层划分为北部拗褶带、北部冲断带、中部拗褶带、南部冲断带和南部拗褶带5个一级构造单元,并利用平衡剖面计算得到措勤盆地晚白垩世缩短约24%。

Tectonic division and crustal shortening in the Coqen Basin,Xizang

The Coqen Basin, Xizang is the second large-scale marine basin only smaller than the Qiangtang Basin on the Qinghai-Xizang Plateau. Tectonically, the basement of the Coqen Basin may be divided into four first-order tectonic units, i.e. , northern depression, northern uplift, central depression and southern uplift, while the cover may be separated into five first-order tectonic units, i. e. , northern downwarped zone, northern thrust fault zone, central downwarped zone, southern thrust fault zone and southern downwarped zone. The shortening rates during the Late Cretaceous are estimated at about 24% on the basis of the balanced cross-section calculations.