酒泉早白垩世盆地群构造特征和成因

Tectonic Characteristics and Origin of Jiuquan Basin Group

本文对酒泉盆地群充填物、早白垩世火山岩、早白垩世原型盆地构造样式和新生代反转构造的特征进行了分析,旨在查明酒泉原型盆地群的成因。初步认为,酒泉盆地群是早白垩世陆内热事件的表部响应,为近南北向或北东向裂谷盆地。在新生代,由于印度板块的挤压作用,北祁连山前展式北向推覆作用可能使早白垩世酒泉盆地群的南部地区转换为山脉,现今的盆地边界被掩覆在北祁连山之下;同时,印度板块的挤压作用还造成控制酒泉盆地群内部次级构造单元沉积体系的近南北向和北东向正断层转换为逆冲断层,盆地发生反转。

In order to study the origin of NNE- or NE-striking Jiuquan prototype basins, which locate between northern Qilian orogene of NWW-striking and Alxa block, this paper analysed the tectonic style of Jiuquan prototype basin group, the basin fills, early Cretaceous volcanic rock and Cenozoic reversible tectonic. The author initively think that Jiuquan basin group is rift basin of NNE- or NE-striking, and it was resulted from continental tectonic thermal event which took place in depth in early Cretaceous. During Cenozoic, the pigback thrust-napping of northern Qilian Mountains, which were caused by the squeenzing of India plate must have made southern part of Jiuquan basin group to become northern Qilian Mountains; at the same time, the squeezing action of India plate controlled the basin reversion, in the form of changing the NNE or NE-striking normal fault which controlled the sedimentation system of secondary tectonic unit in Jiuquan basin group in early Cretaceous to be thrust fault. In a word, Jiuquan basin group was longer and wider in early Cretaceous than now.