柴达木盆地东部中生代以来构造应力场及构造演化

柴达木盆地具有复杂的构造演化史，周围三大板块对盆地的构造改造、演化有重要的控制作用。基于野外基础地质资料，利用德令哈及周缘地区构造要素测量分析、ASR法地应力测量、构造演化史剖面分析，阐述古、今地应力状态及可能的转变，从动力学机制方面分析柴达木盆地东部构造变形的主导因素，并对中生代以来构造演化过程进行探讨。该构造演化过程分为5个阶段:①晚二叠世—三叠纪抬升剥蚀阶段，受NE—SW向挤压；②早—中侏罗世伸展断陷阶段，受SN向弱拉张形成了一些差异断陷沉降带(如德令哈凹陷等)，阿尔金断裂、柴达木盆地东部均发生左旋走滑；③晚侏罗世—白垩纪挤压反转阶段，白垩纪应力场转变为NE—SW向挤压，阿尔金断裂左旋走滑，柴达木盆地东部受挤压应力作用单纯地向祁连山产生推覆；④古近纪挤压断陷-坳陷阶段，受近SN向挤压应力作用，阿尔金断裂强烈右滑，沿NW—SE向的分量可使柴达木盆地东部发生右旋走滑运动；⑤新近纪—第四纪阶段，柴达木盆地遭受强烈挤压，近SN向挤压应力作用在喜山晚期达到最强，奠定了柴达木盆地现今构造格局。

Tectonic-stress Field and Tectonic Evolution in the Eastern Qaidam Basin Since Mesozoic

Qaidam Basin has a complex tectonic evolution history. The surrounding three plates play important roles on controlling tectonic reconstruction and evolution of the basin. Based on the field geological data, the state of ancient and modern in-situ stresses and the possible transition were explained according to the measurement analysis of tectonic elements, the in-situ stress measured by ASR method and the cross-section analysis of tectonic evolution history in Delingha area and its adjacent areas; according to the dynamic mechanics, the primary factors of tectonic deformations in the eastern Qaidam Basin were analyzed, and the tectonic evolution process since Mesozoic was discussed. The tectonic evolution process includes five stages: ①from Late Permian to Triassic, the basin is uplifted and eroded by NE-SW compression; ②there are some differential rift subsidence belts (such as Delingha depression) formed by the SN weak extension at Early-Middle Jurassic extensional rift stage, and both Altyn Tagh fault and the eastern Qaidam Basin show left lateral slip; ③at Late Jurassic-Cretaceous compression inversion stage, the stress field turns to NE-SW compression in Cretaceous, and Altyn Tagh fault shows left lateral slip, while the eastern Qaidam Basin simply thrusts onto Qilian Mountains by compression; ④at Paleogene compressive rift-depression stage, Altyn Tagh fault shows strongly left lateral slip because of SN compression, and the eastern Qaidam Basin experiences right lateral slip along the NW-SE component of SN compression; ⑤from Neogene to Quaternary, the basin experiences intensive SN compression which reaches to the maximum at Late Himalayan, and lays the modern tectonic framework of Qaidam Basin.