西秦岭南缘玛曲断裂中段构造特征及其意义

Structural Features of the Middle Sector of the Maqu Fracture Zone on the southern margin of the West Qinling Mts and Their Significances

玛曲断裂为西秦岭南缘一条NWW-SEE走向的区域性大断裂,区域上为由北向南的逆冲断层。研究结果表明:玛曲断裂中段主要经过3期构造运动事件,早期受NNE向应力强烈挤压形成NWW—NW向褶皱,主要为印支晚期的左旋逆冲运动;中期以燕山期的右旋张性走滑为主;晚期则以喜马拉雅晚期的左旋逆冲为主。

The Maqu fracture zone is a NWW- trending regional thrust fault zone on the southern margin of the west Qinling Mts. The study indicates that the middle sector of the Maqu fracture zone resulted from such three tectonic events as early NNE - trending compressional event forming NWW - NW- trending folds and sinistral thrusts in the Late Indo - Chinese epoch, middle dextral strike - slip faulting event in the Yanshanian epoch and late sinistral thrusting in the Himalayan epoch.