银川盆地断裂体系发育特征及其对盆地的控制作用

Development characteristics of the fault system in Yinchuan Basin and its control action on the Basin

以银川盆地断裂体系为研究对象,对其几何学特征与运动学特征进行系统描述,并且进一步结合各层系地层的展布特征探讨了断层活动对银川盆地的控制作用。研究结果表明,银川盆地发育新生代与中生代两大断裂体系在平面与剖面上均存在多种组合形态;晚侏罗世时期,贺兰山东麓断层发生自东向西挤压逆冲,断层上盘遭受不均衡剥蚀,致使中—古生界现今呈现西薄东厚的特征;渐新世时期,贺兰山东麓断层反转为正断层,黄河断层开始活动,整个新生代二者活动强度大,控制了银川盆地的形成与演化,其不同区段活动性的差异导致盆地南北沉降中心发育位置的不同;银川断层与芦花台断层的活动强度相对较弱,二者控制了盆地内部中央构造带的形成。

The fault system of Yinchuan Basin was studied from geometry and kinematic characteristics.Combined with distribution of strata,the control of the fault activity on the Yinchuan Basin was further discussed.The results show that the Cenozoic and Mesozoic fault systems were developed in Yinchuan Basin.There are various combination types of the fault in vertical and horizontal direction.In the age of Late Jurassic,the faults of the eastern piedmont of Helan Mountain thrusted from east to west and the upper wall suffered from imbalanced erosion,resulting in that the Mesozoic and Palaeozoic are formed thin in the west to thick in the east.In the age of Oligocene,the faults of the eastern piedmont of Helan Mountain reversed to normal fault and the faults of the Yellow River began to develop,with strong intensity of activity during the entire Cenozoic,the faults of the eastern piedmont of Helan Mountain and the faults of the Yellow River controlled the formation and evolution of the Yinchuan Basin.The differences between their activities resulted in the different development positions of subsidence centers in the northern and southern parts of the Yinchan Basin.By contrast,the activity intensity of Yinchuan Fault and Luhuatai Fault was relatively weak,and they both together controlled formation of central structural belt of the Yinchuan Basin.