麻城-团风断裂带中段新活动特征及构造变形机制研究

STUDY OF QUATERNARY ACTIVITY AND TECTONIC DEFORMATION MECHNISM OF MACHENG-TUANFENG FAULT BELT

通过对麻城-团风断裂带中段构造地貌、水系及断裂带特征的调查,应用地震地质学方法分析了其第四纪活动特征,并结合研究区地震震源深度剖面,讨论了麻城-团风断裂带中段构造变形机制。初步分析认为,麻城-团风断裂中段最新活动时代主要在中更新世中-晚期,晚更新世有减弱趋势,活动方式以正断为主,兼有右旋走滑分量;断裂中段水系右旋扭曲位移达2～3 km;麻城地震的分支断层受主干断层控制,在深部形成共同的滑脱面;壳幔尺度差异隆升和区域NE-NEE向主压应力场为该断裂正断兼走滑运动提供了动力来源。

On the basis of geological survey of tectonic landform and drainage as well as fault feature to the middle segment of Macheng-Tuanfeng fault belt, this paper involves its quaternary activity characteristic in seismology and geology and discusses on the tectonic deformation mechanism of the fault, combining the depth of earthquake source in study area. The preliminary analysis can be drawn from this study. The fault, which is characterized by normal faulting and right-lateral offset, is predominantly active in the middle Pleistocene and is weakening in the Late Pleistocene. The drainage offset is up to 2 -3 km in the way of dextral motion. The host fault controls the branch fault and they share a sliping plane in the crust. The differential uplifting of crust and mantle depth, as well as regionally tectonic principal pressure stress field of NE-NEE orientation provide the fault motion with dynamic force source.