鲁西地块新生代断裂体系活动性与深部动力机制

根据野外观察分析, 综合前人研究成果, 对新生代时期鲁西地块的深、浅部构造特征、地震活动性以及动力学机制进行了分析。结果表明, 鲁西地块新生代浅表主体断裂构造格局为NW—NWW走向断裂构成的多米诺式组合, 震源机制解和野外观测揭示, 其具有左旋走滑性质, 并与NE向断裂共同控制了新生代盆地的形成和发育。地球物理资料揭示, 鲁西地块深部15~20km处存在一条缓倾滑脱带和大规模低速异常体, 浅表多米诺式断裂体系归并到该滑脱带, 表现为深浅部构造的脱耦性, 深部高低速异常体的过渡区域控制发育了鲁西地区两条NW向中强地震带。动力学成因上与太平洋板块俯冲作用导致地壳减薄、地幔上涌并在地幔楔中发生小尺度对流有关, 并造成了鲁西地块的隆起抬升。

Activity of Cenozoic fault system in the Luxi Block and deep dynamics

Based on field observation and previous researches, this paper devotes to the Cenozoic fault system in the Luxi Block, with focuses on the connection between the shallow and deep earthquakes and geodynamic mechanism.The results show that the NW and WNW-trending shallow faults are both domino-style faults with sinistral strike slipping according to focal mechanisms.The two sets of faults, together with the NE-trending faults control the formation and development of Cenozoic basins.In depth, there is a gently dipping decollement structure on a large-scale low-velocity anomaly, which is coupled with the shallow system.The deep transitional zones between the high and low anomaly zones controls the distribution of two strong NW-trending earthquake zones.The subduction of the Pacific Plate results in crustal thinning and mantle upwelling which triggered a small-scale convetion within the mantle wedge and resulted in uplifting of the Luxi Block.