河北蔚县九宫口断层重叠带的断层生长、位移转移和演化  

FAULT GROWTH, DISPLACEMENT TRANSFER, AND EVOLUTION OF THE JIUGONGKOU FAULT OVERLAP ZONE IN WEIXIAN, HEBEI

作　　者：程绍平[1] 杨桂枝[1] 

机构地区：[1]国家地震局地质研究所

出　　处：《地震地质》1998年第1期1-8,共8页Seismology and Geology

基　　金：国家自然科学基金

摘　　要：对河北蔚县九宫口断层重叠带进行了地质和地貌观察、年龄测定和断层落差分析。结果表明，伴随重叠带内的断层生长，位移发生转移，而且，原来两个独立的断层段演化成为互相关联的单一断层。岩浆活动和掀斜作用是该重叠带演化的原因。When normal faults overlap each other in extentional direction the overlapping faults and the overlapping area will compose a fault overlap zone. Fault overlap zones with a separation more than several kilometers are usually considered as segment boundaries in studying earthquake rupture segmtntation. The Jiugongkou fault overlap zone in Weixian, Hebei, however, presents a typical opposite example which can not be regarded as a segment boundary. The Jiugongkou fault overlap zone is located on the southern marginal fault zone of the Guangling Weixian Basin, with 7km of an overlapping length and 2.2～5.7km of an overlapping separation. The latest Pleistocene alluvial fan developed within the overlapping area. Geological and geomorphological investigations provide evidences for the fault growth: abandonment of the latest Pleistocene alluvial fan, offset of the fan gravels, doposition of the fault scarp derived colluvial deposits, instrusion of docite magma along the fault, occurrence of the antithetic faults, and fracture clevages developed in loesses. Throw analysis indicates that no displacement deficit has happened within the overlap zone, but interaction and displacement transfer have occurred between the two overlapping faults. They manifeste as asymmetric throw profiles for both the main overlapping fautls, symmetry of a composite throw distribution for all the fault traces characterized by a single fault, and a significant increasment of the throw within the overlap zone. Moreover, dating of the faulted materials shows that the fault growth and the displacement transfer occurred in a same time period, starting between (27 400±2 200) and (26 000± 2 100)a B.P. and continuing to after (18 700±1 500)～(1 300±1 000)a B.P. For the overlap zone the mechanisms of displacement transfer may be associated with magmatic activity and tectonic tilting. The overlap zone experienced evolutionary stages offset and overlap, however, has not been breached or linked yet. The Jiugongkou fault overlap zone has evolut

关 键 词：正断层 断层位移 断层分段 断层演化 

分 类 号：P542.3[天文地球—构造地质学] P315.2[天文地球—地质学]