河南中北部北西向断裂及其地质意义

NW TRENDING FAULTS IN MIDDLE NORTH OF HENAN PROVINCE AND THEIR GEOLOGICAL SIGNIFICANCE

河南中北部晚古生代含煤建造展布区北西向断裂非常醒目。很多滑覆构造体发育在断裂旁侧;自南向北,断裂旁侧北西轴向的褶皱逐渐减少,其煤厚、薄条带与褶曲轴向平行;中、新生代发育的一些断陷盆地也以北西向断裂为界;有史记载的一些地震发生于北西向断裂和北西向与北北东-北东向断裂的交汇处;现代一些温泉及地热异常中心往往位于断裂带展布区及其旁侧。上述地质现象表明北西向断裂是长期活动的断裂。重磁方法和岩浆活动特征研究表明其断裂属切穿地壳的深断裂。断裂活动对其滑覆构造体的形成、断裂旁侧厚、薄煤带展布、地震、地热等都有一定的控制作用。研究表明,北西向断裂最初形成于印支期,其形成和发育与板块构造活动密切相关。

NW faults in area of coal-bearing formation of late paleozoic are striking in Middle North of Henan province.A number of gliding structures are found on both sides of the faults.From south to north,the number of foldings in NW axial trend reduce gradually,and coal zones,in which thick coal seams alternating with thin seams are parallel to the NW fold axial trend.And the NW faults are the boundaries of some fault basins of the Mesozoic and the Cenozoic era.According to records in the history,earthquakes often took place in the NW faults or the intersection of the NW faults and NNE-NE faults.Some hot springs and geothermal anomaly centers are usually located in fault zones or sides of the zones. The above-mentioned geological phenomena show that the NW faults were active ones for long periods.Results of investigation by using gravitational and magnetic methods,and of characteristics of magma activities show that the fractures are deep faults that cut through the earth crust.The formation of sliding structures,development of coal zones on both sides of faults,occurrence of earthquakes and geothermy are controlled to some extent by the fault activities. The NW faults were initially formed in Indo-China period,and their formation and development were closely related to plate tectonics.