从地震信息看阿尔金断裂带构造和塔里木盆地花彩弧断裂体系

阿尔金断裂带由多条断裂组成,主要有阿尔金断裂、且末断裂、三危山断裂。其中阿尔金断裂为主断裂,它呈左旋走滑兼具逆冲性质,中生代—古近纪为左旋走滑,新近纪由东南向西北逆冲推覆。且末断裂和三危山断裂均具左旋走滑性质。且末断裂受统一的阿尔金断裂带左旋应力场控制,但又叠加了塔里木台盆区向南挤压的应力场,从而具有双重属性。塔里木盆地的断裂总体上组成古生界塔北花彩弧断裂束和塔南花彩弧断裂束,展布成全盆地的菱形断裂系统,且末断裂构成其东南边界。在该菱形断裂系统的北弧顶和菱形内的中央轴部为背冲式的构造断裂带,显示挤压特征;在花彩弧两翼转弯处展布正花状构造样式,显示走滑特征。阿尔金断裂带及其两侧,主要在柴达木、塔里木两大盆地发现了大油气田,两者都是由断层控制油气的垂向运移与分布。柴达木盆地具有双重断—坳的特点,但油气田只分布在中—新生界构造层内;塔里木盆地,南北翘板式的构造运动是其形成复式油气区的最重要的地质构造条件。

Seismic Features of Altun Fault Belt and Festoon Fault System in Tarim Basin

The giant Altun Fault Belt comprises Altun Fault,which is the major fault,Qiemo Fault and Sanweishan Fault.Altun Fault is a left-lateral slip fault containing thrusting component.This fault was left lateral slipping during Mesozoic and Paleogene and was over-thrusting from SE to NW in Neogene and other two faults have sinistral slipping components.Qiemo Fault has double properties in which the southward expressive character comes from Tarim Basin superimposes onto the sinistral feature.The fault system of Tarim basin,which are bounded by Qiemo Fault in the southeast,include Tabei festoon fault group and Tanan festoon fault group,which generally appear as a rhombus fault system in the area between the two festoon-fault groups.Back thrusting structural zones that exist at the arcuate top in the north and the central axis within rhombus block suggests a compressive feature while positive flower type structures that exist at the turn positions in both limbs of two festoon fault groups suggest a lateral slipping feature.Giant fields have been discovered in Tarim and Qaidam basins which lie at both sides of Altun Fault.Distribution and vertical migration of hydrocarbon in the basins are controlled by these faults.Qaidam Basin is characteristic of a rift-sag texture and hydrocarbon reservoirs only occur in Cenozoic and Mesozoic formations.In Tarim basin,alternative basculating movements toward to south and north are the key conditions of geological structures for forming the complex hydrocarbon reservoirs.