准噶尔盆地中部永进地区走滑断裂发育特征及成因物理模拟

Development characteristics and analogue modelling of strike-slip faults in the Yongjin area,central Junggar basin

永进地区位于准噶尔盆地中部,最近发现了多个与走滑断层相关的含油气构造,但关于走滑断层的发育特征及成因机制研究程度不够深入。本文通过三维地震资料精细解释,在研究区三叠系—侏罗系内识别出近东西向、北西西向以及北东东向的三组走滑断裂体系,平面上呈“网格状”展布,剖面上具有不同深度几何学形态差异展布特征。在此基础上基于相似性原理设计四组砂箱模拟对比实验,重现研究区构造演化过程。模拟结果表明,这类走滑断裂的形成与基底先存断层的发育位置有关,是受先存构造和地层属性双重控制的广布式走滑断裂系统,从而建立了研究区的断裂系统成因模式。研究成果对具有相似地质背景地区的走滑断裂成因解释具有借鉴意义。

Yongjin area is located in the middle of Junggar basin,northwestern China,where several hydrocarbon-bearing structures associated with strike-slip faults have recently been discovered.However,the development characteristics and genetic mechanism of strike-slip faults are not thoroughly studied.Based on detailed interpretation of three dimensional seismic data,three groups of strike-slip fault systems are identified in the Triassic-Jurassic strata in the study area,which are nearly east-west,north-west-west and north-east-east trends.The distribution characteristics of the strike-slip fault system are longitudinal stratified and planar“grid”pattern structure.Based on the similarity principle,four groups of structural physical sandbox simulation and comparison experiments were designed to reproduce the tectonic evolution process in the study area.The simulation results indicated that the formation of such kind of strike-slip faults is related to the location of pre-existing faults of the basement.This kind of distributed strike-slip fault system in Yongjin area was controlled by both pre-existing structures and stratum properties,thus a genetic model of the study area has been established.The research results have guiding significance for the genesis of strike-slip fault systems in areas with similar geological settings.