Abstract: The active features of the Huo-Ma-Tu fault in the southern Junggar Basin were studied by analyzing microstructures of fault rock.According to the former research on fault rock and stream-cut terrace age,the fault opened in history for three times corresponding to three tectonic activities in the late stage of early Pleistocene,from the late stage of middle Pleistocene to the early stage of late Pleistocene and the end of late Pleistocene.The measured homogeneous temperatures of inclusions in fault rock and C and O isotope values in calcite vein demonstrate that the fault extents downward to a depth of 6500 meters at least.That means the source rocks in the Jurassic formation were connected by the fault when the fault opened.The fault is close at present and acts as a sealed condition for oil and gas accumulation.The middle accumulation system of the Huoerguosi,Manasi and Tugulu structures is the best prospective exploration targets.

Key words: Junggar Basin, Huo-Ma-Tu fault, microstructure, fault seal, hydrocarbon migration, hydrocarbon accumulation

摘要： 以准噶尔盆地南缘霍-玛-吐断层的野外观测为基础,对断层岩显微构造进行了观察.结果表明,该断层大致经历了3次构造运动.结合前人对该区断层岩以及三级河流阶地的年代学研究结果,确定了该断层3次活动的时间分别为早更新世晚期、中更新世晚期至晚更新世早期、晚更新世末期.根据断层岩中发育的包裹体的均一温度、断层带中方解石脉的碳氧同位素测定结果,确定了该断层的最小贯穿深度为6 500m,至少断至侏罗系的烃源岩.对准噶尔南缘油气成藏条件的分析结果表明,霍-玛-吐断层向下断至侏罗系烃源岩,并在侏罗系主力烃源岩大量生、排烃之后,经过3次启闭过程,对应了3次成藏过程.断层目前处于封闭状态,可对油气藏形成遮挡.对成藏过程进行的分析表明,霍尔果斯、玛纳斯、吐谷鲁构造的中部成藏系统成藏条件最为有利,是有利的勘探远景区.

关键词: 准噶尔盆地, 霍-玛-吐断层, 显微构造, 断层封闭, 油气运移, 油气成藏