【摘要】 祁连山北缘冲断带是中国西部一条十分重要的新生代冲断带,它的研究不仅对探讨青藏高原新生代隆升过程和板内造山作用具有重要的意义,而且对酒泉盆地南缘的油气勘探也具有重要的意义。在大量野外地质调查、地震资料解释和钻井资料分析的基础上,开展祁连山北缘冲断带的特征与空间变化规律研究。祁连山北缘冲断带具有多层次的逆冲结构,包括浅层的远距离冲断系统、中层的近距离冲断系统和深层的原地冲断系统,其中原地冲断系统又可划分为原地隐伏和原地显露冲断系统。冲断带变形特征自西向东可分为三段。酒泉盆地南缘的冲断带是一水平位移量较大的、沿着至少三个滑脱面由南而北产生收缩变形的薄皮冲断系统,原地隐伏冲断系统发育很宽。榆木山南缘—民乐盆地南缘西段的冲断带中发育较宽的原地显露冲断系统,而原地隐伏冲断系统较窄。民乐盆地南缘东段—武威盆地南缘发育宽度较大的原地显露冲断系统,由三叠系、石炭系—二叠系、奥陶系、寒武系和岩体组成的冲断片相互叠置,形成冲断带宽广的"显露式"前锋,原地隐伏系统不发育。祁连山北缘冲断带的变形量由西往东逐渐减小。酒西坳陷旱峡剖面构造缩短率为55.1%;民乐盆地魏拉达坂构造剖面缩短率最大为43.4%;武威盆地天桥沟—西马河构造剖面缩短率最大为40.4%。祁连山北缘冲断带西段的变形时期大致开始于9Ma,并以"前展式"向北扩张,变形时间向北变新,前锋断层开始活动时间约为8.3Ma。更多还原

【Abstract】 The northern Qilianshan thrust belt in the southern Jiuquan basin is an important thrust belt in western China.This thrust belt plays a very important role not only in the uplift of Tibet plateau and Cenozoic intraplate deformation in western China,but also in the oil and gas exploration in the Hexi corridor basins.Based on the result of geological surveys,seismic profile interpretations and borehole data analysis,the deformation characteristics and rules of spatial change of the northern Qilianshan thrust belt are discussed in this paper.This thrust belt is a multi-layer thrust system and consists of a long distance thrust system in the upper part,a short distance thrust system in the central part and an in-situ thrust system in the lower part(blind and exposed).In the long distance thrust system,the thrust fault has long thrusting and thrust nappe develops very well,but in-situ thrust system,the thrust distance is small and the thrust block consists of Mesozoic strata.From west to east,the thrust belt can be divided into three segments.In the southern Jiuquan basin,the thrust is a thin-skin system with large structural shortening and has a wide in-situ blind thrust system.In the western part of the southern Minle basin,there exists a wide exposed thrust system,with the blind thrust system being very narrow.However,in the eastern part of the southern Minle basin and in the southern Wuwei basin,only a very wide in-situ exposed thrust system developed,which consists of Triassic,Permian-Carboniferous,Ordovician and Cambrian thrust sheets,and no in-situ blind thrust system developed.The deformation effects decreases gradually from west to east.The shortening ratio of the Hanxia cross section is about 55.1% in the western segment of the thrust belt;the maximum shortening ratio of Weiladaba cross section is about 43.4% in the central segment of the thrust belt;and the maximum shortening ratio of Tianqiaogou-Ximahe cross section is about 40.4% in the eastern segment of the thrust belt.The deformation of the northern Qilianshan thrust belt began at 9 Ma,and the fault in the front of thrust belt began at 8.3 Ma.The deformation sequence of this thrust belt is that of a forward thrust belt.更多还原