【作者】 吴建勇；

【导师】 陈汉林； 肖安成；

【作者基本信息】 浙江大学 ， 构造地质， 2006， 硕士

【摘要】 通过对酒泉盆地东部金佛寺花岗岩体野外变形特征调查、地震剖面解释的研究，分析了金佛寺花岗岩体受后期区域构造作用的冲断变形特征，发现：金佛寺花岗岩体经历了多期的变形，特别是在印度板块和欧亚板块碰撞的远程效应作用下，形成于加里东晚期的规模巨大的金佛寺花岗岩岩体在新近纪以来经历了强烈的冲断变形，对东北侧的营尔坳陷的变形和沉积具有控制作用，与前人的观点“规模巨大的金佛寺花岗岩体源于深部、类似于一个直立的巨型固定楔，祁连山的冲断作用在此受到阻挡”完全不同。通过野外的地质调查和岩体冷凝后的地质历史研究，发现金佛寺花岗岩体自志留纪晚期冷凝后经历了四次挤压变形，第一次挤压变形事件发生于志留纪末至泥盆纪，第二次挤压变形事件发生于三叠纪末，第三次挤压变形事件发生于白垩纪末期到古近纪早期，第四次挤压变形事件发生于新近纪，本论文重点对岩体的新生代变形进行了研究。在新近纪，金佛寺地区发生了大规模的冲断作用，整体由南向北逆冲推覆，形成了上、中、下三层的冲断构造。作为中层变形体的金佛寺岩体受控于一中等角度的主冲断层，发育了一系列次一级的冲断层，形成了多个北陡南缓的断层传播褶皱，岩体内部十分破碎。时间偏移数据体和叠前深度偏移数据体的综合解译表明，金佛寺岩体新生代以来的平均推覆量为14.2km，反映金佛寺岩体所受的构造运动之强烈。将金佛寺冲断带的变形特征与典型冲断带的变形特征相比，认为金佛寺冲断带是较为典型的基底卷入挤压变形，并在此基础上提出了金佛寺花岗岩体的基本变形模式。祁连乡公社剖面发育的褶皱构造所卷入的地层包括花岗岩及古近纪白杨河组以上的地层，地震剖面中①号主冲断层下盘的N—Q₃地层表现出微弱的生长地层现象，表明金佛寺花岗岩岩体的第四次挤压构造变形发生于新近纪。这期的挤压变形也是金佛寺岩体冷凝后受到的规模最大的一次作用。时间偏移数据体和叠前深度偏移数据体的综合解译同时表明金佛寺岩体北东侧存在由①号主冲断层引起的新生代前陆坳陷，在坳陷内部发育有冲断层，说明金佛寺花岗岩体东北侧的酒东坳陷营尔凹陷并没有因为金佛寺花岗岩体的存在而变形减弱。综合解译还表明有较大规模的中生代断陷盆地为金佛寺花岗岩岩体所掩盖，从而大大扩大了原先在金佛寺岩体有根思维下的油气勘探面积。而①号主冲断层下盘的中新生代地层又受控于深部冲断层的控制，形成了断层传播褶皱，更使金佛寺地区具有较好的油气勘探远景。更多还原

【Abstract】 The author analyzes the thrust deformation features of the Jinfosi pluton in the eastern Jiuquan Basin which were controlled by the effect of later regional structure, based on investigating the field deformation features and interpreting the seismic profiles which passed the pluton, and finds that Jinfosi pluton had been distorted many times, especially in the long-distance effect of the collision between India plate and Eurasian plate in Neogene Period, the pluton, which formed in the late Caledonian, experienced fierce distortion and controlled the deformation and deposit of northeastern Yiner depression. This is different to predecessors’ opinions that the large-scale Jinfosi pluton, rooted from deep earth, was similar to a perpendicularly fixed sphenoid of large scale, and the thrust action of Qilianshan had been blocked here.The author finds that Jinfosi pluton had been distorted four times since it has been refrigerated from Silurian Period, based on investigating the field deformation features and studying the geological history of the pluton. The first event of the distortion was happened in the period between last stage of Silurian Period and Devonian Period. The second was happened in last stage of Triassic Period. The third was happened in the period between last stage of Cretaceous Period and the forepart of Paleogene Period. The fourth was happened in Neogene Period. And the author will detailedly discuss Cenozoic deformation of the pluton in this paper.During Neogene Period, the area of Jinfosi pluton had been unitarily thrust from south to north because of the thrust action of large scale, and formed a thrust structure with three different layers: upper layer, middle layer, and down layer. The pluton, which was the middle deformation layer, was controlled by a main thrust fault with a middle-angle, and developed a series of secondary thrust faults and many fault-propagation folds. The average distance of thrust is 14.2km, based on interpreting the time migration data and depth migration data. The author considers that Jinfosi thrust belt was a typical deformation of basement-involved compressive deformation by comparing the feature of Jinfosi thrust belt with the deformation feature of typical thrust belt, and presents basic deformation mode of the pluton.The fourth event of the distortion was happened in Neogene Period, for granite and the stratums after paleogene Baiyang river series had been entangled into the fold at the profile of Qilian community, and the stratums of N- Q₃ under the①main thrust fault had a feeble phenomena of growth stratum in seismic profiles.In the northeast of the pluton, there is a Cenozoic foreland sag with some thrust faults, controlled by①main thrust fault, which shows the deformation of Yiner depression has not been weakened, based on interpreting the time migration data and depth migration data. It also shows the pluton had covered a large-scale fault basin of Mesozoic, which greatly enlarges the area of exploring gas and oil. The structural shape of Mesozoic and Cenozoic stratums under the main thrust fault was fault-propagation fold, which promotes the prospect of oil and gas exploration in this area.更多还原