【作者】 刘恩山；

【导师】 李三忠；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2010， 硕士

【摘要】 雪峰陆内构造系统在燕山期经历了强烈的改造,基本奠定了现今的构造格架。但我们对燕山期陆内构造变形的特征,古油藏的破坏和保存规律,以及陆内构造演化的动力机制的认识还尚未透彻。本文通过结合野外地质考察、地球物理资料解释,以及整理相应的测年资料,分析了雪峰陆内构造系统燕山期褶皱变形特征及断裂活动规律,并结合燕山期华南大地构造背景和花岗岩-火山岩的展布规律和成因,探讨了雪峰陆内构造系统的动力机制,最终得出以下5点新认识和新结论：(1)燕山期有两期褶皱变形,早期褶皱轴向总体为NE向,晚期褶皱轴向为S-N向或NNE向；雪峰山西侧构造样式具有强烈的断块效应,各次级构造单元的边界断裂对构造样式具有强烈的控制作用,褶皱形态受多边界条件的制约。(2)研究区在燕山早期和晚期分别受到自南东向北西和自东向西的挤压,产生了两幕断层活动。在雪峰基底隆升带东侧,断层活动在印支期活动的基础上继承性发展;在雪峰基底隆升带内,早期为一幕低角度的逆冲,晚期为高角度的逆冲;在雪峰西侧,早期为北东向断层逆冲活动,晚期为南北向断层逆冲活动。研究区发育多套滑脱层,在雪峰西侧北段,滑脱层逐级跃迁向北西拓展。(3)雪峰基底隆升带经历了加里东,印支等多期构造运动,先存断裂呈现出不对称的扇状结构。在燕山期构造运动北西南东向或东西向的挤压下,雪峰基底通过双向逆冲断层垂向挤出和双向走滑断层侧向挤出,断块单元的垂向挤出或侧向挤出的程度具有不均一性。(4)研究区尤其雪峰西侧虽然有较厚的海相地层沉积,但燕山期构造运动对雪峰陆内构造系统油气保存的破坏是致命的。通过褶皱抬升、相关断裂的切割及其以后的长期剥蚀,对古油藏造成了巨大破坏,但部分破坏较少的地区仍有较好的勘探前景。(5)雪峰陆内构造系统在燕山期构造演化的直接动力是湘赣地区的岩石圈伸展减薄和地幔上涌造成的侧向挤压,可能由古太平洋板块的俯冲启动和转向诱发,或两者共同受控于更高层次的地球内部的热-构造动力机制,既体现了大陆动力学范畴的独特动力机制,又反映了板块构造和大陆动力学的互动联系,是大陆改造、保存和发展过程中的重要表现。更多还原

【Abstract】 The Xuefeng intracontinental tectonic system forms the basic tectonics of this area after the transformation by Yanshanian movement. However, our knowledge to the nature of intracontinental tectonic deformation, destroy and preservation of paleo-reservoir, and the mechanism of intracontinental tectonic evolution is quite incomplete. With field geological observation, geophysical data interpretation and dating data collection combined, this thesis studies Yanshanian characteristics and activity of folds and faults; and combined with tectonic setting of South China in Yanshanian, and distribution rules and causes of granite-volcanic, the dynamics of the Xuefeng intracontinental tctonic system in Yanshanian is discussed. The major conclusions are presented as follows.(1) There are two-stage Yanshanian foldings. The early-stage fold axis is NE-NNE trending while the late-stage fold axis is SN-NNE. Structural pattern west of the Xuefengshan has obvious characteristics of block-faulting-controlled effect and boundary faults of the sub-tectonic units play a significant role in structural styles. Fold morphology is controlled by multi-boundary states.(2) The southeast to northwest-dierected compression in the early Yanshanian and the east to west-directed one in the late Yanshanian result in two-stage thrusting activities, respectively. In the east of the Xuefeng uplift belt, the fault movement has the characteristics of inheritance. In the Xuefeng uplift belt, the early faulting shows low angle thrust and the late faulting shows high angle thrust. In the northwest of the Xuefeng uplift belt, the major detachment faults take on jumping propagation from SE to NW.(3) Because the Xuefeng uplift belt had experienced Caledonian, Indosinian movements, the pre-existing faults show an asymmetric fan structure. Under the SE-NW-directed shortening in Yanshanian movement, the Xuefeng uplift suffers from not only the vertical extrusion, but also the lateral extrusion, and the degree of Fault-block extrusion are inhomogeneous.(4) The study area, especially the western flank of the Xuefengshan, has relatively thick formation of pelagic sediment, Yanshanian movement, however, has a great influence on the Xuefeng intracontinental tectonic system, consequently destroying the preservation condition of oil-gas. Because of uplift of folds cut of related fractures and afterwards, long period of erosion, the paleo-oil reservior was destroyed enormously. However, some area being not destroyed still have great prospect to explore.(5) The direct dynamics of the evolution of the Xuefeng intracontinental tectonic system during Yanshanian is the stretching and thinning of the Xiang-Gan area and lateral compression caused by the mantle upwelling, which may be induced by the starting and change of direction of the Paleo-Pacific Plate subduction, or both of the two mechanisms are dominated by higher level thermo-tectonic process in the inner Earth. These mechanisms imply both the unique dynamic mechanism in the concept of the Continental Dynamics and the relationship of the plate tectonic and the Continental Dynamics. It is important manifestation of the reworking, preservation and evolution of the continent.更多还原