【作者】 王涛；

【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】 华南陆块东部包括扬子地块和华夏地块,而雪峰陆内构造系统又是扬子地块的重要组成部分。本文通过对雪峰山地区深入调查,研究华南内陆地区印支期构造变形过程,对理解华南早中生代的构造演化有着重要意义。通过对雪峰山基底隆起带及其两侧的大量野外调查,分析古地理面貌和花岗岩分布,侧重从其印支期不整合面的分布和特征、印支期褶皱特征以及断裂特征等角度。以构造分析为主,结合地球物理学、岩石学、古地磁学知识和资料来力求揭示该区印支期构造演化特征以及动力学演化模式。最后,得出以下几点结论：(1)印支期角度不整合分布规律由东往西表现为：高角度不整合—微角度不整合—平行不整合—整合四个递变区域,且空间分布区域依次由东往西递变渐新。据此可知,华南地区印支期构造运动或构造变形强度从东向西由强变弱,且早期变形范围宽大,后期逐渐向东退缩。(2)陆内变形的边界效应：研究区印支期在南、北边缘有强大的南北向挤压作用的情况下,却发育有南北向弧形构造线和北东向构造线,其重要原因之一是在同一构造作用下受陆内不同边界控制的结果,与古太平洋无关,与秦岭—大别造山带也无关。(3)差异旋转导致陆内两幕变形：印支早期NEE向的构造线原始可能也为NNE向或NE向,是印支晚期顺时针旋转变位为现今NEE向的方位,而印支晚期NNE向褶皱依然是在前期同一应力方向下形成的(都属于古特提斯洋构造域),也就是说印支期以后整个华南旋转是整体旋转,不存在华夏地块和扬子地块之间的差异旋转；而印支期华夏地块和扬子地块之间存在差异旋转。(4)南、北方的构造线呈垂直格局：扬子地块内部印支期总体北东向的构造线与东西轴向的秦岭-大别造山带和扬子地块南部东西轴向的构造线相垂直,其原因是：扬子地块与华夏地块最终陆内收缩变形的时间要比扬子地块与华北陆块沿秦岭-大别造山带的陆间碰撞拼合的时间要早,印支早期的先存北北东向构造线在印支晚期由于扬子地块顺时针旋转变位为北东东向；新的第二幕构造线是在与早期第一幕变形相同的构造应力方向的作用下形成北北东向；秦岭-大别造山带近东西向的构造线是取决于近东西向的华北陆块南缘边界,其原始方位为总体近东西向。这些复杂的边界条件和旋转作用决定了先形成彼此近于垂直的构造线,然后拼接形成现今构造线垂直的格局。更多还原

【Abstract】 The eastern South China Continental Block can be subdivided into the Yangtze Block and the Cathaycian Block. The Xuefengshan Introcantinental Tectonic System is one important part of the Yangtze Block. By outdoor investigating in the Xuefengshan area, we study evolutionary process of Indosinian intracontinental structures in South China, which is very important for understanding the structural evolution of the Early Mesozoic in South China. We surveys the Xuefengshan Precambrian basement and its neighboring, analyzing paleogeography and granite distribution, focusing on Indosinain distribution and features of the angular unconformity, folds and faults. Mainly by structural analysis, with a combination of geophysics, petrology and paleomagnetism, this paper tries to reveal features of Indosinian evolution, structures and geodynamics. At last, the following conclusions are summerized:(1) The distribution of the Indosinian unconformities in the Xuefengshan Tectonic System reveals four kinds of contact interfaces, including high-angle unconformity, low-angle unconformity, disconformity and conformity and becoming younger and younger to the west. Then the intensity of tectonism becoming weaker and weaker to the west. The distortion area is wider in earlier times, and retreats to the east at latest.(2) Boundary effect of intracontintal:the Indosinian folds are subdivided into two directions of folds in terms of axial traces, northeast and meridional striking folds, which were between the north and south trending thrusts. One of the most important reason is a control of different block borders under the same stress field, not paleo-Pacific ocean, or Qinling-Dabie continent.(3) Differential rotation leading to two-stage intracontinental deformation. The first-genenration NEE-striking folds are rotated from the earlier NNE-striking folds or NE-striking due to late block rotation. While, the second-generation NNE-striking folds are also under the same stress field for the first-generation ones. There is an overall rotation of the South China, rather than a differential rotation between the Yangtze and Cathaysian blocks after Indosinian orogeny, but there is a differential rotation between the two blocks in this time.(4) The southern and northern structural lines are perpendicular to each other. The reason for perpendicular tectonic lines is that the first-genenration NEE-striking folds are rotated from the earlier NNE-striking folds due to late block rotating. The second-genenration NNE-striking folds superimpose the NEE-striking folds. The intracontinental shortening between the Yangtze and Cathaysian Blocks was earlier than the collision of the South China Block with the Qinling-Dabie Micro-continent, and the Yangtze Block and the Qinling-Dabie Micro-continent had rotated in early Indosinian orogeny, these resulted in a difference between those earlier structural lines formed in early Triassic, the perpendicular relation to these structural lines was at last remained although they underwent small rotation between the Yangtze and Cathaysian Blocks.更多还原