【摘要】 在南大巴山西北段镇巴—下高川地区进行1∶50 000地质填图基础上,通过对地质构造现象野外的详细观测,运用持平投影的构造几何学和运动学等方法对主要断层面擦痕和断层两侧不对称褶皱枢纽以及褶皱两翼产状进行统计分析和构造解析,结合区域沉积资料和地质年代学资料,对该区构造进行构造序列分析,并探讨南大巴山构造带的变形时限、动力学机制及其演化。研究表明:南大巴山西北段镇巴—下高川地区断裂构造特征表现为高角度逆冲推覆兼有右行走滑性质的叠瓦式逆冲推覆构造;与逆冲推覆构造相关褶皱多为轴面东倾西倒的同斜褶皱和斜歪褶皱,而且由东向西褶皱紧闭程度逐渐减弱,表明逆冲推覆方向由东向西,扩展方式为前展式。该区是在印支期扬子地块与秦岭造山带全面碰撞造山作用基础上,在燕山期中—晚期整个大巴山构造系由北东向南西方向大规模的陆内造山,形成了现今的构造几何形态,其中右行走滑构造是燕山期中—晚期(J3-K2)逆冲推覆构造持续向西南推移过程中形成的。更多还原

【Abstract】 On the basis of geological mapping with the scale 1∶50 000 of Zhenba-Xiagaochuan Area in the northwest section of Southern Dabashan,the field occurrences of the hinge lines and two limbs of the asymmetry folds were analyzed in tectonic statistics by the means of detailed wild-field observations and measurement and stereographic method.With regional sedimentary and geological age data,the mechanism of tectonics and dynamics and the evolution of Southern Dabashan were discussed with structural sequences analyzing of its structural geometry and kinematics.The results showed that the northwest section of Southern Dabashan in Zhenba-Xiagaochuan Area was characterized by high-angle thrust with imbricate thrust fan-type nappe of right-type strike-slide in structure;the folds related to thrust fan-type nappe were predominated by the syn-incline and inclined ones with its axis planes incline to the east and the angles between limbs of which became larger and large from east to west,representing their thrust direction and indicating forward developing.Thus,it is believed that the thrust in the area,which inherited from previous complete collision between Yangtze Plate and Qinling orogenic belt in Indosinian,was ultimately forged through large-scale thrust of intra-continental collisions of the whole Dabashan tectonic belt from northeast to southwest during middle-late period of Yanshanian,in which the present structural model of Zhenba-Xiagaochuan Area was brought out,and the right-type strike-slide structure grew in the continuous process of movement of the thrust towards southwest during middle-late period of Yanshanian(J3-K2).更多还原