米仓山与龙门山接合部叠加褶皱特征及构造演化

Superposed fold characteristics and structural evolution in the junction area of Longmenshan Mountains and Micangshan Mountains in the southwest of China

探讨米仓山和龙门山成生关系对于研究油气保存极为重要。对龙门山和米仓山接合部位叠加褶皱特征以及应力场恢复研究,表明该区域发育3组构造形迹,至少经历了4次构造作用。米仓山构造变形具有继承性,在晚三叠世第一期近S-N向挤压应力场下,形成了米仓山早期的隆起;晚白垩世-古新世的近S-N挤压应力场才使得米仓山急剧隆升;龙门山陆内复合造山带变形启动时间稍微滞后于米仓山,但其主体变形却早于米仓山大规模隆起的时间;龙门山、米仓山、大巴山构造变形均是多期次、向盆内逐级递进扩展,总体表现为交替式发展。

Micangshan Mountains and Longmenshan Mountains,as the boundary of Yangtze plate,are located in the north and west of Sichuan Basin in China.Their genetic relations are of extremely importance to the study of the hydrocarbon preservation conditions.The superimposed folds are very important pathways to study compounding and combining superposition of the structures.The junction area of Longmenshan Mountains and Micangshan Mountains is the polyphase compounding superposition of the structures and there are a great quantity of superimposed folds.By researching the superposed folds characteristics and restoring the palaeostress field,3 group structure traces and at least 4 tectonisms are found in the junction area of Longmenshan Mountains and Micangshan Mountains.The Micangshan Mountains deformation has inheritance.In the Late Triassic,the earlier Micangshan Mountains uplift formed by the first phase S-N compressive stress field.In the Late Cretaceous-Paleocene,Micangshan Mountains were rapidly uplifted by S-N compressive stress field.Longmenshan Mountains intracontinental composite orogenic belt began later than Micangshan Mountains,but its major structure deformation was earlier than Micangshan Mountains large-scale uplifted.The deformations in Longmenshan Mountains,Micangshan Mountains,and Dabashan Mountains are polyphase,and their extensions are all successively forward basin,so they alternatively process.