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柴北缘东段古生界构造变形特征、构造演化过程研究较为薄弱,尤其是古构造应力场性质及其转变机制尚不明确。文中对欧龙布鲁克地区野外剖面及应力感构造要素(褶皱、节理、擦痕)进行了系统观测和分析,结果表明:加里东晚期应力场为NE向;晚海西—印支期早期为SN向,晚期NW向两期挤压应力场;燕山早期近EW向拉张,燕山晚期及喜山晚期处于NE向挤压应力场。根据欧南凹陷平衡剖面反演结果,对比不同时代地层收缩速率可知,柴北缘东段寒武纪—新近纪构造演化可以分为4个阶段:(1)加里东早期(-C—O1)弧后伸展、晚期(O2—S)弧后挤压,导致柴北缘东段初步形成NW向的背斜凸起;(2)晚海西—印支期(P—T)隆升阶段,欧龙布鲁克地区整体处于水体之上,并没有造成盆内二叠系—三叠系的沉积;(3)燕山早期(J1—J2)陆内伸展断陷、晚期(J3—K)挤压反转,欧龙布鲁克地区为继承性隆起,未完全接受沉积;(4)喜山晚期(N—Q)强烈挤压构造变形,逆断层强烈活动使山体快速隆升,基底卷入型构造样式广泛分布。
The Paleozoic tectonic deformation characteristics and tectonic evolution of eastern Qaidam Basin are relatively weak, especially the paleo-tectonic stress field and its transformation mechanism are not yet clear. The results show that the stress field in the late Caledonian is NE direction, and the SN in the Late Hercynian-Indosinian period is SN To the late NW stage. The EW stretching in early Yanshan period, the late Yanshan and late Xishishan are in the NE crushing stress field. According to the inversion results of the equilibrium sections in the Ou Nan Depression and comparing the shrinkage rates of different age strata, it can be seen that the Cambrian-Neogene tectonic evolution in the eastern part of the northern Qaidam Basin can be divided into four stages: (1) the early Caledonian arc (O2-S) arc back-extrusion, resulting in the NW-shaped anticline being initially formed in the eastern segment of the northern Qaidam margin. (2) During the late Hercynian-Indosinian (P-T) (3) the Yanshanian early (J1-J2) intracontinental stretching fault, late (J3-K) extrusion reversal, (4) In the late Himalayan period (N-Q), the tectonic deformation was intensively squeezed, intense reverse thrusting led to the rapid uplift of the mountain, and the basal-infill tectonic styles were widely distributed.