摘要
大量野外构造地质调查和深部构造解释表明柯坪塔格推覆构造由多组倒转复式背斜、复式箱状背斜构成的推覆体及其前缘逆冲断裂组成 ,由寒武系—第四系组成的推覆体由北向南逆—斜冲 ,平面上构成向南凸出的弧形推覆构造 ;普昌断裂由各不相连的逆冲斜冲断裂段组成 ,而不是完整的一条走滑断层 ,各推覆体前缘逆冲断裂与各推覆体的普昌断裂段共同构成统一的前缘逆冲斜冲逆冲断裂和推覆构造系统 ;普昌断裂段以西的推覆体具有向东抬升、向西倾覆的鼻状构造特征 ,普昌断裂段以东的推覆体具有向西抬升、向东倾覆的鼻状构造特征 ,普昌基底隆起带是巴楚隆起隐伏在柯坪塔格推覆构造之下的部分。各推覆体前缘断裂在深部均归并于统一的寒武系底部的滑脱面 ,其南浅北深 ,东浅西深 (普昌隆起带以西 )或西浅东深 (普昌隆起带以东 ) (6 10km ) ,埋深较大区发育多组滑脱面。柯坪塔格推覆构造的形成时期为晚第四纪 ,为现今活动的推覆构造系统。文中认为各推覆体向南西的倾覆端基底滑脱面和中新生界内部的滑脱面没有贯通 ,是未来 6级以上地震的发震构造部位。
In this paper we have discussed the stratigraphy, geometry, kinematics and tectonic evolution of Kepingtage thrust system based on a lot of outcrop geological surveys and comprehensive interpretation with seismic profiles, MT profiles and gravity data. Kepingtage thrust system consists of many arcuate thrust nappes thrusting-oblique thrusting from north to south with inversed multi-anticlines and their front thrust faults, which were formed by Cambrian—Quaternary sedimentary rocks. It is discovered that the Puchang fault was formed by unconnected thrusting-oblique thrusting segments divided by nappes rather than an integrate strike-slip fault. The front thrust faults of each nappe combined with the related segments of Puchang fault form the thrusting-oblique thrusting front faults of the nappes and the whole thrust system. The nappes to the west of Puchang basement uplift show the nose structures dipping to the west, and the nappes to the east of Puchang basement uplift show the nose structures dipping to the east. Puchang basement uplift is a part of Bachu uplift extending below the Kepingtage thrust system. The front faults of the nappes form an integrate detachment surface in the deep along the bottom of Cambrian with the shallower depth in the southeast and deeper depth in the northwest (for the region to the west of Puchang basement uplift) and with the shallower depth in the west and deeper depth in the east (for the region to the east of Puchang basement uplift)(6~10 km). Kepingtage thrust system was formed in Late Quaternary and is still active at present. We consider that the basement detachment and the inner Mesozoic—Cenozoic detachment faults could not have formed some integrate fault surfaces in the dipping end of nappes, so the earthquakes with the magnitude larger than 6 will occur in the near future in these area.
出处
《地学前缘》
EI
CAS
CSCD
2003年第U08期142-152,共11页
Earth Science Frontiers
基金
国家重点基础研究发展规划 (G19990 43 3 0 5 )
国家自然科学基金面上项目 (4 9872 0 75 )
重点项目 (4 983 40 0 5 )
关键词
柯坪塔格
逆-斜冲推覆构造
现今活动
Kepingtage
thrusting-oblique thrusting system
active at present
