龙门山中段山前带浅层冲断系统的结构、形成与演化  

The structures,formation and evolution of the shallow thrusting system in the central Longmen Mountains front belt

作　　者：鲁人齐[1] 何登发[1] John Suppe 马晓鸣[1] 桂宝玲[1] 王明健[1] 高金尉[1] 

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]国立台湾大学地球科学系

出　　处：《地质科学》2010年第4期997-1010,共14页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家重点基础研究发展计划项目(编号:2006CB202300);国家自然科学基金重点项目(编号:40739906)资助

摘　　要：本文依据断层相关褶皱几何学原理,对龙门山中段地震剖面进行了精细解释。研究发现,龙门山中段山前带浅层冲断系统存在多套滑脱层,具有上下分层变形特征。浅层滑脱层为上三叠统须家河组三段(T_3~x3)的碳质页岩夹煤层,其上发育双重构造和叠瓦构造;下三叠统嘉陵江组四、五段(T_1j^(4-5))的膏岩层,发育断层传播褶皱、冲起构造和构造楔;深层为下寒武统的泥页岩层,发育断层转折褶皱和滑脱褶皱。该区滑脱断层所控制的地层变形和缩短量各不相同,其中三叠系上统缩短量最大,大于30 km;三叠系下统至古生界地层缩短量约为14.5 km;侏罗系以上的地层缩短量则较小。研究区内的通济场断裂(F_3)为印支末期形成的一套逆冲断层组,其下部交于下寒武统滑脱层,深度约为10 km;关口断层(F_4)和彭县断裂(F_5)为晚侏罗世一早白垩世形成的逆冲断层,下部交与下三叠统嘉陵江组滑脱层,深度大约为8～10 km。这些断层以前展的方式破裂,并且长期活动。龙门山中段自中生代以来存在多期构造事件,主要发生诺利末期、印支晚幕、燕山期和喜马拉雅期。其中,燕山期和喜马拉雅期是龙门山活动最强烈的两个阶段,在龙门山中段山前带表现为大量断裂的长期活动,地壳缩短和龙门山快速隆升,并形成多种构造样式。In this paper,the fine interpretations of seismic profiles in the central Longmen Mountains have been accomplished with application of fault-related fold geometry principles. Studies find that there are multi-detachment layers with different structural deformation in the shallow thrusting system of Longmen Mountains front belt. The upper level detachment layer is the Upper Triassic Xujiahe Formation （T3x3） ,which develop the imbricate structures and duplex; The middle level detachment layers are the Lower Triassic Jialingjiang Formation （T1j 4-5）, which develop the fault-propagation folds, pop-up structures and structural wedges; The lower level detachment layer is the Lower Cambrian formation and develop fault-bend folds and detachment-folds; These detachments control the deformation with different shortenings. The shortening of the Upper Triassic formation is more than 30 km and below the Lower Triassic formation is about 14.5 km. The strata which above the Triassic formation with few shortening. In this research area, the Tongjichang fault （F3 ） were a set of thrusting faults, which were developing during the Late Indosinian periods. They were rooted in the Lower Cambrian detachment with the depth about 10 km. The Guankou fault（ F4 ） and Pengxian fault（ F5 ） both were rooted in the Lower Triassic Jialingjiang detachment and with the depth about 8 - 10 km. They are brittle and active faults, which were breaking-forward during the Late Jurassic- Early Cretaceous periods. After the Mesozoic Era,There are muti-tectonic events in the central Longmen Mountains. The Late Norian stage, the Late Indosinian epoch, the Yanshan and the Himalayan period are the typical times of tectonic movements in this area. Among them, the latter two periods are the most intense tectonic thrusting faults and developed different structural movements, which made a large number of styles. It also led the crust shortening and uplifting quickly.

关 键 词：地震剖面 滑脱断层 断层相关褶皱 构造演化 龙门山中段 龙泉山 

分 类 号：P542[天文地球—构造地质学]