龙门山构造带北段山前带松木咀区域构造解析  

REGIONAL TECTONIC INVESTIGATION OF THE SONGMUZUI STRUCTURE IN THE NORTHERN SEGMENT OF LONGMENSHAN STRUCTURAL BELT

作　　者：田贤东 赵德军[1] 童馗 TIAN Xiandong;ZHAO Dejun;TONG kui(College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu,Sichuan 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China)

机构地区：[1]成都理工大学地球与行星科学学院,四川成都610059 [2]油气藏地质及开发工程国家重点实验室成都理工大学,四川成都610059

出　　处：《矿物岩石》2024年第2期96-107,共12页Mineralogy and Petrology

基　　金：国家自然科学基金(项目批准号:42230310);马角坝实习基地建设专项(项目编号:20Z06)。

摘　　要：青藏高原东缘的龙门山构造带是连接青藏高原与四川盆地的陆内挤压造山带,带内地质构造复杂,断裂及地震活动强烈,恢复龙门山构造带形成与演化过程对理解青藏高原东缘隆升和生长过程及其动力学机制具有重要意义。通过对龙门山北段松木咀“飞来峰”开展野外地质调查和地震剖面精细解译,揭露研究区地腹构造特征,恢复松木咀地区逆冲推覆构造演化过程。研究结果表明松木咀“飞来峰”系松木咀断层围限的古生界地层,其地层单元源于天井山古隆起南缘的原地系统,并非外来地层单元。松木咀地区的地表及地腹特征表明松木咀断层为一组独立的同倾向断层,不符合龙门山北段滑覆型飞来峰特征。据此将研究区松木咀构造界定为“楔状冲断体”,并提出“褶皱破裂-背冲冲断-挤压递进变形”的构造成因模式,这一模式合理解释了松木咀构造的独特性。松木咀楔状冲断体系龙门山造山带前锋部位准原地系统形成与演化的产物,属造山带中的楔形挤出构造,体现出构造层次转换与递进变形效应引起的构造变形作用,对造山带形成及演化的贡献不容忽视。The Longmenshan tectonic belt,located on the eastern margin of the Tibetan Plateau,is an in-tracontinental compressional orogenic belt that connects the Tibetan Plateau with the Sichuan Basin.Stud-ying the formation and evolution of the Longmenshan tectonic belt is crucial for understanding the uplift and growth processes,as well as the dynamic mechanisms,of the eastern margin of the Tibetan Plateau.This research involves a field geological survey and precise interpretation of seismic sections at the Song-muzui klippe in the northern segment of Longmenshan.The goal is to uncover the characteristics of the hinterland structure in the study area and to reconstruct the evolution of the thrust nappe structure in Songmuzui.The findings reveal that the so-called"Songmuzui klippe"is composed of Paleozoic strata bounded by the Songmuzui fault.This stratigraphic unit originates from the autochthonous system on the southern margin of the Tianjingshan paleo-uplift,rather than being an exotic unit.The surface and hinter-land characteristics of the Songmuzui area indicate that the Songmuzui fault comprises a set of independent faults with the same dipping direction.This configuration does not align with the characteristics of gliding-induced klippe in the northern segment of Longmenshan.Consequently,the Songmuzui structure in the study area can only be classified as a"wedge thrust body"with a tectonic genetic model of"fold fracturing-backthrusting-compressive progressive deformation,"reflecting the unique characteristics of the Songmu-zui structure.It is proposed that the formation and evolution of the quasi-autochthonous system in the front part of the Longmenshan Mountain orogenic belt result from a wedge-shaped extrusion structure.This reflects the tectonic deformation caused by tectonic level transformation and the progressive deforma-tion effect,significantly contributing to the formation and evolution of the orogenic belt.

关 键 词：青藏高原东缘 龙门山构造带 楔状冲断体 准原地系统 天井山古隆起 

分 类 号：P542[天文地球—构造地质学]