REGIONAL TECTONIC INVESTIGATION OF THE SONGMUZUI STRUC-TURE IN THE NORTHERN SEGMENT OF LONGMENSHAN STRUCTURAL BELT
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.
eastern margin of the Tibetan PlateauLongmenshan structural beltwedge-shaped thrusting bodypara-autochthonous systemTianjingshan paleo-uplift
万方数据
维普
