龙门山推覆构造带中段前缘构造浅析

ON THE OVERTHRUSTING TECTONICS OF THE FRONT MARGIN ALONG THE MIDDLE SECTION OF THE LONGMENSHAN TECTONIC BELT

曹伟

Cao Wei

地质矿产部西南石油地质局, 成都 610081

Southwest China Bureau of Petroleum Geology, MCMR

本文分析了逆掩断裂带的动力学、运动学和几何学形变特征,并以川西彭县鸭子河构造为例,重点解剖龙门山推覆构造带中段前缘的构造特征.提出龙门山中段前缘为一以叠覆双重构造为特征的隐伏冲断构造模式,其主断层末端未波及地表,滑动多转化为顺层滑脱,形成应力消减的前缘三角带,而数条低角度的冲断层形成造成顶、底板主滑脱层之间地层的多次重叠和厚度的剧烈加积.

In this paper,the comprehensive studies are carried out on the tectonic characters of the front margin along the middle section of the Longmenshan Overthrusting Belt based onthe analysis of dynamics,kinematics and geometric deformations on the overthrusting beltwith the example from the Yazi River Strticture in Peng County,west Sichuan.It is proposed that the tectonics of the front margin along the middle section of the LongmenshanOverthrusting Belt shotild be a superimposed duplex tectonic characterized by a buried overthrusting tectonic model,of which the major detachment is not outcropped.The transformation of the detachment into decoupling structure brought about the stress reliefzone of front delta-belt while the multiple superimposition and increasing thickness of theimbricated overthrusts should consist of a number of low angle overthrusts between theroof and footwall of the major detachment.

https://doi.org/10.11781/sysydz199401035