【摘要】 大凉山地区位于青藏高原的东南边缘,具体指鲜水河-小江断裂带中段安宁河断裂带和则木河断裂带以东的菱形地区。新生代以来大凉山地区的新构造运动不仅表现为沿区内大凉山断裂带的左旋走滑和逆冲2种分量的断层运动,还表现为轴向近SN的褶皱缩短。利用平衡剖面方法结合误差分析得出研究区的地壳平均缩短量为(10.9±1.6)km,缩短率为(17.8±2.2)%。研究区发生缩短变形的时间段主要集中在中新世和上新世(12～3.4MaBP),结合地壳缩短量计算出的研究区地壳缩短速率为(1.3±0.2)mm/a。对比沿大凉山断裂带的左旋滑动量,可以看出这种褶皱形式的地壳缩短在沿鲜水河-小江断裂带向SE方向传递左旋位移的过程中起着重要的作用。更多还原

【Abstract】 Daliangshan tectonic zone is the rhombic area east of the Anninghe and Zemuhe Fault zones,southeast of the Tibetan Plateau.The Daliangshan tectonic zone is enclosed by three tectonic units:the Bayan Har terrane in its northwest,the Yangzi platform in its southeast and the Longmen Mountain-Yanyuan nappe tectonic belt in the middle.The Daliangshan Fault zone is the most important fault zone in the Dalianshan tectonic zone.This fault zone,together with the Anninghe Fault zone and the Zemuhe Fault zone,make up of the middle part of the Xianshuihe-Xiaojiang Fault zone.The Daliangshan Fault zone consists of 4 branches:the Shimian-Yuexi Fault,the Puxiong Fault,the Butuo Fault and the Jiaoji River Fault.Since Cenozoic,the neotectonic deformation in Daliangshan zone has shown not only sinistral slip and reverse faulting along Dalianshan Fault zone,but also crust shortening.It was estimated that the average crust shortening in Daliangshan zone is(10.9±1.6)km and the crust shortening rate is(17.8±2.2)% by using balanced cross-sections.The crust shortening by folding occurred mainly in the Miocene and the Pliocene,lasting no more than 8.6Ma.Then,the crust shortening velocity of(1.3±0.2)mm/a can be estimated.Comparing with the left offset along the Daliangshan Fault zone,it is recognized that the crust shortening by folding plays an important part in transferring crust deformation southeastward along the Xianshuihe-Xiaojiang Fault system.更多还原