南大巴构造带中新生代构造变形特征研究

TECTONIC DEFORMATION CHARACTERISTICS OF THE SOUTH DABA TECTONIC BELT DURING MESOZOIC AND CENOZOIC

裴振洪

Pei Zhenhong

成都理工大学, 成都, 610059 2. 中国石油化工股份有限公司, 南方分公司, 长沙, 410007

Chengdu University of Technology, Chengdu, Sichuan 610059, China 2. South Branch Company, SINOPEC, Changsha, Hu'nan 410007, China

南大巴构造带是一个自印支期以来长期发展的冲断推覆构造带,其发生发展主要受控于秦岭方向及雪峰方向的构造挤压及其联合作用。其组合主应力存在早期正旋、晚期反旋2个时期。由于应力的时空变化及区域多套滑脱层的存在,其中生代变形具有多期次、多方向、多层次、多期复合等特点。多期次性表现为印支晚期以来本区经历了晚印支的轻度褶皱、早燕山的褶皱发育、中燕山的冲断褶皱、早喜山的冲断作用、晚喜山的抬升剥蚀等多期构造变形或改造作用。本区的主导力源来自秦岭方向,其次来自雪峰方向以及米仓山和龙门山方向,多方向的力源联合或复合控制了本区的中新生代构造变形。应力传递的表层化以及塑性层的存在,使本区变形具有平面及纵向上多层次性的特点。多力源、多方向的交替与联合作用,使本区中新生代变形呈现复杂性与复合性的特征。

Compressed from both Qinling and Xuefeng directions,the South Daba Tectonic Belt,known as a typical thrust and fold belt,has experienced long history of development ever since the Indo-Chinese period.The composite stress displays a clockwise movement during the early stage and an anticlockwise movement during the late stage respectively.Because of the time and spatial changes in stress direction and the existence of multiple layers of detachment,deformations during Mesozoic and Cenozoic are cha-racterized by multiple phases,multiple directions,multiple layers and multiple phases'composition.The tectonic deformations include gentle fold(late Indo-Chinese),fold generation(early Yanshanian),thrust and fold(middle Yanshanian),thrust(early Himala-yan) and uplift and erosion(late Himala-yan).The major compression comes from Qinling and the minor from Xuefeng Mountain as well as Micang and Longmen Mountains.Tectonic deformations during Mesozoic and Cenozoic are controlled by either simultaneous or un-simultaneous composite actions.Due to the southward shoaling of stress in its transfer process and the existence of plastic layers,the deformation exhibits a vertical and planar pattern of multiple layers.Influenced by the multiple originated and multiple directional compression simultaneously or un-simultaneously,the deformation in this area is both complicated and complex.

https://doi.org/10.11781/sysydz200703269