雪峰山陆内复合构造系统印支—燕山期构造穿时递进特征

Diachronous and progressive deformation during the Indosinian-Yanshanian movements of the Xuefeng Mountain intracontinental composite tectonic system

金宠 李三忠 王岳军 张国伟 刘丽萍 王建

Jin Chong Li Sanzhong Wang Yuejun Zhang Guowei Liu Liping Wang Jian

通过分析雪峰山陆内变形构造区内三叠系—白垩系中不整合面的分布以及不整合面上下地层的夹角情况,明确了早-中三叠世构造运动波及范围以及高角度不整合和低角度不整合分布的分界线,且变形具有由东向西的逐渐减弱的规律;自晚三叠世以来,构造运动仍体现出由东向西的穿时递进扩展变形,继而得出各时期变形时间的分界线。另外,通过计算各时期穿时变形的传递速率,并且通过传递速率作为联系纽带,得出燕山期向西递进变形的直接原因为湘赣及华夏陆块等地岩石圈减薄软流圈上涌,而间接原因是古太平洋板块对欧亚板块的俯冲方式,而滑脱层在燕山期构造传递过程中也扮演了重要角色。

The distribution of angular unconformity and included angle between strata above and below the unconformity in the Triassic and Cretaceous in the Xuefeng Mountain intracontinental tectonic system are studied.Based on that,we identify the range of deformation during the Early(T) and Middle Triassic(T) and the boundary line between high-angle and low-angle unconformities.It is indicated that the deformation intensity in the study area decreases from east to west during T-T.Since the Late Triassic,tectonic movements have been featured by east-to-west diachronous and progressive deformation,which helps to define the boundary lines among each period of deformation.Propagation rates of diachronous deformation in each period are calculated.From these propagation rates,it is concluded that the direct causes for the westward progressive deformation during the Yanshanian period are the thinning of lithosphere and the upsurging of asthenosphere in the cathaysia and other plates,while the indirect cause is the subduction of the Paleo-Pacific Plate beneath the Eurasia Plate.Moreover,the decollement surfaces also play an important role in tectonic propagation during the Yanshanian period.

10.11743/ogg20090510