雪峰山陆内造山带变形特征及挤压推覆-伸展滑脱构造的物理模拟

本文分析了雪峰山陆内造山带的变形特征,认为雪峰山造山带是在克拉通边缘裂陷槽基础上发育起来的,历经了加里东陆缘褶皱始造山、印支一早燕山陆内褶断主造山、晚燕山一早喜马拉雅陆内盆后(重)造山等过程而最后定型的.中生代以来,岩石圈向西北的俯冲,地壳层次向西挤压产生基底滑脱、推覆增厚,进而在松弛伸展过程出现山链两侧双极性的重力滑脱.在分析变形特征的基础上,对本区的挤压推覆-伸展滑脱构造进行了物理模拟实验,实验表明,来自于SE方向的挤压作用是产生大规模的推覆-滑脱构造的动力来源.在后期的应力松弛阶段,产生伸展滑脱构造.

Deformation Features and Modeling Experiments of Nappe/Decollement Structure in Xuefeng Mountain Intracontinental Orogenic Belt

In this paper, the authors have analyzed the deformation features of Xuefeng Mountain intracontinental orogenic belt, and pointed out that Xuefeng Mountain orogenic belt was developed on the basis of the marginal rifted depressive trough of the craton, and experienced Caledonian pre-orogenic epicontinental folding, main orogenic epoch in Indosinian-Yanshanian movement, re-orogenic epoch in late Yanshanian-early Himalayan movement. From Mesozoic, the lithosphere subducted northwestward and the crust was compressed westward. The base surge and nappe were formed and thickened in middle-upper crust. The twin-polarity gravity surge was formed on each side of the orogenic belt during laxity and extension. The model experiment of nappe/decollement structure was done, and the result indicates that the pressure from southeast was the major stress that formed the nappe/decollement structures. The extension structures was formed at the stage of relaxation.