中西部冲断带形成于两古板块“镶嵌式”拼接成陆后的再冲断.多尺度地球物理资料解释表明,浅层构造变形具有“横向有序分带、垂向多属性分层、纵向差异分段”特征,深部构造变形表现为分层解耦和差异收缩,造山带与盆地的岩石圈在咬合冲断时强-弱层对置.本文利用物理模拟实验和延时摄影方法,基于“挤压-碰撞”模型正演了冲断带变形过程,实验结果表明:造山带仰冲盆地并相互拼接,前者冲起折返,后者前陆冲断;盆内滑脱层的存在会产生构造分层,上构造层的变形以断层相关褶皱为主,且扩展范围受控于滑脱层;上构造层的挤压缩短量比下构造层大,变形扩展更远;下构造层的变形以叠瓦构造和双重构造为主,其断层倾角由前陆向腹陆逐渐增大,断面由下凹变为上凸,断片由侧向叠置变为垂向叠置;高角度逆断层的变形经历了脆性变形、韧-脆性变形和韧性变形三个阶段.%The thrust belts resulted from the re-thrusting after the mosaic welding between two paleo-blocks in Central-West China.Shallow-level structures are characterized by vertical multiattribute stratification,horizontal ordered zonation,longitude-directed differential segmentation according to the interpretation of multiple-scale geophysics.The lithospheres of the orogens and basins are decoupled and differentially shortened by layering,and their competent and weak beds are opposed as they thrust like dental articulation.The paper takes "compression-collision" model to forward the formation of thrust belts by physical modeling and time-lapse photographing.The results show that the orogen exhumed by the way of pop-up structures,the thrusting happened in the front of basin.The existence of detachment layers results in structural stratification.The deformation pattern of upper layer is mainly the fault-related folds,and its range is controlled by the distribution of detachment layer.The upper layer was shortened much more and propagated farther compared with lower layer.The deformation pattern of lower layer is mainly the reverse faults,and their structural patterns are imbricate and duplex.Meanwhile,the faults' dip increases gradually from foreland to hinterland,the fault planes change from concave to convex,each horse lies above the other from lateral to vertical.The high angle faults experienced three stages-brittle deformation,ductile-brittle deformation,ductile deformation.
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