PHYSICAL MODELING ON DOUBLE DECOLLEMENTS STRUCTURE IN FOLD-AND-THRUST BELT
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摘要: 褶皱冲断带是造山带—前陆盆地系统的重要组成部分,滑脱层在其形成和发展过程中起了显著作用。应用物理模拟实验方法,在模型中设置2套滑脱层,并改变其厚度和位置,研究了褶皱冲断带的几何学和运动学特征。实验结果表明,在双滑脱层褶皱冲断带中,主要形成自底部滑脱层向上传播的正向逆冲断层,断层以前展式发展,岩层在上部滑脱层以上弯曲形成断层相关褶皱。当2个滑脱层距离相近时,作为一个整体对断层起控制作用,形成的正向逆冲断层数目少,有利于反向逆冲断层形成;与2个滑脱层距离较远时,下部滑脱层对逆冲断层起主要控制作用,形成较多的正向逆冲断层和较少的反向逆冲断层。Abstract: Fold-and-thrust belt is an important component in orogen-foreland basin system.Decollement plays a remarkable role in its formation and development.In order to study geometric and kinematic characteristics of fold-and-thrust belt which has 2 decollements with different thickness and position,a series of scaled physical modeling experiments have been done.Deformations of models with shortening increase are photoed.In fold-and-thrust belt with 2 decollements,forward thrusts which propagate from the lower decollement form the main thrusts,and their development obeys forward pattern.In the hanging wall of thrust,rock layers bend above the upper decollement and form fault-related fold.When the 2 decollements are close to each other,they work together and control thrust development,forming less forward thrusts,yet favorable for backward thrusts.While they are widely spaced,the lower decollement mainly controls thrusts development.More forward thrusts and less backward thrusts are formed.
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Key words:
- physical modeling /
- decollement /
- fault-related fold /
- fold-and-thrust belt
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