半地堑反转构造的砂箱实验模拟

SANDBOX EXPERIMENTAL MODELING ON THE INVERSION TECTONICS OF HALF-GRABEN

设计了两组半地堑反转构造的理想砂箱实验模型． 实验结果表明， 边界条件对半地堑反转构造形成特征有着十分明显的影响． 刚性边界条件下， 沿着边界断层可以产生一定的反转逆冲现象， 反转逆冲的程度与边界断层的倾角大小有关， 倾角越缓反转逆冲现象越显著． 而在自由边界条件下， 边界断层均无反转逆冲现象， 只是发生倾角变陡现象． 沿半地堑边界断层的反转逆冲作用十分有限， 反转逆冲主要通过新生低角度逆冲断层得以实现， 地堑内部断层通常不发生反转逆冲， 仅有倾角变陡现象． 新生低角度逆冲断层的倾角与其距盆地边部的距离有关， 距离越大倾角越小．

Two groups of concept sandbox experimental model on inversion tectonics in half-graben were designed. The experiment results indicated that boundary conditions are of very distinct affects on characteristics of inversion tectonics in a half-graben. Under condition of grid boundary,obvious inversion thrusting took place along the boundary fault of a half-graben. The degree of inversion thrusting is relevant to the dip angle of the boundary fault. The smaller the dip angle is,the more obvious the degree of inversion thrusting is. But under conditions of free boundary,all of boundary faults have no inversion thrusting phenomenon,but deeper dip angle. Inversion thrusting along a boundary fault of half-graben is often very limited. Most inversion thrusting deformation is accommodated mainly by new thrust faults of low angle. Generally,the normal faults in inner of a half-graben also have no inversion thrusting phenomenon,but deeper dip angle. The dip angles of new thrust faults of low angle are related to the distances to the basin's edge. The larger the distance is,the smaller the dip angle is.