基底仰冲—俯冲碰撞对盖层构造的影响物理模拟实验

PHYSICAL MODELING ON THE OVERBURDEN DEFORMATION INFLUENCED BY THE OBDUCTION-SUBDUCTION OF THE BASEMENTS

根据相似性原理,选择橡皮泥和松散的细沙为实验材料分别模拟盆地的基底和盖层,在挤压应力条件下,模拟基底的仰冲-俯冲碰撞对盖层构造的影响。实验表明:①盆地基底在碰撞接触初期因接触面积较小而拼接不稳固,可以导致仰冲—俯冲碰撞,盆地基底碰撞部位的产状可能是决定该侧基底是俯冲抑或仰冲的重要因素。②盆地基底的微弱变形即可引起盖层较大形变;③基底的仰冲-俯冲使盖层的主要构造倾向仰冲基底一侧。

According to the analogy theory, rubber and sands were selected as model materials in the experiments on overburden deformation influenced by the basement obduction-subduction. Firstly, experiments have shown that splice of two basements was unstable in the initial stage of collision because of their small interfacing area, which led to obducting or subducting collision of two basements. The attitude of the basement was possibly one of the key factors which determined whether the basement was subducting or obducting basement. For another, the deformation of overburdens could be resulted from small deformation of basements. In addition, the dip direction of overburden deformation faced to the overriding basement.