软弱地质体对反转构造变形制约作用的物理模拟及其应用

Discussion on the influence of weakness body on inversion structure deformation through analogue modeling and its application

深水盆地的构造变形表明,大陆边缘上常存在与刚性地质体相对应的软弱地质体,它们不仅加强了裂陷期的沉降变形,而且加强了挤压反转期的褶皱隆升。为了揭示软弱地质体对构造变形的影响,作者利用物理模拟方法设置了4组实验,基于模拟结果讨论了琼东南盆地西南部反转构造的发育机制。实验对比分析发现,无论哪种应力场下反转变形都更容易在软弱区集中,软弱区所处构造位置及其所受应力性质对反转构造发育起着重要的控制作用。通过模拟结果与实际构造对比分析,认为琼东南盆地西南部构造反转发育主要受斜向挤压应力和软弱体的共同影响,推测其挤压应力来源于盆地西北部,可能与印支地块的旋转挤出作用有关。

Deep-sea basin structural deformation indicated that the exist of weakness body in continental margin not only make the sedimentation deformation stronger in rift stage but also make the uplift-fold stronger in inversion stage.In order to investigate the impact of weakness body on structural deformation,we carried out four sets of analogue modeling experiments. Based on the modeling results,we discussed the impact of weakness body on inversion structure deformation in the southwest of the Qiongdongnan Basin.The modeling experiments show that no matter in extension stage or in compression stage,the inversion structural deformation first appears and propagates in weakness zone,the location and the stress direction of weakness body play an important role in the deformation of inversion structure.Based on comparison of modeling results with the actual structures,it is concluded that the deformation of inversion structure in southwest of the Qiongdongnan Basin is mainly influenced by the existence of weakness body and oblique compression;the oblique compression tectonic stress may come from the northwest of the basin and keep its relationship with the revolved Indochina Block by inference.