多轴水平拉伸盆地三维古构造重建探讨

现行的平衡剖面技术应用于盆地古构造重建在绝大多数情况下是偏离构造变形事实的,绝大多数盆地构造变形属多轴水平拉伸的三维变形。三维变形古构造恢复一般应视为二维变形的某种叠加,叠加方式视断裂总体变形特征而定。三维变形盆地中断裂可分为孤立断裂和各种断裂组合,恢复时需分别处理。作为实例,我们重建了汤原断陷早第三纪中期白垩系顶界三维古构造。

RECONSTRUCTION OF 3-D PALEOSTRUCTURES OF MULTI AXIS HORIZONTAL EXTENSIVE BASIN

Current cross section balancing technique is not suitable for the paleostructure reconstruction of most of extensive basins since they underwent 3-D deformation.The reconstruction of the 3-D deformed paleostructures should be considered as the superimposition of 2-D deformation.The faults in the 3-D deformed basins could be divided into isolated faults and fault complex,and they should be treated separately in reconstruction.As an example,the 3-D paleostructure of the boundary between Middle Eogene and Cretaceous in Tangyuan Depression is reconstructed and described in this paper.