汤原断陷早第三纪中期基底顶界的三维古构造重建

RECONSTRUCTION OF 3D PALEOSTRUCTURESOF THE BASEMENT TOP IN THETANGYUAN FAULT DEPRESSION DURING MIDDLE EOCENE

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迭加，迭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孤立断裂和各种断裂组合，恢复时分别处理之。

As a matter of fact,current cross-section balancing technique is not suited for reconstruction of paleostructure of most of the extensional basins which have undergone 3D extension and where no vertical cross-sections have realy satisfied the equirement of plain strain. In order to reconstruct their paleostructures,the present paper dessolves 3Dstrains into 2D strains in different derections.First reconstructing 2D paleostructures in each direction and then superimposing 2D reconstructed paleostructures of the different directions using the method we have reconstruct 3D paleostructures of the basement top in the Tangyuan fault depression during the middle Eocene,where three trendings of normal faults with strike slip developed.