区域伸展体制下盆-山构造耦合关系的探讨——以渤海湾盆地和太行山为例

A Preliminary Study of the Coupling Relationship between Basin and Mountain in Extensional Environments——A Case Study of the Bohai Bay Basin and Taihang Mountain

根据地质、地球物理和构造地貌等资料研究了渤海湾盆地和太行山之间的耦合关系。盆地和山脉是在晚白垩世形成的华北准平原上经新生代裂陷作用产生的。盆地阶段性下沉与山区间歇性抬升彼此相应,相反相成。盆山之间的太行山山前断裂带是上地壳中的大型拆离构造,沿它拉张滑脱而盆降、山隆;区内现今地壳上地幔结构等差异可能是盆-山构造发育过程中形成的,总体为分层拆离、脆韧转换和伸展-收缩组合而成的岩石圈结构构造剖面。盆地和山脉具统一的形成机制和同一动力条件,盆地深部软流圈上隆和侧向分流导致岩石圈地幔和下地壳自下而上同向连锁流变,不仅拖曳传力使上覆壳层拉张裂陷成盆,而且往西推挤山区相同层圈的物质使之缩短增厚并隆升,为盆地伸展让位;山脉伴随盆地发育而形成。

The coupling relationship between the Bohai Bay basin and Taihang Mountain has been studied based on geological, geophysical and structural landform data. The basin and the mountain were formed by Cenozoic rifting on the basis of the North China peneplain, which was formed in the Late Cretaceous. The piedmont fault of Taihang Mountain is a large detachment structure in the upper crust, and the basin's subsidence and the mountain's upheaval occurred by its extension and detachment. The basin's staggered subsidence and the mountain's discontinuous upheaval took place at the same time. The differences of the crust and upper mantle structures in the area were probably formed during the basin/mountain formation period. They are tectonic sections formed by detachment between the layers, brittle/ductile transition and extension/contraction. The basin and the mountain have the same formation mechanism and dynamical condition. The upheaval and lateral diversion of the asthenosphere under the basin produced ductile deformation of the mantle lithosphere and the lower crust from bottom to top, which not only caused the top layers to be extended and rifted to form basin, but also pushed the materials in the same layer in the mountain to the west, so that they were shortened, thickened and upheaved, giving way to the basin's extension. The mountain was formed accompanying the basin's development.