郯庐断裂带渤海段的深部构造与动力学意义

郯庐断裂带渤海段的3条大地电磁测深剖面,揭示了断裂带丰富的深部结构信息。这些剖面显示,郯庐断裂带已切穿了整个地壳,并且向下延入上地幔;该段断裂带在深部显示为陡立的走滑构造,浅部为伸展断层及断陷盆地所叠加,最后又发生过一期明显的逆冲活动;该断裂带的走滑构造在渤海湾内继续存在,指示其早期的走滑活动中向北延入了渤海内;该断裂带内部及其旁侧,浅部的断陷盆地发育与深部的高导层(带)紧密伴生,反映断陷盆地发生时在地壳深部都出现了软弱拆离带,也指示了岩石圈减薄中地壳内所发生的深部过程。

Deep structures of the Bohai part of the Tan-Lu fault zone and their dynamic implications

The three magnetotelluric sections across the Bohai part of the Tan-Lu fault zone show a lot of information about deep textures of the fault zone.Interpretation of these sections reveals that the fault zone cuts cross the whole crust and extends into the upper mantle.Strike-slip structures are shown at deeps whereas the normal faults and faulted basins occur at shallow levels.At the last stage of the evolution,thrusting was overprinted on the fault zone.Presence of the strike-slip structures demonstrates that the fault zone extends into the Bohai Bay.High-conduction layers or zones at deeps are closely associated with the extension basins in and outside the fault zone,which suggests that formation of the extension basins were associated with development of weak detachment zones at deeps,and that the detachment slipping is an deep process during lithospheric thinning.