辽河盆地西部凹陷北部地区古近系地层剥蚀量恢复

辽河盆地新近系(N)、古近系(E)之间不整合面形成于盆地由裂陷发育阶段向坳陷发育阶段转化的过渡时期,古近系地层在沉积后遭受了长期的非均衡剥蚀.通过地质分析及实践,选用地层结构趋势外延法和声波测井曲线法计算了研究区的地层剥蚀量,并在此基础之上,对原型盆地进行了恢复.从所得的两幅形态近似的剥蚀量等值线图上的剥蚀趋势得出:横向上剥蚀量自南西向北东逐渐增大,这种差异性剥蚀是古近纪末期台安—大洼断裂右旋走滑作用在本区形成的北西向褶皱格局所引起.从盆地原始沉积厚度等值线图也可以得出,不同时期原型盆地的形态和盆地的类型具有明显的阶段性差异.导致上述结果的根本原因则是郯庐断裂右旋走滑作用的影响.

Calculation of the denudation amount of the Paleogene in the north part of the west depression,Liaohe Basin

The unconformity surface between the Neogene and the Paleogene in the area is formed in the transition period from rifting stage to downwarping stage in the basin evolution,and the Paleogene is subjected to un-uniform denudation for a long time.The denudation amount of the formation is calculated by strata trend extending method and sonic-logging curve method,and base on this,the primitive basins are recovered.Two denudation amount isoline maps with similar form indicate that,in the whole region,the denudation amount become gradually great from south-west to north-east,which is caused by the north-west fold controlled by the right-lateral slide effect of Taian-Dawa Fault.The isoline map of the sediment thickness of the basin shows that the basin has different shapes and types in different stages,which is caused by the right-lateral slide effect of Tanlu Fault.