【摘要】 在松辽盆地长垣隆起中部,近年来开展的高精度三维地震勘探揭示出该区正断层走向自下而上具有逐渐向西偏移的演化趋势。基本上以白垩系泉头组顶面地震反射层(T2:约98.9×106 a)为界,主要的断层走向在其下为与长垣平行的北北东向或南北向,在其上为北北西向,二者约有60°的偏差。这种变化代表着原地最大水平主压应力的同向变化,应反映邻近陆缘洋壳俯冲速度的变化。120×106 a时伊泽纳崎板块朝欧亚大陆呈高角度斜向俯冲消减,而后被相对正向俯冲的洋壳板块所取代,同时板块运动的速率有所减小,意味着板块的正向俯冲相对斜向俯冲将更加有效、长距离地向板内传递挤压应力。更多还原

【Abstract】 In recent years,high-precise 3D seismic explorations in central placanticline uplift of Songliao basin have revealed that the strikes of faults in this area tend to gradual migrating toward the west from the lower to the upper reflecting horizons.The top reflecting horizon T2(dating about 98.9Ma) of Quantou formation of Cretaceous can be regarded as a reference surface,below which the strikes of major faults are NNE or SN directions,parallel to the placanticline trend;above which they are NNW directions,showing difference of about 60° between them.It is believed that such a migration of strikes represents the concordant variation of in-situ maximum horizontal principal stress,which might reflect the changes of subducted velocity of oceanic crust near continental margin.Before 120 Ma,the Izanagi plate was being subducted obliquely toward the Euro-Asia continent followed by the predominating of orthogonally subduction of the oceanic crust plate,somewhat decreasing of the velocity of the plates motion.Hence,it is suggested that compared with the oblique subduction,the orthogonal subduction could play an effective role in transmitting compressive stress from the continental margin to the interior.更多还原