Characteristics of Two‐Phase Structral Evolution in the Liaohe Basin, China During Paleogene Time

Abstract

AbstractNew geophysical evidence and results of modeling experiments indicate that the structural history of the Liaohe basin, China during the Paleogene time consists of two phases, namely the continental rift and dextral strike‐slip phase. The evolution of the continental rift was driven by extensional stress from upwelling of the mantle during the Fangshenpao and Shahejie period of Paleocene and Eocene, Paleogene time (Ef‐Es1, about 63.0~37.0Ma ). The dextral strike‐slip movement of the Liaohe basin occurred during the Dongying phase of Oligocene, Paleogene time (Ed, about 36.9~24.5 Ma). Two phases of structural movement leaded to formation and evolution of complex fault systems in the Liaohe basin. We propose that dextral strike‐slip movement of post‐rift reactivated older extensional faults and produced new faults. On the basis of results from modeling experiments and analysis of geophysical data, the displacement amount caused by dextral strike movement during the Dongying period of Paleogene time (Ed) is about 4~8 km. New study results prove that complex fault systems of the Liaohe basin were not only strongly controlled by older extensional stress, but also influenced by younger dextral strike‐slip movement. The structural movement of two phases have important impact upon oil and gas migration and accumulation in this area.