Tectonic characteristics and evolution of typical rift basins in eastern China: A case study in the Gudian area, Songliao Basin

The Gudian Rift is a favorable area for deep natural gas exploration in the southern Songliao Basin, and it also records rich information on basin evolution and Mesozoic-Cenozoic plate movements in eastern China.By using the well and high-resolution 3D seismic data, combined with regional tectonics, the geological structure and tectonic evolution of the Gudian Rift were investigated.The results show that the Gudian Rift can be vertically divided into basement, lower, middle and upper structure layers.Due to the subduction of the Pacific Plate beneath to the East Asian Plate and the changes in the regional tectonic stress field since the Late Mesozoic, the Gudian Rift experienced syn-rift, transition, post rift and tectonic inversion periods.The Gudian fault was initially formed from six fault segments in syn rift period(depositional period of the Huoshiling and Shahezi Formations) and the isolated fault segments with different strikes then grew and connected to a unified boundary fault in the late rifting stage(depositional period of the Yingcheng Formation).Afterwards, extensive and intense transtensional activities occurred during transition(depositional period of the Denglouku and Quantou Formations) and depression periods(depositional period of the Qingshankou, Yaojia and Nenjiang Formations), and strong inversion and segmental thrust activities occurred during inversion period(end of the depositional period of the Nenjiang Formation), respectively.This study provides references for the investigation of tectonic activity and evolution in the Songliao Basin and eastern China, and further guides oil and gas exploration.