Mesozoic–Cenozoic tectonic evolution and dynamics of the Songliao Basin, NE Asia: Implications for the closure of the Paleo-Asian Ocean and Mongol-Okhotsk Ocean and subduction of the Paleo-Pacific Ocean

Abstract The Songliao Basin in northeast China in the eastern part of the Central Asia Orogenic Belt is the largest accretionary orogen belt in the world. However, to date, previous studies have not extensively examined the dynamic mechanism of its formation and evolution, especially the pre-Cretaceous. In this study, the Mesozoic–Cenozoic tectonic style, stratigraphic records, sedimentary time, magmatic activity, and tectonic evolution in the Songliao Basin were systematically analysed and summarised. We propose that Songliao Basin experienced multi-stage basin superposition processes: the foreland compression stage, syn-rift and post-rift stage, and structural inversion stage. After Palaeozoic deposition, the basin experienced a strong orogeny with the formation of the Triassic–Middle Jurassic foreland basin. During the syn-rift period, three tectonic movements occurred at the end of the Shahezi Formation (Late Valangnian, ~135 Ma), the end of first member of the Yingcheng Formation (Late Hauterivian, ~129 Ma), and the end of the Yingcheng Formation (Late Barrenian, ~125 Ma) in the Songliao Basin, which ended the evolutional history of the rift. In the post-rift period, three tectonic events occurred at the end of the Nenjiang Formation (Middle Campanian, ~79 Ma), the Mingshui Formation (Late Maastrichtian, ~66 Ma), and the Yi'an Formation (Late Chattian, ~23 Ma), which determined the deformation characteristics of the middle and shallow strata of the basin, such as folding and reverse faults. The rudimentary shape formed at the end of the Nenjiang Formation, was finalised at the end of the Mingshui Formation, and formed at the end of the Yi’an Formation. The largest depth and width influence of the two events was at the end of the Mingshui and Yi’an formations, which played a decisive role in the generation, migration, and accumulation of oil and gas in the middle and shallow strata of Songliao Basin. After a series of asthenospheric mantle upwelling, crustal uplift and extension, and volcanic activity, Songliao Basin was eventually formed. The formation and structural evolution of the Songliao Basin were mainly influenced by the Paleo-Asian Ocean, the Mongol-Okhotsk Ocean, and the Pacific Ocean. The closure of the Paleo-Asian Ocean in the Late Permian-Early Triassic was influenced by the Siberian Plate, which began to contact and collide with the Xingan-Mongolian Block from west to east, causing the Mongol-Okhotsk Ocean to close in a scissor-like structure from west to east in the Early–Middle Jurassic. The subduction and movement of Pacific Rim tectonic systems, such as the Farallon, Izanagi, Pacific, and Philippine plates, led to the formation of Songliao Basin, which has experienced a foreland period via compressive pressure since the Triassic, syn-rift period and post-rift period via extensional stress, and then a structural inversion period.