Late Cretaceous geodynamics of the Palaeo-Pacific plate inferred from basin inversion structures in the Songliao Basin (NE China)

Reconstructing the process of plate subduction is challenging, but clues can be found in sedimentary basins and the nature of deformation of the overriding plate. Here we analyse a seismic-reflection dataset that indicates tectonic inversion in the southwestern Songliao basin, NE China, to construct the geodynamics of Palaeo-Pacific plate. The study area consists of Lower Cretaceous rift sediments that were cut by normal faults, folded, and subsequently overlain by undeformed Upper Cretaceous strata, revealing a process of basin inversion. The timing of inversion is constrained to the interval between deposition of the Lower and Upper Cretaceous sediments (i.e. 87-71 Ma). Mud volcanoes and similar structures associated with inversion are observed in basins throughout the region. The change from tectonic extension to shortening in the overriding plate is recorded by sedimentation and inversion of the basins, and was triggered by an increase in the rate of motion of the subducting Palaeo-Pacific plate.