Early–Middle Jurassic magmatism, stratigraphy, and deformation in North and Northeast China: A prelude to the thinning of the North China Craton and subducted Izanagi Plate, and a Coda to the Mongol-Okhotsk Ocean

The Early–Middle Jurassic period represented a crucial juncture for the Northeast Asian continent, marked by significant geological transformations. These included the initial thinning of the North China Craton (NCC), the closure of the Mongol-Okhotsk Ocean (MOO), and the subduction of the Izanagi Plate. Despite the acknowledged significance of these events, the specific temporal and spatial extents of the two tectonic regimes influencing the Northeast Asian continent remain uncertain. This study aims to elucidate these ambiguities, focusing on the spatiotemporal extents of magmatic activity and deformation driven by these distinct tectonic regimes. To achieve this, our research integrates comprehensive analyses of magmatism, stratigraphy, and deformation across the Northeast Asian continent. Our findings highlight the spatially non-uniform intensity of magmatism in Northeast China and the NCC during the Early–Middle Jurassic, pointing to a heterogeneous influence of the tectonic regimes over time and space. This early stage of the orogeny was also signed by local extensional tectonics within the NCC's eastern parts, as opposed to the compressional deformation in the western part, within the Songliao basin. However, the overall extension intensity over the entire region may not have been very pronounced. During the middle to late Middle Jurassic, there was a shift in the scenario, with compression-dominated deformation expanding across the Northeast Asian continent, indicating a significant change in tectonic dynamics. Further analysis reveals the distinct impacts of the Izanagi Plate's subduction beneath the Jiamusi–Khanka Block and the Yanshan fold-and-thrust belt, as well as the MOO tectonic regime's influence on the western Songliao basin, extending to the northern Ordos basin. Interestingly, a substantial portion of the craton remained relatively unaffected during the initial stages of Izanagi Plate's subduction and MOO's closure. However, these events laid the groundwork for the extensive destruction of the craton witnessed during the Late Jurassic–Early Cretaceous period. This study significantly contributes to our understanding of the geological processes in the Northeast Asian continent during the Mesozoic, offering valuable insights into the dynamic interplay of tectonic regimes that shaped this region. By delineating the spatial and temporal extents of magmatic activity and deformation, we provide a clearer picture of the geological evolution of the Northeast Asian continent, highlighting the complexity and variability of tectonic influences during the Early–Middle Jurassic.