Late Mesozoic tectonic transition of the eastern North China Craton: evidence from basin-fill records

Abstract

AbstractTo better understand Mesozoic tectonic transition processes in Eastern China, this paper offers a comparison of Mesozoic basin-fill records around the eastern North China Craton. These Mesozoic basins have similar evolutionary features: inception since the Early Jurassic; basin-fills recording a tectonic evolution from compression and lithospheric thickening before Late Jurassic and/or Early Cretaceous time to intracontinental stretching and lithospheric thinning from Early Cretaceous time; tectonic transition during the late Jurassic with a time lag in shallow crust relative to deep lithosphere. However, basin-fill records reflect two distinct basin systems occurring in the southern and northern margins of the eastern North China Craton. First, varied volcanic rocks including mafic, intermediate–mafic and intermediate–felsic assemblages occur in the Yanshan–Liaoxi basins on the northern margin of the eastern North China Craton from the Early Jurassic to Cretaceous; in contrast, limited calc-alkaline volcanic rocks filled the Hefei basin system on the southern margin of the eastern North China Craton during the Late Jurassic–Early Cretaceous. Second, late Mesozoic lithospheric thinning began at about 163 Ma and 149 Ma in the northern and southern margins, respectively, culminating in basin-scale extensional events at about 145 Ma and 132 Ma, respectively. Third, coarse clastic sediments developed in the northern and southern basins during the tectonic transition phase reflect fluvial and alluvial systems, respectively, indicating greater topographic relief in the southern area than in the northern area. Fourth, Mesozoic depocentre migration was complicated in the Yanshan–Liaoxi basin but should a south to north trend in the Hefei basin system. Mesozoic basin-fill depositional and volcanic records in the southern margin of the eastern North China Craton were dominantly controlled by early Mesozoic deep subduction of the Yangtze block and subsequent post-orogenic extension of the Dabie Mountains. On the other hand, basin-fill evolution along the northern margin of the North China Craton was principally controlled by intensive crust–mantle and/or asthenosphere–lithosphere interactions, with regional transition from contractile to extensional strain during Mesozoic time. This study suggests that the late Mesozoic tectonic transition was first induced by crust–mantle interactions in the northern North China Craton and then it extended southwards. Late Mesozoic lithospheric thinning and subsequent tectonic transition are a linked systematic geodynamic process that has no direct relation to the Triassic plate convergence events around the North China Craton.