Jurassic tectonics of the eastern North China Craton: Response to initial subduction of the Paleo-Pacific Plate

The Yanshan fold-and-thrust belt (YFTB) on the northern margin of the eastern North China Craton (NCC) contains a succession of Jurassic volcano-sedimentary rocks that record the response of the NCC to the initial stages of subduction of the Paleo-Pacific Plate. We present stratigraphic profiles and new zircon U-Pb data from four basins in the YFTB to constrain the ages of the Jurassic lithological units and tectonic events related to the initial subduction. Following uplift at 200-190 Ma, protracted eruption of basalt at 188-167 Ma reflects the earliest tectonic activity in the YFTB. The eruption occurred in a backarc extensional setting, and migrated toward the west, consistent with WNW-directed subduction of the Paleo-Pacific Plate. The measured profiles and geochronological data demonstrate that the earliest phase of shortening in the YFTB during the Jurassic (event A of the Yanshan Movement in the Chinese literature) took place at 167 Ma. This compression terminated the magmatism and extension of the Early-Middle Jurassic, and resulted in the development of local thrusts, regional uplift, and a disconformity, without involvement of intense folding or the development of an angular unconformity. These observations are consistent with a weak to moderate intensity of deformation. The Jurassic rocks in the YFTB record the response of a backarc to the initial stages of subduction of the Paleo-Pacific Plate. Jurassic tectonics in the YFTB and the entire eastern China continent suggests that initial subduction of the Paleo-Pacific Plate began at ca. 190 Ma, and is consistent with the passive margin collapse model.

Automated summary

The Yanshan fold-and-thrust belt on the northern margin of the eastern North China Craton contains Jurassic volcano-sedimentary rocks that record the response of the NCC to the initial subduction of the Paleo-Pacific Plate. The earliest tectonic activity in the YFTB occurred at 188-167 Ma with the eruption of basalt, and the earliest phase of shortening during the Jurassic took place at 167 Ma, resulting in block movements and regional uplift. This suggests a weak to moderate intensity of deformation in the region.