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

Abstract

AbstractThe 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.