Paleo–Pacific plate subduction on the eastern Asian margin: Insights from the Jurassic foreland system of the overriding plate

Abstract The subduction of the paleo–Pacific plate beneath North China block has been well documented in terms magmatic activity, geophysical investigations, and numerical modeling, but timing its onset along eastern Asian margin tectonic processes involved remain poorly understood. We have now reconstructed structural evolution sedimentation Shihuiyao–Gangzidian–Yuantai region southern Liaodong Peninsula, on overriding at margin, using geologic mapping, borehole data sets, field studies, zircon geochronology. In Shihuiyao area, based mapping drilling, top-to-the-NW thrust faults truncated earlier top-to-the-NE reverse then were subsequently overprinted by normal faults. Gangzidian 40 boreholes allowed us to construct eight cross sections revealing top-to-the-WNW/W from surface a depth least 0.5 km; show that extend basement subsequent dip subvertically. Yuantai system, thrusts, expressed as four windows duplex map scale, intruded late porphyry diabase sills. Integration three study areas identify one angular unconformity two phases later deformation (D1 D2). pre-D1 is marked foreland basin was filled with Middle Jurassic clastic rocks unconformably overlie Neoproterozoic Cambrian basement. D1 represented NE-SW–striking displaced or strata onto strata. D2 defined kilometer-scale, high-angle variable dips strikes. Although samples did not yield ideal maximum deposition ages (MDAs; ca. 246 Ma), dike sill system undeformed yielded U-Pb 124 117 Ma, respectively. Detrital geochronology MDA 129 Ma for Cretaceous deposits graben structures hanging walls formed Thus, events can be constrained Late Early Cretaceous, respectively between 174 after Ma). provenance detritus Wafangdian Formation suggests retroarc had source sheet Paleoproterozoic basement, minigraben (D2) possibly nearby rocks. Therefore, we fold-and-thrust belt Peninsula Toarcian–Aptian (ca. 174–124 Ma) age subduction. interpret synconvergent extension result slab flattening rollback during episodic plate.