The Middle–Late Triassic fold–thrust belt on Liaodong Peninsula, North China Block: Implication for propagation of the Sulu orogeny toward the NE.

Processes related to the subduction of the South China Block beneath the North China Block and collision of the two blocks along the Qingling–Dabie–Sulu Orogenic Belt have been well studied. Different tectonic models have been proposed based on time constraints of metamorphism and magmatism and the uplift and exhumation of the HP–UHP metamorphic belt. However, propagation of the foreland thrust belt during the collision along the eastern North China Block has not been well documented, leading to a weak understanding of the collision process. The Liaodong Peninsula, 200–300 km northeast of the Sulu Orogenic Belt, is an essential area for the study of the foreland thrust belt. The rocks of the peninsula record at least three deformation events during the Mesozoic: D 1 NW–SE folds and thrust faults that were strongly overprinted by D 2 NE–SW thrusts and folds and D 3 large-scale regional extensional structures. According to detailed geological investigation and tectonic stress reconstruction using striations and dolomite twins, seven imbricate fold–thrust units in the Pulandian, Guiyunhua and Qingchengzi areas of Liaodong Peninsula were defined as representing the D 1 deformation. Together with thrust units in the southernmost part of Liaodong Peninsula and on the northern Jiaodong Peninsula, a top-to-the-NE propagated fold–thrust belt is proposed for the eastern North China Block. U Pb ages of zircons from three post-tectonic dyke samples in the Qingchengzi area, combined with previous geochronological results, constrain the D 1 deformation at 249–224 Ma. We suggest that the collision of the South China and North China blocks along the Sulu Orogenic Belt and the subduction of the South China Block beneath the North China Block resulted in NE–SW compression, formation of a detachment fault in the deep crust, and propagation of a fold–thrust belt toward the NE in the upper plate along the eastern margin of the North China Block. [Display omitted] • Middle-Late Triassic fold-thrust belts with top-to-the-NW kinematics were distinguished in Liaodong Peninsula. • New and previous age results constrain the fold-thrust deformation at 249–224 Ma. • The collision between the NCB and SCB is proposed to result in the propagation of foreland thrust belt in northeast China. [ABSTRACT FROM AUTHOR]