Structural style and kinematics of the Taihang-Luliangshan fold belt, North China: Implications for the Yanshanian orogeny

Abstract

The Middle-Late Jurassic to earliest Cretaceous fold belts of the Yanshanian orogen in North China remain enigmatic with respect to their coeval deformation histories and possible relationship to the contemporaneous Cordilleran-style margin of eastern Asia. We present geological mapping, structural data, and a >400-km-long, strike-perpendicular balanced cross section for the Taihang-Luliangshan fold belt exposed in the late Cenozoic central Shanxi Rift. The northeast-southwest-trending Taihang-Luliangshan fold belt consists of long-wavelength folds (~35-110 km) with ~1-9 km of structural relief cored by Archean and Paleoproterozoic metamorphic and igneous basement rocks. The fold belt accommodated ≥11 km of northwest-southeast shortening between the Taihangshan fault, bounding the North China Plain, in the east and the Ordos Basin in the west. Geological mapping in the Xizhoushan, a northeast-southwest-oriented range within the larger Taihangshan mountain belt, reveals two major basement-cored folds: (1) the Xizhou syncline, with an axial trace that extends for ~100 km and is characterized by a steep to overturned forelimb consistent with a southeast sense of vergence, and (2) the Hutuo River anticline, which exposes Archean-Paleoproterozoic rocks in its core that are unconformably overlain by shallowly dipping ( 1000 km from the nearest plate margin, corresponds with the termination of arc magmatism along the eastern margin of Asia, implying a potential linkage to the kinematics of the westward-subducting Izanagi (paleo-Pacific) plate.