Middle Jurassic–Early Cretaceous Intracontinental Compressional Deformation in Beishan, NW China: Insights From Structural Analysis, Seismic Reflection Profiling and Low-Temperature Thermochronology

Abstract

The Beishan Fold-Thrust Belt (BFTB), located in the southern part of the Central Asian Orogenic Belt (CAOB), underwent complex intracontinental deformation during the late Mesozoic and is a key tectonic unit for deciphering the remote effects of plate margin orogenesis. In this study, we selected the Yemaquan region in southern Beishan and conducted remote sensing interpretation, field mapping, seismic profile interpretation and low-temperature thermochronological analyses. The Permian pluton and Carboniferous strata thrust over the Jurassic strata and developed a series of SEE-trending thrusts, NE-striking left strike-slip faults, and several SEE- and NE-trending folds. This area experienced two directions (NE and NW) of compression deformation. Under the joint influence of compression stress and pluton blocking, fold structures related to strike-slip faults also developed (the Big Ear syncline). The above constituted the Yemaquan Fold-Thrust system (YFTS). Zircon (U-Th)/He (ZHe) data reveal cooling events at ∼175–165 Ma; combining the regional deformation, it may indicate the compression time. We concluded that the intracontinental deformation of the BFTB in the southern CAOB was driven by the far-field effects. NE compression is related to the closure of the Mongol–Okhotsk Ocean and the collision of the Lhasa–Qiangtang block; NW compression is related to westward subduction of the Paleo-Pacific plate.

Keywords

Beishan fold-thrust belt / intracontinental deformation / low-temperature thermochronology / Middle Jurassic–Early Cretaceous / seismic profile interpretation / structural analysis

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2026 Geological Society of China.