Early Cretaceous uplift of the Hangay Mountains (central Mongolia): A consequence of lithospheric foundering following oroclinal bending

The Hangay Mountains in central Mongolia, with their distinctive dome-shaped topography, exert a key influence on the modern climate of Mongolia. However, the geodynamic mechanisms responsible for their uplift remain poorly constrained. We report newly identified Early Cretaceous volcanism around the Hangay Mountains, temporally correlated with a major uplift phase as evidenced by thermochronological data. Geochemical analyses indicate that these volcanic rocks were derived from the lithospheric mantle and display elevated primitive mantle-normalized gadolinium/ytterbium (Gd/Yb) ratios, suggesting garnet stability in the source and thus melting depths exceeding ∼80 km. Given that the present-day lithosphere is only ∼70 km thick, this implies that lithospheric thinning or foundering must have occurred during or after Early Cretaceous magmatism. Integrating these findings with regional tectonic constraints, we propose that uplift of the Hangay Mountains was triggered by Early Cretaceous lithospheric foundering, following earlier orocline-driven lithospheric thickening. These insights provide a novel framework for understanding intracontinental magmatism and orogenesis.