First structural observation around the hinge of the Mongolian Orocline (Central Asia): Implications for the geodynamics of oroclinal bending and the evolution of the Mongol-Okhotsk Ocean

ABSTRACT To understand the origin of curved subduction zones has been one major challenges in plate tectonics. The Mongol-Okhotsk Orogen Central Asia is characterized by development a U-shaped oroclinal structure that was accompanied continuous oceanic plate. Therefore, it provides natural laboratory to why and how system became tightly curved. In this study, we provide first structural observation around hinge Mongolian Orocline (the Zag zone Mongolia), with an aim constrain geometry link structures orocline. Our results show rocks are occurrence penetrative foliation commonly subparallel bedding. Both bedding dominant fabric steeply dipping, their strike orientations map view follow simple curve Orocline, thus providing constraint for 3D A secondary parallel axial plane orocline not observed, indicating low degree orogen-parallel shortening during bending. Combining available geological geophysical data, conclude developed period Permian Jurassic, its linked slab. We consider low-strain bending likely resulted from along-strike variation trench retreat, which either triggered negative buoyancy slab, or driven relative rotation Siberian North China cratons. shed light on geodynamic mechanisms large-scale accretionary orogen.