Abstract
An E-to ENE-trending group of shear zones, the Inner Mongolian Shear Zone, is reported from the Central Asian-Mongolian mobile belt along the northern margin of the North China Block (NCB) in the mideastern part of Inner Mongolian Autonomous Region, China. The Inner Mongolian Shear Zone is subdivided into the Bayan Obo-Xar Moron River, Ondor Sum-Xilingol and Erenhot-Hegenshan shear zones from south to north, and all of them runs along the boundaries of previously distinguished tectonic zones. The Inner Mongolian Shear Zone, having sinistral strike-slip displacement component, contains sheared rocks originated from Late Paleozoic "Variscan" granites, but gives no evident deformation to Late Jurassic sedimentary rocks and Cretaceous "Yanshanian" granites. Considering that the "Variscan" granite occurs in both the Central Asian-Mongolian mobile belt and the NCB, we suggest that the Inner Mongolian Shear Zone rearranged the tectonic zones of the mobile belt in the latest stage or after its amalgamation with the NCB.
