Publication Date:
2016-09-11
Description:
This study presents structural and 40 Ar/ 39 Ar geochronological data from the southern part of the Longmen Shan fold-and-thrust belt that forms the eastern margin of the Tibetan Plateau. Investigations focused on hinterland ductile top-to-the-WNW shear deformation, which has been linked previously to late Cenozoic lower crustal flow. Consistent with previous studies, the sense of deformation is mapped as top-to-the-WNW in the Longmen Shan hinterland. The timing of the deformation is constrained by 40 Ar/ 39 Ar geochronological data of recrystallised minerals aligned along the shear foliation as late Cretaceous – earliest Paleogene, thus predating the inferred late Cenozoic crustal flow. This deformation is contemporaneous with SE-verging thrusting and loading along the Longmen Shan front, which formed a coeval ~2-3 km thick foredeep sequence along the southwestern margin of the Sichuan Basin. In the context of the regional geology, this tectonic configuration could result from either extrusion of a crustal wedge or back-thrust in a duplex. Compared to other orogens, where similar crustal configurations have been reported, it is speculated that the eastern Tibetan Plateau margin acquired thickened crust and highly elevated topography in late Cretaceous – earliest Paleogene time.
Print ISSN:
0278-7407
Electronic ISSN:
1944-9194
Topics:
Geosciences
Permalink
