Early Cretaceous extensional reworking of the Triassic HP-UHP metamorphic orogen in Eastern China

Wei Lin (1) , Wenbin Ji (1) , Michel Faure (2) , Lin Wu (1) , Qiuli Li (1) , Yonghong Shi (3) , Urs Scharer (4) , Fei Wang (1, 5) , Qingchen Wang (1)

1 SKL - State Key Laboratory of Lithospheric Evolution
2 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
3 Department of Geology, School of Resource and Environment Engineering
4 GEOAZUR 7329 - Géoazur
5 CAS Center for Excellence in Tibetan Plateau Earth Sciences

Corresponding to the Early Mesozoic continental subduction between the North China Block (NCB) and the South China Block (SCB), the Tongbaishan-Hong’an- Dabieshan-Sulu massifs are famous for their HP-UHP metamorphism. More than 50% of the HP-UHP Orogenic Belt was significantly reworked by Early Cretaceous extensional tectonics. This Early Cretaceous event with a fast cooling period, at 130-120 Ma, superimposed on the Early Mesozoic HP-UHP orogenic belt and intensively changed the architecture of this orogen. Each individual segment documents different Early Cretaceous extensional structures, namely the central Tongbaishan domain is a metamorphic core complex (MCC) represented by an A-type non-cylindrical antiform; the central Dabieshan domain is a typical Cordilleran-type migmatite-cored MCC; the Southern Sulu UHP domain is a “wedge-shaped” structure exhumed by a simple detachment fault. These late stage extensional structures expose the previous HP-UHP orogenic belt as fragments along the NCB-SCB boundary. The geodynamic setting of this Early Cretaceous extensional tectonics along the HP-UHP orogen is a part of a 1000km-scale crustal extension belt that is widespread in eastern Eurasia continent from Trans-Baikal to the central part of SCB. Convective erosion or delamination of the mantle lithosphere might be considered as a possible mechanism for mantle removal.

Mots clés: Early Cretaceous; extensional structures; Late Triassic; HP-UHP orogen; superimposed orogens; Tongbaishan-Dabieshan-Sulu massifs; Eastern China

Domaines: Planète et Univers [physics]; Sciences de la Terre; Tectonique

Wei Lin, Wenbin Ji, Michel Faure, Lin Wu, Qiuli Li, et al.. Early Cretaceous extensional reworking of the Triassic HP-UHP metamorphic orogen in Eastern China. Tectonophysics, 2015, 662, pp.256-270. ⟨10.1016/j.tecto.2015.05.028⟩. ⟨insu-01167486⟩