Seminar

The South China Block (SCB) consists of the Yangtze and Cathaysia blocks that amalgamated in the early-middle Neoproterozoic time. Crustal generation and reworking of South China are closely associated with the global supercontinent cycle and global orogenic activities, although the paleo-geographic position of South China with respect to Rodinia and Gondwana supercontinents are still issues of hot debate. This project attempts to address this issue by conducting an intergrated study of the basement nature, provencance analysis using detrital zircon data, orogenic history constrained by geological and geochronological data in order to unravel a spatial and temporal coupling between tectono-magmatic evolution of the western Yangtze Block and the dispersal and assembly processes of the Rodinia, Gondwana and Pangea supercontinents. The petrogenesis of adakitic tonalites and high-K granites indicates an eastward subduction system with young and hot slab initially operated at ~860 Ma, and the local compressional regime switched to extensional setting at ~830 Ma. Such a Neoproterozoic subduction process along the western Yangtze Block of South China is much younger than the global Grenvillian orogeny, which supports a marginal position of South China with the Rodinia supercontinent at that period. The provenance analysis of the upper Neoproterozoic (Sinian)-middle Paleozoic sedimentary rocks suggest a long-term connection of South China-north India-Himalaya as well as a large similar-sourced drainage area until the dispersal of Gondwana in the late Devonian. Elemental and isotopic data constrain a slab break-off occurred at ~210 Ma that associated with the final closure of the Paleo-Tethys ocean in the western segment of the Yangtze Block, marking the last episode of orogenic magmatism in this region.