Abstract:

The Fanjingshan Mountain in northeast Guizhou Province is located in the southwestern segment of the Jiangnan orogenic belt, and consists of the early Neoproterozoic, late Neoproterozoic and Paleozoic strata. The early Neoproterozoic strata were strongly folded and then intruded by numerous muscovitebearing leucogranites. Both the folded strata and granites were unconformably covered by the Nanhua to Paleozoic strata. Insitu zircon U/Pb analyses reveal the emplacement age of 8385±15 Ma for the leucogranite. Geochemical studies demonstrate that the leucogranite is strongly peraluminous with low to medium CaO/Na2O values （009052） and high A/CNK value >11 （127130）, suggesting that they likely have resulted from a high temperature （>875 ℃） partial melting of clayrich psammitic rocks. The supposed super mantle plume started at ca. 840 Ma may have provided extra heat for the hightemperature partial melting. Insitu zircon Hf isotope suggests two stages of continent growth before the Neoproterozoic for the South China block.

Key words:  , South China；Fanjingshan；strongly peraluminous granite；zircon geochronology； mantle plume