Abstract:The Yunkai area, which spreads along the boundary between Guangdong and Guangxi, is a terrain with independent structure unit and evolution history. The features of the rigid basement, egde faults, sedimentary formation, alkalic basic volcanism, metamorphic facies series and geophysical anomalies of this area indicate that the Yunkai terrain was formed in the geosynclinal-type rift caused by the rigid crust extension at Sinian period of upper Proterozoic subera.

Key words: Yunkai rift　edge faults　sedimentary formation　evolution histor