The Onset and Sedimentary Evolution of the Neoproterozoic Basin in South China: A case study of the Jiangnan sub-basin, northeastern Jiangxi

Key words: 
• south China /
• Jiangnan sub-basin /
• SHRIMP U-Pb zircon age /
• basin onset /
• sedimentary facies /
• rift basin

Abstract: The northeastern Jiangxi region lies in the southeastern part of the Jiangnan sub-basin in the Nanhua rift systems. Recent results of research from the regional geological survey have disclosed that the Nanhua strata of the Neoproterozoic in the Jiangnan sub-basin consist of the rift wedge-shaped sedimentary strata which are overlapped upon the metamorphic basement. More precisely, the continental volcanic rocks and volcaniclastic rocks from the Taoyuan Formation occur in the lowermost horizons of the wedge-shaped strata, representing the onset of a new round sedimentary cycle in the Jiangnan sub-basin of the Nanhua rift systems. The rhyolite samples collected from the Taoyuan Formation give a SHRIMP U-Pb age of 8 039 Ma for the crystalline zircons, an initial age of the Neoproterozoic basin in northeastern Jiangxi. The sedimentary facies analysis indicates that the sedimentation of the wedgeshaped strata in the Jiangnan sub-basin is mainly composed of: (1) continental volcanic rocks association; (2) alluvial-diluvial facies and fluvial-lacustrine facies association; (3) littoral-neritic facies to the bathyal facies association, and (4) tillite facies association. Comparing with the other sub-basins in southeastern margin of Yangtze Block, the sedimentation of the Jiangnan sub-basin is predominated by continental facies other than marine facies, but both of them bears a striking resemblance in sedimentary succession, all went through a onlap process from continental facies to marine facies, representing the sedimentary evolution of the typical rift basin following the breakup of the South China palaeocontinent during the Nanhuan of the Neoproterozoic.