Zircon U-Pb age and Lu-Hf isotopic compositions of the Permian marine volcanic rocks in Qianshan County, Jiangxi Province

Siliceousrocks of the Middle Permian Chetou Formation in Qianshan County, Jiangxi Province, are found to host several layers of tuff. By studying the zircon U-Pb age andLu-Hf isotopic compositions of tuff, this paper discussed the time of submarinevolcanic eruption, and diagenetic environment and diagenetic provenance. LA-ICP-MS zircon U-Pb weighted average age of tuff is 264.8±4.4Ma, indicating thatitformed in the extensional platform-basin environment of continental margin. This can serve as the direct proof to illustrate the occurrence of submarine volcanic eruption during this period. Two-phase Lu-Hf isotopic model age of tuff is1170～1670 Ma(average 1320 Ma), suggesting the Proterozoic age and representing that the diagenetic source may be associated with regional crustal remelting hyperplasia.