摘要
This paper presents the field investigation and zircon U-Pb geochronological data for the Neoproterozoic basal conglomerates and the associated rocks at the Cangshuipu area (Yiyang), Hunan Province. The results show that the Neoproterozoic sequences in this area are composed of the Lengjiaxi, Cangshuipu and Banxi Groups with the Hengluchong conglomerates at the basal part. The Cangshuipu Group consists of the Lingjiawan (the red basal conglomerate) and Yinzhuba (terrestrial volcanic rock) Formations. Integrating with the other geological data, it is inferred that the Lengjiaxi Group might be deposited in Neoproterozoic rather than the previously proposed Meoproterozoic. The conglomerates of the Linjiawan Formation were most likely deposited in the interval of 864~835 Ma. This age probably represents the final amalgamation between the Yangtze and Cathaysian Blocks along the Jiangnan Mountains.