THE ESTABLISHMENT OF THE NEOPROTEROZOIC TANTOU GROUP IN CENTRAL JIANGXI

This is a sequence of strata composed mainly of pyroclastic rocks with acid volcanic lava in central Jiangxi, which overlies comformably black phyllite of the Mesoproterozoic Shenshan Group and underlies meta polymictic conglomerate or conglomeratic phyllite of the early Sinian Gujia Formation. This sequence of strata is called the Tantou Group. This group may be divided in ascending order into the Tiandong, Huoxialing and Shangshi Formations, with a total thickness of nearly 2 000 m. The two formations in the upper part contain abundant microflora fossils, and their age is mostly Jixianian Sinian. The lava of the Tiandong Formation in the lower part of the group has a zircon U P age of （1 027 ±36） Ma.From above it may be considered that the age of the Tantou Group is Neoproterozoic, ranging between 1 050 and 740 Ma.