Abstract: Abstract: Studies of the contact relationships of the Chert Member of the Amugang Group with its overlying and underlying strata and fossils discovered in limestone pebbles and limestone intercalations, as well as comparative study of the data of radiolarian fossils in cherts at Caimarco and Rongma indicate that the Chert Member is not the crystalline basement but Triassic in age and can be correlated with the Late Triassic Gyiza Group.