A DISCUSSION OF THE STRATA CONTAINING THE QIYANGIA FAUNA IN NORTHERN GUIZHOU AND THEIR AGE

The Regional Geological Survey Brigade of Guizhou Province found the Qiyangia fauna—a characteristic Early Jurassic pelecypod fauna of South China—a few years ago when the brigade conducted regional survey work on a scale of 1:20000 in the western part of northern Guizhou. The Qiyangia fauna not only occurs in the lower part of the Ziliujing Group containing the Lufengosaurus fauna but also is found in great abundance in the upper part of the"Xiangxi Group", and is associated with fish fossils resembling the "Yumushan fish group" of Hunan. The pelecypods Qiyangia, Hunanella and Apseudocardinia of the fauna are different from the Late Triassic Indosinion-Permophorus assemblage in the lower part of the"Xiangxi Group"and the Middle Jurassic Lamprotula （Eol.）-Pseudocardinia assemblage in the upper part of the Ziliujing Group. In the light of that, the author suggests that the age of the strata containing the Qiyangia fauna be assigned to Early Jurassic and correlated with the Guanyintan Formation of southwestern Hunan, the Xiangxi Formation of western Hubei and the Lower Lufeng Formation of eastern Yunnan, respectively.