DISCUSSION ON THE AGE OF THE SHANGSI FORMATION IN THE LIGUANQIAO BASIN

There is a conformitive relation between the Shangsi and the Hctao formations. The Shangsi Formation is an overlying sequence with a certain thickness and distinct litho-characteristics, deposited during the basin shrinking rather than a product of lateral facies change within the Hetao Formation. According to priority, the term of the Shangsi Formation should be reserved. Since the fossils produced in the upper section of the Hetao Formation attributed to the age of late Eocene, the authors of this paper think it suitabe to define the age of the Shangsi Formation as Oligoeene.