THE QIXIA FORMATION IN SOUTHERN GUIZHOU AND ITS UPPER AND LOWER BOUNDARIES

The Qixia Formation in Southern Guizhou is of earliest Permian age. Actor- ding to the sedimentary facies, the formation may be divided into open-sea carbonate platform facie and shallow marine shelf facies. The carbonate platform facies is subdivisible into the Huoshui-Shazisha type and the Ginglong-Huagon type.There is a trough zone between the Platform and the shelf, which is named the Ziyun-Saiwa type. Fossils of the Qixia Formation include Misellina, Nankinella, Parafusvlina, Protomichelina, Wentzollophyllum, Yatsengia, etc. These genera first appeared in early Qixia time, but their morphologies are more primitive than those in late Qixia time; besides the fossils of early Qixia age are associated with those from the Maping Formation, such as Rogosofusulina. In late Qixia time there appeared new elements, for example, Pseudodotiolina and Caocellina.Thus early and late Qixia time may be distinguished.In this paper the Misellina claudine zone and the Wentzollophyllum volzi zone are used to mark the beginning of late Qixia-aged deposition.