CRETACEOUS OSTRACODS FROM THE CHANGBA FORMATION IN THE DANXIA BASIN OF NORTHERN GUANGDONG PROVINCE

The Cretaceous ostracods were collected from 39 sample of borehole and outcrop of the Changba Formation in the Danxia Basin,northern Guangdong Province. Totally 50 ostracod species in 15 genera have been recognized,and out of which 47 species in 15 genera are figured herein,including 3 new species described. The ostracod fauna is subdivided into 2 assemblages: (1)Mongolocypris-Cypridea-Darwinula assemblage, from the Member 2 of Changba Formation.This assemblage is very similar to that yielded from the Quantou-Yaojia Formation of the Songliao Basin,the Jiadian Formation in Hubei Province, the Lanxi Formation in Zhejiang Province, and therefore they are also close to each other in geological age.It is obviously different from that of the middle-late Late Cretaceous of the Nanxiong Basin.The most common genera are Mongolocypris, Cypridea and Darwinula. The former reached its most flourishing state,large individual size,displaying a high diversity and a large quantity, with less appearances of the genus Talicypridea. Talicypridea is the index fossil for the middle-late Late Cretaceous in the Far East. Most of its known taxa are frequantly seen during the Late Cretaceous in China,while a few are extensively distributed in the Early Cretaceous. According to the features of ostracod,the Member 2 of the Changba Formation could be assigned to the early Late Cretaceous(i.e.Cenomanian). (2) Cypridea-Altanicypris-Candona assemblage, from the Member 4 of Changba Formation, which belongs to the middle Late Cretaceous(i.e.Turonian).