Ostracods from the Upper Cretaceous–Paleocene Jiaozhou Formation of Jiaozhou, Shandong, China and their biostratigraphic significance

Abstract

Late Mesozoic–Cenozoic non-marine deposits are well developed in the Jiaolai Basin, eastern Shandong Province, China, yielding abundant fossils including ostracods. In order to further understand the geological settings of the basin during the Late Cretaceous–Paleogene, three boreholes (JK-1, JZK-01 and JZK-02) were drilled in the city of Jiaozhou. Nine genera and sixteen species (including six indeterminate species) of ostracods are described from the Jiaozhou Formation in the three boreholes, including Cypridea, Mongolocypris, Talicypridea, Candona, Eucypris, Cyprois, Porpocypris, Sinocypris and Timiriasevia. Of these, Porpocypris sphaeroidalis Guan, 1978 is reported from northern China for the first time, indicating that this species has great potential to be an indicator of the K/Pg boundary. Correlation of these species with the known Cretaceous–Paleogene ostracod assemblages suggests that the age of the Jiaozhou Formation could be latest Cretaceous–Paleocene in borehole JK-1, Campanian–Maastrichtian in borehole JZK-01, and Maastrichtian–Danian in borehole JZK-02. The exact position of K/Pg boundary, however, is unavailable for the present in the Jiaozhou Formation from boreholes JK-1 and JZK-01.