Conodonts from the Hwajeol Formation (Upper Cambrian) in the Seokgaejae area, southeast margin of the Taebaeksan Basin

The Cambrian-Ordovician succession crops out well in the Seokgaejae area of the southeastern margin of the Taebaeksan Basin. The Upper Cambrian Hwajeol Formation of the Seokgaejae section was studied to refine the conodont zones previously proposed and to correlate them with other areas. Based on euconodont species, four zones are recognized: a new and unnamed informal lowermost and the Proconodontus, Eoconodontus notchpeakensis and Cambrooistodus minutus zones in ascending order. This zonal framework is basically equivalent to that of southern (Lee and Lee, 1988; Lee, 2001, 2002) and northern (Lee, 1989, 1990, 2004) limbs of Paekunsan syncline. The four zones of Seokgaejae section are correlated with those of other parts of the world, including North China, North America and Australia. The study was unable to refine conodont zonation of the basal and uppermost parts of the formation. This may be related to either sealevel change or structural control on sediment deposition in the section.