Conodonts from the ‘Lower Limestone’ and Haengmae Formation in western Jeongseon, Korea and their implication for lithostratigraphic correlation

The Middle Ordovician conodont fauna consisting of six species was recovered from the upper part of the Lower Limestone and the middle part of the overlying Haengmae Formation in the western Jeongseon area, Korea. Two conodont biozones are established for this interval, the Erraticodon tangshanensis Interval Zone for the upper part of the Lower Limestone and the Eoplacognathus suecicus Range Zone for the uppermost part of the Lower Limestone to the middle part of the Haengmae Formation. The first biozone is comparable to the Darriwilian (early Dw2) Tangshanodus tangshanensis-Histiodella holodentata Zone in North China and the Tangshanodus tangshanensis Zone in South Korea. The second biozone corresponds to the eponymous Dar-riwilian (late Dw2) zones recognized in North China and Korea. The biostratigraphy indicates that the Lower Limestone and Haengmae Formation in the western Jeongseon area is correlated only with lower and middle parts of the Jeongseon Limestone in the central and eastern Jeongseon area, and thus the Jeongseon Limestone is not a valid lithostratigraphic unit for the western Jeongseon area.