Kayseraspis (Trilobita) from the Mungok Formation in Yeongwol area and its significance for the Lower Ordovician biostratigraphy and chronostratigraphy of the Taebaeksan Basin, Korea

Abstract

This study reports the occurrence of a trilobite Kayseraspis from the uppermost part of the Mungok Formation, Yeongwol Group, Korea. This genus has been known to occur in the upper part of the Dumugol Formation of the Taebaek Group and in the lower part of the Yeongheung Formation of the Yeongwol Group, and to indicate the lowermost Floian in the Taebaeksan Basin. However, the occurrence of Kayseraspis from the Mungok Formation and the comparison between the biostratigraphy of trilobites and graptolites suggest that the Kayseraspis-bearing faunas in Korea can be assigned to the upper Tremadocian. Accordingly, it is plausible that the base of the Floian may be positioned in the overlying strata, the Yeongheung Formation of the Yeongwol Group and the Makgol Formation of the Taebaek Group. In order to consolidate the Lower Ordovician chronostratigraphy of the Taebaeksan Basin, additional integrative studies on trilobites, graptolites, and conodonts are required.