Graptolite biostratigraphy and its correlation of the Mungok and Yeonghung formations at Yeongwol area, Korea

Abstract

Based on graptolites from the Mungok and Yeonghung formations at Yeongwol, Korea and recent taxonomy on graptolites, the previous three graptolite zones are refined as theAnisograptus matanensis, Adelograptus cf.tenellus, Callograptus spp. zones, and two zones are firstly proposed for the Tremadocian rocks in the area: theParadelograptus antiquus andAorograptus victoriae zones, in ascending order: TheAnisograptus matanensis Zone yieldsAnisograptus matanensis indicating an early Tremadoc age. TheAdelograptus cf.tenellus Zone is erected by the occurrence ofAdelograptus cf.tenellus andPsigraptus jacksoni which represent lowermost Late Tremadocian in age. TheCallograptus spp. Zone yielding plenty of dendroids includingCallograptus andDendrograptus, is tentative but useful to correlate with other rocks in the Sino-Korean Block. TheParadelograptus antiquus Zone is recognized by the occurrence ofParadelograptus antiquus andClonograptus aureus and is correlated with the middle Late Tremadoc of Yukon, Canada. TheAorograptus victoriae Zone consists mainly ofAorograptus victoriae and subordinately ofKiaerograptus andClonograptus and corresponds to the eponymous zones elsewhere. The boundary between the Mungok and the Yeonghung formations consists of ribbon rock and grainstone to packstone facies of the Mungok Formation and laminated dolomite, argillaceous limestone, and wackestone to grainstone facies of the Yeonghung Formation and is drawn within theAorograptus victoriae Zone which indicates middle Late Tremadocian.