Late Ordovician (Katian) Graptolites and Shelly Fauna from the Phu Ngu Formation, North-East Vietnam

Two new graptolite assemblages are identified from discrete intervals within the Phu Ngu Formation, Na Ri District, Bac Kan Province, north-east Vietnam. The graptolites occur in laminated mud/siltstones thought to be distal turbidite deposits. A low-diversity diplograptid sensu lato assemblage occurs mud-rich layers that interlaminated with silty and sandy horizons containing dendroid Dictyonema sp. This level also contains orthoconic nautiloids conulariids. few metres stratigraphically above, a second more diverse comprises single Dicellograptus, tentatively as D. flexuosus, together Climacograptus dorotheus Orthograptus truncatus pauperatus mud silt laminae yield brachiopods, nautiloids, conulariids, fragmentary trilobites, ostracods. ostracods include first East Asian occurrence of typically Baltic genus Kinnekullea, we describe species Kinnekullea gaia. suggest Late Ordovician Katian age, most probably Dicranograptus clingani Biozone, this being older than previous biostratigraphical constraints on Formation.