Identification of a distal ignimbrite in Quaternary strata of the Gisborne area: Implications for ignimbrite dispersal, stratigraphy, and paleofauna

The exceptionally widespread 1 Ma ignimbrite associated with the Potaka (= Kidnappers) tephra has been identified near Gisborne, some 170 km east of its source in the Taupo Volcanic Zone. This extends its known dispersal and demonstrates radial emplacement to great distances from the vent. The ignimbrite occurs near the base of the Mangatuna Formation in the Gisborne area, and provides direct correlation for these structurally and geographically isolated sediments to other Quaternary sequences in the eastern and southern North Island. The ignimbrite provides age control for a variety of paleofauna, including at least two fossil moa species, one similar to Euryapteryx geranoides and another to E. curtus. This is one of the few well-constrained moa occurrences beyond the radiocarbon age range to be documented.