New Zealand Journal of Geology and Geophysics abstracts

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

J. L. COLEMAN*
P. A. R. SHANE
J. A. GRANT-MACKIE
M. R. GREGORY

Department of Geology
University of Auckland
Private Bag 92 019
Auckland, New Zealand

*Present address: Beca Carter Hollings & Ferner Ltd, 132 Vincent St, Auckland, New Zealand. Email: jcoleman@beca.co.nz

Abstract  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.

Keywords  Potaka tephra; Taupo Volcanic Zone; early Pleistocene; Mangatuna Formation; Gisborne; tephrostratigraphy; Euryapteryx geranoides; Euryapteryx curtus; Hyridella menziesi

With an appendix: Moa bones from the Matokitoki Gravel Member, Matokitoki Valley Road (Hitchen's) Quarry, Gisborne: T. H. Worthy, Palaeofaunal Surveys, 2A Willow Park Drive,

Masterton, New Zealand

New Zealand Journal of Geology & Geophysics, 2001, Vol. 44: 337-345

0028-8306/01/4402-0337 $7.00/0 (c) The Royal Society of New Zealand 2001

PDF file of entire paper: medium quality (886K); (scanned from paper original: notes about this process)

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