Journal article

Quaternary tephra marker beds and their potential for palaeoenvironmental reconstruction on Chatham Island, east of New Zealand, southwest Pacific Ocean

Katherine A Holt, R Clel Wallace, Vincent E Neall, Barry P Kohn, David J Lowe



Tephras provide one of the most reliable methods of time control and synchronisation within Quaternary sequences. We report on the identification of two widespread rhyolitic tephras - the Kawakawa and Rangitawa tephras - preserved in extensive peat deposits on Chatham Island ~900 km east of New Zealand. The tephras, both products of supereruptions from the Taupo Volcanic Zone, occur as pale, fine-ash dominated layers typically 10-150 mm thick. Mineralogically they are dominated by rhyolitic glass, together with subordinate amounts of quartz, feldspar, hypersthene, hornblende, Fe-Ti oxides and zircon. Phlogopite/biotite was identified additionally in Rangitawa Tephra. Ages for each tephra wer..

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University of Melbourne Researchers


Funding Acknowledgements

We gratefully acknowledge and thank Dr Hamish Campbell (GNS Science) for his valued advice and logistical support in the field. We also thank the many Chatham Island and Pitt Island landowners who generously allowed unrestricted access to field sites. We acknowledge a number of very useful comments by anonymous referees, and the editor, which helped us improve the paper significantly. This work was in part funded by a Wellman Research Award of the Geological Society of New Zealand and a J. Hastie Scholarship to KAH. Support for sample irradiation at the HIFAR reactor in Australia was supplied through an Australian Institute of Nuclear Science and Engineering grant. The University of Melbourne thermochronology laboratory receives infrastructure support under the AuScope Program of NCRIS.