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The origin of scoriaceous rock associated with dacitic ignimbrite in the Mirannie-Mount-Rivers district, New South Wales, Australia

Published online by Cambridge University Press:  05 July 2018

Beryl Nashar
Affiliation:
Department of Geology, The University of Newcastle, N.S.W., and Broken Hill Proprietary Co. Ltd., Australia
Noel C. White
Affiliation:
Department of Geology, The University of Newcastle, N.S.W., and Broken Hill Proprietary Co. Ltd., Australia

Summary

From field and petrographic evidence, some scoriaceous rock from the upper ignimbrite horizon of the Mount Rivers Volcanic Member of the Carboniferous Dyrring Formation in the Mirannie-Mount-Rivers District, New South Wales, Australia, is believed to have a recent origin.

By heating unaltered dacitic ignimbrite in a furnace it was possible to produce in the temperature range 600-1230°C changes in the rock similar to those observed in specimens of scoria collected in the field. Thus a temperature range for the alterations was established. Two possible sources of heat axe suggested as being responsible for the production of the scoriaceous rock, namely a bush fire and a lightning strike, with a preference for the former.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1976

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