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Quartz-albite rocks of ash-fall origin

Published online by Cambridge University Press:  01 May 2009

Evan C. Leitch
Evan C. Leitch
Affiliation:
Department of Geology and Geophysics, University of Sydney, N.S.W. 2006, Australia
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Summary

Thin beds composed mainly of quartz and albite occur interstratified with epiclastic rocks in a thick marine Early Permian sequence in the eastern part of the New England Fold Belt, eastern Australia. The sequence has suffered very low grade regional metamorphism and the quartz-albite rocks retain few primary textural features. A pyroclastic origin for these rocks is argued on the basis of inherited sedimentary characters and their distinctive mineralogical and chemical composition, and it is suggested that they accumulated as glass-rich ash-fall tuffs. The present chemical composition of the quartz-albite rocks suggests the tuffs may have initially altered to zeolitic assemblages. Similar quartz-albite rocks, perhaps misidentified as chert or siliceous siltstone, probably occur in other low-grade metamorphic sequences, the progenitors of which accumulated adjacent to active magmatic arcs.

Type
Articles
Information
Geological Magazine , Volume 118 , Issue 1 , January 1981 , pp. 83 - 88
Copyright
Copyright © Cambridge University Press 1981

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References

Boles, J. R. & Coombs, D. S. 1975. Mineral reactions in zeolitic Triassic tuff, Hokonui Hills, New Zealand. Bull. geol. Soc. Am. 86 163–73.2.0.CO;2>CrossRefGoogle Scholar
Ewart, A. 1963. Petrology and petrogenesis of the Quaternary pumice ash in the Taupo area, New Zealand. J. Petrology 4 392–431.CrossRefGoogle Scholar
Gulbrandsen, R. A. & Cressman, E. R. 1960. Analcime and albite in altered Jurassic tuff in Idaho and Wyoming. J. Geol. 68 458–63.CrossRefGoogle Scholar
Ledbetter, M. T. & Sparks, R. S. J. 1979. Duration of large-magnitude explosive eruptions deduced from graded bedding in deep-sea ash layers. Geology 7 240–4.2.0.CO;2>CrossRefGoogle Scholar
Leitch, E. C. 1969. Igneous activity and diastrophism in the Permian of New South Wales. Spec. Publ. geol. Soc. Austr. 2 21–37.Google Scholar
Leitch, E. C. 1976. Zonation of low-grade metamorphic rocks, Nambucca Slate Belt, northeastern New South Wales. J. geol. Soc. Austr. 22 413–22.CrossRefGoogle Scholar
Leitch, E. C. 1978. Structural succession in a Late Palaeozoic slate belt and its tectonic significance. Tectonophysics 47 311–23.CrossRefGoogle Scholar
Leitch, E. C. & Cawood, P. A. 1980. Olistoliths and debris flow deposits at ancient consuming plate margins: an eastern Australian example. Sediment. Geol. 25 5–22.CrossRefGoogle Scholar
Loughnan, F. C. & Ray, A. S. 1979. The Reid's Mistake Formation at Swansea Head, New South Wales. J. geol. Soc. Austr. 25 473–81.CrossRefGoogle Scholar
McKelvey, B. C. & Gutsche, H. W. 1969. The geology of some Permian sequences on the New England Tablelands, New South Wales. Spec. Publ. geol. Soc. Austr. 2 13–20.Google Scholar
Ninkovich, D. P. & Donn, W. L. 1976. Explosive Cenozoic volcanism and climatic implications. Science, N.Y. 194 899–906.CrossRefGoogle ScholarPubMed
Sparks, R. S. J. & Walker, G. P. L. 1977. The significance of vitric-enriched air-fall ashes associated with crystal-enriched ignimbrites. J. Volcanol. Geotherm. Res. 2 329–41.CrossRefGoogle Scholar
Wright, T. L. 1968. X-ray and optical study of alkali feldspar. II. An X-ray method for determining the composition and structural state from measurements of 2θ values for three reflections. Am. Mineral. 53 88–104.Google Scholar
Wright, T. L. & Stewart, D. B. 1968. X-ray and optical study of alkali feldspar. I. Determination of composition and structural state from refined unit-cell parameters and 2V. Am. Mineral. 53 38–87.Google Scholar