Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-23T16:10:11.115Z Has data issue: false hasContentIssue false
  • English
  • Français

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
Get access Rights & Permissions [Opens in a new window]

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

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