The Delaney Dome Formation, Connemara, W. Ireland, and the Geochemical Distinction of Ortho- and Para-Quartzofeldspathic Rocks

Bernard Elgey Leake and Dharm Singh
Department of Geology, University of Glasgow, Glasgow G12 8QQ; also Department of Geology, University of Western Australia, Nedlands, WA 6009
Department of Geology, University of Glasgow, Glasgow G12 8QQ

Abstract: A number of geochemical plots are suggested by means of which metamorphosed quartzofeldspathic sedimentary rocks (meta-sandstones, meta-arkoses, quartzites, etc.) can be distinguished from their metamorphosed igneous mineralogical analogues (metarhyolite, meta-granite, etc.). These plots are applied to an enigmatic, partly mylonitized, quartzofeldspathic series, the Delaney Dome Formation, which is involved in a major thrust zone. The formation is shown to be igneous and is probably a meta-rhyolite. The plots proposed should have general application in identifying the precursors of both high-grade and low-grade quartzofeldspathic rocks of unknown origin.

Keywords: meta-rhyolite • quartzofeldspathic rocks • Delaney Dome Formation • Ireland

Mineralogical Magazine; June 1986 v. 50; no. 356; p. 205-215; DOI: 10.1180/minmag.1986.050.356.03
© 1986, The Mineralogical Society
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