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Zirconium-bearing amphiboles from the Igaliko Dyke Swarm, South Greenland

Published online by Cambridge University Press:  05 July 2018

N. J. G. Pearce*
Affiliation:
Department of Geological Sciences, University of Durham, South Road, Durham DH1 3LE

Abstract

Sodic-calcic and alkali amphiboles from benmoreitic members of the Igaliko Dyke Swarm contain up to 4.13 wt. % ZrO2. It is proposed that Zr enters the amphiboles by a coupled substitution of

(where C = octahedral site and T = tetrahedral site) to produce the richest Zr-bearing amphiboles so far identified, with compositions ranging up to

These amphiboles crystallize at a late stage from magmas which were Zr-rich, highly peralkaline and hydrous, with an fo2 close to the synthetic QMF buffer. The incorporation of Zr in to the amphibole is a consequence of the failure of other Zr-bearing phases (such as zircon, baddeleyite, eudialyte) to crystallize.

Type
Mineralogy
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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Footnotes

*

Present address: Dept. of Geology, The University College of Wales, Aberystwyth, Dyfed SY23 3DB, Wales.

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