Cordierite in felsic igneous rocks; a synthesis

Saved in:
Authors:Clarke, D. B.
Author Affiliations:Primary:
Dalhousie University, Department of Earth Sciences, Halifax, NS, Canada
Volume Title:Mineralogical Magazine
Source:Mineralogical Magazine, 59(2), p.311-325. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X
Publication Date:1995
Note:In English. 54 refs.; 1 table
Summary:Cordierite is a characteristic mineral of many peraluminous felsic igneous rocks. A combination of T-P-X parameters, which overlap the stability conditions for felsic magmas, control its formation. Critical among these parameters are relatively low T, low P, and typically high (Mg+Fe2+), Mg/Fe2+, A/CNK, aAl2O3) , and fO2) . Spatial and textural information indicate that cordierite may originate in one of three principal ways in felsic igneous rocks: Type 1 Metamorphic: (a) xenocrystic (generally anhedral, many inclusions, spatial proximity to country rocks and pelitic xenoliths); (b) restitic (generally anhedral, high-grade metamorphic inclusions); Type 2 Magmatic: (a,b) peritectic (subhedral to euhedral, associated with leucosomes in migmatites or as reaction rims on garnet); (c) cotectic (euhedral, grain size compatibility with host rock, few inclusions); (d) pegmatitic (large subhedral to euhedral grains, associated with aplite-pegmatite contacts or pegmatitic portion alone); and Type 3 Metasomatic (spatially related to structural discontinuities in host, replacement of feldspar and/or biotite, intergrowths with quartz). Of these, Type 2a (peritectic) and Type 2c (cotectic) predominate in granitic and rhyolitic rocks derived from fluid-undersaturated peraluminous magmas, and Type 2d (pegmatitic) may be the most common type in fluid-saturated systems.
Subjects:Accessory minerals; Aplite; Cordierite; Felsic composition; Granites; Igneous rocks; Metamorphic rocks; Migmatites; P-T conditions; Peraluminous composition; Plutonic rocks; Restites; Rhyolites; Ring silicates; Silicates; Synthesis; Volcanic rocks; Xenocrysts
Abstract Numbers:95M/3429
Record ID:1995056085
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Tags: Add Tag
No Tags, Be the first to tag this record!
Be the first to leave a comment!
You must be logged in first