The aureole of the Rum Tertiary igneous complex, Scotland

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doi: 10.1144/0016-764901-098
Authors:Holness, M. B.; Isherwood, C. E.
Author Affiliations:Primary:
University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, Vol.160(Part 1), p.15-27. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2003
Note:In English. 40 refs.; illus., incl. 4 tables, geol. sketch map
Summary:The aureole of the Tertiary Rum Igneous Complex formed at shallow levels in amphibolite-facies migmatitic Lewisian gneisses and previously unmetamorphosed Precambrian arkose of the Torridonian Group. Contact metamorphism of arkose resulted in the breakdown of chlorite-rich cement and detrital muscovite, feldspar disordering, and melting. A simplified thermal model shows that magma chamber filling may have occurred over a few hundred years. Contact metamorphism of Lewisian gneiss, exposed only within the Main Ring Fault of the complex, resulted in the breakdown of hornblende to pyroxene, plagioclase, biotite and magnetite. Biotite in high-grade gneisses is replaced by feldspar and orthopyroxene. Extensive melting of the gneiss occurred only locally. Prominent migmatitic structures predate contact metamorphism. Significant mobility of Fe, Mg and Al occurred in the aureole, probably effected via circulation of aqueous fluids confined to the metamorphic peak within the Main Ring Fault but extending to lower temperatures outside. Significant differences between cooling rate of rocks within and outside the Main Ring Fault are inferred from textural observations. These probably relate to a combination of a relatively extended metamorphic event for the innermost rocks and a greater cooling influence of circulating aqueous fluids on the outermost rocks.
Subsections:Metamorphism: thermal, metasomatic
Subjects:Amphibolite facies; Aureoles; Chemical reactions; Contact metamorphism; Deformation; Facies; Fluid dynamics; Gneisses; Intrusions; Lewisian; Melting; Meta-arkose; Metamorphic rocks; Metamorphism; Metasedimentary rocks; Mineral assemblages; Mineral composition; P-T conditions; Precambrian; Proterozoic; Textures; Upper Precambrian; Europe; Great Britain; Hebrides; Highland region Scotland; Inner Hebrides; Inverness-shire Scotland; Rhum; Scotland; United Kingdom; Western Europe; Main Ring Fault
Coordinates:N570000 N570000 W0061200 W0061200
Abstract Numbers:03M/2224
Record ID:2003018477
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
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