The upper mantle and deep crust beneath the British Isles; evidence from inclusions in volcanic rocks

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doi: 10.1144/gsjgs.140.1.0105
Authors:Upton, B. J. G.; Aspen, P.; Chapman, Neil A.
Author Affiliations:Primary:
Univ. Edinburgh, Dep. Geol., Edinburgh EH9 3JW, United Kingdom
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 140(1), p.105-121. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:1983
Note:In English. 2 p. refs.
Summary:Coarse-grained inclusions in Upper Palaeozoic alkali basalts, occurring in over 60 localities in the British Isles, include samples of the underlying mantle and lower crust. The ultramafic assemblages imply an extremely heterogeneous upper mantle involving a tectonized spinel lherzolite and harzburgite matrix cut by bodies of wehrlite, websterite, pyroxenite and assorted kaersutite- and biotite-rich ultramafic rocks. Associated megacrysts include anorthoclase, sanidine, clinopyroxene, kaersutite, Ti-biotite, garnet, Ti-magnetite, Mg-ilmenite, apatite, zircon and corundum; these originated partly from disaggregation of pegmatitic alkaline felsic rocks, pyroxenites, hornblendites and glimmerites. Plagioclase-pyroxene granulites are probably samples of the lower crust, with quartzofeldspathic gneisses perhaps derived from shallower levels in a chemically-zoned crust. A high-grade (granulite facies) feldspathic basement is inferred to underlie all the major Scottish structural provinces, including the Midland Valley and Southern Uplands; anorthosite xenoliths imply that anorthositic rocks compose some part of the 'basement' in S and central Scotland. [R.A.H.]
Subjects:Alkali basalts; Basalts; Carboniferous; Crust; Igneous rocks; Inclusions; Lower Permian; Mantle; Paleozoic; Permian; Petrology; Upper mantle; Volcanic rocks; Xenoliths; Europe; Ireland; United Kingdom; Western Europe
Abstract Numbers:83M/3786
Record ID:1986084913
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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