Cognate gabbroic xenoliths from a tholeiitic subvolcanic sill complex; implications for fractional crystallization and crustal contamination processes

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Authors:Preston, R. J.; Bell, B. R.
Author Affiliations:Primary:
University of Glasgow, Department of Geology and Applied Geology, Glasgow, United Kingdom
Volume Title:Mineralogical Magazine
Source:Mineralogical Magazine, 61(3), p.329-349. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X
Publication Date:1997
Note:In English. 79 refs.; 5 tables
Summary:Intruded into the Palaeogene lava field and underlying Moine (Neoproterozoic) crystalline basement rocks around Loch Scridain, Isle of Mull, Scotland, is a suite of high-level, inclined, xenolithic sheets, ranging in composition from basalt, through andesite and dacite, to rhyolite. These sheets, associated with the Mull central volcano, were emplaced post 55 Ma. As well as numerous crustal xenoliths, the more basic members of the complex contain a diverse suite of ultrabasic and basic xenoliths. Xenolith types include feldspathic peridotite with cumulus olivine, pyroxenite, gabbro with cumulus plagioclase and cumulus clinopyroxene, and pure anorthosite. Mineralogical data, coupled with whole-rock major- and trace-element data from a small number of the xenoliths suggest that the xenoliths represent early-formed cumulates cognate with their host basalts. Sr and Nd isotope data from the xenoliths confirms the cognate origin, and also shows that the basic magmas suffered crustal contamination at an early stage.
Subjects:Absolute age; Anorthosite; Cenozoic; Dates; Feldspathoid rocks; Fractional crystallization; Igneous rocks; Inclusions; Intrusions; Magma contamination; Magmas; Nd/Nd; Paleogene; Peridotites; Plutonic rocks; Sills; Tertiary; Tholeiitic composition; Ultramafics; Xenoliths; Argyllshire Scotland; Europe; Great Britain; Hebrides; Inner Hebrides; Mull Island; Scotland; United Kingdom; Western Europe; Loch Scridain; Strathclyde region Scotland
Abstract Numbers:97M/3140
Record ID:1997070773
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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