Aspects of alkali feldspars in Cornubian granites

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Authors:Exley, C. S.; Edmondson, K. M.
Author Affiliations:Primary:
University of Keele Department of Geology, Keele, United Kingdom
Keith Edmonson, United Kingdom
Volume Title:Annual conference of the Ussher Society
Volume Authors:Williams, B.J., editor
Source:Proceedings of the Ussher Society, Vol.8(Part 2), p.117-123; Annual conference of the Ussher Society, United Kingdom, Jan. 1993, edited by B.J. Williams. Publisher: Ussher Society, Bristol, United Kingdom. ISSN: 0566-3954
Publication Date:1993
Note:In English. 76 refs.; illus., incl. 2 tables, geol. sketch map
Summary:The alkali feldspars in Cornubian granites are micro- and crypto- perthites in which the sodic phase is low albite and the potassic phase may be monoclinic orthoclase or triclinic microcline. Optical and XRD studies indicate that although microcline appears to be rare or absent from the biotite granites of the Scilly Isles, Land's End, Carnmenellis, St Austell and Hingston Down, it is more common in the biotite granites of Godolphin, Bodmin Moor and Dartmoor and in the Li-mica granites of Tregonning and St Austell. Since inversion of the monoclinic to triclinic K-feldspar and exsolution are complex processes in which low-T fluids are crucial, it is expected that both occurred during the subsolidus recrystallization stage and that in some areas the intrusion of Li- mica granite was a significant factor in influencing T. [R.A.H.]
Subjects:Alkali feldspar; Cryptoperthite; Feldspar group; Framework silicates; Granites; Igneous rocks; K-feldspar; Microperthite; Plutonic rocks; Silicates; Cornubian Batholith; Cornwall England; England; Europe; Great Britain; United Kingdom; Western Europe
Abstract Numbers:94M/3490
Record ID:1995010488
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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