Late Cadomian intermediate minor intrusions of Guernsey, Channel Islands; the microdiorite group

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Authors:Roach, R. A.; Lees, G. J.
Author Affiliations:Primary:
Keele University, Department of Geology, Keele, United Kingdom
Volume Title:Proceedings of the Ussher Society
Source:Proceedings of the Ussher Society, Vol.8(Part 3), p.224-230. Publisher: Ussher Society, Bristol, United Kingdom. ISSN: 0566-3954
Publication Date:1994
Note:In English. Read at the annual conference of the Ussher Society, Jan. 1994. 21 refs.; illus., incl. 1 table, geol. sketch map
Summary:A distinctive group of intermediate dykes cuts many components of the S metamorphic complex of W Guernsey and post-dates all units of the Cadomian N igneous complex. They are, however, cut by albite dolerite dykes. The microdiorite dykes are generally fine-grained porphyritic rocks, in some places exhibiting a flow fabric; some of them show evidence of a post-emplacement deformation and all have been subjected to varying degrees of low-T metamorphism. The primary mineralogy is essentially zoned intermediate plagioclase and magmatic amphibole ± quartz and biotite. These microdiorites form a coherent petrochemical group with clear calc-alkaline character; they represent the final phase of Cadomian magmatism on Guernsey. [R.A.H.]
Subjects:Calc-alkalic composition; Chemical composition; Chemical ratios; Dikes; Diorites; Igneous rocks; Intrusions; Microdiorite; Mineral composition; Plutonic rocks; Porphyritic texture; Textures; Trace elements; English Channel Islands; Europe; Guernsey; United Kingdom; Western Europe; Upper Cadomian
Coordinates:N492500 N493200 W0023100 W0025000
Abstract Numbers:95M/2137
Record ID:2017056673
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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