Ammonium enrichment associated with hydrothermal activity in the granites of South-West England

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Authors:Hall, A.; Alderton, D. H. M.
Author Affiliations:Primary:
University of London, Department of Geology, Egham, United Kingdom
Volume Title:Proceedings of the Ussher Society
Source:Proceedings of the Ussher Society, Vol.8(Part 3), p.242-247. Publisher: Ussher Society, Bristol, United Kingdom. ISSN: 0566-3954
Publication Date:1994
Note:In English. 17 refs.; illus., incl. 6 tables, geol. sketch map
Summary:Hydrothermal alteration in the granites of SW England has resulted in substantial enrichment in ammonium, from an average of 36 ppm NH + 4 in the fresh granite to an average of 175 ppm NH + 4 in the hydrothermally altered varieties. Greisenization and K-feldspar enrichment both invariably lead to a large increase in ammonium content. Kaolinization by itself results in slight depletion, but is often superimposed on precursory alteration which has caused ammonium enrichment. Very high ammonium contents are found in elvan (rhyolite porphyry) dykes, which show up to 7% molar substitution of NH + 4 for K+. [R.A.H.]
Subjects:Alkali feldspar; Alteration; Ammonium; Chemical composition; Dikes; Feldspar group; Framework silicates; Granites; Greisenization; High temperature; Hydrothermal conditions; Igneous rocks; Intrusions; K-feldspar; Kaolinization; Metasomatism; P-T conditions; Plutonic rocks; Silicates; Temperature; England; Europe; Great Britain; South-West England; United Kingdom; Western Europe
Coordinates:N495600 N513000 W0023500 W0054500
Abstract Numbers:95M/1821
Record ID:2017056676
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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