Replacement of graphic pegmatite by graphic albite-actinolite-clinopyroxene intergrowths (Mjavatn, southern Norway)

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doi: 10.1127/0935-1221/01/0013-0041
Authors:Nijland, Timo G.; Touret, Jacques L. R.
Author Affiliations:Primary:
Rooseveltlaan 964, Utrecht, Netherlands
Vrije Universiteit, Netherlands
Volume Title:European Journal of Mineralogy
Source:European Journal of Mineralogy, 13(1), p.41-50. Publisher: Schweizerbart'sche Verlagsbuchhandlung (Nägele u. Obermiller), Stuttgart, Federal Republic of Germany. ISSN: 0935-1221
Publication Date:2001
Note:In English. 39 refs.; illus., incl. 3 tables, sketch map
Summary:After peak metamorphism, the Sveconorwegian orogen in the Bamble sector underwent three separate events: the intrusion of granitic pegmatites, regional but locally acting metasomatism, and the intrusion of post tectonic granites. Metasomatism resulted in localized but widespread formation of albite-actinolite/clinopyroxene-quartz assemblages, with associated monomineralic veins of actinolite, Ti and other minerals. At one locality, the Mjavatn pegmatite, graphic quartz-K-feldspar intergrowths were replaced by graphic albite-actinolite-clinopyroxene intergrowths. The preservation of the graphic texture, implying conservation of volume, allows quantification of mass transfer. The application of Greens' composition-volume relationships for metasomatism (isocon diagrams) indicates massive influxes of Al, Na, Ca, Mg and Fe, accompanied by removal of K and some Si. Fluid inclusion studies demonstrate that NaCl rich brines were probably the transport medium. Metasomatism is estimated to have occurred at 350-450°C, 2-4 kbar. [R.A.H.]
Subsections:Metamorphism: thermal, metasomatic
Subjects:Actinolite; Albite; Amphibole group; Brines; Chain silicates; Chlorides; Clinoamphibole; Clinopyroxene; Feldspar group; Fluid phase; Framework silicates; Granites; Graphic texture; Halides; Igneous rocks; Intergrowths; Metasomatism; P-T conditions; Pegmatite; Plagioclase; Plutonic rocks; Pyroxene group; Quartz; Silica minerals; Silicates; Sodium chloride; Textures; Europe; Norway; Scandinavia; Western Europe; Mjavatn Norway
Abstract Numbers:01M/3487
Record ID:2001022807
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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