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Hydrothermal alteration of biotite and plagioclase as inferred from intragranular oxygen isotope- and cation-distribution patterns

Jens Fiebig and Jochen Hoefs
Hydrothermal alteration of biotite and plagioclase as inferred from intragranular oxygen isotope- and cation-distribution patterns
European Journal of Mineralogy (February 2002) 14 (1): 49-60

Abstract

The alteration processes of biotite to chlorite and plagioclase to albite in hydrothermally altered granites of the St Blasien pluton, in the S Schwarzwald, were studied on a scale of < or = 250 mu m, using a combination of in situ delta (super 18) O and EPMA cationic compositions. Steep chemical and isotopic gradients occur between secondary and primary phases although both primary and secondary phases appear chemically and isotopically homogeneous. The delta (super 18) O- and cation-exchange between fluid and taking place along microfractures, micropores and grain boundaries. The breakdown of biotite to chlorite occurs once K (super +) is removed from biotite interlayers, probably accompanied by a redistribution of elements in both tetrahedral and octahedral sheets of the biotite. Albite is precipitated from dissolved plagioclase accompanying a restructuring of aluminosilicate tetrahedra within the plagioclase.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 14
Serial Issue: 1
Title: Hydrothermal alteration of biotite and plagioclase as inferred from intragranular oxygen isotope- and cation-distribution patterns
Affiliation: Geochemisches Institut der Universitaet, Gottingen, Federal Republic of Germany
Pages: 49-60
Published: 200202
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 42
Accession Number: 2002-023999
Categories: Isotope geochemistryMineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Update Code: 200209
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