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Zoisite-clinozoisite bearing pegmatites and their importance for decompressional melting in eclogites

Gerhard Franz and Eugene A. Smelik
Zoisite-clinozoisite bearing pegmatites and their importance for decompressional melting in eclogites
European Journal of Mineralogy (December 1995) 7 (6): 1421-1436

Abstract

Field relations, mineral textures and mineral compositions of pegmatite segregations in eclogites from Weissenstein, Munchberg Massif, Germany, indicate that partial melting occurred during isothermal decompression of the eclogite from 25 to approximately 10 kbar. The pegmatites have a leuco-tonalitic bulk composition; their matrix is rich in quartz and plagioclase with graphic intergrowths, whereas zoisite and phengitic white mica coexist with a silicate melt and occur as cm-sized euhedral phenocrysts with less abundant clinozoisite and calcic amphibole. The large zoisite crystals show complex zoning relationships, and are intergrown with narrow lamellae of clinozoisite, albite + or - calcic amphibole along (100) of the zoisite. The complex intergrowth textures and compositional relationships record at least four stages of mineral reaction and growth in the pegmatites during rapid uplift of the eclogites. The P-T path for pegmatite formation is constrained by experimental data on melting in tonalitic systems and zoisite-clinozoisite phase relations. Mass-balance calculations for H (sub 2) O production during uplift and amphibolitization of the eclogites indicate that the partial melting of approximately 2.5 vol.% would generate enough water-saturated melt to produce the volume of pegmatites found in the area.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 6
Title: Zoisite-clinozoisite bearing pegmatites and their importance for decompressional melting in eclogites
Affiliation: Technische Universitaet Berlin, Fachgebiet Petrologie, Berlin, Federal Republic of Germany
Pages: 1421-1436
Published: 199512
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 58
Accession Number: 1996-014815
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, 1 plate
Secondary Affiliation: Princeton University, USA, United States
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199606
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