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First find of coesite in the ultrahigh-pressure metamorphic area of the central Erzgebirge, Germany

Hans-Joachim Massonne
First find of coesite in the ultrahigh-pressure metamorphic area of the central Erzgebirge, Germany
European Journal of Mineralogy (June 2001) 13 (3): 565-570

Abstract

In the ultrahigh-pressure metamorphic area of the Saidenbach reservoir, Erzgebirge, where microdiamond-bearing gneiss occurs, coesite was found as inclusion in garnet and omphacite in an unusually well preserved eclogite. Most of the eclogite bodies of this area are thoroughly altered, with all omphacite transformed to plagioclase+amphibole symplectites. The coesite-bearing eclogite contains abundant dolomite in the matrix and as surprisingly large inclusions in garnet, which is another unusual feature compared to the many eclogites of the Saxonian Erzgebirge. Coesite is at least partly replaced by quartz showing a palisade texture. This pattern is accompanied by abundant radial cracks in the host minerals. Polycrystalline inclusions of equigranular quartz are also related to former coesite because some of them preserve minor coesite relics. In such cases, cracks in the host mineral are not more pronounced than around moderately transformed coesite. No K-feldspar was observed in inclusions consisting of partly replaced coesite. Thus, inclusions in omphacite of K-feldspar-quartz symplectites with abundant cracks around, which occur as well in eclogites near the Saidenbach reservoir, cannot be coesite pseudomorphs.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 13
Serial Issue: 3
Title: First find of coesite in the ultrahigh-pressure metamorphic area of the central Erzgebirge, Germany
Affiliation: Universitaet Stuttgart, Institut fuer Mineralogie und Kristallchemie, Stuttgart, Federal Republic of Germany
Pages: 565-570
Published: 200106
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 24
Accession Number: 2001-055181
Categories: Igneous and metamorphic petrologyMineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N50°10'00" - N51°00'00", E12°00'00" - E14°10'00"
N47°15'00" - N55°00'00", E05°49'60" - E15°00'00"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200117
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