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GEOREF RECORD

Intergrowths between anthophyllite, gedrite, calcic amphibole, cummingtonite, talc and chlorite in a metamorphosed ultramafic rock of the KTB pilot hole, Bavaria

Wolfgang Friedrich Mueller, Esther Schmadicke, Martin Okrusch and Ulrich Schussler
Intergrowths between anthophyllite, gedrite, calcic amphibole, cummingtonite, talc and chlorite in a metamorphosed ultramafic rock of the KTB pilot hole, Bavaria (in Special issue dedicated to the memory of Luciano Ungaretti, Maria Chiara Domeneghetti (prefacer))
European Journal of Mineralogy (April 2003) 15 (2): 295-307

Abstract

A metamorphosed ultramafic rock at a depth of 1382.36 m in the KTB borehole contains a Ca-amphibole-anthophyllite-chlorite-talc assemblage formed at approximately 630 degrees C/10 kbar under conditions of the high-P amphibolite facies; EPMA results are given. TEM studies revealed a complex lamellar intergrowth in the sequence talc --> anthophyllite --> anthophyllite/cummingtonite intercalations --> anthophyllite --> Ca-amphibole. This lamellar intergrowth is approximately 15 mu m wide, but individual cummingtonite lamellae intercalated with dominant anthophyllite are only 1 mu m wide. All the amphiboles share the b* and a* directions; anthophyllite and the monoclinic amphiboles are intergrown along (100); anthophyllite and talc are intergrown with (100) (sub Ath) (001) (sub Tlc) . Within one possible exception, cummingtonite has the space group C2/m. Anthophyllite displays chain multiplicity faults (010) while anthophyllite and cummingtonite chain arrangement faults (100). Microstructures suggest that anthophyllite was formed at the expense of cummingtonite that is interpreted as a high-T precursor phase testifying to a possible earlier, granulite-facies metamorphic stage. During the retrograde P-T path, on cooling presumably below 500-550 degrees C, anthophyllite exsolves platelets or lamellae of gedrite with hk0 composition planes.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 15
Serial Issue: 2
Title: Intergrowths between anthophyllite, gedrite, calcic amphibole, cummingtonite, talc and chlorite in a metamorphosed ultramafic rock of the KTB pilot hole, Bavaria
Title: Special issue dedicated to the memory of Luciano Ungaretti
Author(s): Mueller, Wolfgang FriedrichSchmadicke, EstherOkrusch, MartinSchussler, Ulrich
Author(s): Domeneghetti, Maria Chiaraprefacer
Affiliation: Technische Universitat Darmstadt, Institut fur Angewandte Geowissenschaften, Darmstadt, Federal Republic of Germany
Pages: 295-307
Published: 200304
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 57
Accession Number: 2003-032472
Categories: Mineralogy of silicatesIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N47°40'00" - N50°34'60", E09°30'00" - E13°45'00"
Secondary Affiliation: Universitat Erlangen, DEU, Federal Republic of GermanyUniversitat Wurzburg, DEU, Federal Republic of Germany
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200311
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