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Experimental study of the high-pressure stability limit of osumilite in the system K (sub 2) O-MgO-Al (sub 2) O (sub 3) -SiO (sub 2) ; implications for high-temperature granulites

Yoichi Motoyoshi, Bastiaan J. Hensen and Makoto Arima
Experimental study of the high-pressure stability limit of osumilite in the system K (sub 2) O-MgO-Al (sub 2) O (sub 3) -SiO (sub 2) ; implications for high-temperature granulites
European Journal of Mineralogy (June 1993) 5 (3): 439-445

Abstract

In piston-cylinder solid-media experiments, Mg-osumilite breaks down to enstatite, sillimanite, K-feldspar and quartz at P 11-12 kbar over a T range of 950-1100 degrees C. The reaction has a flat dP/dT slope. The reactions osumilite = cordierite + enstatite + K- feldspar + quartz and osumilite = sapphirine + enstatite + K- feldspar + quartz limit osumilite stability at lower and higher T respectively. Natural osumilite is invariably more magnesian than coexisting ferromagnesian minerals, and the Mg end-member can be predicted to have the greatest stability field. Thus osumilite, like cordierite, can only occur in continental crust of normal thickness. In the Napier complex, Enderby Land,Antarctica, where osumilite occurs on a regional scale, an inferred 'isograd' marking the disappearance of osumilite is the trace of a nearly isobaric surface at a palaeo-depth of approx 35 km. On this surface osumilite breaks down to orthopyroxene, sillimanite, K- feldspar and quartz.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 5
Serial Issue: 3
Title: Experimental study of the high-pressure stability limit of osumilite in the system K (sub 2) O-MgO-Al (sub 2) O (sub 3) -SiO (sub 2) ; implications for high-temperature granulites
Affiliation: National Institute of Polar Research, Yokohama, Japan
Pages: 439-445
Published: 199306
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 26
Accession Number: 1993-017371
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Secondary Affiliation: University of New South Wales, AUS, AustraliaYokohama National University, JPN, Japan
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 1993
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