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New occurrences of non-classical pyriboles formed during ocean-floor and regional metamorphism; estimated PT conditions of formation

Junji Akai, Akira Chiba, Hiromi Konishi, Masayuki Komatsu and Satoshi Matsubara
New occurrences of non-classical pyriboles formed during ocean-floor and regional metamorphism; estimated PT conditions of formation
European Journal of Mineralogy (December 1997) 9 (6): 1237-1255

Abstract

Ocean-floor metamorphism of basalt and dolerite in the Marianas Trench has given disordered pyriboles (clinopyroxenes and amphiboles) and also the non-classical pyriboles jimthompsonite and chesterite. The latter are compared with disordered pyriboles from the Shimokawa dolerite, Japan, and both occurrences are estimated to have been formed at 250-500 degrees C. Jimthompsonite and chesterite are also recorded from regionally metamorphosed greenstones in the Norseman-Wiluna belt of Western Australia, where they may have formed under conditions of high XCO (sub 2) at T up to 600 degrees C. The monoclinic pyriboles clinojimthompsonite and 'clinochesterite' are reported from regionally metamorphosed pelitic rocks at Norseman. HRTEM images are presented and the parageneses are discussed.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 9
Serial Issue: 6
Title: New occurrences of non-classical pyriboles formed during ocean-floor and regional metamorphism; estimated PT conditions of formation
Affiliation: Niigata University, Department of Geology, Niigata, Japan
Pages: 1237-1255
Published: 199712
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 55
Accession Number: 1999-013175
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch maps
S31°30'00" - S31°00'00", E121°30'00" - E122°00'00"
Secondary Affiliation: Ministry of International Trade and Industry, JPN, JapanNippon University, JPN, JapanNational Science Museum, 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: 199905
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