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Wagnerite in high-MgAl granulites of Anakapalle, Eastern Ghats Belt, India

Ralf Simmat and Karen Rickers
Wagnerite in high-MgAl granulites of Anakapalle, Eastern Ghats Belt, India
European Journal of Mineralogy (June 2000) 12 (3): 661-666

Abstract

Wagnerite (Mg,Fe,Ca,Mn) (sub 2) [PO (sub 4) (F,OH)] was found in high-MgAl granulite near Anakapalle, ca. 40 km W of Vishakhapatnam, East-India. This is the first reported occurrence of this mineral in the granulite-facies Eastern Ghats Belt (EGB). The high-MgAl granulite occurs as xenoliths of several meters in diameter within basic granulite. The rocks experienced Grenvillian ultra-high-temperature (UHT) metamoiphism (8 kbar: T > 900 degrees C). Still at high- grade conditions, the rock assemblage was intruded by large volumes of felsic melt (chamockite). Hence, the MgAl granulite became partially metasomatised. resulting in microdomains with variable Ca/(Ca+Mg) - ratios and different assemblages. Three principal wagnerite-bearing petrographic domains are distinguished. Within domains 1 & 2 (Ca/(Ca+Mg) approximately 0.02) wagnerite occurs as a stable phase of the UHT-assemblage and is the major phosphorus-bearing phase, while apatite is absent. In domain 3 (Ca/(Ca+Mg) approximately 0.25), wagnerite reacted with the intruding felsic melt and is now rimmed by apatite. Isokite, CaMg[PO (sub 4) F], was not observed and seems not to be stable at UHT-conditions. Wagnerite from Anakapalle is characterised by unusually high OH content (F/(F+OH) = 0.47-0.60) and low Ca content (0-0.5 wt% CaO). The Fe content in domain 3 is slightly higher (3-3.5 wt% FeO) compared to domains 1 & 2 (1.5-2.5 wt%).


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 12
Serial Issue: 3
Title: Wagnerite in high-MgAl granulites of Anakapalle, Eastern Ghats Belt, India
Affiliation: Universitaet Bonn, Mineralogisch-Petrologisches Institut, Bonn, Federal Republic of Germany
Pages: 661-666
Published: 200006
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 22
Accession Number: 2000-049408
Categories: Mineralogy of non-silicatesIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
N17°41'60" - N17°41'60", E83°17'60" - E83°17'60"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200016
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