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GEOREF RECORD

Origin of coexisting wuestite, Mg-Fe and REE phosphate minerals in graphite-bearing fluorapatite from the Rumburk Granite

Wolfgang Seifert, Rainer Thomas, Dieter Rhede and Hans-Juergen Foerster
Origin of coexisting wuestite, Mg-Fe and REE phosphate minerals in graphite-bearing fluorapatite from the Rumburk Granite
European Journal of Mineralogy (August 2010) 22 (4): 495-507

Abstract

An unique mineral assemblage (graphite + wustite + wagnerite + sarcopside + monazite-(Ce) + xenotime-(Y) + chlorite), included within fluorapatite, was identified in the S-type Caledonian Rumburk granite, Czech Republic. Graphite appears as a finely dispersed phase within apatite and other minerals and as interstitial flakes in the rock matrix; it is probably of restitic origin related to anatectic melting. Wagnerite, wustite, monazite-(Ce), and xenotime-(Y) are commonly intergrown, indicating their cogenetic formation. Magmatic fluids, equilibrated with graphite, caused partial metasomatism of early-formed fluorapatite and triggered the formation of wustite and the various phosphate-mineral inclusions within alteration domains in the apatite host (by dissolution-reprecipitation). The formation of wustite was facilitated by the coexisting graphite, which maintained the required low oxygen fugacity, and the apatite host, which provided a silica-undersaturated environment. The lower temperature limit of the alteration event is defined by the wustite stability field (>570 degrees C). Representative mineral formulae are Fe (super 2+) (sub 0.67) Fe (super 3+) (sub 0.22) [] (sub 0.11) O (wustite), (Mg (sub 0.87) Fe (sub 0.97) Mn (sub 0.15) ) (sub Sigma =1.99) (PO (sub 4) )(F (sub 0.64) OH (sub 0.36) ) (wagnerite), and (Fe (super 2+) (sub 2.27) Mg (sub 0.45) Mn (sub 0.19) ) (sub Sigma =2.91) (PO (sub 4) ) (sub 2) (sarcopside). The results of this study improve knowledge about the natural occurrences of wustite and wagnerite and their paragenetic relations; they permit additional insights into mineral-forming processes in granitic magmas under strongly reducing conditions. This paper provides the first record of wustite occurring in granite.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 22
Serial Issue: 4
Title: Origin of coexisting wuestite, Mg-Fe and REE phosphate minerals in graphite-bearing fluorapatite from the Rumburk Granite
Affiliation: Deutsches GeoForschungsZentrum, Potsdam, Federal Republic of Germany
Pages: 495-507
Published: 201008
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 55
Accession Number: 2010-081051
Categories: Igneous and metamorphic petrologyMineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, geol. sketch map
N50°57'00" - N50°57'00", E14°33'00" - E14°33'00"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201043
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