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Fluorapatite-monazite relationships in granulite-facies metapelites, Schwarzwald, southwest Germany

Published online by Cambridge University Press:  05 July 2018

D. E. Harlov ,
H. R. Marschall  and
M. Hanel
D. E. Harlov*
Affiliation:
GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany
H. R. Marschall
Affiliation:
Mineralogisches Institut, Universität Heidelberg, Im Neuenheimer Feld 236, D-69120 Heidelberg, Germany
M. Hanel
Affiliation:
Mineralogisches Institut, Universität Heidelberg, Im Neuenheimer Feld 236, D-69120 Heidelberg, Germany
*
E-mail: [email protected]
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Abstract

Fluorapatite grains with monazite inclusions and/or rim grains are described in two of four samples from a set of granulite-facies metapelites collected from the Variscan Schwarzwald, southern Germany. Fluorapatite in all four samples appears to have experienced some dissolution in the partial granitic melt formed during granulite-facies metamorphism. Monazite inclusions and rim grains are highly deficient in Th and are presumed to have formed from fluorapatite in association with partial melting during granulite-facies metamorphism. Monazite inclusions range from very small (<1 μm) and very numerous to small (1–2 μm), sometimes elongated, and less numerous; both types are evenly distributed throughout the fluorapatite grain interior. Monazite rim grains tend to be 1–10 μm. The formation of monazite inclusions is proposed to be due to dissolution-reprecipitation of the fluorapatite by the aqueous fluids inherent in the granitic melt. We propose that an increase in inclusion size coupled with a decrease in inclusion number is due to Ostwald ripening (interfacial energy reduction), which is greatly facilitated by the presence of an interconnected, fluid-filled porosity in the metasomatized fluorapatite. We further propose that monazite rim grains formed principally during partial dissolution of the fluorapatite in the granitic melt and to a lesser extent by partial dissolutionreprecipitation of the fluorapatite grain rim area allowing for the partial removal of (Y+REE). We conclude that fluorapatite, with monazite inclusions and rim grains, experienced partial dissolution in a H2O-rich peraluminous granitic melt compared to fluorapatite with monazite rim grains and no inclusions which reacted with a similar, relatively less H2O-rich melt. In contrast, monazite-free fluorapatite experienced partial dissolution in a comparatively H2O-poor, subaluminous, possibly peralkaline melt.

Keywords

fluorapatitemonazitemetapelitesgranulitesVariscanSchwarzwaldGermany
Type
Research Article
Information
Mineralogical Magazine , Volume 71 , Issue 2 , April 2007 , pp. 223 - 234
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2007

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Footnotes

†

Present address: Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, UK

References

Anders, E. and Grevesse, N. (1989) Abundances of the elements: Meteoritic and solar. Geochimica et Cosmochimica Acta, 53, 197–214.CrossRefGoogle Scholar
Green, T.H. and Watson, E.B. (1982) Crystallization of apatite in natural magmas under high pressure, hydrous conditions, with particular reference to ‘orogenic’ rock series. Contributions to Mineralogy and Petrology, 79, 96–105.CrossRefGoogle Scholar
Grew, E.S., Armbruster, T., Medenbach, O., Yates, M.G. and Carson, C.J. (2006) Stornesite-(Y), (Y,Ca)2Na6(Ca,Na)8(Mg,Fe)43(PO4)36, the first terrestrial Mg-dominant member of the fillowite group, from granulite-facies paragneiss in the Larsemann Hills, Prydz Bay, East Antarctica. American Mineralogist, 91, 1412–1424.CrossRefGoogle Scholar
Grew, E.S., Armbruster, T., Medenbach, O., Yates, M.G. and Carson, C.J. (2007) Chopinite, [(Mg,Fe)3](PO4)2, a new mineral isostructural with sarcopside, from a fluorapatite segregation in granulite-facies paragneiss, Larsemann Hills, Prydz Bay, East Antarctica. European Journal of Mineralogy, 19, 229–245.CrossRefGoogle Scholar
Hanel, M. and Wimmenauer, W. (1990) Petrographische Indizien für einen Deckenbau im Kristallin des Schwarzwaldes. Berichte der Deutschen Mineralogischen Gesellschaft, Beihefte zum European Journal of Mineralogy, 2, 1990, No.1, 89.Google Scholar
Hanel, M., Lippolt, H.J., Kober, B. and Wimmenauer, W. (1993) Lower carboniferous granulites in the Schwarzwald basement near Hohengeroldseck (SWGermany). Naturwissenschaften, 80, 25–28.CrossRefGoogle Scholar
Hanel, M., Montenari, M. and Kalt, A. (1999) Determining sedimentation ages of high-grade metamorphic gneisses by their palynological record: a case study in the northern Schwarzwald (Variscan Belt, Germany). International Journal of Earth Sciences, 88, 49–59.CrossRefGoogle Scholar
Hansen, E.C. and Harlov, D.E. (2007) Whole-rock, phosphate, and silicate compositional trends across an amphibolite- to granulite-facies transition, Tamil Nadu, India. Journal of Petrology (in press).CrossRefGoogle Scholar
Harlov, D.E. and Förster, H.-J. (2002) High-grade fluid metasomatism on both a local and regional scale: The Seward Peninsula, Alaska and the Val Strona di Omegna, Ivrea-Verbano zone, northern Italy. Part II: Phosphate mineral chemistry. Journal of Petrology, 43, 801–824.Google Scholar
Harlov, D.E. and Förster, H.-J. (2003) Fluid-induced nucleation of REE-phosphate minerals in apatite: Nature and experiment. Part II. Fluorapatite. American Mineralogist, 88, 1209–1229.Google Scholar
Harlov, D.E., Förster, H.-J. and Nijland, T.G. (2002a) Fluid-induced nucleation of REE-phosphate minerals in apatite: Nature and experiment. Part I. Chlorapatite. American Mineralogist, 87, 245–261.CrossRefGoogle Scholar
Harlov, D.E., Andersson, U.B., Förster, H.-J., Nyström, J.O., Dulski, P. and Broman, C. (2002b) Apatitemonazite relations in the Kiirunavaara magnetiteapatite ore, northern Sweden. Chemical Geology, 191, 47–72.CrossRefGoogle Scholar
Harlov, D.E., Wirth, R. and Förster, H.-J. (2005) An experimental study of dissolution-reprecipitation in fluorapatite: Fluid infiltration and the formation of monazite. Contributions to Mineralogy and Petrology, 150, 268–286.CrossRefGoogle Scholar
Harlov, D.E., Wirth, R. and Hetherington, C. (2007) The relative stability of monazite and huttonite at 300–900°C and 200–1000 MPa: Metasomatism and the propagation of metastable mineral phases. American Mineralogist (in press).Google Scholar
Harlov, D.E., Procházka, V., Förster, H.-J. and Matejka, D. (2008) Origin of monazite-xenotime-zirconfluorapatite assemblages in the peraluminous Melechov granite massif, Czech Republic. Mineralogy and Petrology (in press).Google Scholar
Harrison, T.M. and Watson, E.B. (1984) The behaviour of apatite during crustal anatexis: Equilibrium and kinetic considerations. Geochimica et Cosmochimica Acta, 48, 1468–1477.CrossRefGoogle Scholar
Jarosewich, E. and Boatner, L.A. (1991) Rare-earth element reference samples for electron microprobe analysis. Geostandards Newsletter, 15, 397–399.CrossRefGoogle Scholar
Kalt, A., Grauert, B. and Baumann, A. (1994a) Rb-Sr and U-Pb isotope studies on migmatites from the Schwarzwald (Germany): constraints on isotopic resetting during Variscan high-temperature metamorphism. Journal of Metamorphic Geology, 12, 667–780.CrossRefGoogle Scholar
Kalt, A., Hanel, M., Schleicher, H. and Kramm, U. (1994b) Petrology and geochronology of eclogites from the Variscan Schwarzwald (F.R.G.). Contributions to Mineralogy and Petrology, 115, 287–302.CrossRefGoogle Scholar
Kalt, A., Corfu, F. and Wijbrans, J. (2000) Time calibration of a P-T path from a Variscan hightemperature low-pressure migmatite-gneiss complex (Bayerische Wald, Germany) and the detection of inherited monazite. Contributions to Mineralogy and Petrology, 138, 143–163.CrossRefGoogle Scholar
Kober, B., Kalt, A., Hanel, M. and Pidgeon, R.T. (2004) SHRIMPdating of zircons from high-grade metasediments of the Schwarzwald/SW-Germany and implications for the evolution of the Moldanubian basement. Contributions to Mineralogy and Petrology, 147, 330–345.CrossRefGoogle Scholar
Kossmat, F. (1927) Gliederung des variszischen Gebirgsbaues. Abhand lungen des Sächsischen Geologischen Landesamtes, 1, 1–39.Google Scholar
Lippolt, H.J., Hradetzky, H. and Hautmann, S. (1994) K-Ar dating of amphibole-bearing rocks in the Schwarzwald, SW Germany: I. 40Ar/39Ar age constraints to Hercynian HT metamorphism. Neues Jahrbuch für Mineralogie Monatshefte, 1994(10), 433–448.Google Scholar
Marschall, H.R., Kalt, A. and Hanel, M. (2003) P-T evolution of a Varsican lower-crustal segment: a study of granulites from the Schwartzwald, Germany. Journal of Petrology, 44, 227–253.CrossRefGoogle Scholar
Montel, J.M. (1986) Experimental determination of the solubility of Ce-monazite in SiO2-Al2O3-K2O-Na2O melts at 800°C, 2 kbar, under H2O-saturated conditions. Geology, 14, 659–662.2.0.CO;2>CrossRefGoogle Scholar
Montel, J.M. (1993) A model for monazite/melt equilibrium and application to the generation of granitic magmas. Chemical Geology, 110, 127–146.CrossRefGoogle Scholar
Pan, Y. and Fleet, M.E. (2002) Composition of the apatite-group minerals: Substitution mechanisms and controlling factors. Pp. 13–49 in: Phosphates Geochemical, Geobiological and Materials Importance (Kohn, M.J., Rakovan, J. and Hughes, J.M., editors). Reviews in Mineralogy 48, Mineralogical Society of America, Washington, D.C. Google Scholar
Pan, Y., Fleet, M.E. and Macrae, N.D. (1993) Oriented monazite inclusions in apatite porphyroblasts from the Hemlo gold deposit, Ontario, Canada. Mineralogical Magazine, 57, 697–707.CrossRefGoogle Scholar
Pichavant, M., Montel, J.M. and Richard, L.R. (1992) Apatite solubility in peraluminous liquids: Experimental data and an extension of the Har rison-Watson model. Geochimica et Cosmochimica Acta, 56, 3855–3861.CrossRefGoogle Scholar
Rapp, R.P. and Watson, E.B. (1986) Monazite solubility and dissolution kinetics: implications for the thorium and light rare earth chemsitry of felsic magmas. Contributions to Mineralogy and Petrology, 94, 304–316.CrossRefGoogle Scholar
Rapp, R.P., Ryerson, F.J. and Miller, C.F. (1987) Experimental evidence bearing on the stability of monazite during crustal anatexis. Geophysical Research Letters, 14, 307–310.CrossRefGoogle Scholar
Stormer, J.C., Pierson, M.L. and Tacker, R.C. (1993) Variation of F and Cl X-ray intensity due to anisotropic diffusion in apatite during electron microprobe analysis. American Mineralogist, 78, 641–648.Google Scholar
von Gehlen, K., Kleinschmidt, G., Stenger, R., Wilhelm, H. and Wimmenauer, W. (editors) (1986) Kontinentales Tiefbohr programm der Bundesrepublik Deutschland (KTB), Ergebnisse der Vorerkundungsarbeiten Lokation Schwarzwald. 2nd KTB Colloquium Seeheim/Odenwald, 19–21 September 1986. Göttingen, Germany, 160 pp.Google Scholar
Watson, E.B. (1979) Apatite saturation in basic to intermediate magmas. Geophysical Research Letters, 6, 937–940.CrossRefGoogle Scholar
Watson, E.B. and Capobianco, C.J. (1981) Phosphorus and rare earth elements in felsic magmas: An assessment of the role of apatite. Geochimica et Cosmochimica Acta, 45, 2349–2358.CrossRefGoogle Scholar
Williams, M.L., Jercinovic, M.J., Gonclaves, P. and Mahan, K. (2006) Format and philosophy for collecting, compiling, and reporting microprobe ages. Chemical Geology, 225, 1–15.CrossRefGoogle Scholar
Wolf, M.B. and London, D. (1994) Apatite dissolution into peraluminous haplogranitic melts: An experimental study of solubilities and mechanisms. Geochimica et Cosmochimica Acta, 58, 4127–4145.CrossRefGoogle Scholar
Wolf, M.B. and London, D. (1995) Incongruent dissolution of REE- and Sr-rich apatite in peraluminous granitic liquids: Differential apatite, monazite, and xenotime solubilities during anatexis. American Mineralogist, 80, 765–775.CrossRefGoogle Scholar
Zack, T., Moraes, R. and Kronz, A. (2004) Temperature dependence of Zr in rutile: empirical calibration of a rutile thermometer. Contributions to Mineralogy and Petrology, 148, 471–488.CrossRefGoogle Scholar