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Mineralogy and genesis of pyrochlore apatitite from The Good Hope Carbonatite, Ontario: A potential niobium deposit

Published online by Cambridge University Press:  04 October 2019

Roger H. Mitchell ,
Rudy Wahl  and
Anthony Cohen
Roger H. Mitchell*
Affiliation:
Department of Geology, Lakehead University, Thunder Bay, Ontario, CanadaP7B 5E1
Rudy Wahl
Affiliation:
The Wahl Prospecting Group, Box 1022, Marathon, Ontario, P0T 2E0
Anthony Cohen
Affiliation:
Plato Gold Corp 1240 Bay Street, Suite 800, Toronto, Ontario, M5R 2A7
*
*Author for correspondence: Roger H. Mitchell. Email: [email protected]
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Abstract

The Good Hope carbonatite is located adjacent to the Prairie Lake alkaline rock and carbonatite complex in northwestern Ontario. The occurrence is a heterolithic breccia consisting of diverse calcite, dolomite and ferrodolomite carbonatites containing clasts of magnesio-arfvedsonite + potassium feldspar, phlogopite + potassium feldspar together with pyrochlore-bearing apatitite clasts. The apatitite occurs as angular, boudinaged and schlieren clasts up to 5 cm in maximum dimensions. In these pyrochlore occurs principally as euhedral single crystals (0.1–1.5 cm) and can comprise up to 25 vol.% of the clasts. Individual clasts contain compositionally- and texturally-distinct suites of pyrochlore. The pyrochlores are hosted by small prismatic crystals of apatite (~100–500 μm × 10–25 μm) that are commonly flow-aligned and in some instances occur as folds. Allotriogranular cumulate textures are not evident in the apatitites. The fluorapatite does not exhibit compositional zonation under back-scattered electron spectroscopy, although ultraviolet and cathodoluminescence imagery shows distinct cores with thin (<50 μm) overgrowths. Apatite lacks fluid or solid inclusions of other minerals. The apatite is rich in Sr (7030–13,000 ppm) and rare earth elements and exhibits depletions in La, Ce, Pr and Nd (La/NdCN ratios (0.73–1.14) relative to apatite in cumulate apatitites (La/NdCN > 1.5) in the adjacent Prairie Lake complex. The pyrochlore are primarily Na–Ca pyrochlore of relatively uniform composition and minor Sr contents (<2 wt.% SrO). Irregular resorbed cores of some pyrochlores are A-site deficient (>50%) and enriched in Sr (6–10 wt.% SrO), BaO (0.5–3.5 wt.%), Ta2O5 (1–2 wt.%) and UO2 (0.5–2 wt.%). Many of the pyrochlores exhibit oscillatory zoning. Experimental data on the phase relationships of haplocarbonatite melts predicts the formation of apatite and pyrochlore as the initial liquidus phases in such systems. However, the texture of the clasts indicates that pyrochlore and apatite did not crystallise together and it is concluded that pyrochlores formed in one magma have been mechanically mixed with a different apatite-rich magma. Segregation of the apatite–pyrochlore assemblage followed by lithification resulted in the apatitites, which were disrupted and fragmented by subsequent batches of diverse carbonatites. The genesis of the pyrochlore apatitites is considered to be a process of magma mixing and not simple in situ crystallisation.

Keywords

pyrochloreapatiteapatititecarbonatitemagma mixing
Type
Article
Information
Mineralogical Magazine , Volume 84 , Issue 1 , February 2020 , pp. 81 - 91
Copyright
Copyright © Mineralogical Society of Great Britain and Ireland 2019

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Footnotes

Associate Editor: Sam Broom-Fendley

This paper is part of a thematic set arising from the 3rd International Critical Metals Conference (Edinburgh, May 2019).

References

Atencio, D., Andrade, M.B., Christy, A.G., Gieré, R. and Katashov, P.M. (2010) The pyrochlore supergroup of minerals: nomenclature. The Canadian Mineralogist, 48, 673–698.CrossRefGoogle Scholar
Boynton, W.V. (1985) Cosmochemistry of the rare earth elements: Meteorite studies. Pp. 115–152 in Rare Earth Element Geochemistry (Henderson, P., editor). Developments in Geochemistry 2, Elsevier, Amsterdam.Google Scholar
Chakhmouradian, A.R. and Zaitsev, A.N. (1999) Calcite-amphibole-clinopyroxene rock from the Afrikanda Complex, Kola Peninsula, Russia: mineralogy and a possible link to carbonatites: I, oxide minerals. The Canadian Mineralogist, 37, 177–198.Google Scholar
Chakhmouradian, A.R., Reguir, E.P., Kressall, R.D., Crozier, J., Pisiak, L.K., Sidhu, R. and Yang, P. (2015) Carbonatite-hosted niobium deposit at Aley, northern British Columbia (Canada): Mineralogy, geochemistry and petrogenesis. Ore Geology Reviews, 64, 642–666.CrossRefGoogle Scholar
Doroshkevich, A.G., Veksler, I.V., Klemd, R., Khromova, E.A. and Izbrodin, I.A. (2017) Trace element composition of minerals and rocks in the Belaya Zima carbonatite complex (Russia): implications for the mechanisms of magma evolution and carbonatite formation. Lithos, 284–285, 91–108.CrossRefGoogle Scholar
Hellstrom, J., Paton, C., Woodhead, J.D. and Hergt, J.M. (2008) Iolite: software for spatially resolved LA-(quad and MC) ICPMS analysis. P. 343 in: Laser Ablation ICP–MS in the Earth Sciences: Current Practices and Outstanding Issues (Sylvester, P., editor). Mineralogical Association of Canada Short Course series 40.Google Scholar
Hogarth, D.D. (1977) Classification and nomenclature of the pyrochlore group minerals. American Mineralogist, 62, 403–410.Google Scholar
Hogarth, D.D., Williams, C.T. and Jones, P. (2000) Primary zoning in pyrochlore group minerals from carbonatites. Mineralogical Magazine, 64, 683–697.CrossRefGoogle Scholar
Hornig-Kjarsgaard, I. (1998) Rare earth elements in sövitic carbonatites and their mineral phases. Journal of Petrology, 39, 2105–2121.CrossRefGoogle Scholar
Jago, B.C. and Gittins, J. (1993) Pyrochlore crystallization in carbonatites: the role of fluorine. South African Journal of Geology, 96, 149–159.Google Scholar
Kjarsgaard, B.A. and Mitchell, R.H. (2008) Solubility of Ta in the system CaCO3–Ca(OH)2–NaTaO3–NaNbO3 ± F at 0.1 GPa: Implications for the crystallization of pyrochlore group minerals in carbonatites. The Canadian Mineralogist, 46, 981–990.CrossRefGoogle Scholar
Lee, M.J., Lee, J.L., Garcia, D., Moutte, J., Williams, C.T.Wall, F. and Kim, Y. (2006) Pyrochlore chemistry from the Sokli phoscorite–carbonatite complex, Finland: implications for the genesis of phoscorite and carbonatite association. Geochemical Journal, 40, 1–13.CrossRefGoogle Scholar
Lumpkin, G.R. and Ewing, R.C. (1995) Geochemical alteration of pyrochlore group minerals: pyrochlore subgroup. American Mineralogist, 81, 1237–1248.CrossRefGoogle Scholar
Mitchell, R.H. (2004) Mineralogical and experimental constraints on the origins of niobium mineralization in carbonatites. Pp 201–215 in: Rare Element Geochemistry and Mineral Deposits (Linnen, R.L. and Samson, I.M., editors). Geological Association of Canada, Short Course Notes 17.Google Scholar
Mitchell, R.H. (2014) Cathodoluminescence of apatite. Pp.143–167 in: Cathodoluminescence and its Application to Geoscience (Coulson, I.M., editor). Mineralogical Association of Canada Short Course 45.Google Scholar
Mitchell, R.H. (2015) Primary and secondary niobium mineral deposits associated with carbonatites. Ore Geology Reviews, 64, 626–641.CrossRefGoogle Scholar
Mitchell, R.H. and Kjarsgaard, B.A. (2004) Solubility of niobium in the system CaCO3–Ca(OH)2–NaNbO3 at 0.1 GPa pressure. Contributions to Mineralogy and Petrology, 144, 93–97.CrossRefGoogle Scholar
Mitchell, R.H. and Platt, R.G. (1979) Nepheline-bearing rocks from the Poohbah Lake complex, Ontario: Malignites and malignites. Contributions to Mineralogy and Petrology, 69, 255–264.CrossRefGoogle Scholar
Mitchell, R.H., Chudy, T., McFarlane, C.R.M. and Wu, F.Y. (2017) Trace element and isotopic composition of apatite in carbonatites from the Blue River area (British Columbia, Canada) and mineralogy of associated silicate rocks. Lithos, 286–287, 75–91.CrossRefGoogle Scholar
Nasraoui, M. and Bilal, E. (2000) Pyrochlores from the Lueshe carbonatite complex (Democratic Republic of Congo): a geochemical record of different alteration stages. Journal of Asian Earth Sciences, 18, 237–251.CrossRefGoogle Scholar
Rukhlov, A.S. and Bell, K. (2010) Geochronology of carbonatites from the Canadian and Baltic Shields, and the Canadian Cordillera: clues to mantle evolution. Mineralogy and Petrology, 98, 11–54.CrossRefGoogle Scholar
Sage, R.P. (1987) Geology of Carbonatite-Alkalic Rock Complexes in Ontario: Prairie Lake Carbonatite Complex, District of Thunder Bay. Ministry of Northern Development and Mines, Ontario Geological Survey Study, 46, 91 pp.Google Scholar
Walter, B.F., Parsapoor, A., Braunger, S., Marks, M.A.W., Wenzel, T., Martin, M and Markl, G. (2018) Pyrochlore as a monitor for magmatic and hydrothermal processes in carbonatites from the Kaiserstuhl volcanic complex (SW Germany). Chemical Geology, 498, 1–16.CrossRefGoogle Scholar
Wang, L.X., Marks, M.A., Wenzel, T., Von Der Handt, A., Keller, J., Teiber, H. and Markl, G. (2014) Apatites from the Kaiserstuhl Volcanic Complex, Germany: new constraints on the relationship between carbonatite and associated silicate rocks. European Journal of Mineralogy, 26, 397–414.CrossRefGoogle Scholar
Witt, W.K., Hammond, D.P. and Hughes, M. (2019) Geology of the Ngualla carbonatite complex, Tanzania, and origin of the Weathered Bastaesite Zone REE ore. Ore Geology Reviews, 105, 28–54.CrossRefGoogle Scholar
Wu, F.Y., Mitchell, R.H., Li, Q.L., Zhang, C. and Yang, Y.H. (2017) Emplacement age and isotopic composition of the Prairie Lake carbonatite complex, Northwestern Ontario, Canada. Geological Magazine, 154, 217–236.CrossRefGoogle Scholar
Wyllie, P.J. and Biggar, G.M. (1966) Fractional crystallization in the “carbonatite systems” CaO–MgO–CO2–H2O and CaO–CaF2–P2O5–CO2–H2O. Pp. 92–105 in: International Mineralogical Association Papers, IMA Volume 1966, Mineralogical Society of India.Google Scholar
Zurevinski, S.E. and Mitchell, R.H. (2004) Extreme composition variation in pyrochlore group minerals at the Oka Carbonatite Complex. Québec: evidence of magma mixing? The Canadian Mineralogist, 42, 1159–1168.CrossRefGoogle Scholar
Zurevinski, S.E. and Mitchell, R.H. (2015) Petrogenesis of orbicular ijolites from the Prairie Lake complex, Marathon, Ontario: Textural evidence for rare processes of carbonatitic magmatism. Lithos, 239, 234–244.CrossRefGoogle Scholar
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