Hostname: page-component-78c5997874-v9fdk Total loading time: 0 Render date: 2024-11-10T09:07:58.843Z Has data issue: false hasContentIssue false
  • English
  • Français

Rare-earth mobility as a result of multiple phases of fluid activity in fenite around the Chilwa Island Carbonatite, Malawi

Published online by Cambridge University Press:  26 January 2018

Emma Dowman ,
Frances Wall ,
Peter J. Treloar  and
Andrew H. Rankin
Emma Dowman*
Affiliation:
Department of Geography and Geology, Kingston University, Kingston-upon-Thames KT1 2EE, UK Camborne School of Mines, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK The Natural History Museum, Cromwell Road, London SW7 5BD, UK
Frances Wall
Affiliation:
Camborne School of Mines, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK The Natural History Museum, Cromwell Road, London SW7 5BD, UK
Peter J. Treloar
Affiliation:
Department of Geography and Geology, Kingston University, Kingston-upon-Thames KT1 2EE, UK
Andrew H. Rankin
Affiliation:
Department of Geography and Geology, Kingston University, Kingston-upon-Thames KT1 2EE, UK
*
* E-mail: emma@abdm.co.uk
Get access Rights & Permissions [Opens in a new window]

Abstract

Carbonatites are enriched in critical raw materials such as the rare-earth elements (REE), niobium, fluorspar and phosphate. A better understanding of their fluid regimes will improve our knowledge of how to target and exploit economic deposits. This study shows that multiple fluid phases penetrated the surrounding fenite aureole during carbonatite emplacement at Chilwa Island, Malawi. The first alkaline fluids formed the main fenite assemblage and later microscopic vein networks contain the minerals of potential economic interest such as pyrochlore in high-grade fenite and rare-earth minerals throughout the aureole. Seventeen samples of fenite rock from the metasomatic aureole around the Chilwa Island carbonatite complex were chosen for study. In addition to the main fenite assemblage of feldspar and aegirine ± arfvedsonite, riebeckite and richterite, the fenite contains micro-mineral assemblages including apatite, ilmenite, rutile, magnetite, zircon, rare-earth minerals and pyrochlore in vein networks. Petrography using a scanning electron microscope in energy-dispersive spectroscopy mode showed that the rare-earth minerals (monazite, bastnäsite and parisite) formed later than the fenite feldspar, aegirine and apatite and provide evidence of REE mobility into all grades of fenite. Fenite apatite has a distinct negative Eu anomaly (determined by laser ablation inductively coupled plasma mass spectrometry) that is rare in carbonatite-associated rocks and interpreted as related to pre-crystallization of plagioclase and co-crystallization with K-feldspar in the fenite. The fenite minerals have consistently higher mid REE/light REE ratios (La/Sm ≈ 1.3 monazite, ≈ 1.9 bastnäsite, ≈ 1.2 parisite) than their counterparts in the carbonatites (La/Sm ≈ 2.5 monazite, ≈ 4.2 bastnäsite, ≈ 3.4 parisite). Quartz in the low- and medium-grade fenite hosts fluid inclusions, typically a few micrometres in diameter, secondary and extremely heterogeneous. Single phase, 2- and 3-phase, single solid and multi solid-bearing examples are present, with 2-phase the most abundant. Calcite, nahcolite, burbankite and baryte were found in the inclusions. Decrepitation of inclusions occurred at ∼200°C before homogenization but melting-temperature data indicate that the inclusions contain relatively pure CO2. A minimum salinity of ∼24 wt.% NaCl equivalent was determined. Among the trace elements in whole-rock analyses, enrichment in Ba, Mo, Nb, Pb, Sr, Th and Y and depletion in Co, Hf and V are common to carbonatite and fenite but enrichment in carbonatitic type elements (Ba, Nb, Sr, Th, Yand REE) generally increases towards the inner parts of the aureole. A schematic model contains multiple fluid events, related to first and second boiling of the magma, accompanying intrusion of the carbonatites at Chilwa Island, each contributing to the mineralogy and chemistry of the fenite. The presence of distinct rare-earth mineral microassemblages in fenite at some distance from carbonatite could be developed as an exploration indicator of REE enrichment.

Keywords

feniterare earthsfluid inclusionsapatite
Type
Research Article
Information
Mineralogical Magazine , Volume 81 , Issue 6 , December 2017 , pp. 1367 - 1395
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2017

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Andersen, T. (1989) Carbonatite-related contact metasomatism in the Fen complex, Norway: effects and petrogenetic implications. MineralogicalMagazine, 53, 395–414.Google Scholar
Andrade, F., Möller, P., Lüders, V., Dulski, P. and Gilg, H. (1999) Hydrothermal rare earth elements mineralisation in the Barra do Itapirauã carbonatite, southern Brazil: behaviour of selected trace elements and stable isotopes (C,O). Chemical Geology, 155, 91–113.CrossRefGoogle Scholar
Bailey, D. (1977) Lithospheric control of continental rift magmatism. Geological Society of London Journal, 133, 103–106.CrossRefGoogle Scholar
Belousova, E., Griffin, W., O’Reilly, S. and Fisher, N. (2002) Apatite as an indicator mineral for mineral exploration: trace-element compositions and their relationship to host rock type. Journal of Geochemical Exploration, 76, 45–69.CrossRefGoogle Scholar
Brimhall, G. and Crerar, D. (1987) Ore fluids: magmatic to supergene. Pp. 235–321 in: Thermodynamic Modeling of Geologic Materials: Minerals, Fluids, and Melts (I.S.E. Carmichael and H.P. Eugster, editors). Reviews inMineralogy, Vol. 17. Mineralogical Society of America, Washington, D.C.CrossRefGoogle Scholar
Broom-Fendley, S., Wall, F., Brady, A., Gunn, A., Chenery, S. and Dawes, W. (2013) Carbonatite-hosted late-stage apatite as a source of heavy rare earth elements? 12th SGA Biennial Meeting, Uppsala, Sweden. Society for Geology Applied to Mineral Deposits.Google Scholar
Bühn, B. (2008) The role of the volatile phase for REE and Y fractionation in low-silica carbonate magmas: implications from natural carbonatites, Namibia. Mineralogy and Petrology, 92, 453–470.CrossRefGoogle Scholar
Bühn, B. and Rankin, A. (1999) Composition of natural, volatile-rich Na-Ca-REE-Sr carbonatitic fluids trapped in fluid inclusions. Geochimica et Cosmochimica Acta, 63, 3781–3797.CrossRefGoogle Scholar
Bühn, B., Rankin, A., Radtke, M., Haller, M. and Knöchel, A. (1999) Burbankite, a (Sr,REE,Na,Ca)-carbonate in fluid inclusions from carbonatite-derived fluids: Identification and characterisation using Laser Raman spectroscopy, SEM-EDX and synchrotron micro-XRF analysis. American Mineralogist, 84, 1117–1125.CrossRefGoogle Scholar
Bühn, B., Wall, F. and Le Bas, M. (2001) Rare-earth systematics of carbonatitic fluorapatites and their significance for carbonatite magma evolution. Contributions to Mineralogy and Petrology, 141, 572–591.CrossRefGoogle Scholar
Candela, P. (1997) A review of shallow, ore-related granites: textures, volatiles and ore metals. Journal of Petrography, 38, 1619–1633.Google Scholar
Candela, P. and Blevin, P. (1995) Physical and chemical magmatic controls on the size of magmatic-hydrothermal ore deposits. Pp. 2–37 in: Giant Ore Deposits, II (A. Clark, editor). QMinEx Associates and Queen’s University, Kingston, Ontario, Canada.Google Scholar
Carmody, L. (2012) Geochemical Characteristics of Carbonatite-Related Volcanism and Subvolcanic Metasomatism at Oldoinyo Lengai, Tanzania. PhD Thesis, University College of London, Earth Sciences, London.Google Scholar
Chakhmouradian, A. and Reguir, E. (2013) REE partitioning between crystals and melts: beyond the test tube. 125th Anniversary of GSA. Geological Society of America, Denver, USA.Google Scholar
Chakhmouradian, A. and Wall, F. (2012) Rare earth elements: minerals, mines, magnets (and more). Elements, 8, 333–340.CrossRefGoogle Scholar
Cooper, A. and Paterson, L. (2008) Carbonatites from a lamprophyric dyke swarm, South Westland, New Zealand. The Canadian Mineralogist, 46, 753–777.CrossRefGoogle Scholar
Coulson, I. and Chambers, A. (1996) Patterns of zonation in rare-earth-bearing minerals in nepheline syenites of the North Qôroq Centre, South GREEnland. The Canadian Mineralogist, 34, 1163–1178.Google Scholar
Dowman, E. (2014) Mineralisation and Fluid Processes in the Alteration Zone Around the Chilwa Island and Kangankunde Carbonatite Complexes, Malawi. PhD Thesis, Kingston University, London.Google Scholar
Drake, M. and Weill, D. (1972) New rare earth element standards for electron microprobe analysis. Chemical Geology, 10, 179–181.CrossRefGoogle Scholar
Drüppel, K., Hoefs, J. and Okrusch, M. (2005) Fenitising processes induced by ferrocarbonatite magmatism at Swartbooisdrif,, NW Namibia. Journal of Petrology, 46, 377–406.CrossRefGoogle Scholar
Eby, G., Roden-Tice, M., Krueger, H., Ewing, W., Faxon, E. and Woolley, A. (1995) Geochronology and cooling history of the northern part of the Chilwa Alkaline Province, Malawi. Journal of African Earth Sciences, 20, 275–288.CrossRefGoogle Scholar
Endurance Gold Corporation. (2012) Bandito REENiobium Project, Yukon. Retrieved 27 Sept 2013 from www.endurancegold.com: http://www.endurancegold.com/s/Bandito.asp Google Scholar
Endurance Gold Corporation. (2013) The Bandito Intrusive Related Rare Earth-Niobium (Nickel- Copper) Project, Yukon. Retrieved 18 May 2016 from EnduranceGold.com: http://www.endurancegold.com/bandito/edg_bandito_jan_2013.Pdf Google Scholar
Finch, A. (1995) Metasomatic overprinting by juvenile, igneous fluids, Igdlerfigsalik, South GREEnland. Contributions to Mineralogy and Petrology, 122, 11–24.CrossRefGoogle Scholar
Finch, A. and Walker, F. (1991) Cathodoluminescence and microporosity in alkali feldspar from the Blå Måne Sø perthosite, South GREEnland. Mineralogical Magazine, 55, 583–589.CrossRefGoogle Scholar
Garson, M. (1965) Carbonatites in Southern Malawi. The Government Printer, Zomba, Malawi.Google Scholar
Garson, M. and Campbell Smith, W. (1958) Chilwa Island. The Government Printer, Zomba, Malawi.Google Scholar
Gieré, R. (1996) Formation of rare earth minerals in hydrothermal systems. Pp. 105–150 in: Rare Earth Minerals (W.F. Jones, editor). Chapman & Hall, London.Google Scholar
Goodenough, K., Upton, B. and Ellam, R. (2000) Geochemical evolution of the Ivigtut granite, South GREEnland: a fluorine-rich “A-type” intrusion. Lithos, 51, 205–221.CrossRefGoogle Scholar
Haggerty, S. (1991) Oxide textures – a mini-atlas. Pp. 129–220 in: Oxide Minerals: Petrologic and Magnetic Significance (D.H. Lindsley, editor). Reviews in Mineralogy and Geochemistry, 25. Geological Society of America, Washington, DC.Google Scholar
Harlov, D. (2011) Formation of monazite and xenotime inclusions in fluorapatite megacrysts, Gloserheia Granite Pegmatite, Froland, Bamble Sector, southern Norway. Mineralogy and Petrology, 102, 77–86.CrossRefGoogle Scholar
Harlov, D. and Förster, H.-J. (2003) Fluid-induced nucleation of (Y + REE)-phosphate minerals within apatite: Nature and experiment. Part II. Fluorapatite. American Mineralogist, 88, 1209–1229.CrossRefGoogle Scholar
Hayward, C. and Jones, A. (1991) Cathodoluminescence petrography of Middle Proterozoic extrusive carbonatite from Qasiarsuk, South GREEnland. Mineralogical Magazine, 55, 591–603.CrossRefGoogle Scholar
Hetherington, C., Harlov, D. and Budzyń, B. (2010) Experimental metasomatism of monazite and xenotime mineral stability, REE mobility and fluid composition. Mineralogy and Petrology, 99, 165–184.CrossRefGoogle Scholar
Hogarth, D. (1989) Pyrochlore, apatite and amphibole: distinctive minerals in carbonatite. Pp. 105–148 in: Carbonatites: Genesis and Evolution (K. Bell, editor). Unwin Hyman, London.Google Scholar
Hoskin, P., Kinny, P.,Wyborn, D. and Chappell, B. (2000) Identifying accessory mineral saturation during differentiation in granitoid magmas: an integrated approach. Journal of Petrology, 41, 1365–1396.CrossRefGoogle Scholar
Hughes, J. and Rakovan, J. (2002) The crystal structure of apatite. Pp. 1–12 in: Phosphates (Kohn, M.L., Rakovan, J. and Hughes, J.M., editors). Reviews in Mineralogy and Geochemistry, 48. Mineralogical Society of America and the Geochemical Society, Chantilly, Virginia, USA.Google Scholar
Kempe, U. and Götze, J. (2002) Cathodoluminscence (CL) behaviour and crystal chemistry of apatite from rare-metal deposits. Mineralogical Magazine, 66, 151–172.CrossRefGoogle Scholar
Keppler, H. (2003) Water solubility in carbonatite melts. American Mineralogist, 88, 1822–1824.CrossRefGoogle Scholar
Keppler, H. and Wyllie, P. (1990) Role of fluids in transport and fractionation of uranium and thorium in magmatic processes. Nature, 348, 531–533.CrossRefGoogle Scholar
Kresten, P. and Morogan, V. (1986) Fenitisation at the Fen complex, southern Norway. Lithos, 19, 27–42.CrossRefGoogle Scholar
Kröner, A., Willner, A., Hegner, E., Jaeckel, P. and Nemchin, A. (2001) Single zircon ages,, PT evolution and Nd isotopic systematics of high-grade gneisses in southern Malawi and their bearing on the evolution of the Mozambique belt in southeastern Africa. Precambian Research, 109, 257–291.CrossRefGoogle Scholar
Le Bas, M. (1977) Carbonatite-Nephelinite Volcanism. J Wiley & Sons, New York.Google Scholar
Le Bas, M. (1981) Carbonatite magmas. Mineralogical Magazine, 44, 133–140.CrossRefGoogle Scholar
Le Bas, M. (1987) Nephelinites and carbonatites. Pp. 53–84 in: Alkaline Igneous Rocks (U.B. Fitton, editor). Blackwell, Oxford.Google Scholar
Le Bas, M. (1999) Sövite and alvikite: two chemically distinct calciocarbonatites C1 and C2. South African Journal of Geology, 102, 109–121.Google Scholar
Le Bas, M. (2008) Fenites associated with carbonatites. The Canadian Mineralogist, 46, 915–932.CrossRefGoogle Scholar
Leeman, W. and Phelps, D. (1981) Partitioning of rare earths and other trace elements between sanidine and co-existing volcanic glass. Journal of Geophysical Research: Solid Earth, 86, 10193–10199.CrossRefGoogle Scholar
Lindsley, D. (1963) Fe-Ti oxides in rocks as thermometers and oxygen barometers: Equilibrium relations of coexisting pairs of Fe-Ti oxides. Carnegie Institution Washington Yearbook, 1962–63, 100–106.Google Scholar
Lipin, B.R. and McKay, G.A. (editors) (1989) Geochemistry and Mineralogy of Rare Earth Elements. Reviews in Mineralogy 21. Geological Society of America, Washington DC.CrossRefGoogle Scholar
Mariano, A. (1978) The application of cathodoluminescence for carbonatite exploration and characterisation. Pp. 39–57 in: Proceedings of the First International Symposium on Carbonatites (C. Brega, editor). Brasil Departamento Nacional da Producao Mineral Brasilia.Google Scholar
Mariano, A. (1988) Some further geological applications of cathodoluminescence. Pp. 112–113 in: Cathodoluminescence of Geological Materials (D. Marshall, editor). Unwin Hyman, Boston.Google Scholar
Mariano, A. (1989) Nature of economic mineralisation in carbonatites and related rocks. Pp. 147–176 in: Carbonatites: Genesis and Evolution (K. Bell, editor). Unwin Hyman.Google Scholar
Mariano, A. and Ring, P. (1975) Europium-activated cathodoluminescence in minerals. Geochimica et Cosmochimica Acta, 39, 649–660.CrossRefGoogle Scholar
Mariano, A., Ito, J. and Ring, P. (1973) Cathodoluminescence of plagioclase feldspars. P. 726 in: Geological Society of America conference, Boulder, Colorado, 5. Geological Society of America, Boulder, Colorado, USA.Google Scholar
Markl, G., Marks, M. and Frost, B. (2010) On the controls of oxygen fugacity in the generation and crystallization of peralkaline melts. Journal of Petrology, 51, 1831–1847.CrossRefGoogle Scholar
Martin, R., Whitley, J. and Woolley, A. (1978) An investigation of rare-earth mobility: fenitized quartzites, Borralan Complex N.W. Scotland. Contributions to Mineralogy and Petrology, 66, 69–73.CrossRefGoogle Scholar
McCreath, J., Finch, A., Simonsen, S., Donaldson, C. and Armour-Brown, A. (2012) Independent ages of magmatic and hydrothermal activity in alkaline igneous rocks: The Motzfeldt Centre, Gardar Province, South GREEnland. Contributions to Mineralogy and Petrology, 163, 967–982.CrossRefGoogle Scholar
McKie, D. (1966) Fenitisation. Pp. 261–294 in: Carbonatites (G.J. Tuttle, editor). Wiley Interscience, New York.Google Scholar
Migdisov, A. and Williams-Jones, A. (2014) Hydrothermal transport and deposition of the rare earth elements by fluorine-bearing aqueous liquids. Mineralium Deposita, 49, 987–007.CrossRefGoogle Scholar
Miles, A., Graham, C., Hawkesworth, C., Gillespie, M. and Hinton, R. (2013) Evidence for distinct stages of magma history recorded by the compositions of accessory apatite and zircon. Contributions to Mineralogy and Petrology, 166, 1–9.CrossRefGoogle Scholar
Mills, S., Kartashov, P., Kampf, A., Konev, A., Koneva, A. and Raudsepp, M. (2012) Cordylite-(La), a new mineral species in fenite from the Biraya Fe-REE deposit, Irkutsk, Russia. The Canadian Mineralogist, 50, 1281–1290.CrossRefGoogle Scholar
Morogan, V. (1989) Mass Transfer and REE mobility during fenitisation at Alnö, Sweden. Contributions to Mineralogy and Petrology, 103, 25–34.CrossRefGoogle Scholar
Morogan, V. and Woolley, A. (1988) Fenitisation at the Alnö carbonatite complex, Sweden: distribution, mineralogy and genesis. Contributions to Mineralogy and Petrology, 100, 169–182.CrossRefGoogle Scholar
Norton, G. and Pinkerton, H. (1997) Rheological properties of natrocarbonatites from Oldoinyo Lengai, Tanzania. European Journal of Mineralogy, 9, 351–364.CrossRefGoogle Scholar
Palmer, D. (1998) The Evolution of Carbonatite Melts and their Aqueous Fluids: Evidence from Amba Dongar, India and Phalaborwa, South Africa. PhD Thesis, McGill University, Quebec, Canada.Google Scholar
Pirajno, F. (2009) Hydrothermal Processes and Mineral Systems. Springer, Perth, Australia.CrossRefGoogle Scholar
Platt, R. and Woolley, A. (1990) The carbonatites and fenites of Chipman Lake, Ontario. The Canadian Mineralogist, 28, 241–250.Google Scholar
Portnov, A. and Gorobets, B. (1969) Luminescence of apatite from different rock types. Doklady Akademii Nauk USSR, 184, 199–202.Google Scholar
Rae, D., Coulson, I. and Chambers, A. (1996) Metasomatism in the North Qôroq centre, South GREEnland: apatite chemistry and rare-earth element transport. Mineralogical Magazine, 60, 207–220.CrossRefGoogle Scholar
Robb, L. (2009) Introduction to Ore-Forming Processes. John Wiley & Sons.Google Scholar
Rubie, D. and Gunter, W. (1983) The role of speciation in alkaline igneous fluids during fenite metasomatism. Contributions to Mineralogy and Petrology, 82, 165–175.CrossRefGoogle Scholar
Rubin, J., Henry, C. and Price, J. (1993) The mobility of zirconium and other “immobile” elements during hydrothermal alteration. Chemical Geology, 110, 29–47.CrossRefGoogle Scholar
Shepherd, T., Rankin, A. and Alderton, D. (1985) A Practical Guide to Fluid Inclusion Studies. Blackie & Son Ltd, Glasgow, UK.Google Scholar
Smith, M. (2007) Metasomatic silicate chemistry at the Bayan Obo Fe-REE-Nb deposit, Inner Mongolia, China: Contrasting chemistry and evolution of fenitising and mineralising fluids. Lithos, 93, 126–148.CrossRefGoogle Scholar
Smith, M., Henderson, P. and Peishan, Z. (1999) Reaction relationships in the Bayan Obo Fe-REE-Nb deposit Inner Mongolia, China: implications for the relative stability of rare-earth element phosphates and fluorocarbonates. Contributions to Mineralogy and Petrology, 134, 294–310.CrossRefGoogle Scholar
Smith, M., Henderson, P. and Campbell, L. (2000) Fractionation of the REE during hydrothermal processes: Constraints from the Bayan Obo Fe-REE-Nb deposit, Inner Mongolia, China. Geochimica et Cosmochimica Acta, 64, 3141–3160.CrossRefGoogle Scholar
Snelling, N. (1965) Age determinations on thREE African carbonatites. Nature, 205, 491.CrossRefGoogle Scholar
Southwick, D. (1968) Mineralogy of a rutile- and apatitebearing ultramafic chlorite rock, Harford County, Maryland. Geological Survey Research, 600-C, C38–C44.Google Scholar
Sverjensky, D. (1984) Europium redox equilibria in aqueous solution. Earth and Planetary Science Letters, 67, 70–78.CrossRefGoogle Scholar
Vartiainen, H. and Woolley, A. (1976) The petrography, mineralogy and chemistry of the fenites of the Sokli intrusion, Finland. Geological Survey of Finland Bulletin, 280, 1–87.Google Scholar
Verplanck, P.L. and Van Gosen, B.S. (2011) Carbonatite and Alkaline Intrusion-Related Rare Earth Element Deposits – A Deposit Model. Retrieved 01 August 2013 from USGS: http://pubs.usgs.gov/of/2011/1256/report/OF11-1256.pdf.CrossRefGoogle Scholar
Verschure, R. and Maijer, C. (2005) A new Rb-Sr isotopic parameter for metasomatism, it, and its application in a study of pluri-fenitised gneisses around the Fen ring complex, South Norway. Norges geologiske undersøkelse, Bulletin, 445, 45–71.Google Scholar
Viladkar, S. (2012) Evolution of calciocarbonatite magma: Evidence from the sövite and alvikite association in the Amba Dongar Complex, India. Pp. 485–500 in: Geochemistry – Earth's System Processes (D. Panagiotaras, editor). InTech, Rejeka, Croatia.Google Scholar
Voron’ko, Y.K., Gorbachev, A.V., Zverev, A.A., Sobol, A. A., Morozov, N.N., Murav’ev, E.N., Niyazov, S.A. and Orlovskii, V.P. (1992) Raman scattering and luminescence spectra of compounds with the structure of apatite Ca5(PO4)3F and Ca5(PO4)3OH activated with Eu3+ ions. Neorganicheskie Materialy, 28, 582–589 [in Russian, English version: Inorganic Materials, 28, 442–447].Google Scholar
Wall, F. (2000) Mineral chemistry and petrogenesis of rare earth-rich carbonatites with particular reference to the Kangankunde carbonatite, Malawi. PhD Thesis, University of London, UK.Google Scholar
Wang, R., Yu, A.-P. C., Xie, L., Lu, J.-J. and Zhu, J.-C. (2012) Cassiterite exsolution with ilmenite lamellae in magnetite from the Huashan metaluminous tin granite in southern China. Mineralogy and Petrology, 105, 71–84.CrossRefGoogle Scholar
Waychunas, G. (2002) Luminescence of natural and synthetic apatites. Pp. 701–742 in: Phosphates (Kohn, M.L., Rakovan, J. and Hughes, J.M., editors). Reviews in Mineralogy and Geochemistry, 48. Mineralogical Society of America and the Geochemical Society, Chantilly, Virginia, USA.Google Scholar
Williams-Jones, A. and Palmer, D. (2002) The evolution of aqueous-carbonic fluids in the Amba Dongar carbonatite, India: implications for fenitisation. Chemical Geology, 185, 283–301.CrossRefGoogle Scholar
Woolley, A. (1969) Some aspects of fenitisation with particular reference to Chilwa Island and Kangankunde, Malawi. Bulletin British Museum of Natural History (Mineralogy), 2, 191–219.Google Scholar
Woolley, A. (1982) A discussion of carbonatite evolution and nomenclature, and the generation of sodic and potassic fenites. Mineralogical Magazine, 46, 13–17.CrossRefGoogle Scholar
Woolley, A. (2001) Alkaline Rocks and Carbonatites of the World Part 3: Africa. The Geological Society, London.Google Scholar
Woolley, A. and Kempe, D. (1989) Carbonatites: nomenclature, average chemical composition and element distribution. Pp. 1–14 in: Carbonatites: Genesis and Evolution (K. Bell, editor). Unwin Hyman, London.Google Scholar
Zaitsev, A., Wall, F. and Le Bas, M. (1998) REE-Sr-Ba minerals from the Khibina carbonatites, Kola Peninsula, Russia: their mineralogy, paragenesis and evolution. Mineralogical Magazine, 62, 225–250.CrossRefGoogle Scholar