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A mantle-derived dolomite silicocarbonatite from the southwest coast of Ireland

Published online by Cambridge University Press:  05 July 2018

A. E. Brady  and
K. R. Moore
A. E. Brady*
Affiliation:
Department of Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland Mkango Resources Ltd, Suite 1400, 700 2nd Street SW, Calgary, Alberta T2P 4V5, Canada
K. R. Moore
Affiliation:
Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall TR10 9EZ, UK
*
*E-mail: [email protected]
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Abstract

The magma source and evolution of a zoned breccia pipe on the southern Beara Peninsula in southwest Ireland are investigated using the geochemistry of the host mineral assemblages. The clast-poor inner zone of the pipe has a magnesium-rich silicocarbonatite whole-rock composition (14.30 wt.% MgO; 31.80 wt.% SiO2). The silicocarbonatite has retained an ultimate mantle source 13C isotopic composition after metamorphism, consistent with the presence of mantle debris. The silicocarbonatite is Cr-, Ni- and Co-rich (847 ppm, 611 ppm and 60 ppm, respectively) but REE depleted compared with volcanic dolomite carbonatites worldwide. The mineral assemblage consists of Sr-rich (0.55 wt.% SrO) ferroan dolomite, magnesite and pseudomorphs of chlorite after phlogopite, consistent with derivation from a carbonated and hydrated mantle. However, chrome spinel crystals (≤4 40.14 wt.% Cr2O3) are compositionally indistinguishable from unmetasomatized spinel macrocrysts in kimberlites. The silicocarbonatite is inferred to represent a magma produced by partial melting of metasomatized mantle at physical conditions between those in which primary dolomite carbonatite and ultramafic magmas of high-pressure origin form. The primary silicocarbonatite magma ascended and sampled mantle material in a manner similar to kimberlite, and subsequently lost volatile components due to release of metasomatic fluids and later metamorphism.

Keywords

Cahermorecarbon isotopecarbonatitechloritedolomiteIrelandmantlemagnesiteoxygen isotopesilicocarbonatitespinel
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 2 , April 2012 , pp. 357 - 376
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

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References

Andersen, T. (1986) Magmatic fluids in the Fen complex, SE Norway. Evidence of mid-crustal fractionation from solid and fluid inclusions in apatite. Contributions to Mineralogy and Petrology, 93, 491–503.CrossRefGoogle Scholar
Armstrong, J.P., Wilson, M., Barnett, R.L., Nowicki, T. and Kjarsgaard, B.A. (2004) Mineralogy of primary carbonate-bearing hypabyssal kimberlite, Lac de Gras, Slave Province, Northwest Territories, Canada. Lithos, 76, 433–450.CrossRefGoogle Scholar
Bailey, D.K. (1993) Carbonate magmas. Journal of the Geological Society, London, 150, 637–651.CrossRefGoogle Scholar
Bailey, D.K. and Kearns, S. (2011) Dolomitic volcanism in Zambia: Cr and K signatures and comparisons with other dolomitic melts from the mantle. Pp. 211–222. in: Volcanism and Evolution of the African Lithosphere (L. Beccaluva, G. Bianchini, and Wilson, M., editors). Geological Society of America Special Paper, 478. Geological Society of America, Boulder, Colorado, USA, http://dx.doi.org/DOI:10.1130/2011.247811).CrossRefGoogle Scholar
Bailey, D.K., Garson, M., Kearns, S. and Velasco, A.P. (2005) Carbonate volcanism in Calatrava, central Spain: a report on the initial findings. Mineralogical Magazine, 69, 907–915.CrossRefGoogle Scholar
Bailey, D.K., Kearns, S., Mergoil, J., Mergoil Daniel, J. and Paterson, B. (2006) Extensive dolomitic volcanism through the Limagne Basin, central France: a new form of carbonatite activity. Mineralogical Magazine, 70, 231–236.CrossRefGoogle Scholar
Barker, D.S. (1993) Diagnostic features in carbonatites: implications for the origins of dolomite-and ankerite-rich carbonatites. South African Journal of Geology, 96, 131–138.Google Scholar
Bau, M. (1991) Rare-earth element mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium. Chemical Geology, 93, 219–230.CrossRefGoogle Scholar
Bau, M. and Moller, P. (1992) Rare earth element fractionation in metamorphogenic hydrothermal calcite, magnesite and siderite. Mineralogy and Petrology, 42, 231–246.CrossRefGoogle Scholar
Blackmore, R. (1995) Low-grade metamorphism in the Upper Palaeozoic Munster Basin, southern Ireland. Irish Journal of Earth Sciences, 14, 115–133.Google Scholar
Brady, A.E. (2010) The role of carbonate in diatremerelated magmatism. Unpublished PhD thesis, National University of Ireland, Galway, Ireland. Buckley, H.A. and Woolley, A.R. (1990) Carbonates from the magnesite-siderite series from four carbonatite complexes. Mineralogical Magazine, 54, 413–418.Google Scholar
Chakhmouradian, A.R., Bohm, C.O., Demeny, A., Reguir, E.P., Hegner, E., Creaser, R.A., Halden, N.M. and Yang, P. (2009) “Kimberlite” from Wekusko Lake, Manitoba: actually a diamondindicator-bearing dolomite carbonatite. Lithos, 112(S1), 347–357.Google Scholar
L.B., Clarke, Le Bas, M.J. and Spiro, B. (1994) Rare earth, trace elements and stable isotope fractionation of carbonatites at Kruidfontein, Transvaal, South Africa.Pp. 236–251. in: Proceedings of the 5th Kimberlite Conference, Volume 1: Kimberlite, Related Rocks and Mantle Xenoliths. (H.Meyer, O.A. and Leonardos, O.H., editors). CPRM Special Publication 1/B Jan/94, Companha de Pesquisa de Recursos Minerais, Brasilia.Google Scholar
Coe, K. (1966) The geology of the minor intrusions of West Cork. Quarterly Journal of the Geological Society, London, 122, 1–28.CrossRefGoogle Scholar
Coe, K. (1969) The geology of minor intrusions of West Cork, Ireland. Proceedings of the Geologists’ Association, 80, 441–457.CrossRefGoogle Scholar
Dalton, J.A. and Presnall, D.C. (1998) Carbonatitic melts along the solidus of model lherzolite in the system CaO-MgO-Al2O3-SiO2-CiO2 from 3 to 7 GPa. Contributions to Mineralogy and Petrology, 131, 123–135.CrossRefGoogle Scholar
Dalton, J.A. and Wood, B.J. (1993) The compositions of primary carbonate melts and their evolution through wallrock reaction in the mantle. Earth and Planetary Science Letters, 119, 511–525.CrossRefGoogle Scholar
Deines, P. (1989) Stable isotope variations in carbonatites. Pp. 301–359. in: Carbonatites: Genesis and Evolution (Bell, K., editor). Unwin Hyman, London.Google Scholar
Demény, A. and Harangai, S. (1996) Stable isotopes and processes of carbonate formation in Hungarian alkali basalts and lamprophyres. Lithos, 37, 355–348.CrossRefGoogle Scholar
Doroshkevich, A.G., Wall, F. and Ripp, G.S. (2007a) Calcite-bearing dolomite carbonatite dykes from Veseloe, North Transbaikalia, Russia and possible Cr-rich mantle xenoliths. Mineralogy and Petrology, 90, 19–48.CrossRefGoogle Scholar
Doroshkevich, A.G., Wall, F. and Ripp, G.S. (2007b) Magmatic graphite in dolomite carbonatite at Pogranichoe, North Transbaikalia, Russia. Contributions to Mineralogy and Petrology, 153, 339–353.CrossRefGoogle Scholar
Doroshkevich, A.G., Ripp, G. and Viladkar, S. (2010) Newania carbonatites, Western India: example of mantle derived magnesium carbonatites. Mineralogy and Petrology, 98, 283–295.CrossRefGoogle Scholar
Drüppel, K., Hoefs, J. and Okrusch, M. (2005) Fenitizing processes induced by ferrocarbonatite magmatism at Swartbooisdrif, NW Namibia. Journal of Petrology, 46, 377–406.CrossRefGoogle Scholar
Frey, F.A., Green, D.H. and Roy, S.D. (1978) Integrated models of basalt petrogenesis-a study of quartz tholeiites to olivine melilitites from southeastern Australia utilizing geochemical and experimental petrological data. Journal of Petrology, 19, 463–513.CrossRefGoogle Scholar
Govindaraju, K. (1994) Compilation of working values and sample description for 383 geostandards. Geostandards Newsletter, 18, 1–158.CrossRefGoogle Scholar
Gudfinnsson, G.H. and Presnall, D.C. (2005) Continuous gradations among primary carbonatitic, kimberlitic, melilititic, basaltic, picritic, and komatiitic melts in equilibrium with garnet lherzolite at 3–8. GPa. Journal of Petrology, 46, 1645–1659.Google Scholar
Haggerty, S.E. (1989) Mantle metasomes and the kinship between carbonatites and kimberlites. Pp. 546–560. in: Carbonatites: Genesis and Evolution (Bell, K., editor). Unwin Hyman, London.Google Scholar
Halama, R., Venneman, T., Siebel, W. and Markl, G. (2005) The Grønnedal-Ika carbonatite-syenite complex, South Greenland: carbonatite formation by liquid immiscibility. Journal of Petrology, 46, 191–217.CrossRefGoogle Scholar
Harmer, R.E. and Gittins, J. (1998) The case for primary, mantle-derived carbonatite magma. Journal of Petrology, 39, 1895–1903.CrossRefGoogle Scholar
Humphreys, E.R., Bailey, K., Hawkesworth, C.J., Wall, F., Najorka, J. and Rankin, A.H. (2010) Aragonite in olivine from Calatrava, Spain-evidence for mantle carbonatite melts from >100 km depth. Geology, 38, 911–914.CrossRefGoogle Scholar
Ionov, D.A. and Harmer, R.E. (2002) Trace element distribution in calcite-dolomite carbonatites from Spitskop: inferences for differentiation of carbonatite magmas and origin of carbonates in mantle xenoliths. Earth and Planetary Letters, 198, 495–109.CrossRefGoogle Scholar
Johnson, L.H., Jones, A.P., Church, A.A. and Taylor, W.R. (1997) Ultramafic xenoliths and megacrysts from a melilitite tuff cone, Deeti, northern Tanzania. Journal of African Earth Sciences, 25, 29–42.CrossRefGoogle Scholar
Keller, J. and Hoefs, J. (1995) Stable isotope characteristics of recent natrocarbonatites from Oldoinyo Lengai.Pp. 112–123. in: Carbonatite Volcanism: Oldoynio Lengai and the Petrogenesis of Natrocarbonatites (Bell, K. and Keller, J., editors). Springer, Berlin.Google Scholar
Le Bas, M.J. (1999) Sövite and alvikite: two chemically distinct calciocarbonatites C1 and C2. South African Journal of Geology, 102, 109–121.Google Scholar
Le Bas, M.J. (2008) Fenites associated with carbonatites. The Canadian Mineralogist, 46, 915–932.CrossRefGoogle Scholar
Lee, W.-J. and Wyllie, P.J. (1998a) Processes of crustal carbonatite formation by liquid immiscibility and differentiation, elucidated by model systems. Journal of Petrology, 39, 2005–2013.Google Scholar
Lee, W.-J. and P.J., Wyllie (1998b) Petrogenesis of carbonatite magmas from mantle to crust, constrained by the system CaO–(MgO+FeO*)– (Na2O+K2O)–(SiO2+Al2O3+TiO2)–CiO2. Journal of Petrology, 39, 495–517.Google Scholar
Lee, W.-J. and Wyllie, P.J. (2000) The system CaO-MgO-SiO2-CiO2 at 1 GPa, metasomatic wehrlites, and primary carbonatite magmas. Contributions to Mineralogy and Petrology, 138, 214–228.CrossRefGoogle Scholar
Le Maitre, R.W. (editor) (2002) Igneous Rocks: A Classification and Glossary of Terms: recommendations of International Union of Geological Sciences, subcommission on the systematics of igneous rocks. Cambridge University Press, Cambridge, UK, 236 pp. Lloyd, F.E., Woolley, A.R., Stoppa, F. and Eby, G.N. (2002) Phlogopite-biotite parageneses from the Kmafic-carbonatite effusive magmatic association of Katwe-Kikorongo, SW Uganda. Mineralogy and Petrology, 74, 299–322.Google Scholar
Meere, P.A. (1995) Sub-greenschist facies metamorphism from the Variscides of SW Ireland: an early synextensional peak thermal event. Journal of the Geological Society, London, 152, 511–521.CrossRefGoogle Scholar
Menge, G.F.E. (1986) Sodalite carbonatite deposits of Swartbooisdrift. South West Africa/Namibia.Pp. 2261–2268. in: Mineral deposits of Southern Africa (C.R, Anhaeusser and Maske, S., editors). Geological Society of South Africa, Johannesburg, South Africa.Google Scholar
Mitchell, R.H. (1986) Kimberlites: Mineralogy, Geochemistry, and Petrology. Plenum Press, New York, 442 pp.Google Scholar
Moore, K.R. (2012) Experimental study in the Na2O– CaO–MgO–Al2O3–SiO2–CiO2 system at 3 GPa: the effect of sodium on mantle melting to carbonate-rich liquids and implications for the petrogenesis of silicocarbonatites. Mineralogical Magazine, 76, 285–309.CrossRefGoogle Scholar
Nixon, P.H., Rogers, N.W., Gibson, I.L. and Grey, A. (1981) Depleted and fertile mantle xenoliths from southern African kimberlites. Annual Review of Earth Planetary Sciences, 9, 285–309.CrossRefGoogle Scholar
Platt, R.G. and Woolley, A.R. (1990) The carbonatites and fenites of Chipman Lake, Ontario. The Canadian Mineralogist, 28, 241–250.Google Scholar
Pracht, M. (1994) The geology of the Beara Peninsula, Ireland. Unpublished PhD thesis, National University of Ireland, Cork, Ireland. Pracht, M. (2000) Controls on magmatism in the Munster Basin, SW Ireland. Pp. 303–317. in: New Perspectives on the Old Red Sandstone (Friend, P.F. and, B. Williams, P.J., editors). Geological Society of London Special Publications 180. Geological Society of London, London.Google Scholar
Pracht, M. and J.A., Kinnaird (1995) Mineral chemistry of megacrysts and ultramafic nodules from an undersaturated pipe at Black Ball Head, County Cork. Irish Journal of Earth Sciences, 14, 47–58.Google Scholar
Pracht, M. and Kinnaird, J.A. (1997) Carboniferous subvolcanic activity on the Beara Peninsula, SW Ireland. Geological Journal, 32, 297–312.3.0.CO;2-X>CrossRefGoogle Scholar
Pracht, M. and Timmerman, M. J. (2004) A late Namurian (318 Ma) 40Ar/39Ar age for kaersutite megacrysts from the Black Ball Head diatreme: an age limit for the Variscan deformation in South-West Ireland. Irish Journal of Earth Sciences, 22, 33–43.CrossRefGoogle Scholar
Quinn, D., Meere, P.A. and Wartho, J. (2005) A chronology of foreland deformation: ultra-violet laser 40Ar/39Ar dating of syn/late-orogenic intrusions from the Variscides of southwest Ireland. Journal of Structural Geology, 27, 1413–1425.CrossRefGoogle Scholar
Ripp, G.S., Karmanov, N.S., Doroshkevich, A.G., Badmatsyrenov, M.V. and Izbrodin, I.A. (2006) Chrome-bearing mineral phases in the carbonatites of Northern Transbaikalia. Geochemistry International, 44, 395–402.CrossRefGoogle Scholar
Rock, N.M.S. (1991) Lamprophyres. Blackie, Glasgow, UK, 285 pp. Roeder, P.L. and Schulze, D.J. (2008) Crystallization of groundmass spinel in kimberlite. Journal of Petrology, 49, 1473–1495.Google Scholar
Rugless, C.S. and Pirajno, F. (1996) Geology and geochemistry of the Copperhead Albitite ‘Carbonatite’ Complex, east Kimberley, Western Australia. Australian Journal of Earth Sciences, 43, 311–322.CrossRefGoogle Scholar
Santos, R.V. and Clayton, R.N. (1995) Variations of oxygen and carbon isotopes in carbonatites: a study of Brazilian alkaline complexes. Geochimica et Cosmochimica Acta, 59, 1339–1352.CrossRefGoogle Scholar
Scott Smith, B.H. (1996) Kimberlites. Pp. 217–243. in: Undersaturated Alkaline Rocks: Mineralogy, Petrogenesis and Economic Potential (Mitchell, R.H., editor). Mineralogical Association of Canada, Short course. Mineralogical Association of Canada, Winnipeg, Manitoba, Canada.Google Scholar
Secher, K. and Larsen, L.M. (1980) Geology and mineralogy of the Sarfartoq carbonatite complex, southern West Greenland. Lithos, 13, 199–212.CrossRefGoogle Scholar
Sindern, S. and Kramm, U. (2000) Volume characteristics and element transfer of fenite aureoles: a case study from the Iivaara alkaline complex, Finland. Lithos, 51, 75–93.CrossRefGoogle Scholar
Smith, C.B., Pearson, D.G., Bulanova, G.P., Beard, A.D., Carlson, R.W., Wittig, N., Sims, K., Chimuka, L. and Muchemwa, E. (2009) Extremely depleted lithospheric mantle and diamonds beneath the southern Zimbabwe Craton. Lithos, 112(S2), 1120–1132.Google Scholar
Sokolov, S.V. (1985) Carbonates in ultramafite, alkalirock and carbonatite intrusions. Geochemistry International, 22, 150–166.Google Scholar
Stoppa, F. and Woolley, A.R. (1997) The Italian carbonatites: field occurrence, petrology and regional significance. Mineralogy and Petrology, 59, 43–67.CrossRefGoogle Scholar
Sun, S-S. and McDonough, W.F. (1989) Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Pp. 313–345. in: Magmatism in the Ocean Basins (Saunders, A.D. and Norry, M.J., editors). Geological Society of London Special Publications, 42. Geological Society of London, London.Google Scholar
Sweeney, R.J. (1994) Carbonatite melt compositions in the earth’s mantle. Earth and Planetary Science Letters, 128, 259–270.CrossRefGoogle Scholar
Tappe, S., Foley, S.F., Jenner, G.A., Heamen, L.M., Kjarsgaard, B.A., Romer, R.L., Stracke, A., Joyce, N. and Hoefs, J. (2006) Genesis of ultramafic lamprophyres and carbonatites at Aillik Bay, Labrador: a consequence of incipient lithospheric thinning beneath the North Atlantic craton. Journal of Petrology, 47, 1261–1315.CrossRefGoogle Scholar
Tappe, S., Foley, S.F., Kjarsgaard, B.A., Romer, R.L., Heaman, L.M., Stracke, A. and Jenner, G.A. (2008) Between carbonatite and lamproite-diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes. Geochimica et Cosmochimica Acta, 72, 3258–3286.CrossRefGoogle Scholar
Taylor, H.P. Jr, Frechen, J. and Degens, E.T. (1967) Oxygen and carbon isotope studies of carbonatites from Laacher See district, West Germany and Alno district, Sweden. Geochimica et Cosmochimica Acta, 31, 407–430.CrossRefGoogle Scholar
Thompson, R.N., Smith, P.M., Gibson, S.A., Mattey, D.P. and Dicken, A.P. (2002) Ankerite carbonatite from Swartbooisdrift, Namibia: first evidence for magmatic ferrocarbonatite. Contributions to Mineralogy and Petrology, 143, 377–395.CrossRefGoogle Scholar
Wallace, M.E. and Green, D.H. (1988) An experimental determination of primary carbonatite magma composition. Nature, 335, 343–346.CrossRefGoogle Scholar
Wall, F., Zaitsev, A.N. and Mariano, A.N. (2001) Rare earth pegmatites in carbonatites. Journal of African Earth Sciences, 32, A35-A36. Woolley, A.R. (1982) A discussion of carbonatite evolution and nomenclature, and the generation of sodic and potassic fenites. Mineralogical Magazine, 46, 13–17.Google Scholar
Woolley, A.R. and Church, A.A. (2005) Extrusive carbonatites: a brief review. Lithos, 85, 1–14.CrossRefGoogle Scholar
Woolley, A.R. and D.R.C., Kempe (1989) Carbonatites: nomenclature, average chemical compositions, and element distribution.Pp. 1–14. in: Carbonatites: Genesis and Evolution (Bell, K., editor). Unwin Hyman, London.Google Scholar
Wyllie, P.J. and Lee, W.J. (1998) Model system controls on conditions for formation of magnesiocarbonatite and calciocarbonatite magmas from the mantle. Journal of Petrology, 39, 1885–1893.CrossRefGoogle Scholar
Zaitsev, A.N. (1996) Rhombohedral carbonates from carbonatites of the Khibina Massif, Kola Peninsula, Russia. The Canadian Mineralogist, 34, 468–482.Google Scholar
Zaitsev, A.N. and Chakhmouradian, A.R. (2002) Calcite-amphibole-clinopyroxene rock from the Afrikanda complex, Kola Peninsula, Russia: mineralogy and a possible link to carbonatites. II. Oxysalt minerals. The Canadian Mineralogist, 40, 103–120.CrossRefGoogle Scholar
Zaitsev, A.N., Sitnikova, A., Subbotin, V.V., Fernandez-Suarez, J. and Jeffries, T.E. (2004) Sallanlatvi Complex-a rare example of magnesite and siderite carbonatites. Pp. 201–242. in: Phoscorites and Carbonatites from Mantle to Mine: the Key Example of the Kola Alkaline Province (Wall, F. and Zaitsev, A.N., editors). Mineralogical Society Series, 10. Mineralogical Society, London.Google Scholar