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The geochemical evolution of Nb–Ta–Sn oxides from pegmatites of the Cape Cross–Uis pegmatite belt, Namibia

Published online by Cambridge University Press:  02 October 2018

Warrick C. Fuchsloch ,
Paul A. M. Nex  and
Judith A. Kinnaird
Warrick C. Fuchsloch*
Affiliation:
School of Geosciences, University of the Witwatersrand, South Africa
Paul A. M. Nex
Affiliation:
School of Geosciences, University of the Witwatersrand, South Africa
Judith A. Kinnaird
Affiliation:
School of Geosciences, University of the Witwatersrand, South Africa
*
*Author for correspondence: Warrick C. Fuchsloch, Email: wfuchsloch@gmail.com
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Abstract

The Cape Cross–Uis pegmatite belt, Damara Orogen, north-central Namibia hosts multiple Ta–Nb- and Sn-oxide-bearing pegmatites. Columbite-group minerals, tapiolite, cassiterite and minor ixiolite and wodginite occur in abundance within pegmatites and display various compositional and internal structural mineralogical variations. Ta–Nb oxides display various zonation patterns indicative of multiple crystallisation phases, whereas cassiterite is dominantly homogeneous with minor euhedral columbite-group mineral inclusions. Ta–Nb oxides are mostly rich in Fe, with fractionation patterns in the columbite quadrilateral being sub parallel to the Ta/(Ta + Nb) axis; increasing Ta/(Ta + Nb) with little change in Mn/(Mn + Fe), which is consistent with classical trends in beryl-to-spodumene rare-element pegmatites. In addition, these trends suggest that co-crystallising minerals compete with Ta–Nb oxides for elements such as Mn, preventing Ta–Nb oxides from attaining Mn-rich compositions during the fractionation process. Cassiterite shows similar fractionation patterns with Fe > Mn and notable increases in the Ta content. Minor-element substitution in Ta–Nb oxides shows sharp decreases with increasing fractionation supporting the hypothesis that newly stabilised co-occurring minerals compete with columbite-group minerals for certain elements. Tapiolite shows the same minor-element trend, however, only for Sn and Ti suggesting cassiterite was a dominant competing mineral. Although crystallisation of Ta–Nb oxides from an aqueous fluid at the late-stages of pegmatite genesis is highly debated, significantly elevated Ta contents in metasomatised country rock, compared to unaltered country rock, may give new insight, suggesting that Ta may indeed partition into, and be transported by, an exsolved aqueous fluid. However, further studies of the country rock metasomatic contacts are required as currently the dataset is limited. The degree of fractionation as depicted by Ta–Nb and Sn oxides within pegmatites, indicate that a zonation from primitive to evolved pegmatites surrounding granites is not present and that pegmatites are probably not related to granites in the typical parent–daughter relationship.

Keywords

columbite-group mineralstapiolitecassiteritegranitic pegmatiteDamara OrogenNamibia
Type
Article
Information
Mineralogical Magazine , Volume 83 , Issue 2 , April 2019 , pp. 161 - 179
Copyright
Copyright © Mineralogical Society of Great Britain and Ireland 2018 

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Footnotes

Associate Editor: Sam Broom-Fendley

References

Alfonso, P.A., Corbella, M.C. and Melgarejo, J.C.D. (1995) Nb-Ta-Minerals from the Cap de Creus pegmatite field, eastern Pyrenees: Distribution and geochemical trends. Mineralogy and Petrology, 55, 53–69.10.1007/BF01162579Google Scholar
Alfonso, P. and Melgarejo, J.C. (2008) Fluid evolution in the zoned rare-element pegmatite field at Cap de Creus, Catalonia, Spain. The Canadian Mineralogist, 46, 597–617.10.3749/canmin.46.3.597Google Scholar
Ashworth, L. (2013) Mineralised Pegmatites of The Damara Belt, Namibia. Fluid Inclusion and Geochemical Characteristics with Implications of Post Tectonic Mineralisation. Unpublished PhD thesis, University of the Witwatersrand, Johannesburg.Google Scholar
Ballourad, C., Poujol, M., Boulvais, P., Branquet, Y., Tartèse, R. and Vigneresse, J-L. (2016) Nb-Ta fractionation in peraluminous granites: a marker of the magmatic-hydrothermal transition. Geology, 44, 231–234.10.1130/G37475.1Google Scholar
Baumgartner, R., Romer, R.L. and Moritz, R. (2006) Columbite-tantalite-bearing granitic pegmatites from the Seridó belt, northeastern Brazil: genetic constraints from U-Pb dating and Pb isotopes. The Canadian Mineralogist, 44, 69–86.10.2113/gscanmin.44.1.69Google Scholar
Beurlen, H., Da Silva, M.R.R., Thomas, R., Soares, D.R. and Olivier, P. (2008) Nb-Ta-(Ti-Sn) oxide mineral chemistry as tracer of rare-element granitic pegmatite fractionation in the Borborema Province, northeastern Brazil. Mineralium Deposita, 43, 207–228.Google Scholar
Briqueu, L., Lancelot, J.P., Valois, J.P. and Walgenwitz, F. (1980) Géochronologie U-Pb d'un type de mineralisation uranifère: les alaskites de Goanikontes (Namibie) 231 et leur encaissant. Bulletin du Centre de Récherches-Production, Elf-Aquitaine, 4, 759–811.Google Scholar
Černý, P. (1989) Exploration strategy and methods for pegmatite deposits of tantalum. Pp. 274–310 in: Lanthanides, Tantalum and Niobium (Möller, P., Černý, P. and Saupé, F., editors) Springer-Verlag, Heidelberg.10.1007/978-3-642-87262-4_13Google Scholar
Černý, P. and Ercit, T.S. (1985) Some recent advances in the mineralogy and geochemistry of Nb and Ta in rare-element granitic pegmatites. Bulletin de Minéralogie, 108, 499–532.Google Scholar
Černý, P. and Ercit, T.S. (1989) Mineralogy of niobium and tantalum: crystal chemical relationships, paragenetic aspects and their economic implications. Pp. 27–79 in: Lanthanides, Tantalum and Niobium (Moller, P., Černý, P. and Saupe, F., editors) Springer, Berlin, Heidelberg, New York, Tokyo.10.1007/978-3-642-87262-4_2Google Scholar
Černý, P. and Ercit, T.S. (2005) The classification of granitic pegmatites revisited. The Canadian Mineralogist, 43, 2005–2026.Google Scholar
Černý, P., Chapman, R., Chackowsky, L.E. and Ercit, T.S. (1992 a) A ferrotantalite-ferrotapiolite intergrowth from Spittal a.d. Drau, Carinthia, Austria. Mineral Petrology, 41, 53–63.10.1007/BF01164810Google Scholar
Černý, P., Ercit, T.S. and Wise, M.A. (1992 b) The tantalite-tapiolite gap: natural assemblages versus experimental data. The Canadian Mineralogist, 30, 587–596.Google Scholar
Černý, P., Chapman, R., Ferreira, K. and Smeds, S.-A. (2004) Geochemistry of oxide minerals of Nb, Ta, Sn and Sb in the Varuträsk granitic pegmatite, Swede: The case of an “anomalous” columbite tantalite trend. American Mineralogist, 89, 505–518.10.2138/am-2004-0405Google Scholar
Chevychelov, V., Zaraisky, C., Borisovskii, S. and Borkov, D. (2005) Effect of melt composition and temperature on the partitioning of Ta, Nb, Mn and F between granitic (alkaline) melt and fluorine-bearing aqueous fluid: fractionation of Ta and Nb and conditions of ore formation in rare-metal granites. Petrology, 13, 339–357.Google Scholar
De Kock, G.S., Eglington, B., Armstrong, R.A., Harmer, R.E. and Walraven, F. (2000) U-Pb and Pb-Pb ages of the Naauwpoort rhyolite, Kawakeup leptite and Okongava Diorite: implications for the onset of rifting and orogenesis in the Damara Belt, Namibia. Communications of the Geological Survey of Namibia, Henno Martin Volume, 12, 81–88.Google Scholar
Diehl, B.T.M. (1993) Rare metal pegmatites of the Cape Cross – Uis pegmatite belt, Namibia: geology, mineralisation, rubidium-strontium characteristics and petrogenesis. Journal of African Earth Sciences, 17, 167–181.Google Scholar
Ercit, T.S., Wise, M.A. and Černý, P. (1995) Compositional and structural systematics of the columbite group. American Mineralogist, 80, 613–619.Google Scholar
Fuchsloch, W.C. (2018) Pegmatites of the Cape Cross-Uis Pegmatite Belt, Namibia: Structural, Mineralogical, Geochemical and Mineral Chemical Characterisation with Implications for Petrogenesis and Mineralisation. Unpublished PhD thesis, University of the Witwatersrand, Johannesburg.Google Scholar
Fuchsloch, W.C., Nex, P.A.M. and Kinnaird, J.A. (2018) Classification, mineralogical and geochemical variations in pegmatites of the Cape Cross – Uis pegmatite belt, Namibia. Lithos, 296–299, 79–95.Google Scholar
González, T.L., Polonio, F.G., Moro, F.J.L., Fernández, A.F., Contreras, J.L.S. and Benito, M.C.M. (2017) Tin-tantalum-niobium mineralisation in the Penouta deposit (NW Spain): Textural features and mineral chemistry to unravel the genesis and evolution of cassiterite and columbite group minerals in a peraluminous system. Ore Geology Reviews, 81, 79–95.10.1016/j.oregeorev.2016.10.034Google Scholar
Goscombe, B., Gray, D. and Hand, M. (2004) Variation in metamorphic style along the northern margin of the Damara Orogen. Journal of Petrology, 45(6), 1261–1295.10.1093/petrology/egh013Google Scholar
Gray, D.R., Foster, D.A., Goscombe, B., Passchier, C.W. and Trouw, R.A.J. (2006) 40Ar/39Ar thermochronology of the Pan-African Damara Orogen, Namibia, with implications for tectonothermal and geodynamic evolution. Precambrian Research, 150, 49–72.10.1016/j.precamres.2006.07.003Google Scholar
Haack, U. and Gohn, E. (1988) Rb-Sr data on some pegmatites in the Damara Orogen, Namibia. Communications of the Geological Survey of South West Africa/Namibia, 4, 13–17.Google Scholar
Hanson, S.L., Simmons, W.B. and Falster, A.U. (1998) Nb-Ta-Ti oxides in granitic pegmatites from the Topsham pegmatite district, Southern Maine. The Canadian Mineralogist, 36, 601–608.Google Scholar
Hoffman, P.F., Hawkins, D.P., Isachsen, C.E. and Bowring, S.A. (1996) Precise U-Pb zircon ages for early Damaran magmatism in the Summas Mountains and Welwitschia Inlier, northern Damara Belt, Namibia. Communications of the Geological Survey of Namibia, 11, 47–52.Google Scholar
Keller, P., Robles, E.R., Pérez, A.P. and Fontan, F. (1999) Chemistry, paragenesis and significance of tourmaline in pegmatites of the southern Tin Belt, central Namibia. Chemical Geology, 158, 203–225.10.1016/S0009-2541(99)00045-5Google Scholar
Kinnaird, J.A. and Nex, P.A.M. (2007) A review of geological controls on uranium mineralisation in sheeted leucogranites within the Damara Orogen, Namibia. Trans I.M.M. Applied Earth Sciences, 116(2), 68–85.10.1179/174327507X167091Google Scholar
Kisters, A.F.M. (2005) Controls of gold-quartz vein formation during regional folding in amphibolite-facies, marble-dominated metasediments of the Navachab Gold Mine in the Pan-African Damara Belt, Namibia. South African Journal of Geology, 108, 365–380.10.2113/108.3.365Google Scholar
Kovalenko, N.I., Ryzhenko, B.N., Barsukov, V.L., Klintsova, A.P., Velyukhanova, T.K., Volynets, M.P. and Kytayeva, L.P. (1986) The solubility of cassiterite in HCl + NaCl(KCl) solutions at 550 °C and 1000 atm under fixed redox conditions. Geochemistry International, 23, 1–16.Google Scholar
Lahti, S.I. (1987) Zoning in columbite-tantalite crystals from the granitic pegmatites of the Eräjärvi area, southern Finland. Geochimica et Cosmochimica Acta, 51, 509–517.Google Scholar
Linnen, R.L. (1998) The solubility of Nb-Ta-Zr-Hf-W in granitic melts with Li and Li + F: Constraints for mineralisation in rare metal granites and pegmatites. Economic Geology, 93, 1013–1025.10.2113/gsecongeo.93.7.1013Google Scholar
Linnen, R.L. and Keppler, H. (1997) Columbite solubility in granitic melts: consequences for the enrichment and fractionation of Nb and Ta in the Earth's crust. Contributions to Mineralogy and Petrology, 128, 213–227.Google Scholar
Linnen, R.L., Pichavant, M. and Holtz, F. (1996) The combined effects of fO2 and melt composition on SnO2 solubility and tin diffusivity in haplogranitic melts. Geochimica et Cosmochimica Acta, 60, 4965–4976.Google Scholar
London, D. (2008) Pegmatites. Canadian Mineralogist Special Publication, 10, 347 pp.Google Scholar
Longridge, L. (2012) Tectonothermal Evolution of the Southwestern Central Zone, Damara Belt, Namibia. Unpublished PhD thesis, University of the Witwatersrand, Johannesburg, 524 pp.Google Scholar
Macey, P. and Harris, C. (2006) Stable isotope and fluid inclusion evidence for the origin of the Brandberg West area Sn-W vein deposits, NW Namibia. Mineralium Deposita, 41, 671–690.Google Scholar
Martin, H. and Porada, H. (1977) The intracratonic branch of the Damara Orogen in South West Africa. I. Discussion of geodynamic models. II. Discussion of relationships with the Pan-African Mobile Belt system. Precambrian Research, 5, 311–338 and 339–357.10.1016/0301-9268(77)90039-0Google Scholar
Martins, T., Lima, A. and Noronha, F. (2009) Evolution trends in columbite-tantalite minerals from pegmatites from the Barroso-Alvão pegmatite field – Northern Portugal. Estudos Geológicos, 19, 212–216.Google Scholar
Melcher, F., Graupner, T., Gäbler, H.-E.Sitnikova, M., Henjes-Kunst, F., Oberthür, T., Gerdes, A. and Dewaele, S. (2013) Tantalum-(niobium-tin) mineralisation in African pegmatites and rare metal granites: Constraints from Ta-Nb oxide mineralogy, geochemistry and U-Pb geochronology. Ore Geology Reviews, 64, 667–719.10.1016/j.oregeorev.2013.09.003Google Scholar
Melcher, F., Graupner, T., Gäbler, H.-E.Sitnikova, M., Henjes-Kunst, F., Oberthür, T., Gerdes, A. and Dewaele, S. (2015) Tantalum-(niobium-tin) mineralisation in African pegmatites and rare metal granites: Constraints from Ta–Nb oxide mineralogy, geochemistry and U-Pb geochronology. Ore Geology Reviews, 64, 667–719.Google Scholar
Melcher, F., Graupner, T., Gäbler, H.-E.Sitnikova, M., Oberthür, T., Gerdes, A., Badanina, E. and Chudy, T. (2017) Mineralogical and chemical evolution of tantalum-(niobium-tin) mineralisation in pegmatites and granites. Part 2: Worldwide examples (excluding Africa) and an overview of global metallogenetic patterns. Ore Geology Reveiws, 89, 946–987.10.1016/j.oregeorev.2016.03.014Google Scholar
Milani, L., Kinnaird, J.A., Lehmann, J., Naydenov, K.V., Saalmann, K., Frei, D. and Gerdes, A. (2015) Role of crustal contribution in the early stage of the Damara Orogen, Namibia: New constraints from combined U-Pb and Lu-Hf isotopes from the Goas Magmatic Complex. Gondwana Research, 28, 961–986.Google Scholar
Miller, R.McG. (1983) The Pan-African Damara Orogen of South West Africa/Namibia. Pp. 431–515 in: The Evolution of the Damara Orogen of South West Africa/Namibia (Miller, R.McG., editor) Geological Society of South Africa Special Publication, 11.Google Scholar
Miller, R.McG. (2008) Neoproterozoic and early Palaeozoic rocks of the Damara Orogen. Pp. 13–1 to 13–410 in: The Geology of Namibia 2 (Miller, R.McG., editor). Ministry of Mines and Energy, Geological Survey, Windhoek.Google Scholar
Miller, R.McG. and Frimmel, H.E. (2009) Syn- to post-orogenic magmatism. Neoproterozoic evolution of southwestern Africa. Pp. 219–226 in: Neoproterozoic-Cambrian tectonics, global change and evolution: a focus on southwestern Gondwana (Gaucher, C., Sial, A.N., Halverson, G.P. and Frimel, H.E., editors) Precambrian Geology, 16.10.1016/S0166-2635(09)01615-6Google Scholar
Mulja, T., Williams-Jones, A.E., Martin, R.F. and Wood, S.A. (1996) Compositional variation and structural state of columbite-tantalite in rare-element granitic pegmatites of the Preissac-Lacorne batholith, Quebec, Canada. American Mineralogist, 81, 146–157.Google Scholar
Neiva, A.M.R. (1996) Geochemistry of cassiterite and its inclusions and exolutions products from tin and tungsten deposits in Portugal. The Canadian Mineralogist, 34, 745–768.Google Scholar
Novák, M. and Černý, P. (1998) Niobium-tantalum oxide minerals from complex granitic pegmatites in the Moldanubicum, Czech Republic: primary versus secondary compositional trends. The Canadian Mineralogist, 36, 659–672.Google Scholar
Prave, A.R. (1996) Tale of three cratons: tectonostratigraphic anatomy of the Damara Orogen in north-western Namibia and the assembly of Gondwana. Geology, 24, 1115–1118.Google Scholar
Richards, T.E. (1986) Geological characteristics of rare-metal pegmatites of the Uis type in the Damara Orogen, South West Africa/Namibia. Pp. 1845–1862 in: Mineral Deposits of Southern Africa 2 (Anhaeusser, C.R. and Maske, S., editors) Society of South Africa, Johannesburg.Google Scholar
Raimbault, L. (1998) Compositions of complex lepidolite-type pegmatites and of constituent columbite-tantalite, Chédeville, Massif central, France. The Canadian Mineralogist, 36, 563–583.Google Scholar
Romer, R.L. and Lehmann, B. (1995) U-Pb columbite age of Neoproterozoic Ta–Nb mineralization in Burundi. Economic Geology, 90, 2303–2309.10.2113/gsecongeo.90.8.2303Google Scholar
Singh, P.K. (2007) Tantalite exploration in “Block A” of Uis region, Namibia. Trabajos de Geologia, 27, 41–69.Google Scholar
Singh, P.K. (2008) Revelation of tin and niobium occurrences in southern Uis region of Namibia through a geological reconnaissance study. Trabajos de Geologia, 28, 33–39.Google Scholar
Smirnov, S.Z., Thomas, V.G., Kamenetsky, V.S., Kozmenko, O.A. and Large, R.R. (2012) Hydrosilicate liquids in the system Na2O-SiO2-H2O with NaF, NaCl and Ta: Evaluation of their role in ore and mineral formation at high T and P. Petrology, 20, 271–285.Google Scholar
Smith, S.R., Foster, L.G., Romer, R.L., Tindle, A.G., Kelley, S.P., Noble, S.R., Horstwood, M. and Breaks, F.W. (2004) U-Pb columbite-tantalite chronology of rare-element pegmatites using TIMS and Laser Ablation-Multi Collector-ICP-MS. Contributions to Mineralogy and Petrology, 147, 549–564.Google Scholar
Splide, M.N. and Shearer, C.K. (1992) A comparison of tantalum-niobium oxide assemblages in two mineralogically distinct rare-element granitic pegmatites, Black Hills, South Dakota. The Canadian Mineralogist, 30, 719–737.Google Scholar
Swart, R. (1992) The sedimentology of the Zerrissene turbidite system, Damara Orogen, Namibia. Memoirs of the Geological Society of Namibia, 13, 54.Google Scholar
Tack, L., Williams, I. and Bowden, P. (2002) SHRIMP constraints on early post collisional granitoids of the Ida Dome, central Damara (Pan-African) Belt, western Namibia. IAGOD Quadrennial Symposium and Geocongress, Windhoek, Namibia, 11th, abstracts. Geological Survey of Namibia.Google Scholar
Tindle, A.G. and Breaks, F.W. (2000) Columbite-tantalite mineral chemistry from rare-element granitic pegmatites: Separation Lake area, N.W. Ontario, Canada. Mineralogy and Petrology, 70, 165–198.10.1007/s007100070002Google Scholar
Trompette, R. (1997) Neoproterozoic (~600 Ma) aggregation of western Gondwana: a tentative scenario. Precambrian Research, 82, 101–112.Google Scholar
Van Lichtervelde, M.V., Beziat, S.S.D. and Linnen, R.L. (2007) Textural features and chemical evolution in tantalum oxides: magmatic versus hydrothermal origins for Ta mineralization in the Tanco Lower Pegmatite, Manitoba, Canada. Economic Geology, 102, 257–276.Google Scholar
Van Lichtervelde, M.V., Grégoire, M., Linnen, R.L., Béziat, D. and Salvi, S. (2008) Trace element geochemistry by laser ablation ICPMS of micas associated with Ta mineralization in the Tanco pegmatite, Manitoba, Canada. Contributions to Mineralogy and Petrology, 155, 791–806.10.1007/s00410-007-0271-zGoogle Scholar
Van Lichtervelde, M.V., Grand'Homme, A., de Saint-Blanquat, M., Olivier, P., Gerdes, A., Paquette, J-L., Melgarejo, J.C., Druguet, E. and Alfonso, P. (2017) U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain. Mineralogy and Petrology, 111, 1–21.10.1007/s00710-016-0455-1Google Scholar
Wagener, G.F. (1989) Systematic variation in the tin content of pegmatites in western central Namibia. Journal of Geochemical Exploration, 34, 1–19.Google Scholar
Wise, M.A., Francis, C.A. and Černý, P. (2012) Compositional and structural variations in columbite-group minerals from granitic pegmatites of the Brunswick and Oxford fields, Maine: Differential trends in F-poor and F-rich environments. The Canadian Mineralogist, 50, 1515–1530.Google Scholar
Zhang, A.C., Wang, R.C., Hu, H., Zhang, H., Zhu, J.C. and Chen, X.M. (2004) Chemical evolution of the Nb-Ta oxides and zircon from the Koktokay No. 3 granitic pegmatite, Altai, northwestern China. Mineralogical Magazine, 68, 739–756.10.1180/0026461046850216Google Scholar
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