Mineralium Deposita

, Volume 43, Issue 1, pp 37–60 | Cite as

The composition of magmatic Ni–Cu–(PGE) sulfide deposits in the Tati and Selebi-Phikwe belts of eastern Botswana

  • W. D. MaierEmail author
  • S.-J. Barnes
  • G. Chinyepi
  • J. M. BartonJr
  • B. Eglington
  • I. Setshedi


We studied a number of magmatic Ni–Cu–(PGE) sulfide deposits in two distinct belts in eastern Botswana. The Tati belt contains several relatively small deposits (up to 4.5 Mt of ore at 2.05% Ni and 0.85% Cu) at Phoenix, Selkirk and Tekwane. The deposits are hosted by ca 2.7 Ga, low- to medium-grade metamorphosed gabbroic–troctolitic intrusions situated within or at the periphery of a greenstone belt. The deposits of the Selebi-Phikwe belt are larger in size (up to 31 Mt of ore grade). They are hosted by high-grade metamorphosed gabbronorites, pyroxenites and peridotites believed to be older than ca 2.0 Ga that intruded gneisses of the Central Zone of the Limpopo metamorphic belt. The composition of the sulfide mineralisation in the two belts shows systematic variation. Most of the mineralisation in the Tati belt contains 2–9% Ni and 0.05–4% Cu (Cu/Cu + Ni = 0.4–0.7), whereas most of the mineralisation in the Selebi-Phikwe belt contains 1–3% Ni and 0.1–4% Cu (Cu/Cu + Ni = 0.4–0.9). The Cu–Ni tenors of the ores in both belts are consistent with crystallization from a basaltic magma. The Tati ores contain mostly >3 ppm Pt + Pd (Pt/Pd 0.1–1), with Pd/Ir = 100–1,000, indicative of a differentiated basaltic magma that remained S-undersaturated before emplacement. Most of the Selebi-Phikwe ores have <0.5 ppm Pt + Pd (Pt/Pd < 0.1–1), with Pd/Ir = 10–500. This suggests a relatively less differentiated magma that reached S saturation before emplacement. The Tati rocks show flat mantle-normalised incompatible trace element patterns (average Th/YbN = 1.57), except for strong enrichments in large ion lithophile elements (Cs, Rb, Ba, U, K). Such patterns are characteristic of relatively uncontaminated oceanic arc magmas and suggest that the Tati intrusions were emplaced in a destructive plate margin setting. Most of the Selebi-Phikwe rocks (notably Dikoloti) have more fractionated trace element signatures (average Th/YbN = 4.22), possibly indicating digestion of upper crustal material during magma emplacement. However, as there are also samples that have oceanic arc-like signatures, an alternative possibility is that the composition of most Selebi-Phikwe rocks reflects tectonic mingling of the intrusive rocks with the country rocks. The implication is that orogenic belts may have a higher prospectivity for magmatic Ni–Cu ores than presently recognised. The trigger mechanism for sulfide saturation and segregation in all intrusions remains unclear. Whereas the host rocks to the intrusions appear to be relatively sulfur poor, addition of crustal S to the magmas is suggested by low Se/S ratios in some of the ores (notably at Selebi-Phikwe). External S sources may thus remain unidentified due to poor exposure and/or S mobility in response to metamorphism.


Nickel-copper deposits Platinum-group elements Phoenix Selkirk Selebi-Phikwe Tekwane Dikoloti Botswana 



We thank Tati Nickel for facilitating sampling of the Phoenix and Selkirk deposits and for allowing publication of the data. Richard Lewis, Admore Botepe and Kebalemogile Tau assisted WM and GC during the fieldwork. Falconbridge Ventures of Africa allowed sampling at Tekwane. The analytical work was partly funded by the Centre for Research on Magmatic Ore Deposits at the University of Pretoria (to WDM) and NSERC (to SJB). Peter Lightfoot and an anonymous reviewer provided detailed reviews that greatly improved earlier versions of this paper. Additional suggestions for improvement were made by Larry Meinert.


  1. Arndt NT, Czamanske GK, Wooden JL, Fedorenko VA (1993) Mantle and crustal contributions to continental flood volcanism. Tectonophysics 223:39–52CrossRefGoogle Scholar
  2. Bagai Z, Armstrong RA, Kampunzu AB (2002) U-Pb single zircon geochronology of granitoids in the Vumba granite-greenstone terrain (NE Botswana): implications for the evolution of the Archean Zimbabwe craton. Precambrian Res 118:149–168CrossRefGoogle Scholar
  3. Baldock JW, Hepworth JV, Marengwa BS (1976) Gold, base metals, and diamonds in Botswana. Econ Geol 71:139–156Google Scholar
  4. Barnes S-J, Lightfoot PC (2005) Formation of magmatic nickel sulfide ore deposits and processes affecting their copper and platinum-group element contents. Economic Geology 100th Anniversary Volume. Denver, pp 179–213Google Scholar
  5. Barnes S-J, Maier WD (1999) The fractionation of Ni, Cu and the noble metals in silicate and sulphide liquids. In: Keays RR, Lesher CM, Lightfoot PC, Farrow CEG (eds) Dynamic processes in magmatic ore deposits and their application to mineral exploration. Geological Association of Canada, Short Course Notes 13:69–106Google Scholar
  6. Barnes S-J, Maier WD (2002) Platinum-group elements and microstructures of normal Merensky Reef from Impala Platinum Mines, Bushveld Complex. J Petrol 43:103–128CrossRefGoogle Scholar
  7. Barnes S-J, Naldrett AJ, Gorton MP (1985) The origin of the fractionation of platinum-group elements in terrestrial magmas. Chem Geol 53:303–323CrossRefGoogle Scholar
  8. Barnes S-J, Couture J-F, Sawyer EW, Bouchaib C (1993) Nickel–copper occurrences in the Belleterre-Angliers belt of the Pontiac Subprovince and the use of Cu–Pd ratios in interpreting platinum-group element distributions. Econ Geol 88:1402–1419Google Scholar
  9. Barnes S-J, Makovicky E, Makovicky M, Rose-Hansen J, Karup-Moller S (1997) Partition coefficients for Ni, Cu, Pd, Pt, Rh and Ir between monosulfide solid solution and sulphide liquid and the formation of compositionally zoned Ni–Cu sulphide bodies by fractional crystallization of sulfide liquid. Can J Earth Sci 34:366–374CrossRefGoogle Scholar
  10. Barrett FM, Binns RA, Groves DI, Marston RJ, McQueen, KG (1977) Structural history and metamorphic modification of Archean volcanic-type nickel deposits, Yilgarn Block, Western Australia. Econ Geol 72:1195–1223Google Scholar
  11. Barton JM, Klemd R, Zeh A (2006) The Limpopo Belt: a result of Archean to Proterozoic, Turkic-type orogenesis? In: Reimold WU, Gibson RL (eds) Processes on the Early Earth. Geological Society of America Special Paper 405, pp 315–332Google Scholar
  12. Bédard P, Barnes S-J (2002) A comparison of the capacity of FA-ICP-MS and FA-INAA to determine platinum-group elements and gold in geological samples. J Radioanal Nucl Chem 254:319–329CrossRefGoogle Scholar
  13. Boyd R, Mathiesen CO (1979) The nickel mineralization of the Rana mafic intrusion, Nordland, Norway. Can Mineral 17:287–298Google Scholar
  14. Brown PJ (1988) Petrogenesis of Ni–Cu ore bodies, their host rocks and country rocks at Selebi-Phikwe, eastern Bostswana. Ph.D. thesis, University of Southampton, UK, p 333Google Scholar
  15. Burke K, Kidd WSF, Kusky T (1985) Is the Ventersdorp rift system of southern Africa related to a continental collision between the Kaapvaal and Zimbabwe cratons at 2.64 Ga ago? Tectonophysics 115:1–24CrossRefGoogle Scholar
  16. Cabri LJ (1992) The distribution of trace precious metals in minerals and mineral products. Mineral Mag 384:289–308CrossRefGoogle Scholar
  17. Campbell IH (2005) Large igneous provinces and the mantle plume hypothesis. Elements 1:265–269CrossRefGoogle Scholar
  18. Campbell IH, Naldrett AJ (1979) The influence of silicate:sulfide ratios on the geochemistry of magmatic sulfides. Econ Geol 74:1503–1505Google Scholar
  19. Carney JN, Aldiss DT, Lock NP (1994) The geology of Botswana. Geological Survey of the Botswana Bulletin 37, 113 ppGoogle Scholar
  20. Crocket JH (2002) Platinum-group element geochemistry of mafic and ultramafic rocks. Canadian Institute Mining Metallurgy and Petroleum, special volume 54, pp 177–210Google Scholar
  21. Eckstrand OR, Grinenko LN, Krouse HR, Paktunc AD, Schwann PL, Scoates RFJ (1989) Preliminary data on sulphur isotopes and Se/S ratios, and the source of sulphur in magmatic sulphides from the Fox River Sill, Molson Dykes, and Thompson nickel deposits, northern Manitoba. In Current Research Part C, Geological Survey of Canada, Paper 89-1C, pp 235–242Google Scholar
  22. Falconbridge Ventures of Africa (1998) Summary report of the results from PL 96/93. Unpublished company report, p 12Google Scholar
  23. Gallon ML (1986) Structural re-interpretation of the Selebi-Phikwe nickel–copper sulphide deposits, eastern Botswana. In: Anhaeusser CR, Maske S (eds) Mineral deposits of Southern Africa. Geological Society of South Africa, pp 1663–1669Google Scholar
  24. Gordon PSL (1973) The Selebi-Pikwe nickel–copper deposits, Botswana. In: Lister LA (ed) Symposium on granites, gneisses and related rocks. Special Publication, Geological Society of South Africa 3:167–187Google Scholar
  25. Hawkesworth CJ, O’Nions RK (1977) The petrogenesis of some volcanic rocks from southern Africa. J Petrol 18:487–520Google Scholar
  26. Hawkesworth CJ, O’Nions RK, Pankhurst RJ, Hamilton PJ, Evensen NM (1977) A geochemical study of island arc and back-arc tholeiites from the Scotia Sea. Earth Planet Sci Lett 36:253–262CrossRefGoogle Scholar
  27. Hoatson DM, Blake DH (2000). Geology and economic potential of the Palaeoproterozoic layered mafic-ultramafic intrusions in the East Kimberley, Western Australia. Australian Geological Survey Organization, Bulletin 246:469Google Scholar
  28. Johnson RS (1986) The Phoenix and Selkirk nickel–copper sulphide ore deposits, Tati Greenstone Belt, eastern Botswana. In: Anhaeusser CR, Maske S (eds) Mineral deposits of Southern Africa. Geological Society of South Africa, pp 243–248Google Scholar
  29. Kampunzu AB, Tombale AR, Zhai, M, Bagai Z, Majaule TM, Modisi M (2003) Major and trace element geochemistry of plutonic rocks from Francistown, NE Botswana: evidence for neo-Archean continental active margin in the Zimbabwe craton. Lithos 71:431–460CrossRefGoogle Scholar
  30. Key RM (1976) The geology of the area around Francistown and Phikwe, northeast and central districts, Botswana. Distr Mem Geol Surv Botswana 3:15–25Google Scholar
  31. Lear PA (1979) The ore mineralogy of the Phikwe and Selebi nickel–copper deposits, Botswana. Geological Society of South Africa, Special Publication 5:117–132Google Scholar
  32. Light MPR (1982) The Limpopo mobile belt: a result of continental collision. Tectonics 1:325–342Google Scholar
  33. Maier WD (2005) Platinum-group element (PGE) deposits and occurrences: mineralization styles, genetic concepts, and exploration criteria. J Afr Earth Sci 41:165–191CrossRefGoogle Scholar
  34. Marsh SCK (1978) Nickel-copper occurrences at Dikoloti and Lentswe, eastern Botswana. In: WJ Verwoerd (ed) Mineralization in metamorphic terranes, Geological Society of South Africa, Special Publication 4:131–148Google Scholar
  35. McCourt S, Kampunzu AB, Bagai Z, Armstrong RA (2004) The crustal architecture of Archean terranes in Northeastern Botswana. S Afr J Geol 107:147–158CrossRefGoogle Scholar
  36. McDonough WF, Sun S-S (1995) The composition of the Earth. Chem Geol 120:223–253CrossRefGoogle Scholar
  37. Mitchell AHG, Garson MS (1981) Mineral deposits and global tectonic settings. Academic, London, p 405Google Scholar
  38. Naldrett AJ (1989) Magmatic sulphide deposits. Oxf Monogr Geol Geophys 14:186Google Scholar
  39. Naldrett AJ (2004) Magmatic sulfide deposits. Springer, Berlin Heidelberg New York, p 727Google Scholar
  40. Paktunc AD (1990) Comparative geochemistry of platinum-group elements of nickel-copper sulfide occurrences associated with mafic-ultramafic intrusions in the Appalachian orogen. J Geochem Explor 37:101–111CrossRefGoogle Scholar
  41. Peach CL, Mathez EA, Keays RR (1990) Sulfide melt-silicate melt distribution coefficients for noble metals and other chalcophile elements as deduced from MORB: implications for partial melting. Geochim Cosmochim Acta 54:3379–3389CrossRefGoogle Scholar
  42. Pearce JA (1983) The role of sub-continental lithosphere in magma genesis at destructive plate margins. In: CJ Hawkesworth and MJ Norry (eds) Continental basalts and mantle xenoliths. Shiva, Nantwich, pp 230–249Google Scholar
  43. Peltonen P (1995) Magma-country rock interaction and the genesis of Ni–Cu deposits in the Vammala nickel belt, SW Finland. Mineral Petrol 52:1–24CrossRefGoogle Scholar
  44. Peregoedova AV (1998) The experimental study of Pt–Pd partitioning between monosulfide solid solution and Cu–Ni sulfide melt at 900–840°C. In: 8th International Platinum Symposium, Abstracts, Geological Society of South Africa and S Afr Inst Min Metall, Symposium Series S18, pp 325–327Google Scholar
  45. Pina R, Lunar R, Ortega L, Gervilla F, Alapieti T, Martinez C (2006) Petrology and geochemistry of mafic-ultramafic fragments from the Aguablanca Ni–Cu ore breccia, southwest Spain. Econ Geol 101:865–881CrossRefGoogle Scholar
  46. Ripley EM (1981) Sulfur isotopic studies of the Dunka Road Cu–Ni deposit, Duluth Complex, Minnesota. Econ Geol 76:610–620Google Scholar
  47. Ripley EM, Al-Jassar TJ (1987) Sulfur and oxygen isotope studies of melt-country rock interaction, Babbitt Cu–Ni deposit, Duluth Complex, Minnesota. Econ Geol 82:87–107Google Scholar
  48. Rollinson HR, Lowry D (1992) Early basic magmatism in the evolution of the Northern Marginal Zone of the Archean Limpopo Belt. Precambrian Res 55:33–45CrossRefGoogle Scholar
  49. Steele TW, Levin J, Copelowitz I (1975) Preparation and certification of a reference sample of a precious metal ore—Report No 1696-1975 of the National Institute of Metallurgy, South Africa, pp 4Google Scholar
  50. Sun S-S (1980) Lead isotopic study of young volcanic rocks from mid-ocean ridges, ocean islands and island arcs. Philos Trans R Soc Lond A297:409–445Google Scholar
  51. Taylor ST, McLennan SM (1985) The continental crust: its composition and evolution. Blackwell, Oxford, p 312Google Scholar
  52. Thériault RD, Barnes S-J (1998) Compositional variations in Cu–Ni–PGE sulfides of the Dunka Road deposit, Duluth Complex, Minnesota: the importance of combined assimilation and magmatic processes. Can Mineral 36:869–886Google Scholar
  53. Thompson RN, Morrison MA, Hendry GL, Parry SJ (1984) An assessment of the relative roles of crust and mantle in magma genesis: an elemental approach. Philos Trans R Soc Lond, A310:549–590Google Scholar
  54. Van de Wel L, Barton JM Jr, Kinny PD (1998) 1.02 Ga granite magmatism in the Tati–granite–greenstone Terrane of Botswana: implications for mineralization and terrane evolution. S Afr J Geol 101:67–72Google Scholar
  55. Van Geffen PWG (2004) Geochemistry of the Phoenix Ni–Cu–PGE deposit, Francistown, Botswana. MSc thesis, Utrecht University, pp 88Google Scholar
  56. Vokes FM (1969) A review of the metamorphism of sulphide deposits. Earth Sci Rev 5:99–143CrossRefGoogle Scholar
  57. Wakefield J (1976) The structural and metamorphic evolution of the Phikwe Ni–Cu sulfide deposit, Selebi-Phikwe, eastern Botswana. Econ Geol 71:988–1005CrossRefGoogle Scholar
  58. Whitford DJ, Jezek PA (1982) Isotopic constraints on the role of subducted sialic material in Indonesian island-arc magmatism. Bull Geol Soc Am 93:504–513CrossRefGoogle Scholar
  59. Wilson M (1989) Igneous petrogenesis. Chapman and Hall, London, p 466Google Scholar
  60. Wright L (1977) A structural cross section across the north margin of the Limpopo Belt. Ph.D. thesis, University of Leeds, UKGoogle Scholar

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • W. D. Maier
    • 1
    Email author
  • S.-J. Barnes
    • 2
  • G. Chinyepi
    • 3
  • J. M. BartonJr
    • 4
  • B. Eglington
    • 5
  • I. Setshedi
    • 3
  1. 1.Centre for Exploration TargetingUniversity of Western AustraliaCrawleyAustralia
  2. 2.Sciences AppliquéesUniversité du Québec à ChicoutimiChicoutimiCanada
  3. 3.Department of GeologyUniversity of PretoriaPretoriaSouth Africa
  4. 4.Department of GeologyFort Hare UniversityAliceSouth Africa
  5. 5.Department of GeologyUniversity of SaskatchewanSaskatoonCanada

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