Advertisement

Mineralium Deposita

, 43:641 | Cite as

The Mordor Alkaline Igneous Complex, Central Australia: PGE-enriched disseminated sulfide layers in cumulates from a lamprophyric magma

  • Stephen J. BarnesEmail author
  • J. A. C. Anderson
  • T. R. Smith
  • L. Bagas
Article

Abstract

The Mordor Alkaline Igneous Complex (MAIC) is a composite intrusion comprising a body of syenite and a funnel-shaped layered mafic–ultramafic intrusion of lamprophyric parentage, the Mordor Mafic–Ultramafic Intrusion or MMUI. The MMUI is highly unusual among intrusions of lamprophyric or potassic parentage in containing primary magmatic platinum-group element (PGE)-enriched sulfides. The MMUI sequence consists largely of phlogopite-rich pyroxenitic cumulates, with an inward dipping conformable layer of olivine-bearing cumulates divisible into a number of cyclic units. Stratiform-disseminated sulfide accumulations are of two types: disseminated layers at the base of cyclic units, with relatively high PGE tenors; and patchy PGE-poor disseminations within magnetite-bearing upper parts of cyclic units. Sulfide-enriched layers at cycle bases contain anomalous platinum group element contents with grades up to 1.5 g/t Pt+Pd+Au over 1-m intervals, returning to background values of low parts per billion (ppb) on a meter scale. They correspond to reversals in normal fractionation trends and are interpreted as the result of new magma influxes into a continuously replenished magma chamber. Basal layers have decoupled Cu and PGE peaks reflecting increasing PGE tenors up-section, due to increasing R factors during the replenishment episode, or progressive mixing of between resident PGE-poor magma and more PGE-enriched replenishing magma. The presence of PGE enriched sulfides in cumulates from a lamprophyric magma implies that low-degree partial melts do not necessarily leave sulfides and PGEs in the mantle restite during partial melting.

Keywords

Platinum group elements Lamprophyre Cumulates Magmatic sulfides 

Notes

Acknowledgments

We thank Tanami Gold NL for financial support to SJB and for analytical work, and for permission to publish. The manuscript was greatly improved following reviews by Marco Fiorentini, Wolfgang Maier, Michael Styles, and Larry Meinert. Greg Hitchen provided assistance with microprobe analyses. We thank Marcus Burnham and staff of GeoScience Laboratories, Sudbury, and the staff of Genalysis Laboratories, Perth, for analytical data.

Supplementary material

126_2008_187_MOESM1_ESM.xls (387 kb)
ESM 1 (XLS 387 KB)
126_2008_187_MOESM2_ESM.xls (50 kb)
ESM 2 (XLS 50 KB)
126_2008_187_MOESM3_ESM.xls (34 kb)
ESM 3 (XLS 34 KB)

References

  1. Andronikov AV, Foley SF (2001) Trace element and Nd-Sr isotopic composition of ultramafic lamprophyres from the east Antarctic Beaver Lake area. Chem Geol 175:291–305CrossRefGoogle Scholar
  2. Arndt NT, Lesher CM, Czamanske GK (2005) Mantle derived magmas and magmatic Ni-Cu-PGE deposits. Economic Geology 100th Anniversary Volume:5–24Google Scholar
  3. Atkinson WJ, Hughes FE, Smith CB (1984) A review of the kimberlitic rocks of Western Australia. Kimberlites. Proceedings of the Third International Kimberlite Conference, France, 1982. Volume 1— Kimberlites and Related Rocks:195–224Google Scholar
  4. Barnes Sarah-J, Naldrett AJ, Gorton MP (1985) The origin of the fractionation of the platinum-group elements in terrestrial magmas. Chem Geol 53:303–323CrossRefGoogle Scholar
  5. Barnes Sarah-J, Boyd R, Nilsson LP, Often M, Pedersen RB, Robins B (1988) The use of mantle normalization and metal ratios in discriminating between the effects of partial melting, crystal fractionation and sulphide segregation on platinum group metals, gold, nickel and copper: examples from Norway. In: Prichard HM, Potts PJ, Bowles JFW, Cribbs SJ (eds) Geo-Platinum ’87 Elsevier Science Publishers Ltd., London, pp 113–139Google Scholar
  6. Barnes Stephen J (1986) The effect of trapped liquid crystallization on cumulus mineral compositions in layered intrusions. Contrib Mineral Petrol 93:524–531CrossRefGoogle Scholar
  7. Barnes Stephen J (1989) Are Bushveld U-type parent magmas boninites or contaminated komatiites? Contrib Mineral Petrol 101:447–457CrossRefGoogle Scholar
  8. Barnes Stephen J (1993) Partitioning of the platinum group elements and gold between silicate and sulphide magmas in the Munni Munni Complex, Western Australia. Geochim Cosmochim Acta 57:1277–1290CrossRefGoogle Scholar
  9. Barnes Stephen J, Hoatson DM (1994) The Munni Munni Complex, Western Australia: stratigraphy, structure and petrogenesis. J Petrol 35:715–751Google Scholar
  10. Barnes Stephen J, Naldrett AJ (1985) Geochemistry of the JM (Howland) Reef of the Stillwater Complex, Minneapolis Adit area:I. Sulfide chemistry and sulfide–olivine equilibrium. Econ Geol 80:627–645CrossRefGoogle Scholar
  11. Barnes Stephen J, Naldrett AJ (1986) Geochemistry of the J-M Reef of the Stillwater Complex, Minneapolis Adit area II Silicate mineral chemistry and petrogenesis. J Petrol 27:791–825Google Scholar
  12. Barraclough D (1981) Final Report on the Mordor Complex, Central Australia. Northern Territory Geological Survey Report:GS81–48Google Scholar
  13. Barrie CT, MacTavish AD, Walford PC, Chataway R, Middaugh R (2002) Contact type and magnetitite reef-type Pd-Cu mineralization in ferroan olivine gabbros of the Coldwell Complex, Ontario, Canada. In: Cabri LJ (ed.) Canadian Institute of Mining Metallurgy and Petroleum, Special Volume 54, pp 321–338Google Scholar
  14. Black LP, Shaw RD, Stewart AJ (1983) Rb-Sr geochronology of Proterozoic events in the Arunta inlier, central Australia. BMR J Aust Geol Geophys 8:129–137Google Scholar
  15. Campbell IH, Barnes SJ (1984) A model for the geochemistry of the platinum group elements in magmatic sulphide deposits. Can Mineral 22:151–160Google Scholar
  16. Campbell IH, Naldrett AJ (1979) The influence of silicate:sulphide ratios on the geochemistry of magmatic sulphides. Econ Geol 74:503–1505Google Scholar
  17. Campbell IH, Turner JS (1986) The influence of viscosity in fountains in magma chambers. J Petrol 27:1–30Google Scholar
  18. Campbell IH, Turner JS (1989) Fountains in magma chambers. J Petrol 30:885–923Google Scholar
  19. Campbell IH, Naldrett AJ, Barnes SJ (1983) A model for the origin of the platinum-rich sulfide horizons in the Bushveld and Stillwater Complexes. J Petrol 24:33–165Google Scholar
  20. Cawthorn RG, Barnes SJ, Ballhaus C, Malich KN (2005) Platinum group element, chromium and vanadium deposits in mafic and ultramafic rocks. Econ Geol 100th Anniversary volume:215–249Google Scholar
  21. Clark AL, Greenwood WR (1972) Geochemistry and distribution of platinum-group metals in mafic to ultramafic complexes of southern and southeastern Alaska. U.S. Geol Surv Prof Pap 800-C:157–160Google Scholar
  22. Close DF, Scrimgeour IR, Edgoose CJ, Frater KM, Cross AJ (2004) New insights into the geology and prospectivity of the southwestern Arunta region. Northern Territory Geological Survey, Record 2004-001Google Scholar
  23. Crocket JH (2002) Platinum-group elements in basalts from Maui, Hawaii: low abundances in alkali basalts. Can Mineral 40:595–609CrossRefGoogle Scholar
  24. Crocket JH, Paul DK (2004) Platinum-group elements in Deccan mafic rocks: a comparison of suites differentiated by Ir content. Chem Geol 208:273–291CrossRefGoogle Scholar
  25. Garuti G, Fershtater G, Bea F, Montero P, Pushkarev EV, Zaccarini F (1997) Platinum-group elements as petrological indicators in mafic-ultramafic complexes of the Central and Southern Urals—preliminary results. Tectonophysics 276:181–194CrossRefGoogle Scholar
  26. Gunn AG, Styles MT (2002) Platinum-group element occurrences in Britain: magmatic, hydrothermal and supergene. Trans Inst Min Metall B-Appl Earth Sci 111:B2–B14Google Scholar
  27. Haines PW, Hand M, Sandiford M (2001) Palaeozoic synorogenic sedimentation in central and northern Australia; a review of distribution and timing with implications for the evolution of intracontinental orogens. Aust J Earth Sci 48:911–928CrossRefGoogle Scholar
  28. Hamlyn PR, Keays RR (1986) Sulfur saturation and second stage melts: application to the Bushveld platinum metal deposits. Econ Geol 81:1431–1445Google Scholar
  29. Hatton CJ, Sharpe MR (1989) Significance and origin of boninite-like rocks associated with the Bushveld Complex. In: Crawford AJ (ed.) Unwin Hyman Inc., London, pp 174–208Google Scholar
  30. Helmy HM, Mogessie A (2001) Gabbro Akarem, Eastern Desert, Egypt: Cu-Ni-PGE mineralization in a concentrically zoned mafic–ultramafic complex. Mineral Depos 36:58–71CrossRefGoogle Scholar
  31. Hoatson DM, Claoué-Long JC (2002) Event chronology and prospectivity of the mafic magmatic systems in the Arunta Province. Northern Territory Geological Survey, Record 2002/003Google Scholar
  32. Huppert HE, Sparks RSJ (1980) The fluid dynamics of a basaltic magma chamber replenished by influxes of hot, dense ultrabasic magma. Contrib Mineral Petrol 75:279–289CrossRefGoogle Scholar
  33. Irvine TN (1980) Magmatic density currents and cumulus processes. Am J Sci 280-A:1–58Google Scholar
  34. Irvine TN (1982) Terminology for layered intrusions. J Petrol 23:127–162Google Scholar
  35. Keays RR (1995) The role of komatiitic and picritic magmatism and S-saturation in the formation of ore deposits. Lithos 34:1–18CrossRefGoogle Scholar
  36. Langworthy AP, Black LP (1978) The Mordor Complex: a highly differentiated potassic intrusion with Kimberlitic affinities in central Australia. Contrib Mineral Petrol 67:51–62CrossRefGoogle Scholar
  37. Li C, Naldrett AJ (1999) Geology and petrology of the Voisey’s Bay intrusion: reaction of olivine with sulfide and silicate liquids. Lithos 47:1–31CrossRefGoogle Scholar
  38. Maier WD, Barnes SJ, Dewaal SA (1998) Exploration for magmatic Ni-Cu-PGE sulphide deposits — a review of recent advances in the use of geochemical tools, and their application to some South African ores. S Afr J Geol 101:237–253Google Scholar
  39. Maier WD, Barnes SJ, Gartz V, Andrews G (2003) Pt-Pd reefs in magnetitites of the Stella layered intrusion, South Africa: a world of new exploration opportunities for platinum group elements. Geology 31:885–888CrossRefGoogle Scholar
  40. Mathez EA, Peach CL (1989) The geochemistry of the platinum-group elements in mafic and ultramafic rocks. In: Whitney JA, Naldrett AJ (eds.) Ore deposition associated with magmas. Society of Economic Geologists, El Paso, pp 330–43Google Scholar
  41. McDonough WF, Sun S-S (1995) The composition of the Earth. Chem Geol 120:223–253CrossRefGoogle Scholar
  42. Mungall JE (2008) Magmatic ore deposits. In: Treatise on geochemistry (in press). ElsevierGoogle Scholar
  43. Mungall JE, Hanley JJ, Arndt NT, Debecdelievre A (2006) Redox controls on mantle-crust fractionation of platinum-grup elements: evidence from meimechites and other low degree mantle melts. Proc Natl Acad Sci U S A 103:12695–12700CrossRefGoogle Scholar
  44. Peach CL, Mathez EA, Keays RR (1990) Sulfide melt– silicate melt distribution coefficients for the noble metals as deduced from MORB: implications for partial melting. Geochim Cosmochim Acta 54:3379–3389CrossRefGoogle Scholar
  45. Prendergast MD (2000) Layering and precious metals mineralization in the Rincon del Tigre Complex, eastern Bolivia. Econ Geol 95:113–130Google Scholar
  46. Rehkamper M, Halliday AN, Fitton JG, Lee DC, Wieneke M, Arndt NT (1999) Ir, Ru, Pt, and Pd in basalts and komatiites: New constraints for the geochemical behavior of the platinum-group elements in the mantle. Geochim Cosmochim Acta 63:3915–3934CrossRefGoogle Scholar
  47. Riley TR, Leat PT, Storey BC, Parkinson IJ, Millar IL (2003) Ultramafic lamprophyres of the Ferrar large igneous province: evidence for a HIMU mantle component. Lithos 66:63–76CrossRefGoogle Scholar
  48. Robinson BW, Graham J (1992) Advances in electron microprobetrace-element analysis. J Comput-Assist Microsc 4(3):263–265Google Scholar
  49. Rock NMS (1986) The nature and origin of ultramafic lamprophyres: alnoites and allied rocks. J Petrol 27:155–196Google Scholar
  50. Sevigny JH, Theriault RJ (2003) Geochemistry and Sr-Nd isotopic composition of Eocene lamprophyre dykes, southeeastern British Columbia. Can J Earth Sci 40:853–864CrossRefGoogle Scholar
  51. Shee SR, Bristow JW, Bell DR, Smith CB, Allsopp HL, Shee PB (1989) The petrology of kimberlites, related rocks and associated mantle xenoliths from the Kuruman Province, South Africa. Kimberlites and related rocks. Volume 1. Their composition, occurrence, origin and emplacement. Proceedings of the Fourth International Kimberlite Conference:60–82Google Scholar
  52. Sisson TW (2003) Native gold in a Hawaiian alkalic magma. Econ Geol 98:643–648CrossRefGoogle Scholar
  53. Slansky E, Johan Z, Ohnenstetter M, Barron L, Suppel D (1991) Platinum mineralization in the Alaskan-type intrusive complexes near Fifield, N.S.W., Australia. Part 2. Platinum-group minerals in placer deposits at Fifield.. Contrib Mineral Petrol 43:161–180Google Scholar
  54. Styles MT, Gunn AG, Rollin KE (2004) A preliminary study of PGE in the Late Caledonian Loch Borralan and Loch Ailsh Alkaline Pyroxenite–Syenite Complexes, North-West Scotland. Miner Depos 39:240–255CrossRefGoogle Scholar
  55. Tolstykh ND, Foley JY, Sidorov EG, Laajoki KVO (2002) Composition of the platinum-group minerals in the Salmon River placer deposit, Goodnews Bay, Alaska. Can Mineral 40:463–471CrossRefGoogle Scholar
  56. Turner JS, Campbell IH (1986) Convection and magma mixing in magma chambers. Earth Sci Rev 23:255–352CrossRefGoogle Scholar
  57. Watkinson DH, Lavigne MJ, Fox PE (2002) Magmatic-hydrothermal Cu- and Pd-rich deposits in gabbroic rocks from North America. In: Cabri LJ (ed) Canadian Institute of Mining Metallurgy and Petroleum, Special Volume 54299–320Google Scholar
  58. Wilson AH (2001) Compositional and lithological controls on the PGE-bearing sulphide zones in the Selukwe Subchamber, Great Dyke: a combined equilibrium-Rayleigh fractionation model. J Petrol 42:1845–1867CrossRefGoogle Scholar
  59. Wilson AH, Tredoux M (1990) Lateral and vertical distribution of platinum-group elements and petrogenetic controls on the sulfide mineralization in the P1 pyroxenite layer of the Darwendale Subchamber of the Great Dyke, Zimbabwe. Econ Geol 85:556–584Google Scholar
  60. Wilson AH, Prendergast MD (2001) Platinum-group element mineralization in the Great Dyke, Zimbabwe, and its relationship to magma evolution and magma chamber structure. S Afr J Geol 104:319–342CrossRefGoogle Scholar

Copyright information

© Her Majesty the Queen in Rights of Australia 2008

Authors and Affiliations

  • Stephen J. Barnes
    • 1
    Email author
  • J. A. C. Anderson
    • 2
  • T. R. Smith
    • 2
  • L. Bagas
    • 3
  1. 1.CSIRO Exploration and MiningKensingtonAustralia
  2. 2.Tanami Gold NLWest PerthAustralia
  3. 3.Centre for Exploration Targeting, School of Earth and Geographical SciencesThe University of Western AustraliaCrawleyAustralia

Personalised recommendations