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Mineralium Deposita

, Volume 39, Issue 4, pp 473–494 | Cite as

The world-class Wallaby gold deposit, Laverton, Western Australia: An orogenic-style overprint on a magmatic-hydrothermal magnetite-calcite alteration pipe?

  • Brock P. Salier
  • David I. GrovesEmail author
  • Neal J. McNaughton
  • Ian R. Fletcher
Article

Abstract

Gold mineralisation at the Wallaby gold deposit is hosted by a 1,200 m thick mafic conglomerate. The conglomerate is intruded by an apparently comagmatic alkaline dyke suite displaying increasing fractionation through mafic-monzonite, monzonite, syenite, syenite porphyry to late-stage carbonatite. In the mine area, a pipe-shaped zone of actinolite-magnetite-epidote-calcite (AMEC) alteration overprints the conglomerate. Gold mineralisation, associated with dolomite-albite-quartz-pyrite alteration, is hosted in a series of sub-horizontal, structurally controlled zones that are largely confined within the magnetite-rich pipe. The deposit has a current ore reserve of 2.0 Moz Au, and a total resource of 7.1 Moz Au.

TIMS U−Pb analysis of magmatic titanite and SHRIMP U−Pb analysis of gold-related phosphate minerals are used to constrain the timing of magmatism and gold mineralisation at Wallaby. Monzogranite and carbonatite dykes of the Wallaby syenite intruded at 2,664±3 Ma, at least 5 m.y. and probably 14 m.y. before gold mineralisation at 2,650±6 Ma. The significant hiatus between proximal magmatism and gold mineralisation suggests that gold-bearing fluids were not derived from magmas associated with the Wallaby syenite, particularly since intrusive events are unlikely to drive hydrothermal systems for more than 1 m.y.

Analysis of the C and O isotopic compositions of carbonates from regional pre-syenite alteration and AMEC alteration at the Wallaby gold deposit suggests that AMEC alteration formed via interaction between magmatic fluids and the pre-syenite wallrock carbonate. The C and O isotopic composition of gold-bearing fluids, as inferred from ore-carbonate, are isotopically distinct from proximal magmatic fluids, as inferred from magmatic carbonate in carbonatite dykes.

Thus, detailed isotopic and geochronological studies negate any direct genetic link between proximal magmatic activity related to the Wallaby syenite and gold mineralisation at Wallaby. The gold endowment of the Wallaby gold deposit, combined with the relatively low solubility of gold as thiosulfide complexes in low-salinity ore fluids at temperatures of about 300°C, implicates the influx of very large volumes of auriferous hydrothermal fluids. No large-scale shear-zones nor faults through which such large fluid-volumes could pass have been identified within the immediate ore environment, so fluid influx most probably occurred largely in a unit-confined, brittle-ductile fracture system. This was the ~500-m diameter AMEC alteration pipe, which was a brittle, iron-enriched zone in an otherwise massive conglomerate. During compressional deformation, the competency contrast between unaltered and AMEC-altered conglomerate created a zone of increased fracture permeability, and geochemically favourable conditions (high Fe/Fe+Mg ratio), for gold mineralisation from a distal source.

Keywords

Gold Deposit Gold Mineralization Alteration Zone Gold Lode Yilgarn Craton 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

This paper forms part of a PhD project at UWA, carried out by B.P.S, who was in receipt of a University Postgraduate Award. The financial and in-kind support of Placer Dome Asia Pacific is gratefully acknowledged, and the company is thanked for access to drill core from their Granny Smith operation, as well as for their permission to publish. Specifically, thanks also go to G. Hall, R. Keele, E. Maidens, S. Halley, T. Aung and J. Baulch, and all the exploration staff at Placer Granny Smith. Marion Marshall is thanked for her assistance with mineral separation, and the staff of the CMM and CGM at UWA, including R. Weinberg and R. and N. Vielreicher, are thanked for their help and assistance. Wouter Bleeker and Bill Davis at the geochronology division of the Geological Survey of Canada in Ottawa are thanked for the TIMS analysis of titanite. Ion probe analyses of titanite, monazite and xenotime were performed at the Western Australian SHRIMP facility operated by a WA university-government consortium with ARC support. The original manuscript was significantly improved by the helpful comments of R. Kerrich and an anonymous reviewer and the clear and incisive comments of the Editor, L. Meinert.

References

  1. Archibald NJ, Bettenay LF, Bickle MJ, Groves DI (1981) Evolution of Archaean crust in the Eastern Goldfields Province of the Yilgarn Block, Western Australia. In: Glover JE, Groves DI (eds) Archaean geology; second international symposium. (Special Publication 7) Geological Society of Australia, Sydney, pp 491–504Google Scholar
  2. Barley ME, Krapez B, Groves DI, Kerrich R (1998) The late Archaean bonanza; metallogenic and environmental consequences of the interaction between mantle plumes, lithospheric tectonics and global cyclicity. Precamb Res 91:65–90CrossRefGoogle Scholar
  3. Binns RA, Gunthorpe RJ, Groves DI (1976) Metamorphic patterns and development of greenstone belts in eastern Yilgarn Block, Western Australia. In: Windley BF (ed) The Early History of the Earth. Wiley, New York, pp 303–313Google Scholar
  4. Blank JG, Brooker RA (1994) Experimental studies of carbon dioxide in silicate melts: solubility, speciation, and stable carbon isotope behaviour. In: Carroll MR, Holloway JR (eds) Volatiles in Magmas. Rev in Mineral, Min Soc Am 30:157–186Google Scholar
  5. Blewett R, Champion DC, Whitaker AJ, Bell B, Nicoll M, Goleby BR, Cassidy KF, Groenewald PB (2002) Three dimensional model of the Leonora-Laverton transect area: implications for Eastern Goldfields tectonics and mineralisation. In: Cassidy KF (ed) The GA-GSWA North Eastern Yilgarn Workshop. Geoscience Australia, Perth, Record 2002/18, pp 75–92Google Scholar
  6. Bottcher ME (1994) 13C/12C and 18O/16O fractionation during synthesis of Mg(CO3)2. Abstracts with Program, International Mineralogical Association, 16th General Meeting, 4–9 September 1994, Pisa, ItalyGoogle Scholar
  7. Brown SJA, Barley ME, Krapez B, Cas, RAF (2002). The late Archaean Melita Complex, Eastern Goldfields, Western Australia; shallow submarine bimodal volcanism in a rifted arc environment. J Volc Geoth Res 115:303–327CrossRefGoogle Scholar
  8. Burger AJ, von Knorring O, Clifford TN (1965) Mineralogical and radiometric studies of monazite and sphene occurrences in the Namib Desert, South-West Africa. Min Mag 35:519–528Google Scholar
  9. Cassidy KF, Groves DI, McNaughton NJ (1998) Late-Archean granitoid-hosted lode-gold deposits, Yilgarn Craton, Western Australia; deposit characteristics, crustal architecture and implications for ore genesis. Ore Geol Rev 13:65–102CrossRefGoogle Scholar
  10. Cassidy KF, Champion DC, Fletcher IR, Dunphy JM, Black LP, Claoue-Long JC (2002) Geochronological constraints on the Leonora-Laverton transect area, north eastern Yilgarn Craton. In: Cassidy KF (ed) The GA-GSWA North Eastern Yilgarn Workshop. Geoscience Australia, Perth, Record 2002/18, pp 31–50Google Scholar
  11. Cathles LM, Erendi AHJ, Barrie T (1997) How long can a hydrothermal system by sustained by a single intrusive event? Econ Geol 92:766–771Google Scholar
  12. Champion DC, Cassidy KF (2002) Granites in the Leonora-Laverton transect area, northeastern Yilgarn Craton. In: Cassidy KF (ed) The GA-GSWA North Eastern Yilgarn Workshop. Geoscience Australia, Perth, Record 2002/18, pp 13–30Google Scholar
  13. Chen SF, Witt WK, Liu S (2001) Transpression and restraining jogs in the northeastern Yilgarn Craton, Western Australia. Precamb Res 106:309–328CrossRefGoogle Scholar
  14. Coggon J (2004) Magnetism – key to the Wallaby gold deposit. Expl Geophy (in press)Google Scholar
  15. Cumming GL, Richards JR (1975) Ore lead isotope ratios in a continuously changing earth. Earth Planet Sci Lett 28:155–177CrossRefGoogle Scholar
  16. Davis B (2004) Complexity of structural-mineralization history in the Eastern Goldfields Province, Yilgarn Craton: evidence and implications from study of gold mineralized systems. Econ Geol (in press)Google Scholar
  17. Davis B, Maidens E (2001) Structural age of mineralisation at Wallaby and Sunrise - evidence for emplacement of mineralisation during orogenic collapse. 2001 - A Hydrothermal Odyssey, extended abstracts volume. James Cook University EGRU, Townsville, Australia, pp 46–47Google Scholar
  18. Davis WJ, McNicoll VJ, Bellerive DR, Santowski K, Scott DJ (1997) Modified chemical procedures for the extraction and purification of uranium from titanite, allanite, and rutile in the Geochronology Laboratory. Geol Surv Can, Radiogenic Age and Isotopic Studies 10, pp 33–35Google Scholar
  19. Dugdale AL, Hagemann SG (2001) The Bronzewing lode-gold deposit, Western Australia; P-T-X evidence for fluid immiscibility caused by cyclic decompression in gold-bearing quartz-veins. Chem Geol 173:53–90CrossRefGoogle Scholar
  20. Eilu P, Mathison C, Groves DI, Allardyce W (1999) Atlas of alteration assemblages, styles and zoning in orogenic lode-gold deposits in a variety of host rock and metamorphic settings. Geology and Geophysics Department and UWA Extension, The University of Western Australia, Publ 30, 50 ppGoogle Scholar
  21. Fletcher IR, Rasmussen B, McNaughton NJ (2000) SHRIMP U–Pb geochronology of authigenic xenotime and its potential for dating sedimentary basins. Aust J Earth Sci 47:845–859CrossRefGoogle Scholar
  22. Fletcher IR, McNaughton NJ, Aleinikoff JA, Rasmussen B(2004) Improved calibration procedure and new standards for U-Pb and Th-Pb dating of Phanerozoic xenotime by ion microprobe. Chem Geol (in press)Google Scholar
  23. Foster G, Kinny P, Vance D, Prince C, Harris N (2000) The significance of monazite U-Th-Pb age data in metamorphic assemblages; a combined study of monazite and garnet chronometry. Earth and Planetary Science Letters 181:327–340CrossRefGoogle Scholar
  24. Golding SD, Barley ME, Cassidy KF, Groves DI, Ho SE, Hronsky J, McNaughton NJ, Sang JH, Turner JV (1990) Constraints on genesis of primary gold deposits: oxygen and hydrogen isotope studies. In: Ho SE, Groves DI and Bennett JM (eds) Gold Deposits of the Archaean Yilgarn Block, Western Australia: Nature, Genesis and Exploration Guides. Geol Dept Univ Ext, Univ West Aust, Publ 20, pp 253–258Google Scholar
  25. Groves DI (1993) The crustal continuum model for late-Archaean lode-gold deposits of the Yilgarn Block, Western Australia. Miner Deposita 28:366–374Google Scholar
  26. Groves DI, Goldfarb RJ, Robert F, Hart CJ (2003) Gold deposits in metamorphic belts: overview of current understanding, outstanding problems, future research, and exploration significance. Econ Geol 98:1–29Google Scholar
  27. Hall GA, Wall VJ, Massey S (2001) Archaean pluton-related (thermal aureole) gold: the Kalgoorlie exploration model. 2001 - A Hydrothermal Odyssey, extended abstracts volume. James Cook University EGRU, Townsville, Australia, pp 66–67Google Scholar
  28. Hallberg JA (1985) Geology and mineral deposits of the Leonora—Laverton area, northeastern Yilgarn Block, Western Australia. Hesperian Press, Australia, 140 ppGoogle Scholar
  29. Hill RI, Chappell BW, Campbell IH (1992) Late Archaean granites of the southeastern Yilgarn Block, Western Australia; age, geochemistry, and origin. In: Brown PE, Chappell BW (eds) The second Hutton symposium on the origin of granites and related rocks; proceedings. (Special Paper 272) Geol Soc Am, New York, pp 211–226Google Scholar
  30. Jaffey A, Flynn K, Glendenin L, Bentley W, Essling A (1971) Precision measurement of half-lives and specific activities of 235U and 238U. Phys Rev C4:1889–1906Google Scholar
  31. Kerrich R, Wyman DA (1990) Geodynamic setting of mesothermal gold deposits: an association with accretionary tectonic regimes. Geology 18:882–885CrossRefGoogle Scholar
  32. Kinny P (1997) Users guide to U-Th-Pb dating of titanite, perovskite, monazite and baddeleyite using the W.A. SHRIMP. Curtin University, School of Physical Sciences, Report SPS 693 (available from the author)Google Scholar
  33. Kositcin N, McNaughton NJ, Griffin BJ, Fletcher IR, Groves DI, Rasmussen B (2003) Textural and geochemical discrimination between xenotime of different origin in the Archaean Witwatersrand Basin, South Africa. Geochim Cosmochim Acta 67:709–731CrossRefGoogle Scholar
  34. Krapez B, Brown SJ, Hand J, Barley ME, Cas RA (2000) Age constraints on recycled crustal and supracrustal sources of Archaean metasedimentary sequences, Eastern Goldfields Province, Western Australia; evidence from SHRIMP zircon dating. Tectonophysics 322:89–133CrossRefGoogle Scholar
  35. Ludwig KR (2001) Users manual for Isoplot/Ex. Berkeley Geochronology Centre, Special Publication 1aGoogle Scholar
  36. McCuaig TC, Kerrich R (1998) P-T-t deformation-fluid characteristics of lode gold deposits: evidence from alteration systematics. Ore Geol Rev 12:381–453CrossRefGoogle Scholar
  37. McNaughton NJ, Barley ME, Cassidy KF, Golding SD, Groves DI, Ho SE, Hronsky J, Sang JH, Turner JV (1990) Constraints on genesis of primary gold deposits: carbon isotope studies. In: Ho SE, Groves DI, Bennett JM (eds) Gold Deposits of the Archaean Yilgarn Block, Western Australia: Nature, Genesis and Exploration Guides. Geol Dept Univ Ext, Univ West Aust, Publ 20, pp 246–251Google Scholar
  38. Mikucki EJ (1998) Hydrothermal transport and depositional processes in Archean lode-gold systems; a review. Ore Geol Rev 13:307–321CrossRefGoogle Scholar
  39. Myers JS (1997) Preface; Archaean geology of the Eastern Goldfields of Western Australia; regional overview. Precamb Res 83:1–10CrossRefGoogle Scholar
  40. Nelson DR (1997) Evolution of the Archaean granite-greenstone terranes of the Eastern Goldfields, Western Australia; SHRIMP U-Pb zircon constraints. Precamb Res 83:57–81CrossRefGoogle Scholar
  41. Ohmoto H, Rye RO (1979) Isotopes of sulfur and carbon. In: Barnes HL (ed) Geochemistry of Hydrothermal Ore Deposits. Wiley, New York, pp 509–567Google Scholar
  42. Ojala VJ (1995) Structural and depositional controls on gold mineralisation at the Granny Smith Mine, Laverton, Western Australia. Unpublished PhD Thesis, The University of Western AustraliaGoogle Scholar
  43. Parish RR, Bellerive D, Sullivan RW (1992) U-Pb chemical procedures for titanite and allanite in the Geochronology Laboratory, Geol Surv Can, Radiogenic Age and Isotopic Studies 7, pp 187–190Google Scholar
  44. Phillips GN, Groves DI (1983) The nature of Archaean gold-bearing fluids as deduced from gold deposits of Western Australia. J Geol Soc Aust 30:25–39Google Scholar
  45. Pidgeon RT, Wilde SA (1990) The distribution of 3.0 Ga and 2.7 Ga volcanic episodes in the Yilgarn Craton of Western Australia. Precamb Res 48:309–325CrossRefGoogle Scholar
  46. Pigois J, Groves DI, Fletcher IR, McNaughton NJ, Snee LW (2003) Age constraints on Tarkwaian palaeoplacer and lode-gold formation in the Tarkwa-Damang district, SW Ghana. Miner Deposita 38:695–714CrossRefGoogle Scholar
  47. Platt JP, Allchurch PD, Rutland RWR (1978) Archaean tectonics in the Agnew supracrustal belt, Western Australia. Precamb Res 7:3–30CrossRefGoogle Scholar
  48. Potma W, Schaubs P, Hobbs B, Ord A (2004) Mohr-Coulomb theory and numerical modelling: unravelling the Wallaby Au ore system. In: Dynamic Earth: Past, Present and Future, 17th Australian Geological Convention, Hobart 8–13 Feb, p. 111Google Scholar
  49. Purdie RP (2000) Depositional history and provenance characteristics of the host rock succession, Wallaby Gold Deposit, Eastern Goldfields Western Australia. Unpublished Honours Thesis, Monash University, 117 ppGoogle Scholar
  50. Qui Y, McNaughton NJ (1999) Source of Pb in orogenic lode-gold mineralisation; Pb isotope constraints from deep crustal rock from the southwestern Archaean Yilgarn Craton, Australia. Miner Deposita 34:366–381CrossRefGoogle Scholar
  51. Rasmussen B, Fletcher IR, McNaughton NJ (2001). Dating low-grade metamorphic events by SHRIMP U-Pb analysis of monazite in shales. Geology 29:963–966CrossRefGoogle Scholar
  52. Rattenbury MS (1993) Tectonostratigraphic terranes in the northern Eastern Goldfields. In: William PR, Haladane JA (eds) Kalgoorlie ‘93 - an International conference on crustal evolution, metallogeny and exploration of the Eastern Goldfields Province, extended abstracts volume. Aust Geol Surv Org, Record 1993/54, Perth, pp 73–75Google Scholar
  53. Roberts D (1988) Kambalda-St. Ives area and the Victory-Defiance Complex. In: Groves DI, Barley ME, Ho SE, Hopkins GMF (eds) Bicentennial Gold 88. (Excursion Guide Book) Geol Soc Aust, Perth, pp 109–113Google Scholar
  54. Salier B (2004) The timing and source of gold-bearing fluids in the Laverton Greenstone Belt, Yilgarn Craton, Western Australia. Unpublished PhD Thesis, The University of Western AustraliaGoogle Scholar
  55. Smith JB, Barley ME, Groves DI, Krapez B, McNaughton NJ, Bickle MJ, Chapman HJ (1998) The Sholl shear zone, West Pilbara; evidence for a domain boundary structure from integrated tectonostratigraphic analyses, SHRIMP U-Pb dating and isotopic and geochemical data of granitoids. Precamb Res 88:143–171CrossRefGoogle Scholar
  56. Smithies RH, Champion DC (1999) Late Archaean felsic alkaline igneous rocks in the Eastern Goldfields, Yilgarn Craton, Western Australia; a result of lower crustal delamination? J Geol Soc London 156:561–576Google Scholar
  57. Swager CP (1995) Geology of the greenstone terranes in the Kurnalpi-Edjudina region, southeastern Yilgarn Craton. Geol Surv West Austr, Report 47, 31 ppGoogle Scholar
  58. Swager CP (1997) Tectono-stratigraphy of late Archaean greenstone terranes in the southern Eastern Goldfields, Western Australia. Precamb Res 83:11–42CrossRefGoogle Scholar
  59. Swager CP, Nelson DR (1997) Extensional emplacement of a high-grade granite gneiss complex into low-grade greenstones, Eastern Goldfields, Yilgarn Craton, Western Australia. Precamb Res 83:203–219CrossRefGoogle Scholar
  60. Swager C, Witt WK, Griffin TJ, Ahmat WM, Hunter WM, McGoldrick PJ, Wyche S (1990) Part I: a regional overview of the Archaean granite-greenstones of the Kalgoorlie Terrane. In: Glover JE, Ho SE (eds) Third International Archaean Symposium, Perth, 1990, abstracts volume. Geoconferences, Perth, pp 205–220Google Scholar
  61. Vielreicher N, Groves DI, McNaughton NJ, Fletcher IR, Rasmussen B (2003) Hydrothermal monazite and xenotime geochronology: a new direction for precise dating of orogenic gold mineralisation. Soc Econ Geol Newslett 53:1–16Google Scholar
  62. Walshe JL, Halley SW, Hall GA, Kitto P (2003) Contrasting fluid systems, chemical gradients and controls on large-tonnage, high-grade Au deposits, Eastern Goldfields Province, Yilgarn Craton, Western Australia. In: Eliopoulos DG (ed) 7th Biennial SGA Meeting, extended abstracts. SGA, Athens, pp 407–410Google Scholar
  63. Williams PK (1994) Relationship between magnetic anomalism and epigenetic gold mineralisation in the Victory-Defiance area, Western Australia. Expl Geophy 25:167–168CrossRefGoogle Scholar
  64. Wooley AR, Kempe DR (1989) Carbonatites, nomenclature, average chemical compositions, and element distribution. In: Bell K (ed) Carbonatites; Genesis and Evolution. Unwin Hyman, London, pp 1–14Google Scholar

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Brock P. Salier
    • 1
  • David I. Groves
    • 1
    Email author
  • Neal J. McNaughton
    • 1
  • Ian R. Fletcher
    • 1
  1. 1.Centre for Global Metallogeny, School of Earth and Geographical SciencesThe University of Western AustraliaCrawley

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