Advertisement

Mineralium Deposita

, 44:245 | Cite as

Quartz vein fabrics coupled to elevated fluid pressures in the Stawell gold deposit, south-eastern Australia

  • C. J. L. WilsonEmail author
  • J. A. Robinson
  • A. L. Dugdale
Article

Abstract

Shear and extensional veins formed during the reactivation of the Magdala shear system at Stawell in western Victoria, Australia, contribute to the formation of the auriferous Central and Basalt Contact lodes. Within this shear system is a range of fault rocks accompanied by steep-dipping (>65°) quartz-rich laminated shear veins and relatively flat-lying extensional veins. Both vein sets appear to have been a primary source for the host rock permeability during fluid flow in a regime of significant deviatoric stresses. The macro- and microstructures suggest that the dilatancy, that produced mineralized veins, formed under conditions of overpressure generated by fluid infiltration late in a tectonic regime. A new microfabric analysis technique is used to investigate the quartz-rich veins, which allows rapid integration of the microstructure with the crystallographic preferred orientations (CPOs). Both the shear and extensional quartz veins have a random CPO with ∼120° dihedral angles between the quartz–quartz grains, which is typical of a metamorphic equilibrium microfabric. The microstructures indicate that the quartz has undergone extensive grain adjustment in the solid-state, with grain shape and size affected by interfacial solution (pressure solution) effects. These features are consistent with inferences from experimental rock deformation studies, where grain boundary migration is enhanced in a water-rich environment. The onset of solution-transfer processes (pressure solution) developed as the quartz microfabric stabilized and continued to modify the CPO and microstructure significantly. It is concluded that grain growth and pressure solution are coupled diffusive mass transfer processes, related to fluctuations in pore fluid pressures in a region undergoing deformation at near lithostatic pressures.

Keywords

Brittle deformation Fluid pressure Gold mineralization Microstructure Crystallographic orientation distribution 

Notes

Acknowledgements

CJLW thanks Jean-Pierre Burg for serving as host at ETH, Zürich, where the first draft of this paper was written. This project was funded by Leviathan Resources and the Predictive Mineral Discovery Cooperative Research Centre. The authors wish to thank Perserverance Corporation (who have merged with Leviathan Resources) for allowing the publication of this paper. Finally, we would like to thank Alan Boyle and Andrew Ham for their constructive reviews and the editorial comments of Jim Barrie.

References

  1. Bettermann P, Liebau F (1975) The transformation of amorphous silica to crystalline silica under hydrothermal conditions. Contrib Mineral Petrol 53:25–36CrossRefGoogle Scholar
  2. Bons PD (2001a) The formation of large quartz veins by rapid ascent of fluids in mobile hydrofractures. Tectonophysics 336:1–17CrossRefGoogle Scholar
  3. Bons PD (2001b) Development of crystal morphology during unitaxial growth in a progressively widening vein: I. The numerical model. J Struct Geol 23:865–872Google Scholar
  4. Bons PD, Montenari M (2005) The formation of antitaxial calcite veins with well developed fibres, Oppaminda Creek, South Australia. J Struct Geol 27:231–248Google Scholar
  5. Cox SF (1995) Faulting processes at high fluid pressures: an example of fault valve behavior from the Wattle Gully Fault, Victoria, Australia. J Geophys Res 100:12841–12859CrossRefGoogle Scholar
  6. Cox SF, Etheridge MA (1983) Crack-seal fibre growth mechanisms and their significance in the development of oriented layer silicate microstructures. Tectonophysics 92:147–170CrossRefGoogle Scholar
  7. Cox SF, Knackstedt MA, Braun J (2001) Principles of structural control on permeability and fluid flow in hydrothermal systems. Soc Econ Geol Rev 14:1–24Google Scholar
  8. de Boer RB, Nagtegaal PJC, Duyvis EM (1977) Pressure solution experiments on quartz sand. Geochim Cosmochim Acta 41:257–264Google Scholar
  9. Drury MR, Urai JL (1990) Deformation-related recrystallisation processes. Tectonophysics 172:235–253CrossRefGoogle Scholar
  10. Dugdale AL, Wilson CJL, Squire RJ (2006) Hydrothermal alteration at the Magdala gold deposit, western Victoria. Aust J Earth Sci 53:733–757CrossRefGoogle Scholar
  11. Elliott MT, Cheadle MJ, Jerram DA (1997) On the identification of textural equilibrium in rocks using dihedral angle measurements. Geology 25:355–358CrossRefGoogle Scholar
  12. Elmer FL, Dugdale AL, Wilson CJL (2008) Application of mineral equilibria modeling to constrain T and X CO2 conditions during the evolution of the Magdala gold deposit, Stawell, Victoria, Australia. Mineralium Deposita 43:759–776Google Scholar
  13. Farver J, Yund R (2000) Silicon diffusion in a natural quartz aggregate: constraints on solution-transfer diffusion creep. Tectonophysics 325:193–205CrossRefGoogle Scholar
  14. Frondel C (1938) Stability of colloidal gold under hydrothermal conditions. Econ Geol 33:1–20Google Scholar
  15. Géraud Y, Caron J-M, Faure P (1995) Porosity network of a ductile shear zone. J Struct Geol 17:1757–1769Google Scholar
  16. Herrington RJ, Wilkinson JJ (1993) Colloidal gold and silica in mesothermal vein systems. Geology 21:539–542CrossRefGoogle Scholar
  17. Hilgers C, Koehn D, Bons PD, Urai JL (2001) Development of crystal morphology during unitaxial growth in a progressively widening vein: II. Numerical simulations of the evolution of antitaxial fibrous veins. J Struct Geol 23:873–885Google Scholar
  18. Hippertt JFM (1994) Grain boundary microstructures in miceous quartzite: significance of fluid movement and deformation processes in low metamorphic grade shear zones. J Geol 102:331–348CrossRefGoogle Scholar
  19. Hirth G, Tullis J (1989) The Effects of Pressure and Porosity on the micromechanics of the Brittle-Ductile transition in quartzite. J Geophys Res 94:17825–17838CrossRefGoogle Scholar
  20. Hirth G, Tullis J (1994) The brittle-plastic transition in experimentally deformed quartz aggregates. J Geophys Res 99:11731–11748 doi: 10.1029/93JB02873 CrossRefGoogle Scholar
  21. Holness MB (1993) Temperature and pressure dependence of quartz-aqueous fluid dihedral angles: the control of absorbed H2O on the permeability of quartzite. Earth Planet Sci Lett 117:363–377CrossRefGoogle Scholar
  22. Holness MB (1997) Deformation-enhanced fluid transport in the Earth’s crust and Mantle. Chapman & Hall, London, p 333Google Scholar
  23. Holyoke CW II, Tullis J (2006) Formation and maintenance of shear zones. Geology 34:105–108CrossRefGoogle Scholar
  24. Karato SI, Masuda T (1989) Anisotropic grain-growth in quartz aggregates under stress and its applications for foliation development. Geology 17:695–698CrossRefGoogle Scholar
  25. Koehn D, Hilgers C, Bons PD, Passchier CW (2000) Numerical simulation of fibre growth in antitaxial strain fringes. J Struct Geol 22:1311–1324Google Scholar
  26. Mancktelow NS, Pennacchioni G (2004) The influence of grain boundary fluids on the microstructure of quartz-feldspar mylonites. J Struct Geol 26:47–69Google Scholar
  27. Miller JMcL, Wilson CJL (2002) The Magdala lode deposit, Stawell, south eastern Australia: Structural style and relationship to gold mineralisation across the western Lachlan Fold Belt, Australia. Econ Geol 97:325–349CrossRefGoogle Scholar
  28. Miller JMcL, Wilson CJL (2004a) The Magdala lode system, Stawell, southeastern Australia: structural style and relationship to gold mineralization across the western Lachlan Fold Belt. Econ Geol 97:325–345Google Scholar
  29. Miller JMcL, Wilson CJL (2004b) Application of structural analysis to faults associated with a heterogeneous stress history: the reconstruction of a dismembered gold deposit, Stawell, western Lachlan Fold Belt, Australia. J Struct Geol 26:1231–1256Google Scholar
  30. Miller JMcL, Wilson CJL, Dugdale LJ (2006) Ordovician to Early Devonian structural evolution of the western Victorian gold deposits. Aust J Earth Sci 53:677–696CrossRefGoogle Scholar
  31. Passchier CW, Trouw RAJ (2005) Microtectonics, 2nd edn. Springer, Berlin, p 366Google Scholar
  32. Paterson MS (1973) Non-hydrostatic thermodynamics and its geologic applications. Rev Geophys Space Phys 11:355–389CrossRefGoogle Scholar
  33. Paterson MS (1986) The thermodynamics of water in quartz. Phys Chem Mineral 13:245–255Google Scholar
  34. Plummer HC (1940) Probality and frequency. MacMillan, London, p 277Google Scholar
  35. Poirier JP (1980) Shear localization and shear instability in materials in the ductile field. J Struct Geol 2:135–142Google Scholar
  36. Ramsay JG (1980) The crack seal mechanism of rock deformation. Nature 284:135–139CrossRefGoogle Scholar
  37. Ramsay JG, Huber MI (1983) Techniques in modern structural geology, vol 1; strain analysis. Academic, London, p 307Google Scholar
  38. Renard F, Ortoleva P, Gratier JP (1999) An integrated model for transitional pressure solution in sandstones. Tectonophysics 312:97–115CrossRefGoogle Scholar
  39. Revil A (2001) Pervasive pressure solution transfer in a quartz sand. J Geophys Res 106:8665–8686CrossRefGoogle Scholar
  40. Robert F, Boullier A-M, Firdaous K (1995) Gold-quartz veins in metamorphic terranes and their bearing on the role of fluids in faulting. J Geophys Res 100:12861–12879CrossRefGoogle Scholar
  41. Robinson JA, Wilson CJL, Rawling TJ (2006a) Influence of volcano-sedimentary facies architecture on strain partitioning during the evolution of an orogenic-gold lode system, Stawell, western Victoria. Aust J Earth Sci 53:721–732Google Scholar
  42. Robinson JA, Wilson CJL, Rawling TJ (2006b) Numerical modelling of an evolving gold system: Structural and lithological, controls on ore shoot formation within the Magdala Mine, western Victoria. Aust J Earth Sci 53:799–823Google Scholar
  43. Sander B (1950) Einfhürung in die Gefügekunde der geologischen Körper. Springer, Berlin, p 399Google Scholar
  44. Schaubs PM, Rawling TJ, Dugdale LJ, Wilson CJL (2006) Factors controlling the location of gold mineralisation around basalt domes in the Stawell corridor: insights from 3-D deformation-fluid flow numerical models. Aust J Earth Sci 53:841–862CrossRefGoogle Scholar
  45. Schmocker M, Bystricky M, Kunze K, Burlini L, Stünitz H, Burg J-P (2003) Granular flow and Riedel band formation in water-rich quartz aggregates experimentally deformed in torsion. J Geophys Res 108(No. B5):2242 doi: 10.1029/2002JB001958 CrossRefGoogle Scholar
  46. Sheldon HA, Wheeler J (2003) Influence of pore fluid chemistry on the state of stress in sedimentary basins. Geology 31:59–62CrossRefGoogle Scholar
  47. Sibson RH (1996) Structural permeability of fluid-driven fault-fracture meshes. J Struct Geol 14:1031–1042Google Scholar
  48. Sibson RH (2001) Seismogenic framework for hydrothermal transport and ore deposition. Soc Econ Geol Rev 18:25–50Google Scholar
  49. Sibson RH, Robert F, Poulsen KH (1988) High-angle reverse faults, fluid pressure cycling and mesothermal gold-quartz deposits. Geology 16:551–555CrossRefGoogle Scholar
  50. Sprunt ES, Nur A (1976) The reduction of porosity by pressure solution: experimental verification. Geology 4:463–466CrossRefGoogle Scholar
  51. Swanson MT (1992) Late Acadian-Alleghenian transpressional deformation: evidence from asymmetric boudinage in the Casco Bay area, coastal Maine. J Struct Geol 14:323–341Google Scholar
  52. Tullis J, Yund RA (1982) Grain Growth kinetics of quartz and calcite aggregates. J Geol 90:301–318Google Scholar
  53. Urai JL, Williams PF, Roermund HLM (1991) Kinetics of crystal growth in syntectonic fibrous veins. J Struct Geol 13:823–836Google Scholar
  54. Vearncombe JR (1993) Quartz vein morphology and implications for formation depth and classification of Archaean gold-vein deposits. Ore Geol Rev 8:407–424Google Scholar
  55. Watchorn RB, Wilson CJL (1989) Structural setting of gold mineralisation at Stawell, Victoria, Australia. Econ Geol Monogr 6:292–309Google Scholar
  56. Wilson CJL (1973) The prograde microfabric in a deformed quartzite sequence, Mount Isa, Australia. Tectonophysics 19:39–81Google Scholar
  57. Wilson CJL (1994) Crystal growth during a single-stage opening event and implications for syntectonic veins. J Struct Geol 16:1283–1296Google Scholar
  58. Wilson CJL, Russell-Head DS, Sim HM (2003) The application of an automated fabric analyser system to the textural evolution of folded ice layers in shear zones. Ann Glaciol 37:7–17CrossRefGoogle Scholar
  59. Wilson CJL, Russell-Head DS, Kunze K, Viola G (2007) The analysis of quartz c-axis fabrics using a modified optical microscope. J Microsc 227:30–41CrossRefGoogle Scholar
  60. Zhang S, Paterson MS, Cox SF (1994) Porosity and permeability evolution during hot isostatic pressing of calcite aggregates. J Geophys Res 108:15741–15760Google Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • C. J. L. Wilson
    • 1
    Email author
  • J. A. Robinson
    • 1
    • 2
  • A. L. Dugdale
    • 1
    • 3
  1. 1.Pmd*CRC, School of Earth SciencesThe University of MelbourneMelbourneAustralia
  2. 2.CSIRO Exploration and MiningAustralian Resources Research CentreBentleyAustralia
  3. 3.Ballarat Goldfields Pty LtdBallaratAustralia

Personalised recommendations