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Porphyry Deposits

Porphyry Deposits. The Importance of Porphyry Deposits as a Copper and Gold Resource. Gold Resources. Copper Resources. A Geological Cross Section through the Batu Hijau Porphyry Deposit, Indonesia. (920 million tons of ore grading 0.55 wt.% Cu, 0.42 g/t Au).

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Porphyry Deposits

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  1. Porphyry Deposits

  2. The Importance of Porphyry Deposits as a Copper and Gold Resource Gold Resources Copper Resources

  3. A Geological Cross Section through the Batu Hijau Porphyry Deposit, Indonesia (920 million tons of ore grading 0.55 wt.% Cu, 0.42 g/t Au)

  4. Batu Hijau Porphyry Cu-Au Deposit, Indonesia

  5. Batu Hijau Porphyry Cu-Au Ores Hypogene Supergene Malachite Bornite Chalcopyrite

  6. Spatial Distribution of Porphyry Deposits

  7. The Origin of Porphyry Cu-Au-Mo Magmas Hydration Melting

  8. Porphyry-epithermal-skarn system - overview

  9. Idealized Porphyry Alteration/Mineralization (Lowell and Gilbert, 1970)

  10. Schematic Porphyry-Epithermal Alteration Sillitoe (2010)

  11. Bornite Chalcopyrite High Grade Ore Potassic Alteration Porphyry Ore and Alteration Textures Phyllic Alteration

  12. Potassic Alteration Revealed by Staining

  13. Hydrothermal Alteration – Chemical Controls 3KAlSi3O8 + 2H+ = KAl3Si3O10(OH)2 + 6SiO2 + 2K+ K-feldspar Quartz Muscovite 2KAl3Si3O10(OH)2 + 2H+ + 3H2O = 3Al2Si2O5(OH)4 + 2K+ Muscovite Kaolinite

  14. Metal Zonation in Porphyry Systems Bingham Mineral Park

  15. Tectonic Setting of Porphyry Deposits

  16. Porphyry metal associations as a function of intrusive composition

  17. Fluid Overpressure and Porphyry Ore Formation

  18. Porphyry-Epithermal System Evolution

  19. LV inclusions Fluid Inclusions in Porphyry Ore Depositing Systems VL inclusions LVHS inclusions Aqueous-carbonic Fluid inclusion

  20. 100 mm Primary, Pseudosecondary and Secondary Fluid Inclusions Primary and pseudosecondary fluid inclusions in dolomite

  21. Fluid Inclusion Microthermometry

  22. Salinity Determination from Ice Melting

  23. Microthermometry of Aqueous Fluid Inclusions

  24. Salinity Determination from Halite Dissolution

  25. Isochores for Fluid Inclusions in the System H2O

  26. Isochores for Halite-bearing inclusions

  27. Isochores for the System NaCl-H2O

  28. P-T-X Relationships in the System NaCl-H2O

  29. Salinity-Temperature Relationships in Porphyry Systems Note existence of high temperature VL and LVS inclusions. Evidence of boiling or condensation? Data from the Sungun Cu-Mo porphyry, Iran (Hezarkhani and Williams-Jones, 1997)

  30. Laser Ablation ICP-MS and Fluid inclusions

  31. Stable Isotope Data for Porphyry Deposits

  32. Chemical Controls on Ore Formation Deposition of Chalcopyrite (CuFeS2) CuClo +FeCl2o + 2H2S + 0.5O2= CuFeS2 + 3H+ + 3Cl- + 0.5H2O Deposition favoured by an increase in f O2, an increase in f H2S and an increase in pH What about temperature?

  33. Decreasing Temperature – the Main Control on Porphyry Copper Ore Formation (Hezarkhani and Williams-Jones, 1998)

  34. Cu-Mo Zoning in Porphyry Systems Porphyry Cu-Mo deposits are commonly zoned with a deeper, higher temperature molybdenite-rich zone and a shallower, lower temperature chalcopyrite-rich zone. Cooling of an aqueous fluid initially containing 2 m NaCl, 0.5 m KCl, 4000 ppm Cu and 1000 ppm Mo in equilibrium with K-feldspar, muscovite and quartz.

  35. Magma Emplacement, and the Nature of the Exsolved Fluid

  36. A Model for the Formation of Porphyry Deposits

  37. Summit of Merapi volcano, Indonesia Transport of Metals by Vapour? Fumarole emitting magmatic gases at 600 oC Extinct fumarole Ilsemanite Mo3O8.nH2O

  38. The Bingham Porphyry Deposit - A Case for the Vapour Transport of Copper (Williams-Jones and Heinrich, 2005)

  39. The Solubility of Chalcopyrite in Water Vapour Increasing PH2O promotes hydration (and solubility) and increasing temperature inhibits hydration. Migdisov et al. (2014)

  40. From Hypogene to Supergene Hypogene Supergene Malachite Bornite Chalcopyrite

  41. Supergene enrichment Leached zone Mineralized gravel Oxidised zone Barren gravel Enriched zone Primary zone Mineralized bedrock Leached zone – acidity creation FeS2 + H2O + 7/2O2= Fe2+ + 2SO42- + 2H+ CuFeS2 + 4O2= Fe2+ + Cu2+ + 2SO42- Oxidised zone – Fe and Cu oxides, acidity creation 2Fe2+ + 2H2O + 1/2O2 = Fe2O3 + 4H+; 2Cu+ + H2O = Cu2O + 2H+ Enriched zone – reduction and sulphide deposition 2Cu+ + SO42- = Cu2S+ 4O2

  42. Supergene enrichment O2 H2O Cu2+ Malachite Cu2(OH)2CO3 Covellite Cuprite Cu2O Eh Native Cu H2O H2 Chalcocite pH

  43. References Evans, A.M., 1993, Ore geology and industrial minerals, an introduction: Blackwell Science, Chapter 14. Pirajno, F. 2009, Hydrothermal processes and mineral systems, Springer, Chapter 5. Seedorff, E., Dilles, J.H., Proffett Jr, J.M., Einaudi, M.T., Zurcher, L., Stavast, W.J.A, 2006, Porphyry Deposits: Characteristics and origin of hypogene features in Hedenquist et Al. (eds) Economic Geology One Hundreth Anniversary Volume, p.251-298. Sillitoe, R.H., 2010, Porphyry copper systems: Econ. Geol., 195, 3-41. Williams-Jones, A.E. and Heinrich, C.H., 2005, Vapor transport of metals and the formation of magmatic-hydrothermal ore deposits: Econ. Geol., 100, p.1287-1312.

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