EOSC 595 (Directed Studies) – HYDROTHERMAL GEOCHEMISTRY OF ORE DEPOSITS

EOSC 5XX: Geochemistry of Hydrothermal Ore Deposits 1

EOSC 539: Geochemistry of Hydrothermal Ore Deposits (Instructor S.M.Rowins)

Course Description:

Students are introduced to modern geochemical techniques commonly used to study ore deposits formed by hydrothermal processes. These techniques include fluid inclusion microthermometry, stable isotope analysis, and alteration/ore mineral chemistry. The initial series of lectures reviews the scientific principles underlying the different geochemical techniques. Subsequent lectures use recent case studies to demonstrate how these techniques may be used, in conjunction with supporting geological data, to understand ore-forming processes in the Earth's crust. Visits to fluid inclusion and stable isotope laboratories demonstrate the practical aspects of geochemical analysis. Students are required to complete home assignments and present a seminar on a topic relevant to the course. A final exam is administered at the end of term.

Prerequisite: The normal prerequisite is completion of a senior undergraduate course in economic geology. Special cases will be considered on an individual basis.

Course format: Lecture/seminar format with meetings once a week in a 3-hour time slot. EOSC 5XX: Geochemistry of Hydrothermal Ore Deposits 2

Outline:

Week 1 (Sept 16): - Review principles of stable isotope geochemistry (theory, definitions, notation, standards, and conventions). - Analytical methodology: the mass spectrometer design and operation. - Usefulness of stable isotopes (S, C, O, H, D, B) in mineral deposit research. (geothermometry, determination of fluid redox state, fluid and metal source tracers, recorders of fluid/rock interactions,  versus  diagrams). - Read Ohmoto and Goldhaber (1997).

Week 2 (Sept 23): - Review S-, C-, and O-isotope systems as applied to sulphide, sulphate, and carbonate minerals. - Establishment of isotopic equilibrium and the use of S-, C-, & O-isotopes as geothermometers. - Control of redox over isotopic fractionation of S, C, & O. - “Source” versus “process” control over isotopic ratios. - Stable isotope reservoirs in the Earth. - Typical isotopic ranges found in S-, C-, and O-bearing minerals in ore deposits. - Handout Assignment #1 on the manipulation of S-, C-, and O-isotopic data (use the stable isotope fractionation website at Laval).

Week 3 (Sept 30): - Visit the stable isotope lab in EOS-Oceanography (See operation of Isomass DeltaPLus and old Finnigan VG machine). - Discuss in situ microanalytical techniques for measuring stable isotope ratios (e.g., SHRIMP and MILES) - Critique the results of an in situ laser-ablation S-isotope study of sulphides from the Wolverine massive sulphide deposit in Yukon, Canada. - Read Cameron and Hattori (1987) and Rowins et al. (1997).

Week 4 (Oct. 7): - Review Archean-lode/orogenic/reduced intrusion-related gold deposits. - Critique the use of C-, O-, and S-isotope data in the study of Archean lode- gold deposits at Kirkland Lake, Ontario. - Review porphyry copper-gold deposits. - Examine the use of C-, O-, and S-isotope data to differentiate between, porphyry, skarn, manto, and sediment-hosted gold-copper deposits in the Paterson Orogen, Telfer district, Western Australia. - Read Taylor (1997) and Nesbitt et al. (1986).

Week 5 (Oct. 14): - Review O- and H-isotope systematics in common silicate minerals. EOSC 5XX: Geochemistry of Hydrothermal Ore Deposits 3

- Discuss the use and misuse of O- and H-isotope geochemistry with respect to orogenic gold deposits in the Canadian Cordillera. - Evaluate B- and Cl-isotopes and other potentially useful heavy stable isotopes (Cu, Zn, and Fe) for the study of mineral deposits. - Handout Assignment #2 on the manipulation of O- and H-isotopic data (use the stable isotope fractionation website at Laval). - Read Roedder and Bodnar (1997).

Week 6 (Oct. 21): - Introduction to the study of fluid inclusions in ore deposits. - Background and basic assumptions. - Information available from fluid inclusions.

- P-V-T-X properties of model systems (H20-NaCl  CO2; CO2-CH4  H20) - Handout Assignment #3 on pressure estimates using fluid inclusion techniques. - Read Shepherd and Rankin (1999).

Week 7 (Oct 28): - Visit the EOS fluid inclusion labs. - Operate fluid inclusion stages. - Learn data manipulation software (Flincor). - Current status of bulk inclusion analysis. - Current status of fluid inclusion microanalysis (PIXE; PIGGE; Laser ablation ICP-MS; Synchrotron). - Read Cline and Bodnar (1994) and Rowins et al. (2002).

Week 8 (Nov. 4): - Use of fluid inclusions to understand P-T-X evolution of ore fluids in polymetallic skarn deposits (case study: Sacrificio, Mexico). - Evaluate ore-forming processes in the porphyry-epithermal environment using fluid inclusion data. Use PIXE microanalytical data from the San Anton- Providencia porphyry-epithermal complex and the 17 Mile Hill porphyry copper deposit. - Applications to exploration.

Week 9 (Nov. 11): - Student seminars

Week 10 (Nov. 18): - Student seminars - Review for final exam

Week 11 (Nov 25): - Final exam (2.5 hours). EOSC 5XX: Geochemistry of Hydrothermal Ore Deposits 4

Reading List:

1. Cameron, E. M., and Hattori, K. (1987) Archean gold mineralization and oxidized hydrothermal fluids. Economic Geology, v. 82, p. 1177-1191. 2. Cline, J.S. and Bodnar, R.J. (1994) Magmatically generated saline brines related to molybdenum at Questa, New Mexico. Economic Geology, v. 89, p. 234-254. 3. Nesbitt, B. E., Muehlenbachs, K., and Murowchick, J. B. (1986) Dual origins of lode gold deposits in the Canadian Cordillera. Geology, v. 14, p. 506-509. 4. Ohmoto, H., and Goldhaber, M. (1997) Sulfur and carbon isotopes, In H. L. Barnes (ed.) Geochemistry of Hydrothermal Ore Deposits 3rd Ed., Wiley, New York, p. 517-612. 5. Roedder, E. and Bodnar, R. J. (1997) Fluid inclusion studies of hydrothermal ore deposits, In H. L. Barnes (ed.) Geochemistry of Hydrothermal Ore Deposits 3rd Ed., Wiley, New York, p. 657-698. 6. Rowins, S. M. Groves, D. I., McNaughton, N. J., Palmer, M. R., and Eldridge, C. S. (1997) A reinterpretation of the role of granitoids in the genesis of Neoproterozoic gold mineralization in the Telfer Dome, Western Australia. Economic Geology, v. 92, no. 2, p. 133-160. 7. Rowins, S. M., Yeats, C. J., and Ryan, C. G. (2002) New PIXE evidence for magmatic vapor phase transport of copper in reduced porphyry copper-gold deposits. Eighth Biennial Pan-American Conference on Research on Fluid Inclusions (PACROFI), Halifax, Canada, v. 8, p. 88-90. 8. Shepherd, T.J., and Rankin, A. H. (1998) Fluid inclusion techniques of analysis. Reviews in Economic Geology, v. 10, p. 125-146. 9. Taylor, H. P. (1997) Oxygen and hydrogen isotope relationships in hydrothermal mineral deposits, In H. L. Barnes (ed.) Geochemistry of Hydrothermal Ore Deposits 3rd Ed., Wiley, New York, p. 229-302.