Hostname: page-component-cd9895bd7-p9bg8 Total loading time: 0 Render date: 2024-12-26T16:09:53.142Z Has data issue: false hasContentIssue false
  • English
  • Français

Controls on ore metal ratios in granite-related ore systems: an experimental and computational approach

Published online by Cambridge University Press:  03 November 2011

Philip A. Candela
Philip A. Candela
Affiliation:
Philip A. Candela, Laboratory for Mineral Deposit Research, Department of Geology,University of Maryland, College Park, Maryland, 20742-4211, U.S.A
Get access Rights & Permissions [Opens in a new window]

Abstract

Size and composition (bulk metal ratios) of magmatic hydrothermal mineral deposits are affected by a number of chemical and physical processes including the nature of the source region and mode of emplacement. At shallow levels, rising plumes of vapour bubbles + melt, and the advection of water through interconnected vapour bubbles, allows access of the magmatic aqueous phase to the upper reaches of a magma chamber. These processes are operative at shallow levels where low water solubility and high molar volume for water make these processes more efficient.

Partitioning experiments suggest that oxygen fugacity-dependent crystal/melt partitioning of ore metals leads to different efficiencies of removal of Cu, W, and Mo from silicate melts into ore-forming aqueous fluids. For example, the Mo/W ratio in magmatic hydrothermal deposits should increase as the oxygen fugacity of the magma increases. Further, Cu should behave as a crystal-compatible element in H2O-undersaturated, sulfide-saturated felsic magmas with fO2 NNO + 1 due to the strong partitioning of Cu from the melt into pyrrhotite.

Cycling of oxidised, hydrated, sulfidised and Cl-enriched oceanic crust into mantle can give rise to magmas that contain S but are oxidised (≥NNO). The combination of high oxidation state, relatively hydrous but shallow conditions and a high Cl/H2O ratio leads to saturation with respect to H2O early during crystallisation, and loss of a large proportion of magmatic Cu to the aqueous phase. Ores formed from these oxidised magmas also possess high Mo/W ratios due to the effect of oxygen fugacity on the sequestering of Mo vs W.

In less oxidised magmas, Cu and Mo are partitioned into sulfides and Ti-bearing phases, respectively, resulting in lower efficiencies of removal of Cu and Mo from melts into aqueous fluids. Further, the partitioning of W into crystallising phases is reduced, producing a more efficient removal of W into ore-forming fluids. This ultimately leads to mineral deposits with higher W/(Mo + Cu) ratios relative to deposits associated with more oxidised systems. Silicic, high-F magmas with fO2 = NNO can be found in tensional environments (e.g. rocks associated with the Climax-type deposits of the Colorado Mineral Belt). High HF/H2O activity ratios in the source regions yield melts that evolve an aqueous phase late during crystallisation, leading to relatively low ratios of compatible/incompatible elements in the melt at H2O saturation.

Keywords

magmatic-hydrothermal processesore metalsgranites
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 83 , Issue 1-2: Second Hutton Symposium: The Origin of Granites and Related Rocks , 1992 , pp. 317 - 326
Copyright
Copyright © Royal Society of Edinburgh 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Auge, J. J. & Brimhall, G. H. 1988. Magmatic arc asymmetry and distribution of anomalous plutonic belts in the batholiths of California: Effects of assimilation, crustal thickness, and depth of crystallization. BULL GEOL SOC AM 100, 912–272.3.CO;2>CrossRefGoogle Scholar
Andiambololona, R. & Dupuy, C. 1978. Répartition et comportment des éléments de transition dans les roches volcaniques. I. cuivre et zinc. BULL B.R.G.M. 2 (II), 121–38.Google Scholar
Barton, M. D. 1990. Cretaceous magmatism, metamorphism, and metallogeny in the east-central Great Basin. In Anderson, J.L. (ed.) The nature and origin of Cordilleran magmatism: Boulder Colorado. GEOL SOC AM MEM 174, 283–302.Google Scholar
Barton, M. D. & 8 others 1988. Mesozoic contact metamorphism in the western United States. In Ernst, W. G. (ed.) Metamorphism and crustal evolution, western conterminous United States, Rubey volume 7 110–178. Englewood Cliffs, New Jersey: Prentice-Hall.Google Scholar
Brandeis, G., Jaupart, C. & Allegre, C. J. 1984. Nucleation, crystal growth and the thermal regime of cooling magmas. J GEOPHYS RES 89, 10161–77.CrossRefGoogle Scholar
Brandeis, G. & Jaupart, C. 1987. Crystal sizes in intrusions of different dimensions: constraints on the cooling regime and the crystallization kinetics. In Mysen, B.O. (ed.) Magmatic processes: physiochemical principles, 307–318. New York.Google Scholar
Brandeis, G. & Marsh, B. D. 1989. The convective liquidus in a solidifying magma chamber: a fluid dynamic investigation. NATURE 339, 613–16.CrossRefGoogle Scholar
Candela, P. A. 1986. Generalized mathematical models for the fractional evolution of vapor from magmas in terrestrial planetary crusts. In Advances in Physical Geochemistry 6: Chemistry and physics of the terrestrial planets, 362–96. New York: Springer.CrossRefGoogle Scholar
Candela, P. A. 1989a. Magmatic ore-forming fluids: thermodynamic and mass transfer calculations of metal concentrations. In Whitney, J. A. & Naldrett, A. J. (eds) Ore Deposits Associated with Magmas, Reviews in Economic Geology 4, 203–21. Society of Economic Geologists.Google Scholar
Candela, P. A. 1989b. Felsic magmas, volatiles, and metallogenesis. In Whitney, J. A. & Naldrett, A. J. (eds) Ore Deposits Associated with Magmas, Reviews in Economic Geology 4, 223–33 Society of Economic Geologists.Google Scholar
Candela, P. A. 1991. Physics of Aqueous Phase evolution in Plutonic environments. AM MINERAL 76, 1081–91.Google Scholar
Candela, P. A. & Bouton, S. L. 1990. The influence of oxygen fugacity on tungsten and molybdenum partitioning between silicate melts and ilmenite. ECON GEOL 85, 633–40.CrossRefGoogle Scholar
Candela, P. A. & Holland, H. D. 1984. The partitioning of Cu and Mo between silicate melts and aqueous fluids. GEOCHIM COSMOCHIM ACTA 48, 373–80.CrossRefGoogle Scholar
Candela, P. A. & Holland, H. D. 1986. A mass transfer model for copper and molybdenum in magmatic hydrothermal systems: the origin of porphyry-type ore deposits. ECON GEOL 81, 1–19.CrossRefGoogle Scholar
Carroll, M. R. & Rutherford, M. J. 1987. The stability of igneous anhydrite: experimental results and implications for sulfur behavior in the 1982 El Chichón trachyandesite and other evolved magmas. J PETROL 28, 781–801.CrossRefGoogle Scholar
Carten, R. B., Walker, B. M., Geraghty, E. P. & Gunow, A. J. 1988a. Comparison of field-based studies of the Henderson porphyry molybdenum deposit, Colorado, with experimental and theoretical models of porphyry systems. In Taylor, R. P. & Strong, D. F. (eds) Recent advances in the geology of granite-related mineral deposits, 351–66. SPEC VOL 39 CIMM.Google Scholar
Carten, R. D., Geraghty, E. P., Walker, B. M. & Shannon, J. R. 1988b. Cyclic development of igneous features and their relationship to high-temperature hydrothermal features in the Henderson porphyry molybdenum deposit, Colorado. ECON GEOL 83, 266–96.CrossRefGoogle Scholar
Delaney, J. R. & Karsten, J. L. 1981. Ion microprobe studies of water in silicate melts: concentration-dependent diffusion in obsidian. EARTH PLANET SCI LETT 52, 191–202.CrossRefGoogle Scholar
Dingwell, D. B. 1988. The structures and properties of fluorine-rich magmas: a review of experimental studies, in Taylor, R. P. & Strong, D. F. (eds) Recent advances in the geology of granite-related mineral deposits, 1–12. SPEC VOL 39 CIMM.Google Scholar
Eichelberger, J. C., Carrigan, C. R., Westrich, H. R. & Price, R. H. 1986. Non-explosive silicic volcanism. NATURE 323, 598–602.CrossRefGoogle Scholar
Haffty, J. & Noble, D. C. 1972. Release and migration of molybdenum during the primary crystallization of peralkaline silicic volcanic rocks. ECON GEOL 70, 857–912.Google Scholar
Hildreth, W. & Moorbath, S. 1988. Crustal contribution to arc magmatism in the Andes of Central Chile. CONTRIB MINERAL PETROL 98, 455–89.CrossRefGoogle Scholar
Irvine, T. N. 1970. Heat transfer during solidification of layeredz intrusions. I. Sheets and sills. CAN J EARTH PLANET SCI 7, 1031–60.CrossRefGoogle Scholar
Jaeger, J. C. 1968. Cooling and solidification of igneous rocks. In Hess, H. H. & Poldervaart, A. (eds) Basalts, 503–36. New York: Interscience Publishers.Google Scholar
Langmuir, C. H. 1989. Geochemical consequences of In Situ crystallization. NATURE 340, 199–205.CrossRefGoogle Scholar
Lehmann, B. 1990. Metallogeny of Tin. Heidelberg: Springer-Verlag.Google Scholar
Lehmann, B. & Harmanto, , 1990. Large-scale tin depletion in the Tanjungpandan tin granite, Belitung Island, Indonesia. ECON GEOL 85, 99–111.CrossRefGoogle Scholar
London, D., Morgan, G. B. VI & Hervig, R. L. 1989. Vapor-undersaturated experiments with Macusani glass + H2O at 200 MPa and the internal differentiation of granitic pegmatites. CONTRIB MINERAL PETROL 102, 1–17.CrossRefGoogle Scholar
Luhr, J. F. 1990. Experimental phase relations of water- and sulfur-saturated arc magmas and the 1982 eruptions of El Chichón volcano. J PETROL 31, 1071–114.CrossRefGoogle Scholar
Luhr, J. F., Carmichael, I. S. E. & Varekamp, J. C. 1984. The 1982 eruptions of El Chichón volcano, Chiapas, Mexico: Mineralogy and petrology of the anhydrite-bearing pumices. J VOLCANOL GEOTHERM RES 23, 69–108.CrossRefGoogle Scholar
Lynton, S. J., Candela, P. A. & Piccoli, P. M. 1990. Experimental determination of copper partitioning between pyrrhotite and high silica rhyolite. GEOL SOC AM ABST PROG 22, 181.Google Scholar
Manning, D. A. C. & Henderson, P. 1984. The behavior of tungsten in granitic melt-vapor systems. CONTRIB MINERAL PETROL 86, 286–93.CrossRefGoogle Scholar
Marsh, B. D. 1982. On the mechanics of igneous diapirism, stoping, and zone melting. AM J SCI 282, 808–55.CrossRefGoogle Scholar
Marsh, B. D. 1988a. Causes of magmatic diversity. NATURE 333, 97.CrossRefGoogle Scholar
Marsh, B. D. 1988b. Crystal capture, sorting, and retention in convecting magma. GEOL SOC AM BULL 100, 1720–37.2.3.CO;2>CrossRefGoogle Scholar
Norton, D.L. & Knight, J. 1977. Transport Phenomena in Hydrothermal Systems: Cooling Plutons. AM J SCI 277, 937–81.CrossRefGoogle Scholar
Norton, D. & Taylor, H. P. Jr 1979. Quantitative simulation of the hydrothermal systems of crystallizing magmas on the basis of transport theory and oxygen isotope data: an analysis of the Skaergaard intrusion. J PETROL 20, 421–86.CrossRefGoogle Scholar
Peck, D. L., Hamilton, M. S. & Shaw, H. R. 1977. Numerical analysis of lava lake cooling models: Part II, Application to Alae Lava Lake, Hawaii. AM J SCI 277, 415–37.Google Scholar
Piccoli, P. M. & Candela, P. M. 1991. Spatial variations in model halogen concentrations in magmas based on apatite chemistry: examples from natural systems. GEOL SOC AM ABSTR PROG 23, 5.Google Scholar
Sato, K. 1982. Chaacteristics of tungsten skarns in Japan, two constrasting types. In Hepworth, J. V. & Yu, H. Z. (eds) Proc. Symp. W Geol. Jiangxi, China, 1981, 203–209.Google Scholar
Tacker, R. C. & Candela, P. A. 1987. Partitioning of molybdenum between magnetite and melt: a preliminary experimental study of the partitioning of ore metals between silicic magmas and crystalline phases. ECON GEOL 82, 1827–38.CrossRefGoogle Scholar
Taylor, B. E. 1988. Degassing of rhyolitic magmas: Hydrogen isotope evidence and implications for magmatic-hydrothermal ore deposits. In Taylor, R. P. & Strong, D. F. (eds) Recent Advances in the Geology of Granite-Related Mineral Deposits. 33–49. SPEC VOL 39, CIMM.Google Scholar
Titley, S. R. & Beane, R. E. 1981. Porphyry copper deposits. In Skinner, B. F. (ed.) Economic Geology 75th Anniversary Volume. Connecticut: Economic Geology.Google Scholar
Urabe, T. 1985. Aluminous granite as a source of hydrothermal ore deposits: an experimental study. ECON GEOL 80, 148–57.CrossRefGoogle Scholar
van Middelaar, W. T. & Keith, J. D. 1990. Mica chemistry as an indicator of oxygen and halogen fugacities in the CanTung and other W-related granitoids in the North American Cordillera. In Stein, H. J. & Hannah, J. L. (eds) Ore-bearing granitic systems; Petrogenesis and mineralizing processes. GEOL SOC AM SPEC PAPER 246, 21–34.Google Scholar
Webster, J. D., Holloway, J. R. & Hervig, R. L. 1987. Phase equilibria of a Be, U, and F-enriched vitrophyre from Spor Mountain. Utah. GEOCHIM COSMOCHIM ACTA 51, 389–402.CrossRefGoogle Scholar
Webster, J. D. & Holloway, J. R., 1990. Partitioning of F and Cl between magmatic hydrothermal fluids and highly evolved granitic magmas. In Stein, H. J. & Hannah, J. L. (eds) Ore-bearing granitic systems; Petrogenesis and mineralizing processes. GEOL SOC AM SPEC PAP 246, 21–34.Google Scholar
Westrich, H. R., Stockman, H. W. & Eichelberger, J. C. 1988. Degassing of rhyolitic magma during ascent and emplacement. J GEOPHYS RES 93, 6503–11.CrossRefGoogle Scholar
Whitney, J. A. & Stormer, J. C. Jr 1983. Igneous sulfides in the Fish Canyon Tuff and the role of sulfur in calcalkaline magmas. GEOLOGY 11, 99–102.2.0.CO;2>CrossRefGoogle Scholar
Wood, S. A. & Vlassopoulos, D. 1989. Experimental determination of the hydrothermal solubility and speciation of tungsten at 500 C and 1 kbar. GEOCHIM COSMOCHIM ACTA 53, 303–12.CrossRefGoogle Scholar