Acta Oceanologica Sinica

, Volume 31, Issue 6, pp 72–82 | Cite as

The occurrence of gold in hydrothermal sulfide at Southwest Indian Ridge 49.6°E

  • Jun Ye
  • Xuefa Shi
  • Yaomin Yang
  • Naisheng Li
  • Jihua Liu
  • Wenchao Su
Article

Abstract

Massive sulfide precipitates found in the Southwest Indian Ridge (SWIR) 49.6°E hydrothermal field are enriched in gold. Here, the mineralogy and mineral chemistry of these massive sulfides to constrain the process of gold precipitation were studied. Sulfide samples in this field include lower-temperature Zn-rich sulfides and relative higher-temperature Fe-rich sulfides. Zn-rich sulfides are dominated by sphalerite-pyrite-chalcopyrite assemblages, with concentrations of gold ranging from 9.08 to 17.0 µg/g. Fe-rich sulfides consist mainly of pyrite-marcasite-isocubanite assemblages, with gold concentrations from 2.17 to 3.79 µg/g. The significant enrichment in gold within the lower-temperature Zn-rich sulfides and the effective separation of Zn and Fe in hydrothermal precipitates at the surface of this field are here interpreted to reflect the strong temperature dependence of gold transportation and deposition within the sulfides. In Zn-rich samples, large amounts of isolated native gold grains were identified. They were found mainly as inclusions up to 8 µm in diameter, occupying porous cavities in sphalerite or in the elevated iron content rim of sphalerite. The fineness of the gold ranged from 810 to 830. Unlike previously published results on other hydrothermal fields, these data show a low gold fineness values in SWIR 49.6°E. The FeS content of sphalerite associated with gold grains ranged from 3.2 mole % to 18.9 mole %. This was higher than in other fields, indicating that the sulfur activity is relatively low during the gold precipitation process and that sulfur activity may be one of the main factors affecting gold fineness in the SWIR 49.6°E hydrothermal field. Evidence regarding gold fineness and sulfur activity suggests that gold was quite likely transported as AuHS0 rather than as a Au(HS)2 complex.

Key words

hydrothermal sulfide Southwest Indian Ridge occurrence of gold mineralogy 

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References

  1. Barton M D. 1980. The Ag-Au-S system. Economic Geology, 75(2): 303–316CrossRefGoogle Scholar
  2. Barton P B, Toulmin P. 1964. The electrum-tarnish method for the determination of the fugacity of sulfur in laboratory sulfide systems. Geochimica et Cosmochimica Acta, 28: 619–640CrossRefGoogle Scholar
  3. Barton P B, Toulmin P. 1966. Phase relations involving sphalerite in the Fe-Zn-S system. Economic Geology, 61(5): 815CrossRefGoogle Scholar
  4. Dick H J B, Lin J, Schouten H. 2003. An ultraslow-spreading class of ocean ridge. Nature, 426: 405–412CrossRefGoogle Scholar
  5. Fouquet Y, Wafik A, Cambon P, et al. 1993. Tectonic setting and mineralogical and geochemical zonation in the Snake Pit sulfide deposit (Mid-Atlantic Ridge at 23°N). Economic Geology, 88(8): 2018–2036CrossRefGoogle Scholar
  6. Georgen J E, Lin J, Dick H J B, et al. 2001. Evidence from gravity anomalies for interactions of the Marion and Bouvet hotspots with the Southwest Indian Ridge: Effects of transform offsets. Earth and Planetary Science Letters, 187(3–4): 283–300CrossRefGoogle Scholar
  7. Hannington M, Herzig P, Scott S D, et al. 1991. Comparative mineralogy and geochemistry of gold-bearing sulfide deposits on the mid-ocean ridges. Marine geology, 101(1–4): 217–248CrossRefGoogle Scholar
  8. Hannington M D, de Ronde C E J, Petersen S, et al. 2005. Sea-floor tectonics and submarine hydrothermal systems. In: Hedenquist J W, Thompson J F H, Goldfarb R J, et al., eds. Economic Geology, 100th Anniversary Volume, 1905–2005. Society of Economic Geologists, Littleton, Colorado, 111–141Google Scholar
  9. Hannington M D, Peter J M, Scott S D, et al. 1986. Gold in sea-floor polymetallic sulfide deposits. Economic Geology, 81(8): 1867–1883CrossRefGoogle Scholar
  10. Hannington M D, Scott S D. 1989a. Gold mineralization in volcanogenic massive sulfides: implications of data from active hydrothermal vents on the modern seafloor. Economic Geology Monograph, 6: 491–507Google Scholar
  11. Hannington M D, Scott S D, 1989b. Sulfidation equilibria as guides to gold mineralization in volcanogenic massive sulfides; evidence from sulfide mineralogy and the composition of sphalerite. Economic Geology, 84(7): 1978–1995CrossRefGoogle Scholar
  12. Hannington M D, Tivey M K, Larocque A C, et al. 1995. The occurrence of gold in sulfide deposits of the TAG hydrothermal field, Mid-Atlantic Ridge. Canadian Mineralogist, 33: 1285–1310Google Scholar
  13. Herzig P M, Hannington M D, Fouquet Y, et al. 1993. Gold-rich polymetallic sulfides from the Lau back arc and implications for the geochemistry of gold in sea-floor hydrothermal systems of the Southwest Pacific. Economic Geology, 88(8): 2182–2209CrossRefGoogle Scholar
  14. Ihle T, Petersen S, Herzig P M, et al. 2005. Siting of gold and characteristics of gold-bearing massive sulfides from the interior of the felsic-hosted PACMANUS massive sulfide deposit, eastern Manus basin (PNG). In: Mao Y, Bierlein F P, eds. Mineral Deposit Research: Meeting the Global Challenge: Proceedings of 8th Biennial SGA Meeting, Beijing, China, 18–25 August 2005. Springer-Verlag: 623–626Google Scholar
  15. Meyzen C M, Ludden J N, Humler E, et al. 2005. New insights into the origin and distribution of the DUPAL isotope anomaly in the Indian Ocean mantle from MORB of the Southwest Indian Ridge. Geochemistry Geophysics Geosystems, 6(11): Q11K11CrossRefGoogle Scholar
  16. Moss R, Scott S D. 2001. Geochemistry and mineralogy of gold-rich hydrothermal precipitates from the eastern Manus Basin, Papua New Guinea. Canadian Mineralogist, 39(4): 957–978CrossRefGoogle Scholar
  17. Mozgova N N, Trubkin N V, Borodaev Y S, et al. 2008. Mineralogy of massive sulfides from the Ashadze hydrothermal field,13°N, Mid-Atlanditc Ridge. Canadian Mineralogist, 46(3): 545–567CrossRefGoogle Scholar
  18. Muller M R, Minshull T A, White R S, et al. 2000. Crustal structure of the Southwest Indian Ridge at the Atlantis II Fracture Zone. J Geophys Res, 105: 25809–25828CrossRefGoogle Scholar
  19. Murphy P J, Meyer G. 1998. A gold-copper association in ultramafic-hosted hydrothermal sulfides from the Mid-Atlantic Ridge. Economic Geology, 93(7): 1076–1083CrossRefGoogle Scholar
  20. Münch U, Lalou C, Halbach P, et al. 2001. Relict hydrothermal events along the super-slow Southwest Indian spreading ridge near 63°56′E—Mineralogy, chemistry and chronology of sulfide samples. Chem Geol, 177: 341–349CrossRefGoogle Scholar
  21. Pal’yanova G. 2008. Physicochemical modeling of the coupled behavior of gold and silver in hydrothermal processes: Gold fineness, Au/Ag ratios and their possible implications. Chemical Geology, 255(3–4): 399–413CrossRefGoogle Scholar
  22. Patriat P, Segoufin J. 1988. Reconstruction of the Central Indian Ocean. Tectonophysics, 155(1–4): 211–234CrossRefGoogle Scholar
  23. Sauter D, Cannat M. 2010. The ultraslow spreading Southwest Indian Ridge, in diversity of hydrothermal systems on slow spreading ocean ridges. Geophys Monogr Ser, 153–173Google Scholar
  24. Schmidt K, Koschinsky A, Garbe-Schnberg D, et al. 2007. Geochemistry of hydrothermal fluids from the ultramafic-hosted Logatchev hydrothermal field, 15 N on the Mid-Atlantic Ridge: temporal and spatial investigation. Chemical geology, 242(1–2): 1–21CrossRefGoogle Scholar
  25. Scott S D, Barnes H L. 1971. Sphalerite geothermometry and geobarometry. Economic Geology, 66(4): 653–669CrossRefGoogle Scholar
  26. Seward T M. 1991. The hydrothermal chemistry of gold. In: Fpster R P, ed. Gold Metallogeny and Exploration. Glasgow: Blochie and Son Ltd, 37–62CrossRefGoogle Scholar
  27. Seward T M, Barnes H L. 1997. Metal transport by hydrothermal ore fluids. Geochemistry of Hydrothermal Ore Deposits, 3: 435–486Google Scholar
  28. Shimazaki Y. 1974. Ore minerals of the Kuroko-type deposits. Mining Geol Spec Issue, 6: 311–322Google Scholar
  29. Tao Chunhui, Lin Jian, Guo Shiqin. 2007. Discovery of the first active hydrothermal vent field at the uhraslow spreading Southwest Indian Ridge: The Chinese DY115-19 Cruise. Ridge Crest News, 16: 25–26Google Scholar
  30. Ye Jun, Shi Xuefa, Yang Yaomin, et al. 2011. Mineralogy of sulfides from ultraslow spreading Southwest Indian Ridge 49. 6°E hydrothermal field and its metallogenic significance. Acta Mineralogica Sinica, 31(1): 17–29Google Scholar

Copyright information

© The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Jun Ye
    • 1
    • 2
    • 3
  • Xuefa Shi
    • 2
  • Yaomin Yang
    • 2
  • Naisheng Li
    • 4
  • Jihua Liu
    • 2
  • Wenchao Su
    • 5
  1. 1.Institute of OceanologyChinese Academy of SciencesQingdaoChina
  2. 2.First Insititute of OceanographyState Oceanic AdministrationQingdaoChina
  3. 3.Graduate University of the Chinese Academy of SciencesBeijingChina
  4. 4.National Oceanographic CenterQingdaoChina
  5. 5.State Key Laboratory of Ore Deposit GeochemistryChinese Academy of SciencesGuiyangChina

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