Advertisement

Mineralium Deposita

, Volume 40, Issue 3, pp 324–336 | Cite as

Infrared spectral reflectance characterization of the hydrothermal alteration at the Tuwu Cu–Au deposit, Xinjiang, China

  • K. Yang
  • C. Lian
  • J. F. Huntington
  • Q. Peng
  • Q. Wang
Article

Abstract

Short-wave infrared (SWIR) reflectance spectroscopy was used to characterize hydrothermal minerals and map alteration zones in the Tuwu Cu–Au deposit, Xinjiang, China. The Palaeozoic hydrothermal system at Tuwu is structurally controlled, developed in andesitic volcanic rocks and minor porphyries. Hydrothermal alteration is characterized by horizontally zoned development of quartz, sericite, chlorite, epidote, montmorillonite and kaolin about individual porphyry dykes and breccia zones, as is shown by changes outward from a core of quartz veining and silicification, through an inner zone of sericite + chlorite to a marginal zone of chlorite + epidote. The alteration system comprises several such zoning patterns. Silicification and sericitization are spatially associated with Cu–Au mineralization. Zoning is also shown by compositional variations such that Fe-rich chlorite and Al-rich sericite occur preferentially toward the core and the most intensely altered parts, whereas Mg-rich chlorite and relatively Al-poor sericite are present on the margin and the relatively weakly altered parts of the hydrothermal alteration system. The compositions of chlorite and sericite, therefore, can be potentially used as vectors to Cu–Au mineralization. Montmorillonite and kaolinite, of probable weathering origin, are located near the surface, forming an argillic blanket overlying Cu–Au mineralization. Sporadic montmorillonite is also present at depth in the hydrothermal alteration system, formed by descending groundwater. Presence of a well-developed kaolinite-bearing zone on the surface is an indication of possible underlying Cu–Au mineralization in this region. Epidote occurs widely in regional volcanic rocks, as well as in variably altered rocks on the margin of the hydrothermal mineralization system at Tuwu. The widespread occurrence of epidote in volcanic country rocks probably reflects a regional hydrothermal alteration event prior to the localized, porphyry intrusion-related hydrothermal process that led to the Cu–Au mineralization at Tuwu.

Keywords

Tuwu Hydrothermal alteration Infrared spectroscopy 

Notes

Acknowledgements

We gratefully acknowledge the financial support for this work by China Geological Survey and AusIndustry, and the technical assistance for field-work by Daquan Zhang, Dawen Liu and Chunhua Yuan. Thanks are also due to Xinjiang Geological Survey for providing working and living facilities in the field camp at Tuwu.

References

  1. Allen MB, Windley BF, Zhang C (1992) Paleozoic collisional tectonics and magmatism of the Chinese Tien Shan, central Asia. Tectonophysics 220:89–115CrossRefGoogle Scholar
  2. Clark RN, King TVV, Klejwa M, Swayze GA (1990) High spectral resolution reflectance spectroscopy of minerals. J Geophys Res 95B:12653–12680CrossRefGoogle Scholar
  3. Duke EF (1994) Near infrared spectra of muscovite, Tschermak substitution, and metamorphic reaction progress: implications for remote sensing. Geology 22:621–624CrossRefGoogle Scholar
  4. Farmer VC, Russell JD (1964) The infrared spectra of layer silicates. Spectrochimica Acta 20:1149–1173CrossRefGoogle Scholar
  5. Hunt GR, Salisbury JW (1970) Visible and near-infrared spectra of minerals and rocks: I. silicate minerals. Mod Geol 1:283–300Google Scholar
  6. Hunt GR, Salisbury JW (1971) Visible and near-infrared spectra of minerals and rocks: II. Carbonates. Mod Geol 2:23–30Google Scholar
  7. Jiang et al (1999) Regional prospect evaluation and typical deposit studies, project proposal submitted to the China Geological Survey (in Chinese), unpublished, 41 ppGoogle Scholar
  8. Long B, Xue Y, Feng J, Zhuang D, Jiang L, Xiao Z, Zhu Y, Xiao K, Song G (2001) On mineralization models of porphyry copper deposits in eastern Tianshan Mountains, Xingjiang (in Chinese). Chin Geol 28:35–38Google Scholar
  9. McLeod RL, Gabell AR, Green AA, Gardavsky V (1987) Chlorite infrared spectral data as proximaty indicators of vocanogenic massive sulfide mineralization. In: Proceedings of Pacific Rim Congress 87, pp 321–324Google Scholar
  10. Merry N, Pontual S (1999) Rapid alteration mapping using field portable infrared spectrometers. In: Proceedings of PACRIM’99, pp 693–698Google Scholar
  11. Post JL, Noble PN (1993) The near infrared combination band frequencies of dioctahedral smectites, micas, and illites. Clays Clay Miner 41:639–644CrossRefGoogle Scholar
  12. Rui Z, Wang F, Li H, Dong L, Wang L, Jiang L, Liu Y, Wang L, Chen W (2001) Advances in understanding the eastern Tianshan porphyry copper belt in Xinjiang (in Chinese). Chin Geol 28:11–16Google Scholar
  13. Rui Z, Liu Y, Wang L, Wang Y (2002a) The eastern Tianshan porphyry copper belt in Xinjiang and its tectonic framework (in Chinese with English abstract). Acta Geol Sinica 76:83–94Google Scholar
  14. Rui Z, Wang L, Wang Y, Liu Y (2002b) Discussion on metallogenic epoch of Tuwu and Yandong porphyry copper deposits in eastern Tianshan Mountains, Xinjiang (in Chinese with English abstract). Miner Deposits 21:16–22Google Scholar
  15. Scott KM, Yang K (1997) Spectral reflectance studies of sericites. CSIRO EM Rpt 439R, 34 ppGoogle Scholar
  16. Scott KM, Yang K, Huntington JF (1998) The application of spectral reflectance studies chlorites in exploration. CSIRO EM Rpt 545R, 43 ppGoogle Scholar
  17. Sun Y, Seccombe PK, Yang K (2001) Application of short-wave infrared spectroscopy to define alteration zones associated with the Elura zinc-lead-silver deposit, NSW Australia. J Geochem Explor 73:11–26CrossRefGoogle Scholar
  18. Thompson AJB, Hauff PL, Robitaille AJ (1999) Alteration mapping in exploration: application of short-wave infrared (SWIR) spectroscopy. SEG Newslett 39:16–27Google Scholar
  19. Wang F, Feng J, Hu J, Wang L, Jiang L, Zhang Z (2001) Characteristics of the Tuwu porphyry copper deposit, Xinjiang: exploration significances. Chin Geol 28:36–39Google Scholar
  20. Yakubchuk A, Seltmann R, Shatov V, Cole A (2001) The Altaids: tectonic evolution and metallogeny. SEG Newslett 46:6–14Google Scholar
  21. Yang K, Huntington JF, Browne PRL, Ma C (2000) An infrared spectral reflectance study of hydrothermal alteration minerals from the Te Mihi sector of the Wairakei geothermal system, New Zealand. Geomatics 29:377–392Google Scholar
  22. Zhang L, Shen Y, Ji J (2003) Characteristic and genesis of Kanggur gold deposit in the eastern Tianshan mountains, NW China: evidence from geology, isotope distribution and chronology. Ore Geol Rev 23:71–90CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • K. Yang
    • 1
  • C. Lian
    • 2
  • J. F. Huntington
    • 1
  • Q. Peng
    • 2
  • Q. Wang
    • 2
  1. 1.CSIRO Division of Exploration and MiningNorth RydeAustralia
  2. 2.China Geological SurveyBeijingChina

Personalised recommendations