1887
Volume 26, Issue 2-3
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

Various geophysical techniques were applied experimentally to exploration for epithermal gold deposits. The Hishikari gold-silver deposit, located in northeastern Kagoshima, Kyushu, Japan, was selected for this study. This paper presents the results from these case studies and discusses the applicability of each method in several stages of the exploration; the reconnaissance stage, the detailed follow-up stage and the final stage where the surveys are directed at detecting veins. The results are summarized as follows;

  1. A high-gravity anomaly was interpreted as the swollen basement. This subsurface structure was considered to be local doming of basement associated with volcanic activity. Local gravity highs are worthy of notice because the doming of basement might cause fractures;
  2. A resistivity cross-section was characterized by three layers; an uppermost layer with high resistivity (100-1000 Ωm) corresponding to unaltered volcanic rocks, an intermediate layer with low resistivity (3-8 Ωm) corresponding to altered volcanic rocks and a bottom layer with relatively high resistivity (80-200 Ωm) corresponding to the basement. Resistivity mapping and sounding are useful to identify lithologies and structures that may control gold mineralization;
  3. IP anomalies (high chargeability) within the area of low resistivity are the most important indicators of vein zones. For this reason, in the detailed follow-up stage and the final stage of exploration, IP surveys play the most important role.

© 1995 ASEG
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/content/journals/10.1071/EG995078
1995-06-01
2026-01-23

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References

  1. Abe, I., Suzuki, H., Isogami, A. and Goto, T, 1986, Geology and development of the Hishikari mine, Mining Geology, Vol.36, pp.117-130 (in Japanese).
  2. Ibaraki, K. and Suzuki, R, 1990, Wall Rock Alteration in the Hishikari Gold Mine, Kagoshima Prefecture, Japan, Vol.40, No.2(no.220), pp.97-106 (in Japanese).
  3. Izawa, E. and Urashima, Y., 1987, Geologic and tectonic setting of the epithermal gold and geothermal areas in Kyushu, Gold deposits and geothermal fields in Kyushu, Soc. Min. Geol. Jpn., Guidebook, 2, pp. 1-12.
  4. Izawa, E., Urashima, Y, Ibaraki, K., Suzuki R., Yokoyama T, Kawasaki K., Koga A. and Taguchi S, 1990, The Hishikari Gold Deposit: High-grade Epithermal Veins in Quaternary Volcanics of Southern Kyushu, Japan, Journal of Geochemical Exploration, Vol.36, pp.1-56.
  5. Kawasaki, K., Okada, K. and Kubota, R., 1986, Geophysical Surveys in the xHishikari Mine Area, Mining Geology, Vol.36, pp.131-147 (in Japanese).
  6. Kawasaki, K., Okada, K. and Matsuda, Y, 1987, TEM Sounding Survey in the Hishikari Mine Area, Proc. 77th SEGJ conference, pp. 198-201 (in Japanese).
  7. MMAJ, 1994, Report of Regional Geological Survey: Hokusathu (A) Area, 1993 fiscal year (in Japanese).
  8. MMAJ and SMM, 1987, Discovery and development of Hishikari mine, Mining Geology, Vol.37, pp.227-236 (in Japanese).
  9. Okada, K., 1991, IP Effects in Transient EM Data, Proc. 84th SEGJ conference, pp.271-276 (in Japanese).
  10. Shiokawa, Y., Okada, K., Kubota, R. and Kawasaki, K., 1992, MT survey for the deep structure of the Hishikari gold mine, Kyushu, Japan, Mining Geology, Vol.42, No.232, pp.73-84 (in Japanese).
  11. Ushijima, K., Mizunaga, H., Kawasaki, K. and Yokoyama, T, 1989, Mise-a-la-masse measurements in Hishikari mine, 81th SEGJ conference, pp.224227 (in Japanese).
  12. Yokoyama, T, Takagi, M. and Takahashi, N., 1987, Subsurface structure of the Hishikari Gold Mine-Comparison of Schlumberger and other geophysical surveys, 77th SEGJ conference, pp. 194-197 (in Japanese).
  13. Yokoyama, T. and Takagi, M., 1990, IP Logging at the Hishikari Mine, 82th SEGJ conference, pp.329-333 (in Japanese).
  14. Zohdy, A. A. R., 1973, A Computer Program for Automatic Interpretation of Schlumberger Sounding Curves Over Horizontally Stratified Media, Nat. Tech. Inform. Serv., PB-232-703, 27.
  15. Zohdy, A. A. R., 1975, Automatic Interpretation of Schlumberger Curves Using Modified DarZarrouk Functions, U.S.G.S. Bull. 1313-E, 39.
  16. Zohdy, A. A. R., 1989, A New Method for the Automatic Interpretation of Schlumberger and Wenner Sounding Curves, Geophysics 54 (2 1989): 245-253.
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  • Article Type: Research Article
Keyword(s): CSAMT; epithermal gold deposits; gravity; Hishikari Gold Mine; MT; resistivity; TEM; Time domain IP

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