1887
Geophysical Signatures of West Australian Mineral Deposits
  • ISSN: 2202-0586
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Abstract

Magnetic susceptibility measurements of rocks obtained from a number of Archaean mesothermal gold deposits have aided the interpretation of their geological and geophysical settings. Five deposits within the Yilgarn Craton were chosen on the basis of their magnetic host rocks: Youanmi (tholeiitic basalts), Greenfields (layered differentiated gabbro), Mount Martin (strongly sheared komatiitic sequence), Queen Margaret (serpentinised komatiitic peridotite) and Bounty (banded iron-formation). Iron-rich minerals associated with the gold ores include: weakly magnetic pyrrhotite (Greenfields and Bounty), magnetite (Mount Martin and Bounty) and non-magnetic pyrite (Youanmi and Queen Margaret).

The existence of two styles of mineralisation, whose apparent susceptibilities are either less than, or greater than, the host rocks, is a consequence of the geochemical interaction between the hydrothermal fluids and the wallrocks. This can have important implications for exploration since the target magnetic anomalies will be different in each case. Where apparent susceptibility values in the ore are greater than the host rocks, the mineralisation would be expected to be represented by a secondary positive anomaly on the flanks of a larger regional anomaly; where they are less, any local magnetic minima could be highly significant in terms of targeting drillholes. A correlation between gold grades and apparent susceptibility at Bounty and Mount Martin suggests that, in some cases, susceptibility measurements can be used as a guide to ore. In deposits containing komatiitic volcanic rocks, such as Queen Margaret and Mount Martin, the susceptibility meter can be used as an effective mapping tool, particularly where facing evidence is required to interpret complex structures.

© ASEG 1994
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1994-12-01
2026-01-14

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References

  1. AHMAT A.L., 1986. Metamorphic patterns in the greenstone belts of the Southern Cross Province, Western Australia. Geological Survey of Western Australia, Report 19, 1-21.
  2. AUDUNSSON H. & LEVI S., 1992. Magnetic property zonation in a thick lava flow. Journal of Geophysical Research 97, No. B4, 4349-4360.
  3. BARLEY M.E., CASSIDY K.F., GOLDING S.D., GROVES D.I. & McNAUGHTON N.J., 1990. Alteration haloes. In Ho S.E., Groves D.I. & Bennett J.M. (eds),Gold Deposits of the Archaean Yilgarn Block, Western Australia: Nature, Genesis and Exploration Guides. Geology Department (Key Centre) & University Extension, The University of Western Australia, Publication 20, 317-327.
  4. CHIN R.J., HICKMAN A.H. & THOM R., 1984. Explanatory Notes on the Hyden 1:250,000 Geological Sheet (SI 50-4), Western Australia. Geological Survey of Western Australia, Perth, 21 pp.
  5. CLARK D.A., 1983. Comments on magnetic petro-physics. Bulletin of the Australian Society of Exploration Geophysicists14,49-62.
  6. CLARK D.A. & EMERSON D.W., 1991. Notes on rock magnetization characteristics in applied geophysical studies. Exploration Geophysics 22, 547-555.
  7. CLARK D.A., FRENCH D.H., LACKIE M.A. & SCHMIDT P.W., 1992. Magnetic petrology: application of integrated rock magnetic and petrologi-cal techniques to geological interpretation of magnetic surveys. Exploration Geophysics 23, 65-68.
  8. DENTITH M.C., JONES M.L & TRENCH A., 1992. Exploration for gold-bearing iron formation in the Burbridge area of the Southern Cross greenstone belt, W.A. Exploration Geophysics 23, 11-116.
  9. FLOYD J.D. & TRENCH A., 1989. Magnetic susceptibility contrasts in Ordovician greywackes of the Southern Uplands of Scotland. Journal of the Geological Society of London146,77-83.
  10. GRANT F.S., 1985a. Aeromagnetics, geology and ore environments. I. Magnetics in igneous, sedimentary and metamorphic rocks: an overview. Geoexploration 23, 303-333.
  11. GRANT F.S., 1985b. Aeromagnetics, geology and ore environments. II. Magnetite and ore environments. Geoexploration 23, 335-362.
  12. GRIFFIN T.J., 1989. Explanatory notes on the Widgiemooltha 1:250,000 Geological Sheet (SH 51-14), Western Australia, second edition. Geological Survey of Western Australia, Record1989/4,88 pp.
  13. GROVES D.I., PHILLIPS G.N., FALCONER L.J., HOUSTOUN S.M., HO S.E., BROWNING P., DAHL N. & McNAUGHTON N.J., 1987. Evidence for an epigenetic origin for BIF-hosted gold deposits in greenstone belts of the Yilgarn Block, Western Australia. In Ho S.E. & Groves D.I. (eds), Advances in Understanding Precambrian Gold Deposits. Geology Department & University Extension, The University of Western Australia, Publication 11, 167-179.
  14. GROVES D.I., KNOX-ROBINSON CM., HO S.E. & ROCK N.M.S., 1990. An overview of Archaean lode-gold deposits. In Ho S.E., Groves D.I. & Bennett J.M. (eds), Gold Deposits of the Archaean Yilgarn Block, Western Australia: Nature, Genesis and Exploration Guides. Geology Department (Key Centre) & University Extension, The University of Western Australia, Publication 20, 2-18.
  15. HAGGERTY S.E., 1979. The aeromagnetic mineralogy of igneous rocks. Canadian Journal of Earth Sciences 16, 1281-1293.
  16. HENKEL H., 1976. Studies of density and magnetic properties of rocks from Northern Sweden. Pageoph 114, 235-249. Birkhauser Verlag, Berlin.
  17. HUNTER W.M., 1988. Kalgoorlie 1:100,000 Geological Series, Sheet SH 51-9-3136. Geological Survey of Western Australia, Perth.
  18. ISLES D.J., COOKE A.C. & HALLBERG J.A., 1990. Aeromagnetic interpretation. In Ho S.E., Groves D.I. & Bennett J.M. (eds), Gold deposits of the Archaean Yilgarn Block, Western Australia: Nature, Genesis and Exploration Guides. Geology Department (Key Centre) & University Extension, The University of Western Australia, Publication 20, 342-347.
  19. KEELE R.A. & SHELTON M.C., 1990. Greenfields Gold Deposit, Coolgardie. In Hughes F.E. (ed.), Geology of the Mineral Deposits of Australia and Papua-New Guinea, pp. 463-466. Australasian Institute of Mining and Metallurgy, Melbourne.
  20. MUELLER A.G. & GROVES D.I., 1991. The classification of Western Australian greenstone-hosted gold deposits according to wall rock alteration mineral assemblages. Ore Geology Reviews 6, 291-331.
  21. MUNRO K.D., 1990. Youanmi gold deposit. In Hughes F.E. (ed.), Geology of the Mineral Deposits of Australia and Papua-New Guinea, pp. 463-466. Australasian Institute of Mining and Metallurgy, Melbourne.
  22. PARASNIS D.S., 1966. Mining Geophysics. Elsevier, Amsterdam, 356 pp.
  23. PHILLIPS G.N. & GROVES D.I., 1983. The nature of Archaean gold-bearing fluids as deduced from gold deposits of Western Australia. Journal of the Geological Society of Australia 30, 25-39.
  24. RUTHERFORD R.A., 1993. Bounty Gold Mine: deformation history and the development of ore fluid pathways within an iron formation host, Western Australia. M.Sc. thesis, University of Tasmania, 88 pp. (unpublished).
  25. STEWART A.J., WILLIAMS I.R. & ELIAS M� 1983. Explanatory Notes on the Youanmi 1:250,000 Geological Sheet (SH/50-4), Western Australia. Department of Resources and Energy, Bureau of Mineral Resources, Geology and Geophysics & Geological Survey of Western Australia, 58 pp.
  26. WASHAUSEN G.F.A., 1990. Mount Martin Gold Deposit. In Hughes F.E. (ed.), Geology of the Mineral Deposits of Australia and Papua-New Guinea , pp. 439-441. Australasian Institute of Mining and Metallurgy, Melbourne.
  27. WITT W., 1993. Lithological and structural controls on gold mineralisation in the Archaean Menzies-Kambalda area, Western Australia. Australian Journal of Earth Sciences 40, 65-86.
  28. WOODALL R., 1990. Gold in Australia. In Hughes F.E. (ed.), Geology of the Mineral Deposits of Australia and Papua-New Guinea, pp.45-67. Australasian Institute of Mining and Metallurgy, Melbourne.
/content/journals/10.1071/ASEGSpec07_23
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  • Article Type: Research Article
Keyword(s): Archaean lode-gold; Hyden SI50-4; magnetic susceptibility; petrophysics; Widgiemooltha SH51-14; Yilgarn Craton; Youanmi SH50-4

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