1887
Volume 28, Issue 1-2
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

The integrated use of airborne magnetic and radiometric data, and SPOT Panchromatic and LANDSAT Thematic Mapper satellite data has proved effective for regolith mapping in the Yilgarn Craton of Western Australia. They can form the basis for designing appropriate soil sampling and regional exploration drilling in gold exploration programs.

Horizontal derivative filters have been applied to airborne magnetic line data to enhance short wavelength magnetic responses of maghemite-rich lateritic weathering products within the regolith profile. Magnetised maghemite-rich pisolites often occur in buried Tertiary palaeo-drainage channels or within residual laterite horizons, and their distribution can be delineated with these filters. Anew filter for magnetic data (REGMAG) is described that maps the distribution of short-wavelength responses and has proved effective in mapping magnetic structures in the regolith.

Ratios of airborne radiometric potassium and thorium channels, and ternary images of potassium, thorium and uranium, are useful in highlighting the radiometric signatures of various weathering products in the regolith. A new ratio normalisation algorithm improves the resolution of ratioed data.

Combined SPOT Panchromatic and LANDSAT Thematic Mapper satellite data are useful for landform mapping. Ratios of LANDSAT Thematic Mapper bands provide discrimination of various weathering products such as saprolite, pisolitic/nodular goethite and hematite-rich laterite, quartz and kaolinite rich alluvial cover, and red-earth calcareous clays.

Examples from the Archaean Yilgarn Craton of Western Australia show how these processing techniques can reveal valuable information from remotely sensed data which can assist with regolith mapping.

© 1997 ASEG
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1997-03-01
2026-01-20

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References

  1. Arakel, A. V. and McConchie, D., 1982, Classification and genesis of calcrete and gypsite lithofacies in palaeodrainage systems of inland Australia and their relationship to carnotite mineralisation: Journal of Sedimentary Petrology 52. 1149-1170.
  2. Bullock, S. J. and Isles, D. J., 1994, Airborne geophysics in Western Australia: pp. 85-103, In Geophysical Signatures of Western Australian Mineral Deposits, Australian Society of Exploration Geophysics Special Publication No. 7
  3. Duval, J. S., 1983, Composite colour images of aerial gamma-ray spectrometric data: Geophysics 48, 722-735.
  4. Gyngell, N. R., 1997, Second horizontal derivatives of ground magnetic data applied to gold exploration in the Yilgarn Craton of Western Australia: Exploration Geophysics (this volume).
  5. Mclntyre, J. L, 1981, Accurate display of fine detail in aeromagnetic data: Exploration Geophysics 12, 82-88
  6. Mudge, S. T., 1991, New developments in resolving detail in aeromagnetic data: Exploration Geophysics 22. 277-284.
  7. Sheard, S. N., Bishop, J. R. and Kissitch, R.V., 1991, A practical approach to filtering of airborne magnetic data in the Cobar region of NSW: Exploration Geophysics 22, 353-356.
  8. Simpson, C. J., 1990, Deep weathering, vegetation and firebum: significant obstacles for geoscience remote sensing in Australia: International Journal of Remote Sensing 11, 2019-2034.
  9. Smith, R. J. and Pridmore, D. F., 1989, Exploration in weathered terrains 1989 per-spective: Exploration Geophysics 20, 411-434.
  10. Stanley, J. M. Sertsrivanit, S. and Clark, P. J., 1992, Magnetic exploration beneath a near surface magnetic noise source: Exploration Geophysics 23, 323-326.
  11. Welch, R. and Ehlers, M., 1987, Merging multiresolution SPOT HRV and LANDSAT TM data: Photogrammetric Engineering and Remote Sensing 3, 301-303.
  12. Wilford, R. J., 1992, Regolith mapping using integrated Landsat TM imagery and high resolution gamma-ray spectrometric imagery - Cape York Peninsula: AGSO Record 1992/78 (unpublished).
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  • Article Type: Research Article
Keyword(s): aeromagnetics; gold; LANDSAT; maghemite; normalised ratio; palaeochannel; radiometrics; REGMAG; regolith; SPOT; weathering; Yilgarn

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