1887
  1. Home
  2. A-Z Publications
  3. Geophysical Prospecting
  4. Volume 20, Issue 2
  5. Article
Volume 20 Number 2
  • E-ISSN: 1365-2478

Abstract

A

The ground follow‐up of a magnetic and radiometric air survey had to cope with the usual dilemma to check a great number of anomalies within a short time. A limited aggregate of magnetic anomalies, expected to correspond to magnetite quartzites was statistically selected for ground identification by this method: the ratios length/width times amplitude were listed for all coherent contours and the calculation of the standard deviation per unit area resulted in different key‐numbers for a new lithological “Salem Unit” and for the charnockitic or gneissic environment. The ground work thus directed and reduced by 85% yielded a substantial potential of iron ore. This was supported by by abundant determinations of the magnetic susceptibilities, confirming the sources of anomalies and revealing the amenabilities of iron ores for the magnetic separation process.

The lines of truncation of anomalies were found to represent a system of local and regional faults and shear zones, which segregated the area into different tectonic blocks. These sutures have also provided the ways of intrusion for alkaline and basic magmae in the style of a “Rift” structure, housing several carbonatites and impregnations of metal sulphides.

The airborne radiometrics obtained many uranium indications by gamma ray spectrometry. However, they led only to disseminated uranium‐silicates, associated with syenites, granites and pegmatites, each emanating a characteristic photon energy spectrum. But in general the radiation of thorium prevails, marking northern Madras as a “Thorium Province”.

Loading

Article metrics loading...

/content/journals/10.1111/j.1365-2478.1972.tb00636.x
2006-04-27
2024-04-26

  • From This Site

    /content/journals/10.1111/j.1365-2478.1972.tb00636.x
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. Grady, J. C., 1971, Deep Main Faults in South India, J. geol. Soc. Ind. vol. 12, no. 1.
    [Google Scholar]
  2. Hepworth, J. V., 1967, The Photogeological Recognition of Ancient Orogenetic Belts in Africa, Q. Journ. geol. Soc. Lond.123, 253–292.
    [Google Scholar]
  3. Hirsch, W. Z., 1967, Introduction to Modern Statistics, Macmillan, New York .
    [Google Scholar]
  4. Hunting Geology and Geophysics Ltd.
    Hunting Geology and Geophysics Ltd. , 1970, Interpretation of an airborne Magnetometer, Gamma Ray Total Count and Gamma Ray Spectrometer Survey in Madras State, India; Report, Boreham Wood, Herts.
  5. Krishnan, M. S., 1968, Geology of India and Burma. Higginbothams, Madras .
    [Google Scholar]
  6. Linsser, H., 1968, Transformation of Magnetometric Data into Tectonic Maps by Digital Template Analysis. Geoph. Prosp.16, 179–207.
    [Google Scholar]
  7. Lockwood Survey Corpn. Ltd.
    Lockwood Survey Corpn. Ltd. , 1968, Aeromagnetic Map Interpretation by Computer Processing, Toronto.
  8. Loevborg, L., Kunzendorf, H. and Hansen, J., 1968, Use of Gamma Spectrometry in the Exploration of Uranium and Thorium Deposits in South Greenland. I.A.E.A. Symposium Lima SM 112/14.
  9. Narayan, S., 1965, Isoline Magnetic Maps of India, N.G.R.I. Hyderabad.
  10. Naudy, H. et Dreyer, H., 1968, Essay de Filtrage Nonlinéaire Appliqué aux Profiles Aeromagnétiques, Geoph. Prosp.16, 171–178.
    [Google Scholar]
  11. Naudy, H., 1970, Une Méthode d'Analyse Fine des Profiles Aeromagnétiques, Geoph. Prosp.18, 56–63.
    [Google Scholar]
  12. Semenov, E. I., 1970, Petrology and Mineralogy of Project Area. United Nations Report, Madras.
  13. United Nations
    United Nations , 1960, Proceedings of the United Nations Seminar on Aerial Survey Methods and Equipment. Mineral Resources Dev. Ser. No. 10, No. E/CN 11/536.
  14. Vogelsang, D., 1957, Beziehungen zwischen der umgekehrten Eigenmagnetisierung und dem Gefüge von Eruptivgesteinskoerpern, Notizbl. Hess. L.A. f. Bodenforschg. vol. 85.
    [Google Scholar]
  15. Vogelsang, D., 1965, Aeromagnetic Prospecting for Ore/Interpretation and Limitations, World Mining Vol. 7.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/j.1365-2478.1972.tb00636.x
Loading
  • Article Type: Research Article

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error