1887
  1. Home
  2. A-Z Publications
  3. Near Surface Geophysics
  4. Volume 8, Issue 6
  5. Article
Volume 8, Issue 6
  • ISSN: 1569-4445
  • E-ISSN: 1873-0604

Abstract

ABSTRACT

A useful property of the anomalous magnetic field associated with some simple geological bodies is that the field is homogeneous with respect to horizontal distance and height. Its horizontal and vertical derivatives are also homogeneous fields so the angle ratio of the lateral gradient over the vertical gradient is constant along rays emanating outward from a single point that represents the body location. Hence drawing these raypaths, which connect the same values at different upward continued heights along a profile, can be used to identify the location and depth of the source. This is the basis for the source location using the total‐field homogeneity (SLUTH) method. A six‐step procedure is proposed to automate the SLUTH method, allowing large amounts of data to be interpreted quickly and easily. Furthermore, the rate of decay of the field along these raypaths provides a means to estimate the type of body that is the cause of the anomaly. Once the type of body is known, a quantity related to the susceptibility can be estimated.

An analysis of the results in the case when there is interaction between two proximal magnetic sheets shows a distortion when the bodies are within 600 m of each other. A similar distortion is seen when analysing field data from Timmins, Ontario, Canada, which consists of many other magnetic body models such as contacts and thin sheets. Adding noise to synthetic data shows that the estimates we obtain for the source parameters are robust for the typical noise levels seen in survey data.

Because a lot of information about the characteristics of the causative geologic body can be determined using the method, it is a challenge to summarize the results on a single map. Our approach is to use different shaped symbols for each type of body, with the size of the symbol being proportional to the susceptibility‐thickness and the shade indicative of the error in estimating the position. Data from Chibougamau, Quebec, Canada are used to illustrate these display techniques.

© European Association of Geoscientists and Engineers © 2010 European Association of Geoscientists and Engineers
Loading

Article metrics loading...

/content/journals/10.3997/1873-0604.2010033
2010-07-01
2024-04-26

  • From This Site

    /content/journals/10.3997/1873-0604.2010033
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. BlakelyR.J.1996. Potential Theory in Gravity & Magnetic Applications.Cambridge University Press.
     [Google Scholar]
  2. FediM., FlorioG. and QuartaT.A.M.2009. Multiridge analysis of potential fields: Geometric method and reduced Euler deconvolution.Geophysics74, L53–L65.
     [Google Scholar]
  3. KeatingP., DumontR. and HouleP.2007. A comparison between old and recent airborne time‐domain electromagnetic surveys flown in the Chibougamau region, eastern Canada. In: Proceedings of Exploration 07: Fifth Decennial International Conference on Mineral Exploration (ed. B.Milkereit ), pp. 863–867.
     [Google Scholar]
  4. MurthyK.S.R. and MishraD.C.1980. Fourier transform of the general expression for the magnetic anomaly due to a long horizontal cylinder.Geophysics45, 1091–1093.
     [Google Scholar]
  5. NabighianM.N.1972. The analytic signal of two‐dimensional magnetic bodies with polygonal cross‐section: Its properties and use for automated anomaly interpretation.Geophysics37, 507–517.
     [Google Scholar]
  6. NabighianM.N., GrauchV.J.S., HansenR.O., LaFehrT.R., LiY., PeirceJ.W., PhillipsJ.D. and RuderM.E.2005. The historical development of the magnetic method in exploration.Geophysics70, 33ND–61ND.
     [Google Scholar]
  7. OGS.
    OGS.1999. Ontario airborne geophysical surveys, magnetic and electromagnetic data.Miscellaneous data release 1101.
     [Google Scholar]
  8. RefordM.S.1964. Magnetic anomalies over thin sheets.Geophysics29, 532–536.
     [Google Scholar]
  9. ReidA.B., AllsopJ.M., GranserH., MillettA.J. and SomertonI.W.1980. Magnetic interpretation in three dimensions using Euler deconvolution.Geophysics55, 80–91.
     [Google Scholar]
  10. SailhacP., GibertD and BoukerboutH.2009. The theory of the continuous wavelet transform in the interpretation of potential fields: A review.Geophysical Prospecting57, 517–525.
     [Google Scholar]
  11. SalemA., RavatD., SmithR. and UshijimaK.2005. Interpretation of magnetic data using an enhanced local wavenumber (ELW) method.Geophysics70, L7–L12.
     [Google Scholar]
  12. SmithR.S., SalemA. and LemieuxJ.2005. An enhanced method for source parameter imaging of magnetic data collected for mineral exploration.Geophysical Prospecting53, 655–665.
     [Google Scholar]
  13. StavrevP. and ReidA.2007. Degrees of homogeneity of potential fields and structural indicies of Euler deconvolution.Geophysics72, L1–L12.
     [Google Scholar]
  14. ThurstonJ. and SmithR.2007. Source location using total‐field homogeneity: Introducing the SLUTH method for depth estimation.The Leading Edge26, 1272–1277.
     [Google Scholar]
  15. UllaJ., SmithR., SamsonC. and ValléeM.2009. Automation of the SLUTH method for deriving depth and location of magnetic sources.79th SEG meeting, Houston, Texas, USA, Expanded Abstract, 903–907.
     [Google Scholar]
  16. ValléeM.A., KeatingP., SmithR.S. and St‐HilaireC.2004. Estimating depth and model type using the continuous wavelet transform and magnetic type.Geophysics69, 191–199.
     [Google Scholar]
  17. ValléeM.A., SmithR.S. and KeatingP.2009. Case history of combined airborne time‐domain electromagnetics and power line field survey in Chibougamau, Canada.Geophysics75, B67–B72.
     [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.3997/1873-0604.2010033
Loading
Automation of the SLUTH method: a novel approach to airborne magnetic data interpretation
Near Surface Geophysics 8, 519 (2010); https://doi.org/10.3997/1873-0604.2010033
/content/journals/10.3997/1873-0604.2010033
/content/journals/10.3997/1873-0604.2010033
Loading

Data & Media 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