Main Article Content

Abstract

A simple method  for determining the depth and radius of some simple geological bodies such as a sphere and a horizontal cylinder  is presented. The method utilizes all of the data points to calculate the  body parameters.  The depth is estimated  from the mean of the depths determined from various fractions of the maximum anomaly and their corresponding widths. The radii of the two bodies are  calculated from the areas under the respective gravity profiles. Additionally , the radial symmetry of the gravity anomaly due to a sphere has been utilized to calculate the excess mass from a single profile. The radius determined from the excess mass is independent of depth estimate. This method of determining the radius is more robust than the one based on calculating the area.  An error analysis showing the effects of truncation and zero-level errors on the estimated radius  is  also discussed.

 

 

Keywords

Gravity Anomaly Excess Mass Characteristic Points Sphere and Cylinder.

Article Details

References

  1. BOTT, M.H.P.and SMITH, R.A. 1958. The estimation of the limiting depth of gravitating bodies, Geophysics. 6 : 1-10.
  2. DOBRIN, M.B. 1970. Introduction to Geophysical Prospecting (3rd Edition), McGraw - Hill Publishing Co., New York.
  3. HUBERT, M.K. 1946. A line integral method of computing the gravimetric effects of 2-D bodies. Geophysics. 13: 215-221.
  4. KOGBETLIANTZ, E.G. 1944. Quantitative Interpretation of magnetic and gravity Anomalies. Geophysics. 9: 463-473.
  5. MILCOVEANU, D.1970. Some formulas useful in the interpretation of gravitational and magnetic profiles. Geophysics. 35: 66-73.
  6. MARTYN-ANTIENZA, B. and GARCIA-ABDESLEM, J. 1999. 2-D gravity modeling with analytically defined geometry and quadratic polynomial density functions, Geophysics. 64: 1730-1734.
  7. NETTLETON, L.L.1976. Gravity and Magnetics in Oil Prospecting (2nd Edition), McGraw-Hill Publishing Co., New York.
  8. NETTLETON, L.L.1962. Gravity and magnetics for Geologists and Seismologists, Bulletin American Association of Petroleum Geologist. 46: 1815-1838.
  9. NETTLETON, L.L.1957. Gravity Survey over a Gulf Coast Continental Mound, Geophysics. 22 : 630-642
  10. PARASNIS, D.S., 1997. Principles of Applied geophysics. Chapman and Hall , London.
  11. PENTZ, H.H., 1940. Formulas and curves for the interpretation of certain 2-D magnetic and gravity anomalies. Geophysics. 5: 295-306.
  12. RUOITSTENMAKI, T., 1992. The gravity anomaly of two dimensional sources with continuous density distribution and bounded by continuous surfaces, Geophysics. 57: 623-628
  13. SKEELS, D.C. and WATSON, R.J. 1949. Derivation of magnetic and gravimetric quantities by surface integrals. Geophysics. 14: 133-145.
  14. SMITH, R.A., 1960. Some formulae for interpreting local gravity anomalies. Geophysics. 8 : 607 - 613.
  15. SMITH, R.A., 1959. Some depth formulae for local magnetic and gravity anomalies. Geophysics. 7: 55-63.