Marine Geophysical Researches

, Volume 2, Issue 1, pp 11–21 | Cite as

Gravity results from the continental margin of south-western Africa

  • R. A. Scrutton
Article

Abstract

Gravity, magnetic and bathymetric data were collected over the continental margin of south-western Africa by H.M.S. ‘Hecla’ in 1966. A study of the gravity measurements shows that the positive free-air anomalies of the continental edge effect are unusually large, and in excess of those calculated for an isostatic model of the Earth's crust. Taking into account the available seismic and magnetic evidence, a two-dimensional crustal model has been designed incorporating a body of relatively high density in the upper crust to account for the unusually large values.

Keywords

Continental Margin Edge Effect Offshore Engineer Gravity Measurement Bathymetric Data 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. AmarelG., CordaniU. G., KawashitaK., and ReynoldsJ. H.: 1966, ‘Potassium-Argon Dates of Basaltic Rocks from Southern Brazil’, Geochim. Cosmochin. Acta 30, 159–189.Google Scholar
  2. Bryan, G. M. and Simpson, E. S. W.: 1971, ‘Seismic Refraction Measurements on the Continental Shelf Between the Orange River and Cape Town’, in: Rep. No 70/16, Inst. Geol. Sci., ‘Geology of the East Atlantic Continental Margin’, (ed. by F. M. Delaney) SCOR Symp., Cambridge, 1970, 186–198.Google Scholar
  3. BurkC. A.: 1968, ‘Buried Ridges Within Continental Margins’, New York Acad. Sci. Trans., Ser. 2, 30, 397–409.Google Scholar
  4. Dingle, R. V.: 1972, ‘The Geology of the Continental Shelf between Luderitz and Cape Town (South-West Africa) with Special Reference to Tertiary Strata’, J. Geol. Soc. London, in press.Google Scholar
  5. DuPlessisA., ScruttonR. A., BarnabyA., and SimpsonE. S. W.: 1972, ‘Shallow Structure of the Continental Margin of South Western Africa’, Mar. Geol. 13, 77–89.Google Scholar
  6. LudwigW. J., EwingJ. I., and EwingM.: 1968, ‘Structure of the Argentine Continental Margin’, Amer. Ass. Petrol. Geol. Bull. 52, 2337–2368.Google Scholar
  7. LudwigW. J., NafeJ. E., and DrakeC. L.: 1971, in A. E.Maxwell (ed.), Seismic Refraction, in ‘The Sea’, Vol. 4, Part 1, Wiley-Interscience, London.Google Scholar
  8. MaskeS.: 1957, ‘The Diorites of Yzerfontein, Darling, Cape Province’, Ann. Univ. Stellenbosch 33A, 32–70.Google Scholar
  9. SiednerG. and MillerJ. A.: 1968, ‘K-Ar Age Determinations on Basaltic Rocks from South-West Africa and their Bearing on Continental Drift’, Earth Planetary Sci. Letters 4, 451–458.Google Scholar
  10. SimpsonE. S. W. and duPlessisA.: 1968, ‘Bathymetric, Magnetic and Gravity Data from the Continental Margin of South-Western Africa’, Can. J. Earth Sci. 5, 1119–1123.Google Scholar
  11. SmitP. J., HalesA. L., and GoughD. I.: 1962, The Gravity Survey of the Republic of South Africa, Geological Survey publ. Pretoria, 486 pp.Google Scholar
  12. TalwaniM.: 1962, ‘Gravity measurements on H.M.S. ‘Acheron’ in South Atlantic and Indian Oceans’, Geol. Soc. Am. Bull. 73, 1171–1182.Google Scholar
  13. TalwaniM., SuttonG. H., and WorzelJ. L.: 1959, ‘Crustal Section Across the Puerto Rico Trench’, J. Geophys. Res. 64, 1545–1555.Google Scholar
  14. VanAndelTj. H. and ClavertS. E.: 1971, ‘Evolution of Sediment Wedge, Walvis Shelf, Southwest Africa’, J. Geol. 79, 585–602.Google Scholar
  15. Vening MeineszF. A.: 1948, Gravity Expeditions at Sea, 1923–1939, Vol. 4, Waltman, Delft, 233 pp.Google Scholar

Copyright information

© D. Reidel Publishing Company 1973

Authors and Affiliations

  • R. A. Scrutton
    • 1
  1. 1.Marine Geophysics Unit of the Geological Survey of South Africa, Dept. of GeologyUniversity of Cape TownSouth Africa

Personalised recommendations