Abstract
This paper describes a compilation of magnetic data collected off West Africa during the period 1961–1988. The internal accuracy of the total data set was assessed using a crossover analysis and the cleaned profile data were gridded to produce, among other things, a colour display of the magnetic anomalies which is presented here. The magnetic anomalies were differentially reduced to the pole using a technique that takes into account variations in the directions of the geomagnetic field and of the magnetization over a study area. A brief description of the magnetic field and its relation to bathymetric features is given. Several sea floor spreading anomalies and fracture zones were identified from the magnetic data and a general flowline pattern of the region is presented.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Arkani-Hamed, J., 1990, Magnetization of the Oceanic Crust Beneath the Labrador Sea, J. Geophys. Res. 95, 7101–7110.
Arkani-Hamed, J., 1988, Differential Reduction to the Pole of Regional Magnetic Anomalies, Geophysics 53, 1592–1600.
Baranov, V., 1957, A New Method for Interpretation of Aeromagnetic Maps: Pseudo-Gravimetric Anomalies, Geophysics 22, 359–383.
Besse, J. and Courtillot, V., 1988, Paleogeographic Maps of the Continents Bordering the Indian Ocean since the Early Jurassic, J. Geophys. Res. 93, 11,791–11,808.
Briggs, I. C., 1974. Machine Countouring Using Minimum Curvature, Geophysics 39, 39–48.
Cande, S. C., 1978, Anomalous Behaviour of the Paleomagnetic Field Inferred from the Skewness of Anomalies 33 and 34, Earth Planet. Sci. Lett. 40, 275–286.
Collette, B. J., 1986: Fracture Zones in the North Atlantic: Morphology and a Model, J. Geol. Soc. London 143, 763–774.
Collette, B. J., Slootweg, A. P., Verhoef, J., and Roest, W. R., 1984, Geophysical Investigations of the Floor of the Atlantic Ocean between 10° and 38° N (Kroonvlag-project), Proc. Kon. Ned. Ak. Wet., series B, 87, 1–76.
Danobeitia, J. J., 1985, Estudio geofisico submarino en el area del Archipielargo Canario, PhD thesis, University of Madrid, pp. 168.
Earth Physics Branch, 1986, Integration of Atlantic Geoscience Centre Marine Gravity Data into the National Gravity Data Base, Geol. Surv. Can., open file 1232, p. 54.
ET0P05, 1986, Relief Map of the Earth's Surface, EOS, Trans. Am. Geophys. Un. 67, p. 121.
GEBCO, 1982, General Bathymetric Charts of the Oceans, Sheet 5.08, Hydrographic Chart Distributing Office, Ottawa.
Hayes, D. E. and Primm, A. C. et al., 1972, Initial Reports of the DSDP, 14, Washington (U. S. Government Printing Office).
Hayes, D. E. and Rabinowitz, P. D., 1975, Mesozoic Magnetic Lineations and the Magnetic Quiet Zone off Northwest Africa, Earth Planet. Sci. Lett. 28, 105–115.
Hinz, K., Dostmann, H., and Fritsch, J., 1982, The Continental Margin of Morocco: Seismic Sequences, Structural Elements and Geological Development, in von, Rad, U., Hinz, K., Sarnthein, M., and Seibold, E. (eds.), Geology of the Northwest African Continental Margin, Springer Verlag, Berlin, pp. 34–59.
IAGA Division I Working Group 1, 1987, International Geomagnetic Reference Field Revision 1987, J. Geomag. Geoelectr. 39, 773–779.
Klitgord, K. D. and Schouten, H., 1986, Plate Kinematics of the Central Atlantic, in Vogt, P. R. and Tucholke, B. E. (eds.), The Geology of North America, vol. M, The western North Atlantic region, Geol. Soc. Amer, pp. 351–378.
Pitman, W. C. and Talwani, M., 1972, Sea Floor Spreading in the North Atlantic, Geol. Soc. Am. Bull. 83, 619–646.
Rabinowitz, P. D., Cande, S. C., and Hayes, D. E., 1979, The J-anomaly in the Central North Atlantic Ocean, in Tucholke, B. E., Vogt, P. R. et al. (eds.), Initial Reports of the Deep Sea Drilling Prog, v. 43, Washington, (U.S. Government Printing Office), pp. 879–885.
Regan, R. D. and Rodriguez, P., 1981, An Overview of the External Magnetic Field with Regard to Magnetic Surveys, Geophys. Surveys, 4, 255–297.
Roeser, H. A., 1972, Geophysikalische Untersuchungen im Ostlichen Kanarenraum, PhD. Thesis, University Goettingen, pp. 78.
Roeser, H. A., 1982, Magnetic Anomalies in the Magnetic Quiet Zone off Morocco, in von, Rad, U., Hinz, K., Sarnthein, M., and Seibold, E. (eds.), Geology of the Northwest African Continental Margin, Springer Verlag, Berlin, pp. 60–68.
Roest, W. R., 1987, Seafloor Spreading Pattern of the North Atlantic between 10° and 40° N, Ph-D. Thesis, Geologica Ultraiectina 48, p. 121.
Slootweg, A. P. and Collette, B. J., 1985, Crustal Structure and Spreading History of the Central North Atlantic in the Cretaceous Magnetic Quiet Zone (African plate), Kon. Ned. Ak. Wet., series B, 88, 251–302.
Srivastava, S. P., Verhoef, J., and Macnab, R., 1988, Results from a Detailed Aeromagnetic Survey across the Northeast Newfoundland Margin, Part II: Early Opening of the Atlantic between the British Isles and Newfoundland, Marine and Petroleum Geology 5, 324–337.
Srivastava, S. P., Levesque, S., Roest, W. R., and Verhoef, J., 1991, Sea Floor Spreading History, Plate Reconstructions/ Bathymetry, Gravity and Magnetic Anomalies, in East Coast Basin Atlas Series: Scotian Shelf, Edwards, A. E. (coordinator), Atlantic Geoscience Centre, Geological Survey of Canada, Dartmouth, Nova Scotia (in press).
Sullivan, K. D. and Keen, C. E., 1978, On the Nature of Oceanic Crust in the Vicinity of the Southeast Newfoundland Ridge, Can. J. Earth Sci. 15, 1462–1471.
Swain, C. J., 1976, A Fortran IV Program for Interpolating Irregularly Spaced Data using the Difference Equations for Minimum Curvature, Computers and Geosciences 1, 231–240.
Swan, D. and Young, I. F., 1978, Crossover Differences as an Indication of Survey Accuracy, Mar. Geophys. Res. 3, 393–400.
Tucholke, B. E. and Ludwig, W. J., 1982, Structure and Origin of the J Anomaly Ridge, Western North Atlantic, J. Geophys. Res. 87, 9389–9407.
Twigt, W., Slootweg, A.P., and Collette, B. J., 1979, Topography and Magnetic Analysis of an Area South of the Azores (36° N, 23° W), Mar. Geoph. Res. 4, 91–104.
Twigt, W., Verhoef, J., Rohr, K., Mulder, Th. F. A., and Collete, B. J., 1983, Topography, Magnetics and Gravity over the Kane Fracture Zone in the Cretaceous Magnetic Quiet Zone (African plate), Proc. Kon. Ned. Ak. Wet., series B, 86, 181–210.
Verhoef, J., 1984, A Geophysical Study of the Atlantis-Meteor Seamount Complex, Ph.D. thesis, Geologica Ultraiectina, 38, 153 pp.
Verhoef, J. and Collette, B. J., 1985, A Geophysical Investigation of the Atlantis-Meteor Seamount Complex, Proc. Kon. Ak. Wet., series B, 88, 427–479.
Verhoef, J., Collette, B. J., Miles, P. R., Searle, R. C., Sibuet, J.-C., and Williams, C. A., 1986, Magnetic Anomalies in the Northeast Atlantic Ocean (35°–50° N), Mar. Geoph. Res. 8, 1–25.
Verhoef, J. and Duin, E. J. Th., 1986, A 3-Dimensional Analysis of Magnetic Anomalies over Fracture Zones in the Cretaceous Magnetic Quiet Zone (Madeira Abyssal Plain), J. Geol. Soc. London 143, 823–832.
Verhoef, J. and Macnab, R., 1988, Magnetic Data over the Continental Margin of Eastern Canada: Preparation of a Data Base and Construction of a 1:5 Million Magnetic Anomaly Map, Geol. Surv. Can. Open File 1504, p. 89.
Williams, C. A., Verhoef, J., and Collette, B. J., 1983, Magnetic Analysis of some large Seamounts in the North Atlantic, Earth Planet. Sci. Lett. 63, 399–407.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Verhoef, J., Collette, B.J., Dañobeitia, J.J. et al. Magnetic anomalies off West-Africa (20–38° N). Marine Geophysical Researches 13, 81–103 (1991). https://doi.org/10.1007/BF00286283
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00286283