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Geophysical evidence for the intersection of the St Paul, Cape Palmas and Grand Cess fracture zones with the continental margin of Liberia, West Africa

January 1, 1974

PUBLISHED reconstructions of Gondwana continent1 (Fig. la) show a gap in fit near the junction of the Americas and Africa. To study this critical area, the Unitedgeo I made geophysical measurements and collected rock samples across the continental margin of Liberia (USGS-IDOE cruise leg 5) in November 1971. Figure Ib indicates the location of the 5,400 km of ship track on a generalised bathymetric map2. We shall discuss the data in detail elsewhere. Here we present the evidence for the existence of three fracture zones, two of which have not been reported previously, intersecting the continental margin at the north end of the South Atlantic, which remained closed probably until Cretaceous time. We suggest that Precambrian structures on the African continent controlled the location of these fracture zones. Figure Ic compares gravity and magnetic profiles and interpretations of the seismic profiles for three selected lines (27, 30 and 34) crossing the Grand Cess, Cape Palmas and St Paul fracture zones, respectively.

Publication Year 1974
Title Geophysical evidence for the intersection of the St Paul, Cape Palmas and Grand Cess fracture zones with the continental margin of Liberia, West Africa
DOI 10.1038/248324a0
Authors John C. Behrendt, J. Schlee, James M. Robb
Publication Type Article
Publication Subtype Journal Article
Series Title Nature
Index ID 70010186
Record Source USGS Publications Warehouse
USGS Organization Woods Hole Coastal and Marine Science Center