Gravity Field of the Niger Delta (West Africa)

Abstract

GRAVITY data are now available for 73 land stations situated in the general area of the Niger Delta, West Africa. The Bouguer anomaly map shows a gravity low of −35 mgal (the ‘Niger Delta Minimum’) which occupies a large part of the sub-aerial Niger Delta, and a gravity high of +40 mgal (the ‘Ekenie High’) situated in the extreme south-western corner of the sub-aerial delta. Isostatic reduction does not very appreciably affect the anomalies, as is only to be expected in an area where the topography is low and gentle. The isostatic anomaly maps, based on various possible systems of isostatic compensation, accordingly do not differ very much one from another or from the Bouguer anomaly map, and show the same general features as the latter. However, there is some difference in the ‘Ekenie High’ area; isostatic anomalies there are less pronounced for a higher degree of regionality. This is interpreted as an indication that the continental slope off the Niger Delta is regionally compensated.