GEOLOGIC ANALYSIS OF REMOTE SENSING IMAGERY OF THE EASTERN NIGER DELTA, NIGERIA
Abstract
The 'Eastern Niger Delta' of Nigeria encompasses an area of more than 350,000 sq. km between longitudes 6(DEGREES)00' - 9(DEGREES)00'E and latitudes 4(DEGREES)00' - 6(DEGREES)00'N. Elevations range form mean sea level at islands in the environs of Brass to the Oban Massif residual hills with peaks of over 1,500 meters. This range in elevations controls run-off and drainage patterns in the delta. Recently acquired cloud free radar imagery of the area along with aerial photographs and Landsat imagery provided excellent tools to update the existing geological map of the area which was published twenty years ago. In addition, the remote sensing imagery aids in monitoring the fluvial dynamics of the delta and in observing the environmental impact of the damming of the Niger River in 1970 with implied decreased run-off. Geologically, rocks range in age from Recent to Precambrian. Major rock types in the area consist of Recent alluvium, Tertiary sandstones and shales (which contain rich petroleum reservoirs), Cretaceous sandstones and shales and the Precambrian basement complex of migmatites and granites. The Cretaceous rocks are locally folded and faulted and are in sharp contact with the migmatitic basement complex, which in turn is marginal to the Cameroon volcanic line. Mapping of rock units on the radar imagery enabled the author to subdivide the stratigraphy into more units than are displayed on existing geologic maps. In addition, the size and areal extent of the granitic bodies in the basement area as mapped on the radar imagery disagrees significantly with granites delineated on published geological maps. Lack of time and climatic factors have not allowed duricrusts and laterites to form in Tertiary and Quaternary deposits of the delta. In these areas, stream density is increased and headward cutting rivers produce gullies which enhance the lineament patterns of the tectonic basement trends. Histograms and Cartesian plots of mapped lineaments show dominant trends of N30(DEGREES)W and N35(DEGREES)E for both the basement and sedimentary areas. It is suggested that there is a correlation of lineament trends between the two areas, implying basement control of the sedimentary wedge of the Niger Delta. The meridional N-S trending lineaments postulated in the literature and considered to predate the NE-SW and NW-SE dominant lineaments sets, were not observed on the radar imagery either in the sedimentary of the basement complex areas. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
Degree
Ph.D.
Subject Area
Geology|Remote sensing
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