Date of Award
Doctor of Philosophy
A study of the mineralogical and chemical composition of recent sediments of the Niger delta, Nigeria was undertaken to provide baseline geochemical data and to relate these data to soil fertility, erosion and engineering problems. The mineralogical composition shows that three areas are distinguished: (1) a large kaolinite-quartz zone; (2) restricted kaolinite-beidellite zone; and (3) a highly restricted metastable smectite zone mainly montmorillonite and nontronite. The mineralogy is interpreted as functions of stability, groundwater flow rates, permeability and sea water incursion. Type 1 occupies the dynamic central part of the delta where permeability exceeds 1 Darcy, with rainfall averaging 6.8 m yr('-1) and little seawater influence. Gibbsite and goethite are also present.;The kaolinite-beidellite type occur near to the stable eastern part of the Niger delta. The permeability is about 0.1 Darcy, seawater influence is high while weathering of young volcanics of unknown composition to the north-east contributes to the smectite composition. The third type occurs along the coastal areas and close to the rivers in the southwest. They are interpreted as metastable phases in the reactions between silica and kaolinite.;Chemical composition of the sediments suggests extreme leaching of cations. Silica and alumina are the major residual chemical components. Detectable cations occur mainly in the smectite-rich sediments in the eastern part of the delta. Trace element chemistry show less depletion. However the heavy mineral analyses show that most of the detectable elements reside in the most insoluble heavy minerals. Statistical treatments employing R-mode factor analysis and Q-mode clustering confirmed this general depletion, and concentration of trace elements within the heavy mineral fraction. It also identifies phosphate-rich sediments in the eastern delta.;Chemical composition of the groundwaters show that the carbonate and chloride type waters dominate in the Niger delta. Salt-water effect on the chemical composition of the waters is evident in the same south-west and eastern part of the delta where the clay mineralogy is also influenced.;Textural and physical characteristics show that rapid loss of interparticle cohesion occurs in the delta soils upon saturation. This piping effect is interpreted as the main source of erosional and engineering problems in the delta. The potential for lime stabilization based on compaction characteristics is marginal. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
Olorunfemi, Biodun Elijah, "The Geochemistry And Mineralogy Of Recent Sediments Of The Niger Delta" (1983). Digitized Theses. 1258.