The inhabitants of this area depend solely on contact springs as supply source of potable water. However, provision of potable water to meet the needs of the people still remains an unsolved problem. Therefore, this p...The inhabitants of this area depend solely on contact springs as supply source of potable water. However, provision of potable water to meet the needs of the people still remains an unsolved problem. Therefore, this paper attempts to solve this problem by using Dar Zarrouk (D-Z) Parameters;Total Transverse Unit Resistance, T (Ωm<sup>2</sup>) and Total Longitudinal Unit Conductance, S (Ω<sup>-1</sup>) to suggest optimal locations for drilling of boreholes in the study area. To attain this purpose, 50 Schlumberger Vertical Electrical Sounding (VES) curves with maximum current electrode spacing of AB/2 = 681 m were interpreted. Thus, the aquifer parameters information estimated from the (VES) curves were used to prepare contour maps of T (Ωm<sup>2</sup>), S (Ω<sup>-1</sup>), aquifer thickness h (m), aquifer resistivity ρ (Ωm), and Water Table Depth (WTD). For effective use of these parameters, iso-thickness and iso-resistivity maps were compared with contour map of transverse resistance. The good agreement between these parameters provided the basis for identification of prolific aquiferous zones. It was observed that the Southern part of the study area majorly underlain by the Afikpo Sandstone of Nkporo Formation (Campanian-Maastrichtian), relatively showed higher T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) values, which implies high yield aquiferous zones. The relatively loose structure of this sandstone unit, coarse grains, and sorting enables it to be porous and permeable. The Northern part of the region which shows low values for T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) suggests low productivity for the aquiferous zones. The paucity of water in this parts of the study area can be explained to be as a result of the dominant geology. The high S, values at the Uburu and Okposi locations in this region suggests the presence of saline aquifer. This study would be relevant to the development of effective ground water scheme and for future hydrogeological investigations in the area.展开更多
This paper deals with the regional and structural framework of the Cretaceous rocks in the Afikpo Basin located in the southeastern part of the Lower Benue Trough. Results from regional tectonics are presented togethe...This paper deals with the regional and structural framework of the Cretaceous rocks in the Afikpo Basin located in the southeastern part of the Lower Benue Trough. Results from regional tectonics are presented together with those of the microtectonic analysis of microfaults in the Owutu-Afikpo-Adadama area in the basin. The Owutu-Afikpo-Adadama ridge at the north-central part of the basin marks the boundary between the Late Cenomanian-Turonian-Conianian sediments and the Campanian-Maastrichtian sandstones. This ridge trends N45oE on average and is faulted in three main directions, namely: (1) N-S normal faults; (2) NE-SW strike-slip faults; and (3) NW-SE strike-slip faults. The faulted rocks along these brittle discontinuities are mainly cataclastics with internal fracture cleavage and sigmoidal quartz mosaics that are reminiscent of extensional deformation. The cataclasites often bear slickenside striations. The NE-SW and NW-SE strike-slip faults are the results of the youngest brittle events on the Owutu-Afikpo-Adadama ridge. These faults were reactivated after deposition of the Campanian-Maastrichtain sediments (post-depositional faults) and, therefore, are post-Maastrichtain. Microfault analysis of these fault trends suggests an extensional regime that prevailed in the Lower Benue Trough. These results are of significance because this event is least poorly understood and less documented in contrast to the Cenomanian and Santonian events that affected the older Cretaceous strata in this region.展开更多
文摘The inhabitants of this area depend solely on contact springs as supply source of potable water. However, provision of potable water to meet the needs of the people still remains an unsolved problem. Therefore, this paper attempts to solve this problem by using Dar Zarrouk (D-Z) Parameters;Total Transverse Unit Resistance, T (Ωm<sup>2</sup>) and Total Longitudinal Unit Conductance, S (Ω<sup>-1</sup>) to suggest optimal locations for drilling of boreholes in the study area. To attain this purpose, 50 Schlumberger Vertical Electrical Sounding (VES) curves with maximum current electrode spacing of AB/2 = 681 m were interpreted. Thus, the aquifer parameters information estimated from the (VES) curves were used to prepare contour maps of T (Ωm<sup>2</sup>), S (Ω<sup>-1</sup>), aquifer thickness h (m), aquifer resistivity ρ (Ωm), and Water Table Depth (WTD). For effective use of these parameters, iso-thickness and iso-resistivity maps were compared with contour map of transverse resistance. The good agreement between these parameters provided the basis for identification of prolific aquiferous zones. It was observed that the Southern part of the study area majorly underlain by the Afikpo Sandstone of Nkporo Formation (Campanian-Maastrichtian), relatively showed higher T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) values, which implies high yield aquiferous zones. The relatively loose structure of this sandstone unit, coarse grains, and sorting enables it to be porous and permeable. The Northern part of the region which shows low values for T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) suggests low productivity for the aquiferous zones. The paucity of water in this parts of the study area can be explained to be as a result of the dominant geology. The high S, values at the Uburu and Okposi locations in this region suggests the presence of saline aquifer. This study would be relevant to the development of effective ground water scheme and for future hydrogeological investigations in the area.
文摘This paper deals with the regional and structural framework of the Cretaceous rocks in the Afikpo Basin located in the southeastern part of the Lower Benue Trough. Results from regional tectonics are presented together with those of the microtectonic analysis of microfaults in the Owutu-Afikpo-Adadama area in the basin. The Owutu-Afikpo-Adadama ridge at the north-central part of the basin marks the boundary between the Late Cenomanian-Turonian-Conianian sediments and the Campanian-Maastrichtian sandstones. This ridge trends N45oE on average and is faulted in three main directions, namely: (1) N-S normal faults; (2) NE-SW strike-slip faults; and (3) NW-SE strike-slip faults. The faulted rocks along these brittle discontinuities are mainly cataclastics with internal fracture cleavage and sigmoidal quartz mosaics that are reminiscent of extensional deformation. The cataclasites often bear slickenside striations. The NE-SW and NW-SE strike-slip faults are the results of the youngest brittle events on the Owutu-Afikpo-Adadama ridge. These faults were reactivated after deposition of the Campanian-Maastrichtain sediments (post-depositional faults) and, therefore, are post-Maastrichtain. Microfault analysis of these fault trends suggests an extensional regime that prevailed in the Lower Benue Trough. These results are of significance because this event is least poorly understood and less documented in contrast to the Cenomanian and Santonian events that affected the older Cretaceous strata in this region.
