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Geophysical survey of basement complex terrain using electrical resistivity method for groundwater potential

100%

Adeeko T. O. , Samson D. O. , Umar M.

tom 23

A geophysical survey of basement complex using electrical resistivity method was carried out so as to provide geological and geophysical information on the different subsurface features. The soughtfor parameters include thickness, depth, basement for groundwater potential and aquifer protective capacity. The acquired data were process using Win-Resist software and surfer 8, and the result was then analyzed and interpreted. Accordingly, 3-4 geoelectrical layers within the subsurface delineate the area: top soil, lateritic layer, weathered/fractured layer and fresh rock. Resistivity values of the top soil range between 55.5 mΩ to 749.7 mΩ, with average thickness of 0.4 m to 3.6 m, while the lateritic layer ranges between 153.3 mΩ to 862.0 mΩ, with average thickness of 4.5 m to 20.7 m, the weathered/fractured layer in turn ranges between 15.6 mΩ to 698.9 mΩ, with average thickness of 7.7 m to 55.2 m, and the fresh rock ranges between 13.4 mΩ to 5102 mΩ, with infinite homogeneous half space. Over all, the longitudinal conductance of the overburden units range from 0.147 mhos to 0.957 mhos and the overburden is thick enough for groundwater exploration activities. The results provide reasonably information that the aquifer units are weathered/fractured layers with a significant groundwater potential that is free of contamination.

Signatures of Late Neoproterozoic Gondwana assembly and Maronian glaciation in Lesser Himalaya: a palaeogeographical and stratigraphical approach

63%

Umar M. , Betts P. , Khan M. M. S. , Sabir M. A. , Farooq M. , Zeb A. , Jadoon U. K. , Ali S.

tom Vol. 65, no. 1

1--19

Stratigraphical and sedimentological analyses of Late Neoproterozoic successions in Lesser Himalaya are combined herein with palaeogeographical considerations and comparisons with equivalent successions in India and South China. The succession starts with the Hazara Formation, which contains complete and incomplete Bouma sequences suggesting its deposition in deep marine turbidite settings. The overlying Tanawal Formation, rich in massive sandstone, shale and siltstone, was deposited in shallow marine conditions, as indicated by the presence of parallel lamination, large scale tabular, trough cross- and hummocky cross-stratifications. The Tanawal Formation facies shift laterally from proximal (south-southeast) to distal (north-northwest). The glaciogenic Tanaki Boulder Bed, overlying the Tanawal Formation, was deposited during the Maronian glaciation. It is equivalent to the Blaini Formation of India, and to the Sinian diamictites of South China. The Abbottabad Formation of Cambrian age overlies the Tanaki Boulder Bed, and is composed of dolomite, chert nodules and phosphate-rich packages; similar successions are documented in India and South China at the same stratigraphical interval. The similarities of the Neoproterozoic successions of Lesser Himalaya (both in Pakistan and India) and South China suggests their possible proximity during the break-up of Rodinia and the assembly of the Gondwana Supercontinent.