ABSTRACT
In Northern Nigeria, four major litho-structural units constitute the main aquifers from which water is abstracted for domestic, industrial and agricultural purposes; the Basement Complex, Sedimentary formations, Younger Granites, and the Volcanics. In general, the Basement Complex units are calc-alkaline displaying a composition that varies from Fe/Mg rich to Na/K rich. The basic and intermediate rock components of these units are Ca/Fe rich with low MgO content. In general, the yields in the Basement Complex terrain are good depending on the degree of weathering of the rock, whereas in the Younger Granites province, the fractured crystalline aquifer has higher yields than the soft overburden and volcanic aquifer. The sedimentary formations are predominately clastic materials intercalated with marine sediments and carbonates. The (Bima) Sandstones are good water reservoirs whose yields depend on their degree of fracturing. Some statistical data on the distribution of Ca and Mg ions is appended.
