Omali A.O., Imasuen, O.I and Okiotor M.E
Basal conglomerate, sandstones, siltstones, and ironstones were the major lithologic units in Mount Patti. They constitute part of the Campanian-Maastrichian Lokoja Formation exposed in the southern Bida Basin of Nigeria. Field Studies and Laboratory analyses were conducted on the sandstone samples to determine the provenance, depositional environment, mineralogical and textural characteristics of the Lokoja sandstone. The Granulometric studies of the deposit are medium to coarse-grained, poorly sorted, dominantly leptokurtic and positively skewed, indicative of river laid sediments. The mean grain size (0.85) suggests medium to high energy depositing stream for the sediments. Morphometric studies of pebbles showed variations in environment of deposition from fluvial to marine settings for the Lokoja sandstone. The scatter plots of maximum projection sphericity index (MPS.I) versus oblate – prolate index (O.P.I.) indicate river origin for the pebbles. The roundness versus elongation ratio (E.R) shows the same fluvial source. The mean roundness value (0.41) reflects angular to subrounded pebbles and short transportation history. Heavy mineral analysis revealed the presence of zircon, rutile, tourmaline, kyanite, sillimanite and opaques indicative of igneous and metamorphic sources, probably the southwest and northcentral Basement Complex terrains. The presence of ironstone, kaolinitic clays, laterite and the heavy mineral suite makes the area economically viable.
