Precambrian, highly foliated, fine -medium grained schists, which comprise migmatitic schist (MS), quartz mica schist (QMS), biotite mica schist (BMS) and hornblende biotite schist (HBS) constitute important lithological unit in Northwest Obudu Plateau. The schists are associated with gneisses, amphibolites and metaquartzites, and variously intruded by granites, pegmatites and quartzo-feldspathic veins. Sedimentary rocks, which are mostly Cretaceous sandstones, flank the western margin of the study area. Modal analysis shows that all the schists are enriched in quartz, plagioclase (An 32 ), biotite and garnet, except the HBS which is relatively depleted in quartz but highly enriched in biotite (25 vol. %) and hornblende (55 vol. %). Sillimanite and epidote occur in accessory amounts. The co-existence of quartz-plagioclase (An 32 )-garnet-biotite-muscovite-sillimanite in the MS assemblage indicates that the Schists are derivatives of metamorphism of pelitic and mafic rocks, which had attained the uppermost amphibolite facies grade. Geochemically, the schists are enriched in Si0 2 , which ranges from 60.11 wt % in the HBS, rising to 62.94 wt % in the BMS and 66.58 wt % in the QMS, with average of 64.56 wt %. The high SiO 2 content points to a probable effect of an intruding granitic magma on the Pan -African schists. The Al 2 O 3 , Fe 2 O 3 , MgO, CaO and alkalies are relatively moderate to high. The samples are quartz normative, have high molecular value of Al 2 O 3 > {CaO + Na 2 O + K 2 O}. Plots in chemical discrimination diagrams confirm the peraluminous characteristics of the schist and suggest pelitic rock protolith except for the HBS.

The determination of the mineralogical composition of rocks that underlie Okom-Ita area, in Oban Massif became necessary for the interpretation of the petrogenesis and protoliths of rocks in the area. Twelve representative rock samples were selected for thin section petrography and bulk rock geochemical analysis. The results reveal that the dominant intrusive rocks in Okom-Ita area are pegmatites, quartz veins and dolerites emplaced within gneisses, schists and phyllites host rocks. The quartz veins and pegmatites are leucocratic consisting predominantly of quartz, plagioclase and subordinate amount of Muscovites. The dolerite is dark grey, fine to medium grained and texturally ophitic and consists dominantly of pyroxenes, olivine and opaques. Three varieties of gneisses were recognized: feldspathic, banded and biotite gneisses. The gneisses, schists, and phyllites are dominated by SiO2 in the range of (60% -75%). The rocks exhibit higher molecular concentration {Al 2 O 3 > (CaO + Na 2 O + K 2 O)}, high alkali concentration with Na 2 O > K 2 O, high Al 2 O 3 to alkali ratios and low TiO 2 , CaO and MgO concentrations. These distribution trends suggest a compensation for the high silica and alumina concentrations and support a granitic protolith for the pegmatites and their host gneisses and schists. The dolerites and amphibolites are impoverished in SiO 2 , but relatively enriched in lime and alkali oxides. Plots in the AFM, TiO diagrams show that the pegmatite was derived from calc-alkaline magmatic source, while the dolerite was derived from tholeiitic basalt magma.

The geoelectrical investigation of the proposed Aba River dam at Amapu-Ideobia, Akanu Ngwa Southeastern Nigeria has been carried out. The objective of this study is to determine the downward and lateral trends of the rock layers or units along and near the proposed dam axis and deduce the possible structures that may enhance workable design of the dam. ABEM Terrameter SAS 4000 model was used and the symmetrical Schlumberger configuration was adopted. Twelve (12) Vertical Electrical Sounding stations were located and fully occupied along the dam axis. Preliminary input data from the field were fed into Zohdy software to generate real resistivities and depths to geoelectric layers. Five geoelectric layers were interpreted as Loamy Top soil, Alluvial matter, Pebble bed, Sandy lateritic and Gravely sand. Layer 1 (the top loamy soil) was encountered in VES 1, 2, 3, 4, 5, 9, 10, 11 and 12 locations with maximum thickness of 1.5 m in VES 3 and 4. Resistivity values ranged from 216 to 519 Ohm-m. The second layer (lateritic matter) had a maximum lower depth of 5 m in VES 3 and 4 points. This was not encountered in VES 6 point being replaced by alluvium. Resistivity values ranged from 101 to 6190 Ohm-m. Layer 3 was interpreted as a restricted pebble bed which occurred only at VES 6, 7 and 8 locations flanking the river course with thickness of about 3.5 m and resistivity values range of 182 -415 Ohm-m. The fourth layer was modeled as the alluvial matter and restricted to the river course (VES 6,7, 8) locations with base at between 12.5 m in VES 8 and 8 m in VES 6. The last modeled layer (Layer 5) was composed of gravely sandstone that underlined the whole study area apart from the restricted pebble bed at the NE crestal portion (VES 12). No structures like fractures, lineaments and faults that would be of deleterious effect were observed in all the VES points down to about 40 m. However, it was observed that the axial length had overriding sandy matter with high porosity and potentially rife for great infiltration; a condition that could facilitate seepage around the reservoir portion of the dam.

Study of rocks of Ugwuajirija Ishiagu area was carried out to determine their mineralization characteristics. This involved 38 samples and elemental ratios, including Ba, Be, Co, Cu, Cs, Nb, Ni, Pb, Sr, Y, Zn and Ba/K2O, Ba/Ni using ICP-MS and ICP-AES techniques. Geological mapping reveals that the area is underlain by four lithostratigraphic formations: Asu River group, Eze-Aku Shale, Nkporo Shale and Mamu Formation. The pre- Santonian formations were affected by magmatic intrusion and emplacement of dolerites, diorites and other diabasic rocks, and hydrothermal solutions leading to mineralization of economic mineral deposits. Modal analysis reveals the dolerite has average plagioclase concentration (41 %), ortho-pyroxene (29 %), clino-pyroxene (7 %), and olivine (9 %). Marly mudstone has quartz (10 %), plagioclase (25 %), orthopyroxene (20 %), clino-pyroxene (8 %) and olivine (8%). Trace and rare earth element analytical results show that all the analyzed samples were depleted in Cs, Sn, and Be < 1.0ppm, but enriched in Ba- 802ppm through 936ppm in the dolerite, to >10,000ppm in the marly-mudstone respectively, which are 2 to 100 times above the average crustal abundance of Ba-400ppm. The mean concentration of Cu, Pb, and Zn increased from 66.2 to 94 ppm in the dolerite at Ugwuele, to 1049ppm in the marly-limestone, to >10,000ppm in the ferruginized mudstones at Ugwuajirija respectively. These enrichments which are above average crustal abundance show that the mudstone and marly limestone in Ugwuajirija Ishiagu area are Ba and Pb mineralized. Further exploration and exploitation are recommended for effective youth empowerment and national development.Keywords: Ba-Pb Mineralization, Ugwuajirija, Lower Benue Trough, Trace Element

Bad conditions of roads and their negative effects on environment and National development necessitated this research on road failures in parts of Imo and Abia States, SoutheasternNigeria, using integrated geological mapping, electrical resistivity measurements and geotechnical analyses, to determine geological factors causing road failures in these areas and proffer sustainable solutions to them. Results reveal the most complex deformations occurred in the Asu River Groups, Eze-Aku, Bende Ameki and Imo Shale formations. These formations consist of alternating sequences of incompetent rocks like clays, shales and mudstones, with resistivity range of 3.5 Ωm -22.0 Ωm, occurring down to depths of 50.0 m in places. The in-situ moisture content ranges from 5.0-21.5 %, with mean of 13.25 %. Sieve analysis shows the lithology consists average fines >80%, sand 15%, gravel<3%, are poorly graded and texturally immature. The drainage system is poor; the water table is shallow with low permeability, causing periodic swelling and shrinkage, which aggravate environmental deformation and road failure. In the northern parts of the area, the NNE -SSW trending faults and folded Okigwe -Abakaliki escarpment zone increases frequency of road failures. In the southern parts Aba, Owerri, Umuahia and Orlu failures are mainly due to unconsolidation, topography/slope instability, erosion and poor engineering practice. For effective performance and durability, pre-construction site investigation and materials standardization involving geologists, engineers and government is necessary. Improvement by surface / subsurface pumping techniques, suitable drainage systems, excavation, filling and stabilization with appropriate geo-textiles are suggested.