This study was carried out to understand structural features of joints of Owo area with the intention of unravelling the paleostress history of the area. The study area is a detachment of the Igarra schist belt, southwestern Nigeria. In this study, field mapping techniques and structural interpretations of joints using acceptable international methods were employed. The study was carried out in Owo, Ondo State, Nigeria from February, 2015 to July, 2016. Field mapping techniques involved the identification of joints and the measurement of strike and dip values using compass clinometer. A total of 623 joints were measured from nine mapping stations and their eigenvalues of with their trends and plunge values were plotted and input into the Win_Tensor Version: 5.8.4 software to determine the tensor direction. Three sets of joints that are gently to moderately dipping were observed in the area. They generally belong to radial and pure extensive regime. These joints were possibly formed under a stress condition of about 30-33 MPa. It further revealed that they were reactivated possibly during the pan-African orogeny. The radial and pure extensional tensor is similar to fracture trend related to major episodes of pan-African orogeny across Nigeria which generally NE-SW.
This study presents the analysis of rainfall and temperature across the climatic zones in Nigeria. Data from ten Global Circulation Models (GCM) regridded to a 1° x 1° spatial resolution was used in this study. Model evaluation was carried out for the models using ground observed data from Nigerian Meteorological Agency (NIMET). Based on the comparison of the models with ground observed data, the ability of the models in simulating the seasonal pattern of precipitation and temperature over each climatic zone and the whole of Nigeria differ to different degrees. Of the four periods, June, July, August (JJA) showed the highest deviation. The seasonal variation of rainfall and temperature across the climatic zones revealed the influence of the Intertropical Discontinuity (ITD) in rainfall variation across each zone with dual rainfall peak over the Guinea. The rainfall distribution showed that Sahel recorded the lowest rainfall while guinea recorded the highest rainfall. Further analysis revealed that rainfall and temperature varied mostly in the sahel. The trend analysis of rainfall and temperature showed increasing trend in rainfall over the whole of Nigeria under RCP45 and RCP85. There was general increase in temperature for all RCPs across the zones and the whole of Nigeria. Further analysis revealed that sahel will experience more dry years in rainfall and more warm years across the zones for temperature. The changes in rainfall and temperature have implications in various sectors of the economy such as agriculture, water resources and health sector. It is well known that research and development complement each other. It is important that further research be carried out particularly in projecting the change in climate at regional scales. This will provide information about the expected change or variation in climate and hence help in the mitigation of the implications of the change in climate.
Removal of Polycyclic Aromatic Hydrocarbons (PAHs) from the environment is important because of their potentially deleterious affect human health. Biological methods that was applied in the present study is typically contain microbial processes. It is the most innocuous and effective solution that transform pollutant to nontoxic or less toxic substances. The objectives of the present study are enrichment, isolation and identification of PAHs degrading bacteria from oil-contaminated soil by molecular detection methods. Eight indigenous bacteria were isolated from oil-contaminated soils by using the enrichment methods. Two isolates with the highest optical density potentials were selected in media with 12.8 mg. L-1 of 16 PAHs as the sole source of carbon. They were identified as Bacillus licheniformis ATHE9 and Bacillus mojavensis ATHE13 by subjected to polymerase chain reaction with 16SrDNA primer and biochemically characterized. The bacterium strain including Bacillus licheniformis ATHE9 was isolated and removed by Acenaphtylene, Acenaphtene and Indeno pyrene in 72, 96 and 96 hours, respectively. The Bacillus mojavensis ATHE13 could remove Naphthalene in 72 hours and Acenaphtene, Acenaphtylene, Benzo(ghi)prylene, Dibenzo(ah)anthracene and Indeno pyrene in 96 hours. The results of this study strongly indicate that some of the indigenous bacteria have the potential role to remediate polycyclic aromatic hydrocarbons from oil-contaminated sites. These bacterial strains were able to grow in media with 12.8 mg. L-1 of 16 PAHs and reach the stationary phase. The results showed that using native bacteria with PAH-utilizing capabilities in contaminated sites could be useful for removal of these compounds from the environment.
Field study of the area shows that the major rock groups are migmatites, gneisses, schists, quartzites and calc-silicate rocks which have been intruded by a series of granites and pegmatites. The gneisses are sandwiched by the migmatites while the schists are highly weathered. Petrographic analysis reveals the presence of quartz, biotite, plagioclase, K-feldspar and accessory minerals in many of the rock samples. Migmatites in the study area range in textural characteristics from medium to coarse-grained with mafic bands defined by biotite and hornblende while feldspar with quartz forms the granular lighter coloured layers. Structural evidence shows that the area is a typical metamorphic terrain with rocks of diverse nature, complexly deformed with development of foliations and lineations and the presence of both planar and linear structures. Structural evidence also shows that most structures in the area include joints, strike-slip faults, quartz veins, asymmetric folds, drag folds. The fracture trends show that the dominant trend is in the N-S and NNW-SSE direction. The plot of foliation trend of the area shows NW-SE and NE-SW, indicating imprint of Pan-African and relict of pre-Pan African structural pattern. The nature of the minerals contain in the rocks, together with their geometry reveal that the rocks have undergone more than one deformational, metamorphic and magmatism event.
The small-scale structural features identified in the field are original sedimentary structures. They were formed as direct results of sedimentation processes and are clearly preserved. The size, shape, and sorting of sedimentary structures within rocks may provide clues to the depositional environment that existed during their formation. They yield evidence of the top and bottom of individual beds and include graded bedding at Agola, current bedding at Fugar, ripple marks and sole marks at Fugar and Okigwe areas. The inclined beds are not due to secondary structures of tectonic origin, but the surfaces on which the original sediments were deposited. It varies from 4° SE at Ihube Okigwe to 7° S at Fugar, Edo state. The presence of Ophiomorha and Skolithos ichnofacies indicates marine environment although Ajali Sandstone is believed to be predominantly continental. Also it shows very poorly sorted and no graded bedding at Fugar, and this points to high-energy environment and current bedding. The Ajali Sandstone has several dome-shaped and circular highlands capped by laterites. The spring water that occurs at the contact between the Mamu – Ajali boundaries are structurally controlled.