Nigeria Mining And Geosciences Society

 Journal

 Hydraulic Conductivity Of Subsoils Vis-à-vis Foundation Applications In Akure, Southwestern Nigeria

 Ademeso, O.A., And Ogunjobi, O.S.

 2021

The effect of the movement of groundwater on a foundation can be destructive. If groundwater permeates a foundation subsoil with ease, the possibility of foundation failure is very high. This research evaluated the hydraulic conductivity (HC) of both cohesive/residual/lateritic and cohesionless/transported subsoils in Akure, Southwestern Nigeria. Thirty-five samples {21 from FUTA-Northgate (FNG) [cohesive] and 14 from Isinkan [cohesionless]}were systematically collected from 13 pits for laboratory tests. The determination of the sample's natural moisture content (NMC), specific gravity, particle size distribution, and hydraulic conductivity followed standard procedures. Isinkan subsoil presented a very high percentage of sand, necessitating the application of constant-head permeameter. In contrast, FNG presented a high percentage of fines necessitating the use of falling-head permeameter. The calculated -7 -3 -3 -2 HC values range from 1.55 x 10 -5.55 x 10 cm/s for FNG and from 9.45 x 10 -1.58 x 10 cm/s for Isinkan. FNG revealed %gravel ranging from 2.1-47.5%, %sand from 18.8-65.1%; and %fines from 17.6-59.9% with averages of 25.74, 39.38, and 34.90% respectively while Isinkan gave %gravel ranging from 1.9-28.9%; %sand from 67.9- 91.5%; and %fines from 2.2-12.9% with averages of 10.94, 82.34, and 6.79% respectively. FNG subsoils possess very low HC, while Isinkan subsoils possess medium HC. Further observations revealed that (i) hydraulic conductivity decreases with depth implying that the deeper the foundation, the better; (ii) well-graded subsoils are better foundation materials than the poorly-graded; (iii) cohesive subsoils are better foundation materials than the cohesionless; and (iv) subsoils with higher HC are less attractive for foundation purposes. It was also observed that %fines are negatively strongly correlated with HC, Conclusively, FNG subsoil, and by extension cohesive/residual/lateritic subsoil, possesses low HC, implying that it is a better foundation subsoil material than Isinkan, the cohesionless/transported subsoil, which possesses higher HC. 

 School Of Engineering And Engineering Technology, Federal University Of Technology, Akure, Nigeria.

 Journal

 Physical And Mechanical Characteristics Of The Conglomeratic Layer In Akure, Southwestern Nigeria

 Ademeso, O.A., And Adeyemo B. I.

 2020

The highly indurated sedimentary layer in Akure, southwestern Nigeria was investigated for the physical and mechanical properties for the purposes of defining the spread, identify and classify it as well as determine the engineering value. The samples were physically and texturally examined on the field and described accordingly. The Uniaxial Compressive Strength (UCS) was determined with the indirect and direct methods using the Schmidt rebound hammer and the MTS Servo Compressive Tester respectively. ISRM (1989) procedures for determining the bulk density, dry density and water absorption were adopted. The immersion method was employed to determining the porosity and moisture content. The physico-mechanical tests results were then used to develop mathematical models. The layer was found to contain clasts embedded in reddish brown matrix. The clasts which are angular to sub-angular are mainly quartzites. Subordinate dark brown ferruginuous clasts were found parts of the study area. The results from the natural moisture content range from 1.32% to 3.88%, the dry density varies from 20.5 to 29.0KN/m3, bulk density ranges from 25.38KN/m3 to 30.38KN/m3, water absorption from 4.36% to 6.58%, porosity values from 11.08% to 18.80%. The Uniaxial Compressive Strength (UCS) value ranges from 32MPa to 69MPa. Correlation between UCS and rebound values gave a coefficient of 0.92. Comparing the UCS with those obtained for associated soils by previous researchers showed the layer having higher values. The layer is therefore classified as clast supported conglomerate and is believed to serve as semi-impervious layer protecting the lower layers of soil and aquifer from pollution and erosion. The preservation of the layer should therefore be of paramount importance to the managers of land and underground resources. 

 College Of Engineering ,Teerthanker Mahaveer University, India

 Journal

 Correlation Of Bulk Density And Abrasion Resistance Of Some Igneous And Metamorpic Rocks.

 Ademeso, Odunyemi Anthony, Adekoya, Adeyinka John, Olaleye, Boluwaji Muraina

 2012

Six igneous and metamorphic rock types were investigated for their petrographic, bulk density and abrasion resistant characteristics. Petrographic microscope to which a digital camera was attached, balance with necessary equipment set up for Archimedes’ principle measurement and abrasion tester were used to determine the petrographic, bulk density and abrasion resistant characteristics respectively of the rock types after various sample preparations. Generally, quartz, biotite, plagioclase, microcline and hornblende constitute the major minerals in the thin sections of the rock types and the microstructures that were exhibited include cleavage, distorted cleavage, mineral inclusions, micro-cracks, bent twin lamellae, mymerkite and compressed twin plane. Biotite granite has the lowest bulk density of 2.63g/cc while the charnockitic rock has the highest of 2.81g/cc. The result of abrasion resistance shows that granite gneiss and porphyritic biotite granite have very low values of 26.50 and 26.65 respectively while lamprophyre and charnockitic rock have very high values of 34.40 and 33.40 respectively. A very high correlation coefficient of 0.9179 was recorded for the relationship between the bulk density (D) and abrasion resistance (Ha)of the rock types. A model relating the two properties, Ha = 46.79D – 97.43, was derived. Conclusively, bulk density has direct relationship with the abrasion resistance of igneous and metamorphic rocks and it is therefore used to estimate it 

 Nigeria Mining And Geosciences Society

 Journal

 A Review Of The Structure And Evolution Of The Northern Parts Of The Igarra Schist Belt, Southwestern Nigeria.

 Ajigo, I.O., Ademeso, O.A. And Odeyemi, I.B.

 2012

Northern part of Igarra Schist Belt typifies the Basement Complex rocks of southwest Nigerian, which is part of a larger West African shield. It constitutes the northern closure of the Igarra Schist Belt. Amulti-technique approach has been used to integrate interpreted satellite imagery and aero-geophysical data with field investigation, the objective of which is to understand structural fabric and to establish various parameters for potential mineralization in this area. Satellite imagery interpretation showed lineaments along WNW-ESE directions as the dominant trend. Aeromagnetic data brought out presence of dominant WNW-ESE magnetic linear, with minor ENE-WSWand NNESSW trends. Aero-radiometric data show overall radio-elemental distribution for various litho-units and hence their contacts; interpreted results indicate E-W and WSW – ENE dominant trends of lineaments. Field investigations revealed that there are five main lithological units in the study area including migmatites, biotite schist, quartz schist, granite gneiss and calc silicate gneiss. At least three successive geotectonic episodes can be structurally distinguished in the study area: the first is captured in relics of meta-pelitic (basic) rocks caught up in the main phase gneisses; the second episode produced the fabric in the main phase gneisses as well as metasedimentary rocks while the third episode is seen to have modified the first two episodes including the Pan African intrusive suite. Orientation of dominant foliation planes of NW-SE and NE-SW in the southeast and southwest respectively of the study area gives an outline of the two opposite limbs of a fold; late-stage, brittle-ductile deformation resulted in the compression of this fold structure and subsequent faulting in one of the limbs. 

 Science Publication

 Journal

 The Petrography And Major Element Geochemistry Of The Granite Gneiss Of Arigidi Area, S/W, Nigeria.

 Ademeso, O.; Adeyeye O.

 2011

The granite gneiss of Arigidi area, falls within the migmatite - gneiss - quartzite complex of the Nigerian basement and occurs in association with grey gneiss, granite, charnockitic rocks and pelitic gneiss lithologies. Th e outcrops of the rock were studied in the field, eight samples were analysed for petrographic and geochemical characteristics. In thin section, quartz, plagioclase, biotite and opaque minerals which are ubiquitous ranged from 16.3 - 42.2, 18.4 - 42.4, 11.3 - 28 .6 and 6 - 10.7vol%, respectively while orthoclase, microcline, pyroxene and hornblende ranged from 0 - 11.1, 0 - 19.3, 0 - 12.4 and 0 - 16.3vol%, respectively showing that most of the samples are tonalitic in composition. Geochemically, the SiO 2 content of the gran ite gneiss ranged from 63.42 - 74.30, Al 2 O 3 ranged from 11.83 - 15.46 while Fe 2 O 3 ranged from 1.33 - 3.22wt%. FeO ranged from 2.13 - 5.83, Na 2 O from 0.40 - 3.91, K 2 O from 0.05 - 3.42, CaO from 0.82 - 5.78 and MgO from 0.42 - 5.47wt%. MnO ranged from 0.03 - 2.11 while TiO 2 r anged from 0.01 - 1.46wt%. Discrimination diagrams revealed a preference for igneous fields by the granite gneiss. It is therefore deduced that this tonalitic granite gneiss has an igneous origin. 

 Science Publication

 Journal

 Geochemical Characteristics Of The Charnockitic And Associated Granitic Rock, Akure Area, Southwestern Nigeria

 Ademeso Odunyemi, Alabi Kayode

 2011

The geochemical characteristics of the charnockitic and associated granitic rocks of Akure area were studied. Field and petrographic characteristics had earlier been reported. The granitic rock within the hybrid (xenoliths) plotted in QAP diagram as tonalite while those outside plotted as granite indicating possible absorption of some of the minerals of the xenoliths. The charnockitics plotted as quartz-diorite while the hybrid plotted as tonalite. The major element geochemistry shows similarity between the granitic rock and the hybrid while the charnockitic is distinct. Middleton discriminating diagram plotted the charnockitics inside the eugeosynclinal sandstone region, the hybrid plotted inside and outside while the granitic plotted outside. Garrels and Mackenzie discriminating diagram plotted the charnockitics as sedimentary/metasedimentary, the granitic as igneous and the hybrid as both. These indicate that the charnockitic magma most likely had sedimentary parentage, the granitic an igneous and the hybrid which seems to possess dual parentage probably resulted from the hybridization of the two rock types.

 

 World Academy Of Science, Engineering And Technology

 Journal

 Field And Petrographic Relationships Between The Charnockitic And Associated Granitic Rock, Akure Area, Southwestern Nigeria

 Ademeso, O Dunyemi A Nthony

 2010

The charnockitic and associated granitic rocks of Akure area were studied for their field and petrographic relationships. The outcrops locations were plotted in Surfer 8 . The granitic rock exhibits a porphyritic texture and outcrops in the north-eastern side of the study area while the charnockitics outcrop in the central/western part. An essentially dark coloured and fine grained intrusive exhibiting xenoliths and xenocrysts (plagioclase phenocrysts) of the granite outcrops between the granitic and charnockitic rocks. Mineralogically, the central rock combines the content of the other two indicating that it is most likely a product of their hybridization. The charnockitic magma is believed to have intruded and assimilated the granite substantially thereby contaminating itself and consequently emplacing the hybrid. The presented model of emplacement elucidates the hybridization proposal. Conclusively, the charnockitics are believed to be (a) younger than the granite, (b) of Pan-African age and (c) of igneous origin. 

 Science Alert

 Journal

 Deformation Traits In The Charnockitic Rocks Of Akure Area, Southwestern Nigeria

 Ademeso O.A.

 2009

The charnockitic rocks of Akure constitute one of the petrologic units of the precambrian basement complex of Southwest Nigeria. The field studies indicate fresh outcrops that show little signs of weathering although the surfaces are rough. The rock is in contact with migmatite and granite gneiss of the migmatite gneiss complex. On the outcrops are the occurrences of pegmatite, aplite and quartz veins as minor intrusions. Petrographic studies revealed hornblende, plagioclase, hypersthene, biotite, quartz, muscovite and opaque minerals as major minerals while zircon is accessory. Bent lamellae in plagioclase, distorted twinning in plagioclase and micro-cracks in virtually all the minerals in the thin sections indicate some element of deformation. Joint sets trend N-S, E-W and NNE-SSW with the N-S set predominating. The trends of the joint sets tally with those of the minor intrusions. The directions of maximum compressional and tensional stresses inferred from the rose diagram are in consonance with the general directions imprinted by the Pan African orogenic events which affected the basement complex rocks. Since, virtually all minerals in the thin sections exhibit traits of deformation indicating that the deformation is penetrative, it is inferred that the cause of the deformation might be tectonic.