Malaysian Journal of Geosciences (MJG)

Geo-electrostratigraphic assessments of flood-laden lithological units within a coastal region in Southern Nigeria were undertaken with the use of geophysical surveys. The region has challenges of extreme flooding, especially during periods of high precipitation, leading to intensive water-logging and its associated problems. Integrated surveys employing vertical electrical soundings and electrical resistivity tomography were undertaken at twenty locations with the use of Schlumberger and Wenner array configurations. Hydro-geophysical findings indicate that the region comprises comprises four of four geo-electric layers: motley topsoil, sandy clay, fine sand, and coarse sand. Interpretation of the geo-stratigraphic data delineated degrees of geo-anisotropy based on measures of the longitudinal conductance, transverse resistance, longitudinal conductivity, transverse conductivity, anisotropic co-efficient, and the reflection coefficient. Via use of Dar-Zarrouk parameters, the water retention capacity assessments show that the region has a generally good retentive capacity, leading to an increased susceptibility to extreme flooding. Results obtained from 2D resistivity tomography surveys corroborated the results obtained from vertical electrical sounding data interpretations. The results showed that area is highly anisotropic, and that the presence of argillaceous sequences intercalated with arenaceous stratigraphic units is the leading cause of the high water retentive capacity of the region, leading to flooding during periods of high precipitation.

The purpose of this investigation was to assess the suitability of the underlying soils for constructing an earth fill dam for irrigation purposes. Eight soil samples were collected from four trial pits and four borrow pits, and were subjected to physical, mechanical and strength performance tests which are natural moisture content, specific gravity, Atterberg limits, grain size analysis, compaction, consolidation, permeability, and triaxial shear strength. The liquid limit, plastic limit, and plasticity index (Atterberg limits) of the soil samples ranged from 33-46%, 22-32.5%, and 6.5-22.2%, respectively. The percentage of fines and coarse contents from the grain size analysis ranged from 7.1% to 52.4% and 44.4% to 91.4%, respectively. The maximum dry density (MDD) values of the soils ranged from 1630 to 2015 Kg/m3, while the optimum moisture content ranged from 9.9% to 27%. The coefficient of permeability (K) ranged from 1.452× 10-6 to 2.196950× 10-3 cm/s. The coefficient of volume compressibility (Cv) and consolidation (Mv) ranged from 0.00020 to 0.88 mm/yr and 0.18 to 144 MPa-1, respectively, and the angle of internal friction ranged from 24.30 to 35.40°. The results indicate that the underlying soils contain a significant amount of moisture due to climatic conditions. They are well-graded soils with low to intermediate plasticity. Clay minerals, specifically Kaolinite, are present and contribute to the low to medium swelling potential of the soils. The low hydraulic conductivity makes the soils suitable for the construction of an earth fill dam, and they exhibit good strength with low settlement potential for the engineering structure.

Watershed are adversely affected by delectable land use land cover changes over the last two decades and these changes witnessed the soil loss in watershed. Soil weathering processes are induced by various factors like aggressive rainfall, hilly topography, land use land cover changes, less vegetation. Most of the watershed of Himalayan Rivers are being affected due to soil loss. The Mandakini River Watershed of Garhwal Himalaya, Uttarakhand has been affected by these soil accelerating components. The remote sensing and GIS can plays a vital role in identification of erosion vulnerable area for estimation of soil loss using revised universal soil loss equation (RUSLE) it provides an erosion scenario on sub-watershed scale. The RUSLE factors (R, K, LS, C and P) acquired using satellite based product and spatial technology. The rainfall map prepared from IMD gridded rainfall data, K-factor map retrieved from NBSS & LUP, Sentinel data and ALOSPALSAR DEM utilized for estimation of LS, C and P factors. All factors integrated in ArcGIS environment and soil loss map for year 2022 were prepared and categorized into 23 sub-watershed. This study classify the sub-watersheds based on various soil classes. Soil loss classified on five major classes where, out of 23 sub-watersheds (SW02, SW12, and SW23) classified in very high erosion category, five sub-watershed classified into high erosion class, two at moderate soil erosion class, and rest of thirteen sub-watersheds falls under less erosion risk. This study can helpful for policy makers and planners to take action for mitigation of natural resources.

Population growth and heightened water demand in the study area, exacerbated by insufficient surface and groundwater resources, lead to severe water shortages, particularly during the dry season. In response, our study in Atibioke Street, Aule Road, Ibulesoro, Akure, Ondo State, employed Horizontal Profiling (HP) and Vertical Electrical Sounding (VES) with electrical resistivity methods. Conducted across three traverses at 5m intervals, with probing levels from 1 to 5, the Combined HP and VES generated 2-D pseudosections, highlighting features and conducive layers for groundwater accumulation. Using Schlumberger configuration with electrode spacings from 1 to 100 m, three Vertical Electrical Soundings classified subsurface layers into Topsoil, Weathered Layer, and Fresh Bedrock within the basement complex terrain. The study emphasized the significance of electrical resistivity in assessing groundwater potential, with recommendations highlighting the unsuitability of VES 1 and VES 2 for exploitation, while VES 3 exhibited favorable conditions. Overall groundwater potential was rated as medium, emphasizing the need for alternative water supply solutions. VES 3 was recommended for well drilling based on promising characteristics, concluding with a suggestion to use these findings as a reference for future geophysical investigations.

Efficient hydrocarbon exploration and resource optimization are vital for sustainable oil reservoir development. This necessitates a profound grasp of source rocks and trapping systems, typically gleaned from subsurface seismic studies followed by drilling for resource extraction. Additionally, interpreting stratigraphic data is critical for identifying productive reservoirs, distinguishing low-yield from high-yield sands, and reducing exploration risks and costs. Our study aims to enhance subsurface structure and stratigraphic understanding, specifically identifying potential hydrocarbon reservoirs, source rock formations, sealing structures, stratigraphic traps, and depositional environments. In the Niger Delta region, we seek to reduce operational costs and exploration risks related to oil and gas exploration. In the “high field” offshore Niger Delta, our research combines well logs and seismic data to define hydrocarbon trapping potential, stratigraphic profiles, and depositional settings. The stratigraphic sequence is systematically divided into system tracts by five sequence boundaries, maximum flooding surfaces, and transgressive surfaces that reveal different depositional environments. This integrated approach pinpoints two prospective areas, P1 and P2, as potential hydrocarbon reservoirs. The analysis of seismic data and well logs is highly effective in identifying subsurface structures conducive to hydrocarbon accumulation within the stratigraphic framework. Furthermore, the alternation of lowstand, transgressive, and highstand system tracts suggests favorable conditions for source rocks, sealing formations, and reservoirs, improving the prospects for successful hydrocarbon exploration and resource optimization.

The study accesses the petrophysical data from the Eocene deposit of the “Thor” field, Coastal swamp depobelt, Niger Delta and process it to decipher the different lithological makeup, the reservoir units, the depositional architecture and how these factors influenced reservoir distribution within the field. The study made use of well logs consisting of gamma ray, resistivity, neutron and density logs. Gamma ray log aided lithological identification, resistivity logs help to isolate reservoir rocks from non-reservoir rocks while neutron and density logs was used to differentiate oil or gas zones. Three hydrocarbon reservoirs designated as R-1, R-2 and R-3 were interpreted from the logs and the sand bodies show a lateral continuity within the field in the north-eastern direction. Log sequences analysis of the field made use of a combination of gamma ray and restively logs via electro-sequence identification and mapping of key stratigraphic surfaces and the identification of para-sequences including retrogadational, aggradational and progradational stacking pattern leading to the delineation of the environment of deposition. The three stratigraphic surfaces enable the classification of the field into two depositional sequences and further subdivision into three system tracts. The first depositional sequence is interpreted as the oldest and lies at the base which is about 1201ft thick while the second depositional sequence overlies the first sequence with about 1605ft in thickness and is interpreted to be younger. Sediments within the two sequences are thought to be deposited in deltaic environment within the marginal to shallow marine settings.

The northeastern part of Bangladesh is facing more diverse problems such as more frequent and severe floods, sea level rise, saltiness water, and loss of biodiversity due to poor management of flooding systems. This article investigates that about 55% ,60% & 50% area was sequentially inundated in A.D. 1988, A.D. 1998 and A.D.2007. These 3 floods were historically more horrible than any other catastrophic flood. In A.D. 2007 flooding made 9 million people homeless and roughly 1000 people died. However, due to institutional limitations, mismanagement and social conflicts, applications of the flood mitigation plan and water management approaches were not implemented. With every major flood in Bangladesh, water security and poverty situations are adversely affected. Heavy monsoon rain and water from upstream sources have triggered drainage levels occasionally considered the main causes of flood in Bangladesh. But this article explores that the main causes of flood of Bangladesh are lack of river beds mining, lack of stabilizing trees, dam, and lack of bank revetment both sides of the river. According to the field data, in Bangladesh there are only 35% of flood protected zone. On the contrary, there are 52% of flood unprotected area. This article analyzed flood hazard in Bangladesh and try to make nature-based solutions for mitigating this vulnerability.

Charnockites could be of magmatic, metamorphic, or metasomatic origin and formed in varying tectonic settings. Lack of detailed geological mapping of plutonic charnockites around Ikare necessitated this work. Hence, this study was designed to investigate the petrography of plutonic charnockites, in order to infer post-cystallization event that prevailed in the area. Ten (10) chip rock samples purposively collected were prepared into thin and polished sections for petrographic studies using petrological microscope. The mineral assemblages observed are quartz, plagioclase feldspar, alkali feldspar, horhblende, biotite, orthopyroxene ± clinopyroxene. The accessory minerals are apatite, magnetite, ilmenite and zircon. Anti-perthite and myrmekite intergrowth are common. BSE images show close association between alkali feldspar and barium suggesting that barium is replacing potassium in the feldspar. Also,hornblende are found enclosing orthopyroxene suggesting a retrograde event. Relicts of quartz and alkali feldspars are found in biotite grain suggesting partial melting of the rock under high temperature conditions. Based on petrographic evidence, the charnockite magma that produced these charnockites must have been emplaced at deep crustal level under granulite facies conditions and followed by strong ductile deformation.

The study area is underlain by migmatite-gneiss quartzite rock suits with infolding mica schist which is intruded by batholitic Pan-African granitoids. Petrographic studies revealed quartz, orthoclase, hornblende and biotite as major minerals which are common to all members of rock units. The geochemical result of gneissic rock shows SiO2 content that range between 77.04%.wt to 80%.wt while mica schist depicts SiO2 content of 74.42 to 77.42%.wt. this implies silicious protolith for the both rock units. On the discrimination diagram gneiss and mica schist plot mainly in High-K calc-alkaline to calc-alkaline fields. Whereas, bivariate diagram of TiO2 versus SiO2 revealed that both gneissic rock and mica schist have sedimentary progenitors. High Rb, La and Th and low Nb, Sr, and Ti values shown by both gneiss and mica schist are compatible with typical crustal melts and suggest evolution from partial melting of crustal materials. The Pan-African granitoids has similar geochemical relationships. Geochemical studies shows that the rock units have limited variation in their major element compositions and give a decrease in CaO wt. %, and increasing Ba/Sr, Zr/Y ratios, K2O wt. % with increasing silica. The rocks are distinctly peraluminous, calc-alkaline as they plot in the High-K calc-alkaline and calc-alkaline, syn-collision fields on various discrimination diagrams. The characteristics suggest that the Basement rocks of the study area were formed from the fractional crystallization of a calc-alkaline magma in a syn- collision tectonic terrain.

The qualities of road construction materials are essential in their choice for various civil works. Therefore, engineering geological properties of the sub-soil that constitute sub-grade materials along Supare- Emure road were investigated in order to determine the causes of the failure of the pavement along the unstable sections. A total of twelve (12) sub- grade soil samples were collected from unstable and stable sections of the road and were subjected to various geotechnical tests. These tests include natural moisture content, atterberg limits, linear shrinkage, plasticity index and grain size. Results showed that the natural moisture content of the stable sections range from 5% to 11%, while those of unstable sections range from 23.8% to 37.2%. The range of the unstable sections fell short of required specification. For the plasticity index, both sections have values less than required 30%, while the unstable sections had linear shrinkage above 8%. On the grain size results, unstable sections have values greater than the specified 35% passing. Bedrock chemistry and clayey nature of sub-grade soils have been found to be responsible for the failed sections of the road investigated..