Geochemistry of Amphibolites in Akom II, Nyong Series, North Western Border of the Congo Craton, South Cameroon

The garnet amphibolites, from the Akom II area in the Archaean Congo Craton, were examined to determine the geochemical affinity and tectonic environment. The study uses mineral assemblages and whole-rock geochemistry to identify the geochemical affinity and tectonic setting of the amphibolites associated with monzogabbro and pyroxenites. The studied rocks of Akom II are garnet amphibolites. Mineralogically, the rocks contain hornblende + plagioclase + garnet ± quartz ± epidote ± apatite ± opaque, indicating that they could have been formed from a basic igneous protolith. The geochemical signature indicates that the rocks are tholeiitic in nature. They are similar to the metamorphosed equivalents of ocean island basalts (OIB), with characteristics typical of Volcanic Arc-Basalt (VAB). The geotectonic diagrams confirm the tholeiitic nature of these amphibolites. High field strength elements ratios (Nb/Ta) range from 14-16, which corresponds to Volcanic Arc Basalt (VAB). The primitive mantle normalized patterns of these rocks show negative anomalies in Ta and Ti suggesting a geotectonic signature characteristic of a subduction zone, consequently suggesting the existence of a suture zone in the study area.

Foraminifera biostratigraphy and paleoenvironmental studies of well-x, eastern Niger delta

Ditch cutting samples from Well-X drilled in the Eastern part of the Niger delta were subjected to biostratigraphy and paleoenvironmental studies using micropaleontological analysis to identify the foraminifera present in the sections penetrated by the well.A total of 50 (fifty) foraminifera species made up of benthonic and planktic spp were recovered from the sections. The marker species identified are Globorotalia acostaensis, Globorotalia mernadii cultrate, Neogloboquadrina dutertrei, Globorotalia plesiotumida, Globorotalia obesa, Globorotalia nepenthes, Sphaeroidinella subdehiscens, Neogloboquadrina dutertrei, Globigerinoides sudquadratus.The four (4) biozones identified are N16 (Late Miocene 9.5Ma - 10.9Ma), N15-N14, N13-N12 and N12-N11 (Middle Miocene with corresponding ages 10.9Ma -11.8Ma, 11.8Ma-12.2Ma and 12.2Ma respectively).Using the encountered benthonic foraminiferal species, the paleoecology was determined; and it was revealed that the paleoenvironment of the section ranges from Inner Neritic to Outer Neritic Environment. Also, the lithological analysis revealed an intercalation of Shale, Mudstone and Sand which indicates various paleoecological episodes that led to their deposition.The age of the well was inferred from the bioevents of the marker species to be Middle Miocene to Late Miocene with the sparse occurrence of the Calcareous Benthic and the Plankonic species suggesting a shallow marine environment.

Factor analyses of transformed geochemical compositional data of meme river stream sediment, Lokoja, north central Nigeria

Geochemical mapping using stream sediments from MRDB, north-central, Nigeria was undertaken towards obtaining multivariate association patterns reflecting the presence of ore mineralization in Lokoja region. The area is underlain by Precambrian crystalline rocks within the Benin-Nigeria Shield and clastic sedimentary rocks of Bida Basin (one of Nigeria inland sedimentary basins). The basement crystalline rocks have been known as a source of ore minerals in Nigeria. The major lithological units are cut by the Meme river watershed which have deposited in their tributaries, large quantities of alluvial and eluvial deposits formed during an extensive period of weathering and surficial processes. The PC analysis was performed on clr-transformed of Meme sediment geochemical compositional data of selected ore forming elements in the hope of obtaining geochemical information that could elucidate on the inferred ore mineralization of the region. The eight PCs explain about 93% of the total variance. The positive and negative loadings of PCs indicated the presences of oxides, sulphides, REEs and gems mineralisation in the region. Further interrogation of Spearman correlation of ilr transformed data with respect to the PC loadings indicated well developed relationship between Sr and V (0.55), Mn and Pb (0.89), Mn and Ta (0.77), Mn and Nb (0.78), Nb vs Ta (0.98), Rb and Cr (0.59), In and As (0.64), Pb and Ga (0.78), Sb and Au (0.52), Ba and Cr (0.50). The elemental association suggests that they are either indicator of their own mineralization or are suitable pathfinders to pertinent minerals in Lokoja region. The negative correlation between Fe with other ore elements indicated that the Fe is from both proximal and dextral sources probably due to many Fe formations and mineralisation (goethite, haematite± siderite – bearing sedimentary ironstone formations in the region). The high Spearman correlation coefficients between Mn, Nb and Ta inferred that these ore elements are from the proximal sources because they are reliable pathfinders to pertinent oxides mineralisation in the region. Inferred proximal mineralisation in the region include beryl, topaz, columbite, quartzofeldspathic and quartz veins with anomalous concentration of Au as well as industrial minerals which are artisanally mined in places for industrial purposes.

Spectral re-evaluation of sediment thickness within Afikpo Basin and environs, southeastern Nigeria, using high resolution aeromagnetic dataset

The discovery of hydrocarbon in the areas bordering Afikpo Basin prompted the re-evaluation of the sedimentary thickness within the basin with high resolution geophysical data. Depth to magnetic sources, sediment thickness, basement topography and structures within it were investigated using spectral analysis, analytic signal and tilt derivative of aeromagnetic data. The results show that the depth to the basement varies between 1.52 and 3.15 km; depth to intermediate magnetic anomaly sources ranges from 0.40 to 1.05 km and depth to the shallow sources varies from 0.10 to 0.34 km. Structures within the basin predominantly have NE-SW trend and the boundary between Afikpo Basin and Southwestern Basement Massif is characterised by NE-SW trending dykes with the longest dyke extending from Amasiri to Abba Omege. The results show that the basin is greatly undulated and the deformation that led to its undulation resulted in the formation of structures which could serve as traps for hydrocarbon accumulation. Sediment thickness greater than 2.3 km associated with some locations within the basin prompted the classification of the places as viable for hydrocarbon formation, if other conditions necessary for its generation are favourable. These places were recommended for further studies for hydrocarbon prospecting on the bases of their sediment structural complexities and thicknesses.

The factor analysis of groundwater quality data of the Tista floodplain and the Dharla floodplain, Kurigram, Bangladesh: Siderite dissolution is a source of iron in groundwater

The present research work deals with the hydrochemical nature of the groundwater samples of the Dharla and the Tista River floodplains of Kurigram district, Bangladesh. The mechanism of groundwater chemistry was studied from the Gibbs plot and it can be summarized that precipitation and rock-water interaction are the major factors that influence the groundwater chemistry. The first four factors comprise 83.243% of the total variability of the groundwater samples of the Dharla floodplain aquifer whereas in case of the groundwater of the aquifers of the Tista floodplain first five factors constitute the 81.298% of the total variability of the original data. The study shows the dominance of HCO3-1 in the anionic part of the groundwater. More than 73.68% of the groundwater samples of the aquifers of the Tista floodplain exceed the maximum permissible limit of WHO for arsenic. The groundwater samples from the Tista floodplain especially from some parts of Rajarhat have high concentrations of iron. The first factor of the Dharla floodplain is dominated by iron and HCO3-1 ions which suggests the derivation of iron in the groundwater of the study area from the chemical weathering of siderite (FeCO3).

Lithological attributes of hd-001 well, shallow offshore, Niger delta basin, Nigeria

Lithological analysis was carried out on 96 ditch cuttings samples from HD-001 well located within the shallow offshore Niger delta basin, Nigeria. Three lithofacies sequences were delineated by the integration of wireline logs textural/lithologic attritudes and the distribution of index accessory minerals. They are transitional paralic, paralic and marine paralic sequences. The lithologic, textural and wireline log data indicate that the entire interval studied in the HD-001 well belongs to the Agbada Formation. The Formation is made up of alternating sand and shale units which suggests rapid shoreline progradation. The grain size increases from essentially fine to medium-grained at the basal part of the well to dominantly coarser grain at the upper part. The index accessories recognize shallow marine to coastal deltaic settings environment of deposition. Sand bodies which represent sub-environments within those settings are deposited in sequences. Each sequence begins with a transgressive phase followed by significant regressions.

Yield contributing characters of BRRI dhan49 as influenced by integrated use of banana leaves with inorganic potassium fertilizer

A field experiment was carried out at the Soil Science Field Laboratory of Bangladesh Agricultural University (BAU), Mymensingh during aman season of 2014 to study the integrated use of banana leaves with inorganic potassium fertilizer on the growth and yield of BRRI dhan49 following Randomized Complete Block Design (RCBD) with eight treatments and three replications. The highest plant height (85.55cm), panicle length (21.46cm), number of effective tillers hill-1 (11.54), number of filled grains panicle-1 (149.53), 1000-grain weight (21.85gm), grain yields (5.66 t ha-1) and straw yield (6.81 t ha-1) were obtained in the treatment T3 and the lowest plant height (77.10cm), panicle length (18.85cm), number of effective tillers hill-1 (8.64), number of filled grains panicle-1 (112.11), 1000-grain weight (19.96gm), grain yields (3.50 t ha-1) and straw yield (4.73 t ha-1) were recorded in the control. It can be recommended to integrated use of 50% K from banana leaves+50% K from MoP on growth and yield of BRRI dhan49.

Petrographic and geochemical interpretations of source provenance and tectonic setting of the Lokoja Sandstone, Bida Basin, Nigeria

The petrography and geochemistry of major and trace elements distribution pattern for the Lokoja Sandstones, Southern Bida Basin, Nigeria; were used to interpret their provenance, weathering conditions and paleotectonic setting. A total of seven (7) representative sandstone samples were selected for petrographic, heavy minerals and inorganic geochemical analyses; that is X- ray diffraction (XRD), X-ray fluorescence (XRF) and Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Results of the petrographic analysis showed 52.14 % quartz, 39.29 % feldspar, 2.00 % rock fragments, 5.14 % matrix and cement fraction as well as 1.43 % unfilled voids. Results of major elements and oxides suggests intermediate to felsic source rocks while the dominance of Na-rich feldspar to the k-feldspar and high value of Fe2O3+MgO shows contribution from ferromagnesian minerals of mafic igneous source provenance and oceanic island arc region. Average concentrations of designated trace elements in the studied sandstones are low in concentrations. The lower concentrations of Cr, Co, and Ni and higher concentrations of Zr, Ba, and Sr suggest a felsic progenitor rock. But significantly high values of Ni (7.02 ppm), La/Co (7.99), and Ni/Co (3.28) as well as the low concentration value of Y, (3.23 ppm) suggests contributions from mafic source rocks. Low average ratios for La/Co, Th/Co, Th/Sc, Ni/Co, Cr/Ni, Cr/Sc, Cr/Th, Ni/Co, Cr/Ni, Cr/Th, Cr/Sc, Th/Sc, La/Co and Th/Co also suggest a felsic source provenance. An average CIA value of 78.04% is indicative of an intense recycling in the source area while an average MIA value of 56.13% suggests a moderate degree of weathering. The high clay matrix and feldspar content have been used to classify the sandstones as feldspathic greywackes deposited in dry arid climatic conditions under a basement uplifted tectonic setting.

Curie depth and heat flow analysis of Ikot Ekpene and environs, Eastern Niger Delta Basin, using airborne magnetic data

Aeromagnetic dataset over Ikot Ekpene and environs, Eastern Niger Delta Basin, was processed to compute the basement depth, Curie isotherm depth, geothermal gradient and heat flow within the area in order to investigate the depth to magnetic sources, geothermal prospect and the hydrocarbon potential of the place. The adopted computational method transformed the spatial data into frequency domain and provided a relationship between radially average power spectrum of the magnetic anomalies and the depths to respective sources. The results of the analysis showed that the depths to centroids and top boundaries range from 7.84 to 13.38 km and 0.233 to 0.459 km respectively. Curie depths within the basin undulate and vary between 15.42 and 26.49 km. The geothermal gradients range between 20.758 and 35.649 ⁰C/km while the corresponding heat flow is about 51.896 mWm⁻² within east of Ikono, north of Mbak and west of Abak Areas and 89.124 mWm⁻² within Amawum, Ndoro, Isiala, Ogbuebule and east of Uyo Areas. Based on the computed sedimentary thicknesses, high geothermal gradients and delineated major faults and fractures which could serve as migratory pathway for hydrocarbon or hydrothermal fluid, some parts of the study area have been demarcated for geothermal prospect and detail hydrocarbon exploration.

Behavior of the clinopyroxenes trace elements in spinel-lherzolite xenoliths from Liri (Kapsiki plateau, Cameroon line)

Spinel-lherzolite xenoliths trapped within the alkali basalts flow in the Liri region (Kapsiki Plateau) have a protogranular texture and consist of olivine, orthopyroxene, clinopyroxene and spinel crystals. These xenoliths are residues of partial melting of the primitive mantle, with the low titanium content in clinopyroxene crystals (TiO2 < 0.5 wt.%). The clinopyroxene of the spinel-lherzolite xenoliths from Liri, are divided into two distinct groups according to their trace element characteristics. The variations in the rare earths elements make it possible to classify the different clynopyroxenes in two groups: the first group consisting of the samples of Liri (Liri 1, Liri 02, Liri 3, Liri 05 and Liri 5) rich in light rare earths elements (LREEs), with ratios (Ce/Yb)N normalized which vary between 3.00 and 7.78. It is probably a cryptic metasomatism due to the absence of hydrated minerals (such as amphibole) which caused these enrichments. The second group comprises samples of Liri (Liri 01, Liri 2, Liri 04, Liri 4) depleted in light rare earths elements, with the ratio in (Ce/Yb) N < 1.2. This depletion in rare earths elements results from the extraction of the melting liquid.