Sedimentary Geology. (Book Reviews: Aspects of Diagenesis. Papers from symposiums, Mar. 1976 and Apr. 1977)

Groundwater is a major source of drinking water for millions of people around the world. Over 400 million people in Africa depend solely on it as their main source of water supply. Fluoride is a co...

A review on the potential sources and health implications of fluoride in groundwater of Sub-Saharan Africa.

Petrogenesis of Metamorphic Rocks. Helmut G. F. Winkler

In this study, the activity concentrations of natural radionuclides in soil and beach sediment samples collected from 15 randomly but uniformly distributed locations in the coastal area of Akwa Ibom (southern Nigeria) were measured using hyper pure germanium (HPGe) detector. The activity concentrations of 238U, 232Th and 40K varied from 9 to 44 Bq/kg, 3 to 72 Bq/kg and 35 to 250 Bq/kg respectively. These results are below the 1000, 1000 and 4000 Bq/kg upper limits of safety for 238U, 232Th and 40K respectively. Except 238U, 232Th and 40K show lower standard deviations than their mean values, which indicate that soils and sediments have high degree of uniformity. The spatial distribution of radionuclide concentrations is nearly uniform except at locations where carbonaceous materials and clay soils exist. Mean value of Th/U ratio across the area was ≤ 7, typical of reducing condition in the depositional environment, thus suggesting enrichment of carbonaceous materials and clays. Additionally, the concentration of 40K was observed to be slightly higher in locations where anthropic activities are prevalent. Apart from excess lifetime cancer risk (average concentration of 0.80 × 10−3), the average concentrations of other radiological parameters: radium equivalent (83 Bq/kg), absorbed dose rate (39 nGy/h), indoor annual effective dose equivalent (0.18 mSv/year), outdoor annual effective dose equivalent (0.05 mSv/y) and annual gonadal dose equivalent (259 μSv/y), are below permissible limits. Hence, the soils and sediments are safe and suitable for all purposes.

Assessment of radionuclide distribution and associated radiological hazards for soils and beach sediments of Akwa Ibom Coastline, southern Nigeria

Coupled geophysical characterization of shallow fluvio-clastic sediments in Agwagune, southeastern Nigeria

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 {Al2O3 > (CaO + Na2O + K2O)}, high alkali concentration with
Na2O > K2O, high Al2O3 to alkali
ratios and low TiO2, 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 SiO2,
but relatively enriched in lime and alkali oxides. Plots in the AFM, TiO2-K2O-P2O5 and Na2O/Al2O3-K2O/Al2O3 diagrams show that the pegmatite was derived from calc-alkaline magmatic
source, while the dolerite was derived from tholeiitic basalt magma.

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Petrology and Geochemistry of Basement Complex Rocks in Okom-Ita Area, Oban Massif, Southeastern Nigeria

The rocks underlying many parts of Southeastern Nigeria had undergone extensive alterations to form considerable clay deposits. The mineralogical compositions of some of these clay deposits were evaluated with the X-Ray Diffraction (XRD) method to ascertain the suitability of the deposits as raw materials. Results of the analyses indicated that kaolinite (Al2Si2O5 (OH)4) is the dominant clay mineral. Traces of bentonite and dickite were also observed, while the identified non-clay minerals were quartz and iron. Chemical analysis of the clays revealed the predominance of SiO2, Al2O3, Fe2O3 and TiO with values ranging from 31.70 to 56.45%, 19.30 to 29.30%, 3.11 to 29.42% and 2.21 to 7.04%, respectively, while the compositions of CaO, MgO, Na2O, and MnO in the analyzed samples were relatively lower with values ranging from 0.19 to 0.29%, 0.13 to 0.19%, 0.11 to 0.70% and 0.01 to 0.03%, respectively. The Al2O3/TiO2 ratio (3.7 to 13.5) of the studied clays indicated a mafic to intermediate igneous rock origin. Binary plots of TiO2 versus Al2O3 to distinguish between granitic and basaltic sourced clays indicated basalt-rhyolite/granite provenances. The high chemical index of alteration (95.8%), chemical index of weathering (98.3%) and low contents of alkali and alkali earth elements (averaging 0.11%) of the clay-rich sediments, is indicative of a relatively intense weathering source area. The SiO2-K2O/Na2O plots suggested that the sediments in the study area were deposited between passive and active continental margins. In comparison with other reference clays and standard specifications, the clay deposits in the study area possess characteristics satisfactory for economic and some engineering purposes.

	Key words: Chemical, clay, deposits, economic, mineralogical, potentials, provenance.

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Mineralogical and geochemical properties of clay deposits in parts of Southeastern Nigeria

Paleoenvironment and Provenance Studies of Ajali Sandstone in Igbere Area, Afikpo Basin, Nigeria

Detailed characterization of the outcropping sediments in the Ikpankwu and Ihube axis was undertaken to validate lithostratigraphic boundaries and nomenclatures which had stirred up debates amongst scholars in recent times. Stochastic method established dominant facies associations and preferred stacking patterns, which were used to interpret environments of deposition (EODs), while foraminiferal and palynological analyses fingerprinted both paleo depths and age of the sediments. The results established the dominance of similar lithofacies at the basal parts of both sections indicating mappable geological units and members of the same lithostratigraphic unit. The basal lithofacies are succeeded up section, however, by different lithological units in both the KM 75 and Ikpankwu sections. Interpretations of EODs using lithofacies successions predicted fluvial to tidally-influenced shallow marine deposits, which are environments in close affinity with each other. Interpretations using abundance and diversity of micro fauna supported non-marine (coastal-deltaic) to middle neritic paleo-water depths also, typical of marginal to shallow marine EODs. Recovered foraminiferal assemblages in the shale samples from the upper parts of both sections, however, depicted deposits of Nsukka Formation despite variations observed in lithofacies assemblages because the identified Haplophragmoides species that populate the upper units had been used to define the Late Maastrichtian-Paleocene age. Sediments at the basal parts with mappable lithological units at both sections were rather populated by species that connote the Campanian-Maastrichtian age when the Mamu Formation sediments were deposited. Palynomorphs recovered from both the basal and upper sections also suggested Campanian-Maastrichtian and Late Maastrichtian-Paleocene age, indicative of Mamu and Nsukka Formation sediments, respectively.

/pdf/characterization-of-the-upper-cretaceous-sediments-in-the-49v3zefqd0.pdf

Characterization of the Upper Cretaceous Sediments in the Ikpankwu-Ihube Axis, Okigwe, Southeastern Nigeria

Since Awka town was made the capital of Anambra State, population growth, innumerable industries and other new land uses have been on the increase. There is the fear that inorganic geochemical elements may have contaminated the groundwater making it unfit for consumption. This research is thus intended to estimate the magnitude to which borehole waters and by extension the groundwater system in the area have been contaminated. Six borehole water samples were collected and analysed for inorganic geochemical elements. The parameters analysed were colour, acidity, pH, conductivity, total dissolved and suspended solids (TDS and TSS). Others are nitrate (NO 3 ), chloride (Cl - ), sulphate (SO 4 2- ), phosphate (PO 4 3 ) copper (Cu 2+ ), lead (Pb 2+ ), cadmium (Cd 2+ ), zinc (Zn 2+ ), iron (Fe 2+ ), total hardness (calcium hardness and magnesium hardness) (total hardness) and alkalinity. The analyses were conducted with appropriate geochemical equipment. It was discovered that other anions apart from phosphate are within the concentrations recommended for safe drinking water. The concentration of the cations is in the following order: Cl> HCO 3 > SO 4 > NO 3, and that for anions is Mg> Ca> K> Na, thus making the water in the area potentially magnesium chloride water. Iron and lead are the only heavy metals whose concentrations are high. Lead is toxic but iron only stains and causes intestinal disturbance.

/pdf/assessment-of-the-concentration-of-inorganic-chemical-4i3ao1slrv.pdf

Assessment of the Concentration of Inorganic Chemical Elements in the Pollution Status of Water Boreholes in Awka- Anambra Sedimentary Basin, Se, Nigeria

K D Opara

Papers

Petrology and Geochemistry of Basement Complex Rocks in Okom-Ita Area, Oban Massif, Southeastern Nigeria

Mineralogical and geochemical properties of clay deposits in parts of Southeastern Nigeria

Paleoenvironment and Provenance Studies of Ajali Sandstone in Igbere Area, Afikpo Basin, Nigeria

Characterization of the Upper Cretaceous Sediments in the Ikpankwu-Ihube Axis, Okigwe, Southeastern Nigeria

Assessment of the Concentration of Inorganic Chemical Elements in the Pollution Status of Water Boreholes in Awka- Anambra Sedimentary Basin, Se, Nigeria