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International Journal of Geosciences 2011年第3期2卷 259-266页

作者： prosper M. nude Gordon Foli Sandow Mark Yidana Department of Earth Science University of Ghana Legon-Accra

Stream sediment samples were analyzed for the concentrations of some trace metals in the Obuasi gold mining environment, Ghana. The objectives were to determine the possible impacts of mining operations in the area on sediments’ trace metal load, and the resulting effects on agriculture and livelihoods. The concentrations of arsenic (As), copper (Cu), lead (Pb), zinc (Zn), iron (Fe), with calcium (Ca) as reference element, were compared to their respective background concentrations to calculate the enrichment and contamination factors, and also geo-accumulation and pollution load indices of each trace metal. These were in turn compared to standard tables to determine the status of contamination. Q-mode hierarchical cluster analysis (HCA) was then applied to the samples for spatial classification. This study suggests probable contribution of mining and associated activities in the Obuasi area to the concentrations of trace metals especially arsenic, in the stream sediments. Three spatial relationships were revealed based on the concentrations of these trace metals from the Q-mode HCA. The samples presented generally high concentrations, which were more profound for samples taken closer to holding pond and tailings dams, and decreased downstream.

关键词： Enrichment Factor Contamination Factor Geo-Accumulation Index Pollution Load Index Trace Metals Obuasi Gold Mine Ghana

Preserved Sm-Nd Isotopic Composition as Useful Provenance Indicators in Neoproterozoic Sandstones in the Voltaian Basin, Ghana

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International Journal of Geosciences 2012年第3期3卷 463-468页

作者： Chris Anani Daniel Asiedu Johnson Manu prosper nude Jacob Kutu Patrick Asamoah Sakyi Department of Earth science University of Ghana Box LG 58 Legon-Accra Ghana

The provenance of sandstones derived from theLower Voltaian Kwahu-Morago Group and the Middle Voltaian Oti-Pendjari Group of the Neoproterozoic Voltaian basin are discriminated by their Sm-Nd Isotopic compositions. Plots from the Sm-Nd data suggested provenance of the Kwahu-Morago Group to be from the Birimian metasediments and associated “basin type”granitoids. The Sm-Nd studies have further revealed an average TDM model age of whole rock samples in the Kwahu-Morago Group to be 2.2 Ga which shows that this portion of the Voltaian Supergroup represents eroded remnants of “basin type” granitoids. Sm-Nd data from the Oti-Pendjari Group suggested provenance from the Birimian volcanic rocks and probably with contribution from the Pan African rocks. Its average TDM model age of whole rock samples was 2.0 Ga, which generally falls in the range of the model ages for the basement Birimian volcanic rocks as well as the model ages for the granitoid rocks and thus suggests the major source rock of the Oti-Pendjari Group as coming from the volcanic belts. The model ages for both groups seem to indicate clastic supply from an early Proterozoic crustal provenance. This study shows that whole rock isotopic analyses can also be complementary in providing an insight into the origin and development of sedimentary successions.

关键词： Isotope Model Age Provenance Sandstone Voltaian Basin

Characterization of the Hydrogeological Conditions of Some Portions of the Neoproterozoic Voltaian Supergroup in Northern Ghana

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Journal of Water Resource and Protection 2011年第12期3卷 861-875页

作者： Sandow Mark Yidana Aliou Abdul-Samed Bruce Banoeng-Yakubo prosper M. nude 不详

Spatial variations in the essential aquifer parameters obtained through regular aquifer tests were evaluated for some aquifers of the Neoproterozoic sedimentary aquifers of the Voltaian Basin. Ordinary least squares regression models have also been developed to relate aquifer transmissivity and specific capacity, and well yield and transmissivity. These analyses suggest that in the northern parts of the Voltaian, aquifer transmissivity exists in a non-linear relationship with specific capacity and yield. This is in keeping with the findings of previous research in the southern part of the Voltaian, and deviates from the regular Dupuit-Thiem relationship between the two major aquifer parameters. Lithology specific models have been developed in this study. The exponent of the non-linear models appears to be related to the lithology, and tends to approach unity in the mudstone and siltstone aquifers, whilst manifesting obvious departures from nonlinearity amongst the sandstone aquifers. This study finds that the sandstone aquifers are the most prolific and offer themselves as the best lithologies for drilling successful wells in the area. Linear prediction maps suggest that the most prolific aquifers are located in the northern parts of the study area, where aquifer transmissivity, specific capacity, and well yield values are quite high due to enhanced secondary permeabilities. There has been no obvious relationship between the major aquifer parameters and static water levels, which are quite high in the middle and western sections of the study area. The hydrogeological properties of rocks within the Voltaian appear to be based on discrete structural entities which manifest high variability in the study area. Even within the same lithology, standard deviations are quite high in the data for all the aquifer parameters examined in this study.

关键词： Savelugu-Nanton Regression Specific Capacity Transmissivity Yield Kriging

Identifying Pathfinder Elements for Gold in Multi-Element Soil Geochemical Data from the Wa-Lawra Belt, Northwest Ghana: A Multivariate Statistical Approach

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International Journal of Geosciences 2012年第1期3卷 62-70页

作者： prosper Mackenzie nude John Mahfouz Asigri Sandow Mark Yidana Emmanuel Arhin Gordon Foli Jacob Mawuko Kutu Department of Earth Science University of Ghana Legon Ghana

A multivariate statistical analysis was performed on multi-element soil geochemical data from the Koda Hill-Bulenga gold prospects in the Wa-Lawra gold belt, northwest Ghana. The objectives of the study were to define gold relationships with other trace elements to determine possible pathfinder elements for gold from the soil geochemical data. The study focused on seven elements, namely, Au, Fe, Pb, Mn, Ag, As and Cu. Factor analysis and hierarchical cluster analysis were performed on the analyzed samples. Factor analysis explained 79.093% of the total variance of the data through three factors. This had the gold factor being factor 3, having associations of copper, iron, lead and manganese and accounting for 20.903% of the total variance. From hierarchical clustering, gold was also observed to be clustering with lead, copper, arsenic and silver. There was further indication that, gold concentrations were lower than that of its associations. It can be inferred from the results that, the occurrence of gold and its associated elements can be linked to both primary dispersion from underlying rocks and secondary processes such as lateritization. This data shows that Fe and Mn strongly associated with gold, and alongside Pb, Ag, As and Cu, these elements can be used as pathfinders for gold in the area, with ferruginous zones as targets.

关键词： Multivariate Analyses Multi-Elements Soil Geochemical Data Pathfinder Elements Gold Northwest Ghana

Characteristics of termite mounds and associated Acrisols in the coastal savanna zone of Ghana and impact on hydraulic conductivity

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Natural Science 2012年第7期4卷 423-437页

作者： Gabriel N. N. Dowuona Pearl Atwere W. Dubbin prosper M. nude Baba E. Mutala Eric K. Nartey Richard J. Heck Department of Earth Science University of Ghana Legon Ghana Department of Soil Science School of Agriculture University of Ghana Legon Ghana Natural History Museum Mineralogy Department London SW7 5BD U.K School of Environmental Sciences University of Guelph Guelph Ontario Canada

Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy clay in contrast to the sandy clay loam of the surface soils. Translocation of fine to medium sized soil materials influenced the relatively higher bulk density (>1.60 Mg/m3) and contents of organic carbon, nitrogen and exchangeable bases in the mounds. Kaolinite was the dominant clay mineral with pH values generally below 5.3 in all the soils reflecting the weathered tropical soil environment. Dispersion ratio values, which were 0.5 for the surface soils, indicated greater stability of the mound due to aggregate cementing action by the termites. Estimated mound density was about 120 mounds per ha, which tied in with known groundwater reserves at the study sites. Majority of the mounds exhibited a cone-shaped morphology with heights varying between 3.05-4.00 m in the Rhodic Acrisol and 2.05-4.20 m in the Haplic Acrisol with corresponding estimated total mass of 96,361 kg and 54,910 kg per 1000 m2 land area. These estimates represented a large amount of material relative to the 25,000-26,000 kg of surface soil material within the same unit area. The K in the surface soils ranged from 3.3 x 10-5 to 5.0 x 10-5 m/s while the value for the mound was ≤0.5 x 10-5 m/s. Lower porosity, θ;the effect was more pronounced when the mound was applied on the soil surface. Improvement in water retention and nutrient availability to plants and prevention of leaching to avoid groundwater contamination are some of the positive attributes of this study.

关键词： Aggregate Stability Clay Mineralogy Dispersion Ratio Hydraulic Conductivity Mound Morphology Termite Mounds