by Subhash Chandra Mondal, Sanjay Sen and Suma Debsarma
Original Research
Numerical techniques based on the finite difference scheme with discontinuity have been developed for problems associated with aseismic ground deformation in seismically active regions. We stress upon the applicability of such numerical techniques in solving problems in geodynamics. A long strike-slip fault is considered in a viscoelastic half space representing the lithosphere-asthenosphere system. The fault undergoes a sudden movement under the action of tectonic forces induced by mantle convection. The resulting boundary value problems have been solved with the help of numerical technique, based on a finite difference scheme with appropriate boundary conditions, developed for the purpose. The numerical techniques developed here can be modified for more general deformation problems where analytical methods become very complicated.
Journal of Geosciences and Geomatics. 2018, 6(1), 27-34. DOI: 10.12691/jgg-6-1-4
Pub. Date: June 15, 2018
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by OFULUME A. B., IBE K. K., IBENEME S. I., DIOHA E. C., CHINEMELU E. S., ELUWA J. C. and ONYEISE U.O.
Original Research
The Ndi-Uduma Ukwu/Ohafia-Ifigh limestone deposit is located approximately 55km East of Umuahia and about 125km Northwest of Calabar, S.E. Nigeria. This coarse grained, light to dark grey limestone is sandwiched between two carbonaceous highly fissile shale units of the Nsukka Formation forming shale-limestone-shale sequence. Outcrop samples were utilized in the petrographic investigation and geochemical analysis using Atomic Absorption Spectrophotometer (AAS). The calcium carbonate content (% CaCO3) of the limestone ranges from 65.08 to 82.41%. The samples from Ohafia-Ifigh are SO3-free and purer while the Ndi Uduma Ukwu had MgO and SO3content of 3.34 and 1% respectively. Petrographic analysis of the limestone reveals a highly fossiliferous limestone infilled with chiefly sparry calcite with micrite envelope, consisting of foraminifera, ostracod, echinoid, bivalve gastropod, coralline algae suggestive of shallow marine environment. Although the limestone does not compare with that of Shapfell, UK and Mfamosing S.E. Nigeria in chemical purity to warrant lime production with it, yet it meets some industrial raw material specification such as for cement, agriculture and poultry applications.
Journal of Geosciences and Geomatics. 2018, 6(1), 21-26. DOI: 10.12691/jgg-6-1-3
Pub. Date: May 14, 2018
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by Rajendrakumar Budihal and Ganapathi Pujar
Original Research
The laterite deposits of Swarnagadde plateau occurs in Uttar Kannada district of Karnataka state, forming low altitude flat topped laterite hills and plateaus adjoining part of Central Western Ghats, in the western continental margin of India. In this study, using geochemical techniques for calculation of relative weathering (SiO2 content), CIA and correlation coefficients, the effective factors in mobilization and redistribution of major and trace elements during lateritization processes across selected profile were considered. According to the Al2O3-Fe2O3-SiO2 ternary diagram of Schellmann [1] the limit of kaolinization on the tri-plot for the protolith of Swarnagadde plateau profile (granite/gneiss rock) is determined to occur at 68.22% SiO2 and gradual change from SiO2-rich to Fe2O3-rich to Al2O3-rich compositions and of increasing degree of lateritization. The laterite samples were highly weathered with chemical index of alteration ca.98.92%, nearly complete loss of Na, Ca, Mg and K in the ferruginous zone. Fe mainly occurred as goethite, hematite, while Al mainly occurred as secondary clay minerals (kaolinite) and gibbsite below the ferruginous zone. On the basis of mineralogy and geochemistry, these deposits are grouped as aluminous laterites, ferruginous laterites and lithomargic clay. The major, trace elements and mineralogical characteristics of laterites, these were formed in situ by the alteration of parent rocks of granite/granitic gneiss compositions. The correlation coefficient patterns of several major and trace elements and their preferential enrichment have suggested that there is an influence of precursor rock on the distribution of trace elements. Significant depletion of base cations and Si, coupled with enrichment of Fe and Al, reveal that intense leaching of cations, kaolinization, desilication and ferruginization took place in lateritic deposits during weathering and lateritization.
Journal of Geosciences and Geomatics. 2018, 6(1), 12-20. DOI: 10.12691/jgg-6-1-2
Pub. Date: March 13, 2018
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by Ameh Peter, Igwe Ogbonnaya, Abdullateef Lawal, Mustapha Aliyu, Isa Abdulmajid and Zakariyau K. Kazeem
Original Research
This study evaluates the index and engineering properties of soils in Otukpa Area of Benue State towards ascertaining their suitability for use as fill and embankment, sub-base and base course material. Otukpa in Benue state Nigeria has vast reserve of sand and other aggregate materials that are presently been mined for various construction purposes. The area holds good potential for human population explosion in the near future. When massive infrastructural development commences, localized sourcing of materials would be necessary. Unfortunately, not much is known of the geotechnical properties of the sands in this area. Index and engineering test was conducted to achieve the aim. Gravel size particles are completely absent. Permeability of soil ranged from 7.8×10-6 to 3.36×10-4m/sec with moisture content of 11.38 to 14.16%. Specific gravity was between 2.63 to 2.67g/cm3. UCS range from 31-45Kpa while LL and PL ranged between 27-35% and 10-18% respectively. MDD peak value was 1.85(g/cm3) at an OMC of 12.11% and lowest at 1.67(g/cm3) at an OMC of 11.99. The geotechnical implication of the observed properties range from susceptibility to marginal volume change, differential settlement to low shearing resistance. These materials are quality reserves for fill, embankment and sub-base construction but not for bases.
Journal of Geosciences and Geomatics. 2018, 6(1), 1-11. DOI: 10.12691/jgg-6-1-1
Pub. Date: February 26, 2018
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