International Journal of Economic and Environmental Geology
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Petrochemistry and Depositional Environment of Permian Coals of Basundhara Block, Ib-Valley Coalfied, Orissa,India
Get PDFThis paper deals with the characteristics of coal formation. A large number of pillar coal samples from Basundharablock were collected and subjected to detailed petrograplhic and geochemical studies. The results show that the Basundharablock (Rampur seam) coals are rich in inerinite group macerals. The rank of Basundhara block coals as per ASTM system and according to the mean of random vitrinite reflectance has been found to range between sub-bituminous '`A' and high volatile bituminous 'B', The proximate analysis exhibit that coals belong to semi-coking to weakly coking range. The ultimate composition shows hydrogen ranges between 4.87 and 6.20%, carbon from 78.7 to 86.3% and oxygen between 7.26 and 13,78% The nitrogen ranges from 0.71 to 0.76% and sulplur is between 0.53 and 0.96%. The quantitative study of macerals, microlithotypes and mineral matter indicate that these coals originated from the plant communities of highly fluctuating oxic and anoxic moorto oxic (dry) moor with sudden high flooding conditions. Low value of Tissue Preservation Index (TPI) and high value of Gelification Index (GI) indicate peat formation in drycondition.
Drainage Characteristics of Tectonically Active Areas: An Example from Rajasthan, India
Get PDFThe morphotectonic studies help in deciphering the role of tectonics and neotectonics in morphological evolution of draiage basins. On the basis of remote sensing technique, the relationship betwcen morphology and tectonics have been investigated in Bundi-Indergarh sector of southeast Rajasthan. The area sclected for present study is drained by Mej river and its tributaries and occupies the southeastern part of the Aravalli Mountain Range (AMR). The course of Mej river is mostly controlled by the Great Boundary Thrust (GBT) and associated tectonic elements. GBT separatcs the folded, faulted and metamorphosed older rocks of the AMR in the west and relativcly undeformed Vindiyan rocks in the east. This study has been carried out using digital and hard copy product of IRS IC/ID LISS III geocoded FCC data. The morphometric and morphotectonic aspects have been studied for identification of present day tectonic activities in the area. The remote sensing data interpretation indicates that the landforms of the area are structurally controlled and mainly covered by linear and parallel strike ridges and valleys. These valleys indicate sign of stream rejuvenation and occasional presence of dynamic ravines. General morphometric parameters, bifurcation ratio, stream lengh and shape parameters have been computed. Longitudinal river profilcs can be quantificd by normalizing the elevation and the distance along rivers. Several parameters such as profile shape (concavity), gradient fluctuations, river grade and valley incision have been derived from longitudinal river profile. These quantified parameters and their interrelations are useful in comparing different drainage basins and also help drawing inferences on neotectonism. The computed values suggest that the area is covered by resistant rock and drainage network, affeced by tectonic disturbance. The valley floor ratio is very low, indicating channel down cutting vis-a-vis ground uplif. The gradient index is most commonly used to define relative diferences in uplift and erosion. The computed values for these parameters indicate ongoing tectonic activity in the area. Migration and/or rejuvenation of rivers, rotational/vertical/lateral movements of crustal blocks and several other evidences bear testimony to ongoing neotectonic activities in the region
Petrochemical Characteristics and Ageof Rare Metal (Ta-Nb) Mineralization in Precambrian Pegmatites, Komu,Nigeria
Get PDFThe Precambrian pegmatites of Komu area intrude semi discordantly older rock types, such as biotite gneiss,amphibolites and pelitic schists. The pegmatites occur as near flat lying bodies. This study aims at elucidating thegeological setting. petrograply, geochemical features and age of mineralization of these pegmatite bodies, with a viewto classifying them and knowing their economic potential. The petrographiic analysis shows that the pegmatite samplescontain mainly quartz (3 59%), plagioclase (15%), microcline (10%) and muscovite (12%) with accessories like tourmaline,tantalum, niobium and illmeno-rutiles. Geochemical analysis of the muscovites extracted from pegmatites show thatthese rocks are enriched in silica (>60%) and A2O3 (>12%) and depleted in Fe2O3, MgO and TIO2, Trace element analysisshows that the pegmatites contain rare metals with moderately high Ta, Nb, Sn, Rb, Li and Cs values and depleted in Ti,Ba and Zr. Elemental ratios indicate low ratios of K/Cs, Th/U and K/Rb. Variation plots of Ta/(Ta+Nb) versus Mn(Mn+Fe) show that the pegmatites plot in the complex (beryl subtype) field The Na/K versus Sn, Nb,Rb variation plotsshow that the pegmatites of Komu area are mineralized and compare favourably with those of other mineralized pegmatitc areas like Egbe and ljero in southwestern Nigeria. The variation plots of Ta versus K/Cs, and Ta/ W versus Cs, also confirm rare metal mineralization of Komu pegmatites, which plot over the mineralized line of Beus and Gordiyenko, TheK/Rb versus Rb,Cs and Sn plots indicate low K/Rb ratios indicating moderate differentiation. The Rare Earh Elements(REE) show high heavy REE values and lower light REE values with prominent positive Ce anomaly and negative Euanomaly from nonalized chondrite plos. K/Ar dating of the age of mineralization of muscovites extracted from thepegmatite yilded late Pan-African ages between 502.8 ± 13Ma and 514.54 ±13.2Ma. This period represents the coolingages of the muscovite and suggests that the pegmatites may not be cogenetic with the surrounding Pan-Africangranitoids
Mineralogical-Geochemical Peculiarities of Ores in Pyritaceous Fields ofFilizchai Type in the Greater Caucasus
No full textPyritaceous fields of the south slope of the Greater Caucasus confined to the Lower-Middle Jurassic sandyclayey deposits are: polygenic polychrone formations which were formed by a complex of hydrothermal sedimentary.hydrothermal metasomatic and hydrothermal metamorphogenic processes of ore formation. Filizchai pyritaceouspolymetallic field is the largest in the region and can be characterized by diversity of texture-mineralogical types ofores, rich mineral composition and with geochemical spectrum. Some of the admixture components (Cd, In, TI, Ga,Ge.Se, Hg) are only in isomorphic forms in ores, others (Te, Bi, Au, Ag, Co, Sn, As) along with it characterize in theirown minerals. The Co is mainly concentrated in pyrite, pyrrhotine; Ag, Bi and also Te -in galenite and chalcopyrite;Se- in pyrite. pyrrhotine and galenite; in sphalerite (mainly in marmatite) and chalcopyrite; Cd. Ga, CGe- in sphalerite.mainly in cleiophane; Au -in pyrite and chalcopyrite; TI -in galenite and colloform pyrite. In all sulphides seleniumprevails over tellurium (excepting the late chalcopyrite) and cobalt over nickel, Maximum amount of cobalt is confinedto pyrite from pyritaceous polymetallic ores and late generation of pyrrhotine, The nature of the connection betweenchemical elements in ores coordinates with determined stages of minerals formation. The main productive stage ofore formation bringing the main mass of gold, silver, rare and other precious components of ores are sulphosaltpolymetallic stage of sulphur ploymetallic stage. Comparative analysis of absolute content of gold, silver and valuesof gold-silver relation in pyrite fields ores of region with appropriate values in meteorite standard indirecty indicatesthe relationship between gold-silver mineralization and assimilation crust source
Petrochemistry and Depositional Environment of Permian Coals of Basundhara Block, Ib-Valley Coal field, Orissa, India
Get PDFThis paper deals with the characteristics of coals of Basundhara block of Ib-valley.The aim of this study is to reconstnict the paleo environment condition of coal formation. A large number of pillar coal samples from Basundhara block were collected and subjected to detailed petrograplic and geochemical studies. The results show that the Basundhara block (Rampur seam) coals are rich in inetinite group of macerals. The rank of Basundhara block coals as per ASTM system and according to the mean of random vitrinite reflectance has been found to range between sub-bituminous `'A' and high volatile bituminous 'B'. The proximate analyses exhibit that coals belong to semi-coking to weakly coking range. The ultimate composition slhows hydrogen ranges between 4.87 and 6.20%, carbon from 78.7 to 86.3% and oxygen between 7.26 and 13.78% The nitrogen ranges from 0.71 to 0.76% and sulplur is between 0.53 and 0.96%. Thecommunities quantitative study of macerals, microlithotypes and mineral matter indicate that these coals originated from the plantof highly fluctuating oxic and anoxic moor to oxic (dry) moor with sudden high flooding conditions. Low value of Tissue Preservative Index and high values of Gelification Index (GI) indcate peat formation in dry conditio
Assessment of Human Impacton Quaternary Aquifers of Rafah Area, NE Sinai, Egypt
Get PDFGroundwater is endangered by agricultural activities, wastes disposal, aquifer over exploitation and seawaterintrusion. The pollution risk is high, as the depth to the water table is shallow and the aquifers are highly permeableand have poor buffering capacity. Intensive farming activities have also put stress on groundwater quality due tointensive use of fertilizers and pesticides. As a result, concentrations of NO-3, SO2-4 and PO4-2 are very high. Most of the house owners do not have access to public sewers, which poses another risk for the aquifers. More than 71.2% of the aerial distribution of nitrate concentration is greater than 44.29 mg/L,thus causing a serious problem. Static waterlevel maps from 1983 to 2000 show the declining of the water level with time. The discharge from Quaternary aquifersexceeds the recharge rates after 1988 resulting in both upward leakage of the deeper high saline water and seawaterintrusion. Factor analyses were used to define the factors that affect the groundwater quality. Dissolution anddepositionof several minerals, evaporation from the groundwater, hurman inpact on the aquifers, cation exchange, mixing betweendifferent waters and rainfall recharge were identified as the main factors impacting the ground waters
Volcanic Successions of the Jebal Remah Volcano,Northeast Jordan
Get PDFJebal Remah volcano is one of huge but very poorly known tephra cones exposed on the basalt province of Harra El-Jabban. Detailed investigations indicate that this volcano is topographically distinct and structurally well developed.It consists of voluminous air-fall scoria, arranged in three distinct horizons; namely lower black lapilli: horizon, middle banded yellow horizon and upper brown blocky horizon. Each horizon consists of friable, loose and well bedded ejecta. Agglutinationand lithification are limited to the upper horizon. A comparison among the volcanic succcssions of three horizons show diffcrent volcanic features that nevertheless retain a comparable overall character. from one horizon to another. In spite of some similarity in the type of ejecta, actually these differ in total thickness number of beds and internal stratification. This dissimilarity within volcanic successions of the volcano support the overall increase in fluidity, temperature and decrease in volatile content of the magma with the time. Thus, volcano shows a complete range of themal facies. The studied volcano appears to have resulted from one prolonged eruptive phase. Its volcanic activity consisted of a series of discrete explosion intervals, separated by quiet periods. Field criteria indicate that the volcano is of sublimation type of volcanicity and resulted in a magmatic fragmentation mode.  
Separation of Regional and Residual Components by Finite Element Analysis -A New Approach for Analysis of Water Level Data
No full textTrend surfaces are generally used in the study of water level data to understanding the causes and efectsof various trend surfaces. In the present paper the separation of regional and residual components of water level datais attempted using a method based on the Finite Element Analysis techniques. The residual is obtained by calculatingthe difference between the computed value of the trend surface at a point and the value of observed actual surface atthat point. If the trend surface is thought to be regional or large scale component representing the total aquifer thenthe residual value can be considered the local ore small scale component representing the local variations in the aquifer.Removal of the regional trend has the effect of isolating and emphasizing local components represented by the residualvalues. Various techniques have been proposed and are widely in use for the separation of regional and the residualcomponents, specially for separating the geophysical data. But the main drawback of all these techniques is that theregional component, so computed, has always the remnance of the residual components.Hence,the regional andresidual components do not give a clear picture of the variations. In the present paper a new technique is suggested,in which the regional and residual components are computed using finite element analysis technique. This techniquerequires the water level data at only eight or twelve points representing the aquifer boundaries for the computationof regional component.A case history is presented wherein the data from the literature is analyzed using the techniqueproposed. The paper gives the details of the method and its advantages over the other methods which are supportedby its application on the field data
Environmental Implications of Moonsoon Seasonal Rainfall on Groundwater Regime of Rajpipla Region, Gujarat, India.
No full textThe monsoon seasonal rainfall record of Rajpipla area confined to Gujarat state of India, for a period of1987-2006, has been treated to mathematical and statistical analyses to observe variation pattern, future trends andtheir environmental impacts on groundwater regime. The mathematical analysis of monsoon seasonal rainfall dataindicates a fairly good range of variation from 321.30 mm to 1319.30 mm with an average rainfall value of 925.61 mmThe years indicating positive trend of departure from the computed value of average seasonal rainfall point outfavourable intervals for recharge of ground water reservoir. The cumulative departure from the average rainfall exceptfor 1998 and 2006 reveals existence of negative trend. The statistical analysis of rainfall data determines statisticalparameters, which indicate rather alternative variation pattern. The forecast of future rainfall trend for a period of nextthree years indicates an increasing trend in the expected rainfall amount. The environmental impacts of rainfallphenomena have been discussed. The strategy for augmentation of rainfall amount to enhance the groundwater rechargesystem for Rajpipla area has been suggested
Petrogenesis of Bir Madi Gabbro-Diorite and Tonalite-Granodiorite Intrusions in Southeastern Desert, Egypt: Implications for Tectono-Magmatic Processes at the Neoproterozoic Shield
Get PDFThe Neoproterozoic rocks of the Bir Madi area, south eastern desert, comprise a Metagabbro-Diorite Complex(GDC) and a Tonalitc-Granodiorite Suite (TGrS), The GDC has a weak tonalitic to strong calc-alkaline character and ismade up of olivine gabbro, hornblende gabbro, diorite and monzodiorite. The olivine gabbro is characterized by abundance of augite and labradorite with psuedomorphic serpentine. The hornblende gabbro is mainly composed of hornblende, labradorite, andesine and minor amounts of quartz with or without augite. The diorite consists essentially of andesine, hornblende, biotite and quartz. The GDC is compositionally broad.,with a wide range of SiO2 (46-57 %) and pronounced enrichment in the LILE (Ba and Sr) relative to the HFSE (Nb,Y and Z). The GDC rocks exhibit petrological and geochemical characteristics of arc-related mafic magmas, derived possibly from partial melting of a mantle wedge above an early Pan-African subduction zone of the Neoproterozoic Shield. The tonalite and granodiorite have a calc alkaline affinity and show the geochemical signatures of I-type granitoids. The TGrS contains an amphibolite enclaves and foliated gabbroic xenoliths. Based on the field evidence and geochemical data, the GDC and TGrS are not related to asingle magma type through fractional crystallization. The precsence of microgranular amphibolite enclaves in the tonaliticrocks suggest against their generation by partial melting of a mantle-derived basaltic source. The tonalitic magma originated partial melting of an amphibolite lower crust by anatexix process at the volcanic arc regime during constnuction of the Arabian-Nubian Shield. Fractional crystalization of K-feldspar and biotite gave more developed granodiorite variety from the tonalitic magma. The gabbroic xenoliths are similar in the chemical composition to the investigated metagabbros. They are incompletely digested segments from the adjacent metagabbro rocks incorporated into the granitic magma through an assimilation process.