IOSR-JAGG   Volume-1 ~ Issue-3 ~ MAY-JUN-2013

Abstract: Placers are deposits of detrital materials in which valuable minerals have been concentrated by the oceanographic processes of waves and currents. These minerals are important economic source as they are useful in many industries for various purposes. India has rich placer mineral deposits at many locations along the long coastline of more than 6000 km. Contrary to the deposits of other countries, Indian deposits of placer are multi mineral in nature consisting of ilmenite, rutile, leucoxene, zircon, monazite, sillimanite garnet, kyanite, magnetite, casseterite, etc. In this study a pilot mining system of capacity 50 tons per hour operating at a maximum depth of 10 meters has been designed and developed to investigate the effect of different parameters, e.g., water jet velocity, distance from the nozzle tip to the mineral bed, time of operation, on the concentration of mineral sand in the discharge water. The solid concentration obtained is 10.6% (v/v) for a water jet velocity of 20 m/s. It has been observed that the solid concentration in the delivery line increases upto 14.8% with the change in the distance between the nozzle tip and the mineral bed.

Keywords: Placer mining; dredge output; mineral sand; translation velocity; soil shear strength

Abstract: A shallow sub-surface electrical resistivity survey (ERS) was carried out at Shaukat Khanum Memorial Cancer Hospital and Research Centre (SKMCH&RC), Peshawar, Pakistan. The main objective of the survey was to capture a clearer picture of the near-surface geologic sequence to study geophysically the attributes (depth & thickness) indirectly of particular horizon lying within five meters beneath the earth's surface for an engineering study supported by actual values (bore hole data and measured values at field). Vertical electrical sounding (VES) data was acquired using Shlumberger configuration with maximum current electrodes separation (ABmax) of 16 feet in order to resolve clearly the target geoelectric layer in the very immediate vicinity of exposed geologic cross section of an excavation designed for construction of basement of massive civil structure (SKMCH&RC). Geophysical electrical resistivity technique mapped the particular layer's depth and associated thickness having values of 4.42m and 2.87 m respectively. VES results (depth & thickness) were validated by the actual field values obtained from measuring tape as well as borehole information of the studied site. Comparison showed that geophysical electrical survey technique imaged the target geologic layer accurately with uncertainty of 0.3 feet only. This study deduced the presence of inhomogeneous near-surface media covering the depth range (< 1 – 5m) where building foundations are usually placed. The error of 0.3 feet in estimation of both parameters guarantees the successful applicability of said geophysical tool in near-surface engineering geophysical investigations with high accuracy in non-destructive, cost effective and faster way. One of the objectives of the study was to introduce ERS technique and encourage utilization of other geophysical tools for such sort of engineering works at Pakistan to avoid any geotechnical hazard.

Keywords: Depth & thickness, Electrical resistivity survey (ERS), Foundation bed, geotechnical hazard, Shallow sub-surface, Vertical electrical sounding (VES), Khyber Pakhtunkhwa, Pakistan.

Abstract: People living in Ibadan, Southwestern Nigeria have started shifting their focus on construction of buildings towards villages that are close to the metropolis. It is therefore imperative to carry out this research in order to recommend the types of structures to be erected at Adumasun area, Oniye, Southwestern Nigeria when the time comes in order to avoid catastrophic failure that might have happened thereafter. The aim of this research is to carry out vertical electrical sounding geophysical survey at Adumasun area, Oniye, Southwestern Nigeria with a view to determining the fracture distribution within the study area. The study area is located between latitude 070 37′ 55.37″ to 070 38′ 00″ North and longitude 0030 11′ 10.2″ to 0030 11′ 16.8″ East. Schlumberger electrode array was employed for the study using R 50 Resistivity meter for the data acquisition. The geoelectric survey comprised of ten depth soundings, with maximum current electrode spacing (AB) of 200m. 40% of the modeled curves are A-type, 50% are H-type, and 10% are KH-type. The geoelectric sections obtained from the sounding curves revealed 3-layer and 4-layer earth models respectively. The models showed that the subsurface layers were categorized into the topsoil, the second layer, and the third layer (where it is present). One-third of the study area showed fresh bedrock while two-third showed fractured bedrock. Areas underlying with fresh bedrock and thin overburden thickness are recommended for the construction of high-rise buildings while areas with fractured basement and thick overburden thickness are recommended for the construction of low-rise buildings. It is concluded that the study area is averagely competent for the construction of high-rise buildings and low-rise buildings depending on where individual builders are located. Keywords:- Fractured Basement, Fresh Bedrock, Geoelectric Section, Overburden Thickness, Precambrian Basement Complex, Vertical Electrical Sounding.

Abstract: The Maastrichtian Mamu and Nsukka Formations in the Anambra Basin (SE Nigeria) consists of a cyclic succession of coals, carbonaceous shales, silty shales and siltstones interpreted as deltaic deposits. Sub-bituminous coals within these formations are distributed in a north-south trending belt from Enugu-Onyeama to Okaba in the north of the basin. Coals from these formations have been characterized by petrological and geochemical techniques. The aims of this study were to assess the quality of its organic matter, evaluate its thermal evolution and highlight its potential as a source rock. The total organic carbon (TOC) (67.21wt%) of the coal constitutes that of a good source rock with gas-prone kerogen indicated by Rock-Eval S2/S3 (21.0). The high oxygen index (OI) (15.72 mgCO2g-1TOC) and pr/ph (7.93) suggest deposition in a shallow marine environment. Maceral analyses showed that the coals are dominated by huminite with lesser amounts of liptinite and inertinite. Despite high liptinite contents in parts of the coals, the n-alkane distribution dominated by n-C24 – n-C31, an HI versus Tmax diagram and atomic H/C ratios of 0.80–0.90 and O/C ratios of 0.11–0.17 classify the organic matter in the coals as Type III kerogen. Vitrinite reflectance values (%Rr ) of 0.44 to 0.59% and Tmax values between 414 and 432oC indicate that the coals are thermally immature to marginally mature with respect to petroleum generation. Hydrogen Index (HI) values for the studied samples range from 183.09 to 344.53 mg HC/g TOC and S1+S2 yields range from 120.5 to 242.04 mg HC/g rock, suggesting that the coals have gas and oil-generating potential. This thermal evolution is thought to account for its current hydrogen index (250.24 mgHCg-1TOC). Generated petroleum may not have reached the threshold for hydrocarbon expulsion but a review of petroleum system elements in the basin will stimulate high prospects in the Anambra basin.

Key words: Organic matter, Kerogen type, Maturity, sub-bituminous coals, source rock, oil generation.

Abstract: Overpressure prediction in the North West of Niger Delta, using porosity data was carried out to safeguard hazards associated with drilling accident due to blowout. In the absence of seismic data to predict overpressure, porosity-dependent parameters and acoustic impedance could be used to predict the tops of overpressured zones in the area of study in the Niger Delta. Overpressure prediction is vital for safe and economic drilling. Composite logs were used to obtain the required data by digitizing the logs and deduction using the appropriate relationships. The findings from the study show that porosity decreases with depth, with overpressure zone detected at about 3500m depth due to porosity deviation from normal trend. Pressure gradient in the upper normal pressure of the field is determined to be 0.989 psi/ft, this implies that within the established normal pressure gradient of 0.71 - 1.1 psi/ft in the Niger Delta. Formation overpressure gradient is determined to be 1.40 psi/ft. The overpressure zone coincides within the high shale-to-sand ratio of Agbada under compacted Formation. The identification of the tops of overpressure zones in any formation penetrated by a borehole enhances the use of normal drilling techniques of the borehole. This also reduces the cost of drilling the entire well as the special drilling technique will be applied only in the overpressure zones. This finding can aid in the prevention of drilling accident and resource wastage in exploration activities.

Key words: Porosity, acoustic velocity, compaction, lithology, overpressure, sedimentary basin.

Abstract: Water is found covering one-third part of the earth in various forms.In India total quantity of water is 1900,000 x 1016 m3. Rajasthan has paucity of water resource due to low and erratic rainfall. In Jhalawar district, Manoharthana block is one of the areas which have been facing the problem of less availability of potable water quantity-wise and quality-wise higher nitrate concentration at few locations is noticed.However,it is not posing serious health hazards in this area. The ground water is only main source of fresh water supply.

Key words: Groundwater, hydrogeology and hydrochemistry, etc.

Abstract: A 10cmx10cmx10cm galena and associate albite from an aplitic albitite vein cutting across a skarn rock, near Garigaipalli village, in the carbonatite complex of Tiruppattur, Tamil Nadu, India were collected and studied for systematic variations in chemical composition from the central portions to outer peripheries. The compositions of albite grains show a linear trend of crystallizations from Ne81Ks0Qz29 to Ne48Ks0Qz52. Co-variation diagrams of Pb-S, Na2O-PbO, (Ca+Na+K)-(Si+Ti+Al+3) and (Ca+Na+K)-S show sequences of crystallizations of albite and galena with miscibility gaps between them. These components in albite and galena negatively vary in opposite directions in these diagrams. Galena mineralization might have been initiated just after immiscible separation of sulphide phases from silicate phases but prior to initial crystallization of albite Tf3 at higher temperature. During the course of crystal growths under the influence of crystal field stabilization forces, mixed pattern of arrangement of individual early formed and late formed microcrystals together was taken place. Incorporations of volatiles into the voids of subsolidus crystal originated pits of galena and albite, play critical role on the increase of viscosity of residual magma and it depends upon the rate of cooling. Progressive depletion of Al, Na, K and S contents in sequentially crystallized albite and galena indicates that residual magma was enriched with these constituents and Si. After this co-magmatic differentiation the residual magma fractionated into silica oversaturated granitic magma as end product.

Keywords: Albite, Galena, Albitite, Carbonatite complex of Tiruppattur, Crystal field stabilization, Crystal imperfections

Abstract: When only direct-waves are inadequate, different combinations of both direct- and refracted-waves are used to determine hypocentral parameters of local earthquakes. Compared with only direct-waves, the addition of refracted-waves tends to increase errors of hypocentral parameters. This is true especially when the velocity structure of the region under investigation is not known. We use an accurate and fast algorithm to determine the hypocentral parameters based on an optimum 1-D velocity model yielding a minimum misfit error in media with multiple refracted-waves as first arrivals. Using the algorithm, we relocated earthquakes that occurred beneath the Parkfield region of California during the period between January 2000 and December 2000. The shallow part of the velocity model used in the study area has high velocity contrast among layers. Therefore, refracted-waves are recorded as first-arrival phases at most stations around the region for events of shallow focal depths (less than 3km). The study area covers the transition between the creeping segment of San Andreas Fault (SAF) to the northwest and the locked segment to the southeast. Accuracy test for the algorithm was conducted using some reference models. We compare the inverted hypocentral parameters with those determined by previous studies using HYPOINVERSE and the HypoDD. The epicentral distributions of the three methods show a close relationship with the regional fault distribution. However, compared to HypoDD, the epicentral distribution of HYPOINVERSE shifted slightly along the fault lines while the epicentral distribution of VELHYPO moved further in the same direction. The result of VELHYPO suggests that the dip of San Andreas Fault is 6-10oSW while the results of HPOINVERSE and HypoDD suggest that the dip of San Andreas Fault is nearly vertical and/or 3-7oNE. This study supports the result of previous studies that San Andreas Fault is non-vertical but dips to southwest as part of a possible propeller-shape.

Keywords: Direct waves and Refracted-waves, Algorithm, Parkfield, Relocate Earthquakes, San Andreas Fault, SW dip, support propeller-shape.

Abstract: The interest in unconventional oil resources such as tar sands and oil shale is known as great economic importance by the governments and industries have encouraged researches in the development of these resources. Vast tar sands resources have not been adequately explored and exploited by the Nigeria Government except for accumulation of oil, natural gas and other minerals but bitumen has proven to be of great value. This motivated this study to map the ttar sands deposit at Imeri in Ijebu-Imushin within the Ijebu-East Local government area in Ogun State using seismic refraction survey. A seismic refraction survey at Imeri, Ijebu-Imushin of Ijebu-east carried out using ABEM seismograph Terraloc Mark 6 Version 2.22. Thirteen (13) traverse were taken along five profiles in which both forward and backward shooting were measured to cover a spread of 72m in each of the traverse. Pickwin software was adopted to analyze the results obtained in order to give information on first arrival time and velocity of the first and second layers. A model of the earth structure was achieved by the used of ploterrafa (refraction) software and interpretation to determine the thickness of the first layer from the processed data based on the known geology of the area. The velocities of the first layers of five profiles ranges from (0.75-1.30)km/s and the second layers velocities ranges were from (1.31-2.51)km/s. The presence of tar sands was observed in traverse 6, 7, 8, 9&12, with velocity values (1.12-1.44)km/s, (1.12-1.86)km/s and (1.10-1.47)km/s respectively. The depth of the first layer of the above profile ranges from (5.00-7.10)m. traverses 1-5, 10,11 and 13 shows the presence of clayed sand, sand, sand stone clay and sand with water saturation respectively was observed. The information provided by the analysis and interpretation of the first arrival time and velocities of the first and second layers concise with geologic trends of the rock type in the study area. It was observed that the velocities of the first and second layers were related to the velocities of different earth materials and their depth to the surface. Keywords: ABEM seismograph Terraloc Mark 6 Version 2.22, first arrival time, Pickwin, ploterrafa (refraction) software.

Abstract: The northwest Indian shield is covered by the Neoproterozoic (750 Ma) Malani magmatic province, which covers a sizable area (around 50,000 km2). It is mostly composed of felsic (rhyolitic) lava flows and granitic plutons, with mafic lavas and felsic and mafic dykes acting as supporting structural elements. Some researchers have referred to the Malani province as a mantle plume since it is a significant, intraplate, anorogenic felsic event. But according to geological data, the parallel crustal fissures that resulted from extensional tectonics are where the Malani volcanism took place. An intra-cratonic rift scenario is suggested, and a deep mantle plume is neither required nor feasible.

Keywords- Malani, Granitic plutons, Mantle plume, etc