Geophysical Exploration of the Gold Deposits in Wadi Allaqi Area-Egypt (original) (raw)
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Journal of Geophysics and Engineering, 2009
The occurrences of gold and disseminated sulfides lie as a part of the shearing fault zone that extends from the north to the south of the study area for a length of about 25 km. The gold and disseminated sulfides are located on the alteration shear zone which is composed of quartz-feldspathic highly ferruginated rock (gossans) occupying the eastern and central parts of the area. Mineralogical analyses that were done on bedrock samples of the oxidized and alteration zones indicated that there are two anomalous spots of gold contents; the first one has values ranging from 5 to 49 g ton-1 and the second anomaly has values ranging from 150 to 502.5 g ton-1. Magnetic, self-potential, resistivity and induced polarization surveys were applied at Wadi El Beida area to delineate the mineral ore deposits in terms of depths and extensions through the structural shearing zone. The quantitative interpretation of magnetic data was carried out by using two techniques; the first is 3D magnetic inversion using Euler deconvolution and the second is magnetic models using the MAGMOD program. The results of the magnetic interpretation indicated that the depths of such ore deposits range from 35.9 to 52.7 m and the half width ranged from 27.2 to 87.8 m. The SP contour maps show negative anomalies with ranges from −70 to 20 mV. Most of these anomalies occupy the shear, silicified zones, alterations and rock contacts. The SP anomalies are correlated with other geophysical ones and also with the geological sources. Quantitative interpretation was done on the selected anomalies along the coded lines on the normal SP contour map. The quantitative interpretation of self-potential anomalies (SP) was carried out using two techniques; the first is a new algorithm constructed by Monteiro Santos (2009) using particle swarm optimization (PSO) and the second is the code constructed by Caglar (2000). The depths range from 20 to 60 m. The gradient resistivity survey was carried out simultaneously with IP measurements. The low-resistivity zones coincide with the altered and sheared acidic meta-volcanics. The quantitative interpretation technique determined the conductive bodies' parameters using the Schulz method (1985) where the depth to the top of the ore body ranged from 21 to 62 m while the maximum width ranged from 52 to 165 m. The induced polarization-chargeability data were measured in the time domain. The positive anomalies on the IP-chargeability map coincide with the sites of alterations, shears and contact zones. Four dipole-dipole sections were carried out along the anomalous sites selected from the constructed maps in the study area and were inverted using the RES2DINV program. The results of resistivity and IP inversions indicated that there are conductive and chargeable
proceedings CAJG-Nov2018
Introduction The magnetite and hematite mines are located in the Eastern Desert in Abu Subera area, of about 35 km far from Aswan city and is known as volcano-tectonic area. It is one of the biggest arc sedimentary rock units in the Precambrian sequence. It was strongly influenced by multiple stage of deformation resulting in folding and faulting. The ironstone deposits of the area are of bedded oolitic type and occur in the form of two bands inter-bedded with ferruginous sandstone and clay capping Precambrian rocks. The thickness of the bands varies from 0.5 to 3.5 m. The magnetic measurements are condensing along the Six mines where the iron ore bodies are concentered. Seven geoelectrical profiles were measurements by using dipole-dipole configuration of electrode spacing 5, 10 and 15 m of lengths ranging from 160-240 m. The results indicate that the ore deposits refer to low resistive zones, high chargeability with moderate to high magnetic anomalies.
Magnetic Signature of Gold Deposits: Example from Um Garayat Region, South Eastern Desert, Egypt
Pure and Applied Geophysics
Magnetic methods of exploration have proved to be efficient and have potential in the gold mineralization industry. New magnetic processing technologies aid in improving the process of interpretation and gold opportunity identification. In this work, we show the possible application of combined digital magnetic filters to explore new gold mineralization localities with application to a well-known Au mineralization zone. Um Garayat (UG) region, southeastern desert, Egypt, is an ancient example of a potential area for gold mining. Modern analysis showed that other types of mineral concentrations are present. So, exploiting the magnetic signature of the area for future investment is of great interest. The old UG gold mine is characterized by volcanic and tectonic features such as faulting and folding that affect the arc sedimentary rock sequence of repeated deformation stages. A thorough geophysical effort has been carried out around the old gold mine in the UG area to explore the exte...
Radiospectrometric and magnetic signatures of a gold mine in Egypt
Journal of Applied Geophysics, 2009
The purpose of this research is to study the signatures of a gold mine (Um Salim), located in the Eastern Desert of Egypt, using aeroradiospectrometric and aeromagnetic data. To achieve this goal, reduction-to-pole (RTP), high-pass filtering and analytical signal techniques were applied to the aeromagnetic data. Besides, interpretation of the total-count (TC) radiometric map, the three radioelements (K, eU and eTh) maps and the ternary radioelement composite image were carried out. Moreover, a two-dimensional trend analysis for the structural lineaments as traced from the geologic, total-count radiometric and reduced-to-pole magnetic maps was conducted to define the relationship which might exist between location of the gold mine, lithologies and major structures of the area under consideration. The study revealed that the known gold mine is associated with a high positive magnetic anomaly that trends in the NE direction and a high-amplitude analytic signal. The Um Salim gold mine is associated with very low aeroradiospectrometric levels on the four maps (TC, K, eU and eTh). The location of the gold mine is controlled by the intersection of both NW and NE trends. There are other particular radiospectrometric ratio signatures for gold deposits (eU/eTh, eU/K and eTh/K). Ternary radioelement maps can discriminate also alteration zones in various degrees that correlate with the gold mine. These zones can be used as a diagnostic exploration guide for various types of non-radioactive mineral deposits (e.g., copper and gold). Four major tectonic trends were identified that have the following directions: NE, NW, N-S and WNW.
Ground Electromagnetic and Electric Studies for Um Salim Gold Mine, Central Eastern Desert, Egypt
Journal of Geoscience and Environment Protection, 2021
Horizontal Loop Electromagnetic (HLEM) and Induced Polarization (IP) methods have been carried out within Um Salim gold mine area. The study area reveals special importance, as it comprises rock units, which show some indication of the presence of various mineralization. The result of HLEM has shown significant and well-defined conductive zones are recorded along with the four used frequencies (110 Hz, 440 Hz, 1760 Hz, and 7040 Hz) at the station 2,782,900 and station 2,782,880 of two (HLEM) profiles (596,050 N & 596,240 N) respectively, that may reflect the sources of the conductive bodies are situated at shallow depths continued to considerable depths. The result of IP exhibits a strong anomalous zone centered at stations 140 and 240, with chargeability values ranging (37 to more than 120 mV/V) on chargeability model section, and corresponding to high resistivity on resistivity model section which may reflect considerable surface and subsurface disseminated mineralization. Through the integration between HLEM and IP a core drilling is recommended at station 140 on IP profile which coincides with station 2,782,850 on HLEM profile (596,240 N) to a depth of concerning 100m take a look at the thickness, depth, and grade of mineralization.
Arabiam Geoscience Journal, 2021
The mines of magnetite and hematite occupy some areas of the Eastern Desert at Wadi Abu Subeira, northeast of Aswan city which is a volcanic and tectonic area. It is one of the largest arc sedimentary rock sequence affected by faulting and folding due to repeated stages of deformation. The iron deposits in this area are of oolitic type and exist in two bands inter-bedded with ferruginous sandstone and clay layers. The thickness of the bands varies from 0.5 to 3.5 m. Detailed geophysical work has been carried out on the promise site of Abu Subeira to identify the lateral and vertical distribution of the iron-ore deposits at this area. Many geophysical methods were applied in this study including Land Magnetic Survey, Electrical Resistivity Imaging (ERI), Induced Polarization (IP), and Time-Domain Electromagnetic (TDEM). Besides, rock samples from the iron ores were collected for chemical analysis. The X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques were applied for estimation of iron concentration (Fe %) and other minerals' contents in the rock samples. The field data sets were measured along the iron ore bodies of Wadi Abu Subeira and were processed and analyzed by the proper software packages. The areas with iron ore deposits were expressed in the geophysical results by low resistivity, high chargeability, and moderate to high magnetic anomalies. Integrated interpretation of the obtained results revealed that the ore deposits exist in the form of lenses with variable thickness ranging from few meters to about 30-m thick. The mineral occurrences in Abu Subeira are managed by the major faults and the hydrothermal fluids flowing along these faults.
Pure and Applied Geophysics
Gold mineralisation is spatially and chronologically correlated with fault/shear zones in many of the world-class gold mines. Hence, the indirect exploration for Au mineralisation is linked with shearing and complex structures in many areas. Hence, in general, the need for a rapid, effective and new technology for gold exploration that reflects the structure set-up, shear zones, faults and related structural elements is crucial in the gold industry. In this article, we present an example of an integrated approach to gold exploration in the Fawakheir-Attala gold mining prospect in the eastern desert of Egypt. Remote sensing is used to test for rock differentiation; intensive field geological investigations were conducted along several traverses. Petrographic and geochemical analysis of selected samples confirmed Au content in some localities. Moreover, magnetic methods are used extensively (either aeromagnetic or measured land profiles) to investigate the magnetic signature of the di...
STDF-Project, 2018
Mineral wealth sector is one of the most important sectors accorded by the State attention due to its directly effects to the national income development of the country, as it provides basic development the mineral ores required for all industrial, agricultural and construction purposes. In fact, the human ability and skill in the use of the natural resources serve as a scale to measure the extent of scientific and technology progress and civilization in the country. The presence of minerals can often be inferred by the presence of other minerals in the surrounding rock. The geologist knows that certain qualities of special nature of economic minerals are haunted by the other minerals, and the existence of any of them in ore bodies is definitive guide to the presence of the other minerals. For example, we find that the metal gold and silver may go hand in hand with the quartz; copper ores are associated with lead and zinc. The role of the geologist who is looking for a metal such as iron is also looking for the accompanying minerals such as sulphides, manganese and phosphate. Nowadays, the government is keen on the development of the Eastern Desert and especially its southern part, such as Aswan-Allaqi and Aswan-Beranice-Roads. The precise evaluations of the mineral resources and earth’s treasures, surface geology and geomorphology are the main target to redistribute the population and to construct the new desert urban. Therefore, this project involves the geological, geophysical and geochemical technical aspects to base a procedure to distinguish the mineral resources distribution for making sustainable development of the areas. So, geophysical studies will be carried out in and around selected areas to determine the location of the economic elements associated with granite rocks. It becomes necessary to make detail assessment of mineral resources, determine their depth and lateral extension, and to find out the most suitable places to extract the host rock and the required minerals.
Localization of probable gold mineralization zones in a selected part of the central Eastern Desert of Egypt has been executed by mapping lithology, structures and hydrothermal alteration zones. In this regard, both aeromagnetic and aeroradiometric data have been utilized in the analysis; by making use of some enhancement techniques such as first vertical derivative, analytic signal and both Center for Exploration Targeting (CET) grid and porphyry. Also, ratio and ternary radiometric maps have been launched to aid in the interpretation process. The results indicated that the study area is dominant by NW, NNW, NNE, WNW, NE, E-W and N-S structural directions. The NW-SE was the most important one and considered as the preferred orientation of ore deposits. Favorable regions of ore deposits were mapped and correlated well with known gold occurrences in the study area beside predicting new zones of mineralization. Analysis of aeroradiometric maps facilitates the correlation and delineation of lithological units based on the concentration of radioelements and ratios. Also, A number of hydrothermal alteration zones were mapped within younger granite, Hammamat felsites and Metasediments. Finally, A composite map consists of geology, structures and hydrothermal altered zones was generated using ArcGIS. Eight known locations of gold mineralization were investigated on this map and also new sites were suggested to be favorable locations for mineralization emplacement.
Magnetic and Geoelectric characteristics of East Rosetta sand placer deposits, Egypt
The black-sand beach deposits are known for many decades of years as a source of strategic and economic heavy minerals. The present study deals with the analysis and interpretation of the results of field geophysical survey and laboratory geophysical measurements conducted on Koam Mashaal area, east Rosetta Mediterranean Sea coast Egypt. These include field measurements of total magneticfield intensity and laboratory geoelectric measurements including resistivity and chargeability. The analysis and interpretation of the field and laboratory magnetic and geoelectric maps demonstrated that the studied black-sand beach deposits of Koam Mashaal area can be subdivided according to their geophysical response into three main zones striking nearly parallel to the shoreline of the Mediterranean Sea. The deep-seated magnetic response was interpreted at an average depth of 239.6 m. Meanwhile, the near-surface magnetic responses were interpreted at average depths of 9.1, 57.9 and 81.8 m, respectively.