Exploration of Economic Minerals (Iron , Copper & Gold) using Geophysical Techniques in South Eastern Desert, Egypt; Pilot areas: Eastern part of Aswan and Wadi Allaqi. (original) (raw)
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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.
Mineral exploration, Mahd adh Dhahab District, Kingdom of Saudi Arabia
Open-File Report, 1978
Mahd adh Dhahab is the largest of numerous ancient gold mines scattered through the Precambrian shield of Saudi Arabia and the only one with recent production. During the period 1939-54, 765,768 fine ounces of gold and 1,002,029 ounces of silver were produced from the mines by the Saudi Arabian Mining Syndicate. Ore minerals at Mahd adh Dhahab include free gold and silver, tellurides, sphalerite, and chalcopyrite in and associated with a system of north-trending quartz veins and quartz veinlet stockworks. Pyrite is a common sulfide gangue mineral. Country rocks are a north dipping sequence of pyroclastic and transported pyroclastic rocks of the Hulayfah Group that are locally highly silicified and potassium-feldspathized. The prime target for this exploration program was a northtrending zone of quartz veins and breccias, faults, alteration, and metalization approximately 400 m wide and 1000 m long. The ancient and recent mine workings are located in the northern part of this zone. Although the quartz veins and alteration cut all lithologies, the major metalization is confined to the intersection of veins and agglomerate. Ten holes were diamond drilled to explore geochemical, geological, and geophysical targets in the area. 1 A significant new zone of metalization was discovered 700 m south of the ancient and recent mine workings and within the same major zone of quartz veins, alteration, and faults. Metalization in this southern mineralized zone is at the intersection of the quartz veins and a distinctive and highly altered agglomerate. The total zone of vein and agglomerate intercept is potentially metalized and comprises a block of ground 40 m thick and 400 m wide along the strike of the agglomerate and projected downdip 250 m. Tonnage of this block is 17.2 million tons. The explored zone, approximately 25 percent of the potentially metalized rock, has a potential resource of 1.1 million tons containing 27 g/t gold and 73 g/t silver.
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
NRIAG Journal of Astronomy and Geophysics, 2015
An integrated approach for geophysical, geological and mineralogical data was followed for Um Naggat area, Central Eastern Desert, Egypt, in order to delineate its mineralized zones. The albitized granites are well-defined on the Th-and U-channel images, by their anomalous shapes, reaching 150 ppm and 90 ppm respectively, beside low K content. Interpretations of the aeromagnetic maps delineated four regional structural trends oriented due NNW, NW, ENE and E-W directions. They are identified as strike-slip faults, which coincide well with field observations, where NW-trending faults cut and displace right laterally ENE-trending older ones. The interaction between these two strike-slip fault systems confining the albite granite is easily identified on the regional data presenting longer wavelength anomalies, implying deepseated structures. They could represent potential pathways for migration of enriched mineralized fluids. Geochemically, albite granites of peraluminous characteristics that had suffered extensive post-magmatic metasomatic reworking, resulted into development of (Zr, Hf, Nb, Ta, U, Th, Sn) and albite-enriched and greisenized granite body of about 600 m thick, and more than 3 km in strike length. The albite granite is characterized by sharp increase in average rare metal content: Zr (830 ppm), Hf (51 ppm), Nb (340 ppm), Ta (44 ppm), and U (90 ppm). Thorite, uranothorite, uraninite and zircon are the main uranium-bearing minerals of magmatic origin within the enclosing granite. However, with respect to Zr, Nb, and Ta, the albitized granite can be categorized as rare metal granite. The integration of airborne geophysical (magnetic and c-ray spectrometric), geological, geochemical and mineralogical data succeeded in assigning the albite granite of Um Naggat pluton as a mineralized zone. This zone is characterized by its high thorium and uranium of
Open Chemistry, 2022
Granite rocks are currently one of the foremost raw materials that can be used for various economic purposes such as ornamentation and building materials, because they do not possess radioactive concentrations and have good physical and mechanical properties. The granite rocks of north Um Taghir are connected to neoproterozoic rocks and integrated to the north Arabian-Nubian Shield (ANS), which lies in Northeast Africa. Inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence analysis, concurrent to some statistical analysis, have been carried for major oxides and some trace elements to extract much fundamental information by following certain mathematical methods. The exposed granite rock units in north Um Taghir are classified into four rock units represented by tonalite, granodiorite, monzogranite, and alkali-feldspar granite which are cut by different types of dikes. The magma of tonalite and granodiorite is low-to-medium K calc-alkaline affinity, while the m...
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.
Geology and Geochemistry of Al Fawakhir Mining District, Central Eastern Desert, Egypt
Al Fawakhir mining district lies in rugged Precambrian mountains of the Central Eastern Desert. It is almost exactly halfway between the Qift, Nile Valley and Quseir, Red Sea. It comprises two gold mines Al Fawakhir and Al Sid. The study area is located between latitudes 25º 57' 00˝ and 26º 00' 00˝ N and longitudes 33º 35' 00˝ and 33º33'30˝ E, covering about 120 km 2 . The mining processes in Al Fawakhir area started early during the Pharaonic time. The mine was working early in the last Century up to 1958. A geologic map to the scale of 1:40,000 was reconstructed based on Landsat enhanced thematic mapper (ETM + ) image and aerial photographs with comprehensive fieldwork during February 2007. Al Fawakhir district is mainly covered by basement peridotite rocks including the oldest rocks of metamorphic ophiolites (serpentinites) followed by metagabbros, granitic rocks, Dokhan Volcanics and the youngest doleritic dykes and quartz veins.