الفهرس 
REMOTE SENSING - GIS MAPPING AND MINERALIZATIONOnly 14 pages are availabe for public view
 |  | from | 262 |  |  |
| | | from | 262 | | |
Abstract
The government of Egypt has recently paid more attention to the developments of mineral resources in the Egyptian deserts. It has launched the mega project of “The Golden Triangle” that is considered as the second largest developmental project run by the government. The present study focuses on the concentrations of mineral deposits around wadi Ranga area, Hamata region, south Eastern Desert that is bounded by latitudes 24° 16` 30” and 24° 20` 30” N, and longitudes 35° 08` and 35° 14` E. It is located about 87 km south of Marsa Alam and covers an area of about 140 km2. It belongs to the northwestern extension of the Arabo-Nubian Shield as an integral part of the Pan-African Orogenic belt. Recent reconnaissance geologic work of the area by the Egyptian Mineral Resources General Authority (EMRA) has shown its importance for national mineral resources development. The investigated area has been subjected to detailed geological and geophysical studies in order to identify and characterize its geology, alteration zones, mineralization and fracture systems in an attempt to define lateral and vertical extensions of possible economic mineralized zones and assess their genesis. Remote sensing techniques were applied to classify the Landsat 8 OLI and ASTER data such as false color composite images production, band ratios, principal component analysis (PCA) and image classifications to detect rock units and mineral occurrences and produce an improved geological map for the study area. Image processing has also helped in locating the alteration zones and identification of mineral occurrences in two selected areas for further geophysical surveys. Lineaments and structural elements were extracted automatically from the digital elevation model (DEM) of SRTM with 30 m resolution. This DEM was used to auto-delineate the drainage network and topographical derivatives (such as slope, shaded relief etc.). The main trends of the extracted lineaments of hillshade are NW-SE, NE-SW, NNE-SSW and N-S. The outcomes of the gravity survey offered a clear picture for the edges and geological boundaries in the study area. This, in turn, helped to select economically promising areas to perform detailed geophysical investigations to further explore their lithology, structure and mineral deposits. Accordingly, two sites were chosen to perform detailed geophysical survey using magnetic, self-potential, electrical resistivity, electromagnetic (VLF), and chargeability methods in an integrated fashion. These targeted sites are selected to perform detailed geophysical surveys are the one at wadi El-Homer and the other one lies to the north of wadi Dendekan. Total intensity magnetic data interpretation provided a lucid picture of the basement features and a good overall picture of the basement faults or shear zones affected the area and may have influenced Precambrian rocks and controlled the distribution of mineralization locations. The lineaments are clearly displayed in the first vertical derivative, source edge detection and Euler deconvolution of the magnetic map. Some of these lineament directions are in match with those obtained from the geological maps and remote sensing with NW-SE, NE-SW and E-W directions. The shallow and deep magnetic depths of analytical signal (AS) and source parameter image (SPI) range between 0 m and 50 m. VLF data were collected along six profiles in the study area with the resulted sections along these profiles interpreted in conjunction with geological and magnetic results. They show conductive bodies and contacts (fault or fracture) with a good compatibility between VLF profiles and 2-D resistivity and chargeability profiles. The SP survey indicates the presence of relatively low to medium anomalies. Examination of SP responses found along four profiles reveals that the average depth (h) to the center of the selected anomaly ranges Chapter Eight between 10 m and 64m. The average half-width of the bodies ranges between 13 m and 78.5m while the polarization angle (θ) varies from 8º to 51º. The gradient resistivity maps and IP-chargeability maps reflect the same trends obtained from low resistivity and high chargeability results in most maps. The depth of the ore body from the gradient resistivity profiles ranges from 8 to 70 m, while the maximum width ranges from 28 to 181 m. Results of the geophysical surveys indicate the possibility of presence of two types of mineralization; disseminated metallic mineralization and concentrated metallic mineralization at depth of about 45 m. This result confirms and validate the recorded metallic mineralization (such as ferric oxides, gossan, alteration zones. etc.) identified by the remote sensing analysis.