Prospecting for new gold-bearing alteration zones at El-Hoteib area, South Eastern Desert, Egypt, using remote sensing data analysis

• Lithological mapping using band ratios prepared from the average spectra of the different rock unites is successful.
• Fieldwork, mineralogical and geochemical analyses, revealed the presence of characteristic ore mineral assemblages.
• The simplified Crósta technique validated the presence of the mineralized areas to occur along fault zones.
• Structural studies revealed that gold precipitation is controlled by WNW-–ESE to NW-–SE dextral strike-slip shear zone.
• Mineralogical studies revealed that the area enriched with zinc carbonates (smithsonite) and zinc silicates (hemimorphite).Gold content is estimated to range from 0.3 to 6.4 g/t in the altered rock and 0.3 to 0.9 g/t in the associated quartz veins.

Gold has been mined in the Eastern Desert of Egypt since the time of the Pharaohs, yet the geological settings of such ore deposits and how certain deposits link to each other are still not fully understood. The application of remote sensing in identifying variations in surface mineralogy, structural elements, and lithologic contacts can help in identifying such relations. Signatures collected from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data is used to map the hydrothermal alteration zones of El-Hoteib area, which is located to the northwest of Iqat and Al-Fawi gold mines and prospective for gold. SPOT5 data is used to highlight the preliminary structural lineaments in the area. Band ratioing and principal component analysis techniques are used to refine the different lithologic units in the area. A simplified Crósta technique has been applied to the ASTER data to identify both the location and spatial extent of the different alteration zones around the Iqat-Al-Fawi area. A new gold-bearing alteration zone is detected to the north of Gabal El-Hoteib. It is structurally controlled by E–W to WNW–ESE structures with evidence of reactivation of such trends during the Quaternary. Ore microscopy examination, induced coupled plasma mass spectrometry and fire assay analysis revealed the presence of gold associated with excess zinc in most samples.