Ore Deposits in the Arabian-Nubian Shield

The Arabian-Nubian Shield (ANS) is the largest tract of juvenile continental crust of Neoproterozoic Age on Earth. It represents the northern sector of the East African Orogen (EAO) and extends over 3500 km north–south and more than 1500 east–west at its widest and occupies an area of about (~1.9 million km2). The shield was formed due to the collision between East and West Gondwana during the closure of the Mozambique Ocean at the Neoproterozoic Pan-African orogenic cycle (ca. 900–550 Ma) and was stabilized as a craton at Early Cambrian times and exhumed in the Neogene as a result of Red Sea rifting and flank uplift. ANS is noteworthy for having a great diversity of geology and this diversity led to a significant variety of mineral deposits ranging in size and volume from occurrences of limited potential to deposits large enough to sustain profitable exploitation. Therefore, it is not surprising that the ANS has been the source of gold, copper, and lead since ancient times. Currently, operating mines in the ANS produce gold from: (1) orogenic gold deposits like As Suq gold prospect in Saudi Arabia; (2) weathered cap above Volcanic Massive Sulfide (VMS) deposit in Ariab district in Sudan, which is considered as one of the largest VMS deposits in the world, and in the recent time, Sudan plays a significant role in the global production of gold, and it is one of the 20 countries producing 38% of world gold production. By the same token, Bisha VMS-oxide gold deposit occurring in the western Nakfa terrane in western Eritrea is a world class gold-bearing VMS deposit; (3) cogenetic VMS-epithermal gold deposits like Al Amar prospect at Saudi Arabia that currently produces gold doré as well as zinc concentrates; (4) volcanic-hosted epithermal gold and polymetallic deposits like Mahd Ad’Dhahab in Saudi Arabia, where the Carbon-In-Leach plant produces gold doré and zinc concentrate. Mahd Ad Dhahab mine produced 31,227 oz in 2018, which constituted 7% of the total gold ounces sold in that year, and the mine produced approximately 21,000 oz of gold in 2019; (5) intrusion-related gold deposits like Ad Duwayhi deposit in Saudi Arabia and Sukari deposit in Egypt. The former produced 274,519 oz of gold which constituted 66% of Saudi Arabia gold production in 2018, and currently is considered as Saudi Arabia’s largest producer, with approximately 263,000 oz of gold produced in 2019. Sukari deposit in the Eastern Desert of Egypt is the first large-scale modern gold mine in Egypt and produced in 2018, 472, 418 oz of gold, and in 2019, the production was 480,528 oz of gold, whereas 125, 090 oz of gold were produced in quarter one of the year 2020. Some VMS deposits are mined principally for base metals as the main product such as the Jabal Sayid copper deposit in Saudi Arabia which produced in 2019, approximately 132,400 lb of copper. Copper and gold are soon to be mined in the near future from the recently recognized Jebel Ohier porphyry Cu–Au deposit in Sudan, where additional 80 diamond and 30 RC drill holes carried out recently in the area, has been upgraded the mineral resources of Jebel Ohier in 2019 to become indicated and inferred resources of 593 Mt at 0.33% Cu and 0.05 ppm Au, for 1.953 Mt of contained Cu and 933,600 oz of Au at 0.15% Cu cut off. Tantalum is mined from Kenticha (Ethiopia), the largest known pegmatitic rare-metal occurrence in the ANS where indicated reserve is ~17 Mt of ore grading 150 g/t Ta2O5. Abu Dabbab and Nuweibi Nb–Ta deposits in the Eastern Desert of Egypt have not yet started production; however, it is expected that these two deposits would rank among the world’s leading producers of tantalum for many years to come. In addition, sub-economic targets occur in the ANS. Examples include: (1) Abu Ghalaga ilmenite ore deposit (40 million tons ore reserves, with an average grade of TiO2 as 35%); (2) titano-magnetite ores at Aqab EL Negum and Gabel Wadhait areas in the south Eastern Desert of Egypt (2930 and 1,839,713 metric tons geological resources with an average grade of TiO2 as 35%, respectively). In the same way, the layered Lakathah complex in Saudi Arabia contains significant resources of low-grade titaniferous rock averaging about 6.2% TiO2 in mineralized zone containing about 175 Mt per 100 m depth; (3) Cu–Ni–Co sulfide deposits in the Eastern Desert of Egypt like Abu Swayel (probable ore reserve is 85,000 tons of ore with the average content of 2.85% copper and 1.53% nickel as well as minor amounts of Co), Gabbro Akarem Cu–Ni deposit (ore reserves are 700,000 tons containing 0.95 wt% combined Ni and Cu), and the Genina Gharbia Cu–Ni sulfide ore (270,000 tons); (4) Precambrian iron ore deposits in the Eastern Desert of Egypt and in Sudan; and (5) chromite ore deposits occurring in the Ingassana Hills in the Blue Nile State in Sudan (reserve has been estimated at 1 Mt @ 58.57% Cr2O3, 3.04% Fe2O3, and 11.42% Al2O3). Hypothetical targets in the ANS include some deposits and occurrences connected with the Late Cryogenian–Ediacaran felsic plutons and hold tin, tungsten, molybdenum, fluorine, beryllium and uranium mineralizations that are currently occur in quantities too low in grade, or too small in size to repay mining. In addition, gold mineralization associated with Algoma-type Banded Iron Formation (BIF) is recorded in six localities in the Eastern Desert of Egypt, and reconnaissance surveys carried out showed reasonable grades of gold in Um Nar, Wadi El Dabbah and Gabal El Hadid localities.