New Neo-Proterozoic Gold-Copper Gossan Discovery, EL Idaira Area, Red Sea Hills – Sudan

Abstract

The study area is a part of the Nubian segment of the Arabian Nubian Shield (ANS) exposed in the Red Sea Hills of NE Sudan in which a new gold-copper gossanic occurrences is discovered  southwest of  Jebel Grain in AL Adara area.The ANS is dominated by low-grade juvenile arc terranes accreted to the Nile Craton to the west during the Neo-Proterozoic era  (Greenwood et al., 1976; Vail, 1983). Volcanic-hosted massive sulphide (VMS) mineralization in the southwestern part of J. Grain located at EL Adara area was associated with hydrothermal episodes during breaks in a submarine  intermediate to felsic eruptions activity within an Upper Proterozoic (900 Ma) tholeiitic to Calc-alkaline arc setting.Gold mineralization is found in the gossanic system (2.7 ppm), indicators for gossanic bodies   are iron oxides, (Pyrite- FeS2, Chalcopyrite- CuFeS2). Gossan rock contains cavities left by leached out sulfide minerals. Boxwork masses are common . Average grade of CuO is (0.05 %), and 2.7 g/t gold.Average grade of 21 Samples for Iron Oxides is (11% Fe2O3), 38.5 ppm Zn, 0.02 % Pb, 0.019% Sb, 0.082% As. Arsenopyrite, malachite, Jarosite, silica-baritic Masses  are the main  mineral constituents in the  enriched supergene oxidation profile. The massive sulphites were associated  accessory calcite grains. Dacite occur by  rock as low outcrops aligned along N-S shearing. Turbidities are exposed  around the gossanic area. The main rock units hosting gossan are  Tuffs, sheared and massive Andesite intercalated with chert, Metasediments such as quartzite, metavolcanic rocks and  argillaceous rocks. Gold values in EL Adaraarea were positively related to both silica baritic rocks and pre-kinematic quartz veins. Massive dark brown to black color Patches or halos were shown around gold-bearing shear zones. The erd halos are believed to be formed by the leaching of pyrite. Both pyrite and chalcopyrite contain gold. Gossanic rocks that form over massive sulfide deposit were can be sizable in area. The first body is about 41931 m2, second  body is 31008m2. Stream courses that drain the gossaneous ridges in the Study area host placer gold  where there is an active artisanal  gold mining take place.