Abstract: The study integrates the results of field observations, petrographic investigations and whole-rock/wall-rock alteration chemistry to emphasize the occurrence of gold mineralization at Al Abeidiya area, Northern Sudan and to determine its type and distribution, as well as the geological, mineralogical and geochemical controlling factors. The area is a regionally metamorphosed terrane underlain by crystalline Proterozoic basement complex comprising predominantly low to medium-grade, altered and polydeformed, calc-alkaline metavolcanic rocks and minor metasediments intruded by medium to high K, calc-alkaline, metaluminous and I-type granitoidal batholiths that emplaced as volcanic arc plutonics above a Noeproterozoic subduction zone during the syn to late collision stages of crust evolution of the Nubian Shield. The study confirmed the existence of promising medium to high-grade gold mineralization (with content ranging between 0.01-24.0 g ton-1) occurring as a shear zone-hosted, gold-quartz, gold-sulfide and disseminated gold formations in gold-bearing quartz veins, veinlets, sub parallel stringers and wall rock alteration zones. It is hosted by intensely sheared and hydrothermally altered granitoids and the surrounding greenschist-facies assemblages as well as, the ophiolitic sequences and controlled by post-batholithic brittle-ductile deformation with different intensity of shearing and hydrothermal alteration. Gold is preferentially encountered as fine to medium-grained native gold or as dispersed, tiny invisible grains associated with sulphides. Pyrite, arsenopyrite, sphalerite, chalcopyrite and minor galena, malachite, pyrrhotite and chalcocite are the sulfide phases associated with the gold, whereas iron oxide (limonite), carbonates (ankerite, siderite and calcite), chlorite and minor talc occur as gangue minerals. The country rocks locally suffered an extensive wall rock alteration that developed around the mineralized zones and encountered as; sericitisation, carbonatisation, chloritisation, pyritazation, silicification kaolinitisation and epidotization. Au-mineralization postdated metamorphism, older shearing/faulting events and batholithic intrusion and was synchronous with the latest stage of shear-induced deformation. The mineralization is interpreted as consistent with mesothermal type of hydrothermal deposits, where post-metamorphic and syn-deformation hydrothermal fluids ascending through channel ways within sheared zone leached elements from the metavolcanics and the nearby mafic/ultramafic rocks and precipitated in the host rocks. The credible energy sources for the hydrothermal activity that brought about the mineralization is likely unexposed intrusions at deeper levels within the shear zones.
N.H. Lissan and A.K. Bakheit, 2010. Nature and Characteristics of Gold Mineralization at Al Abeidiya Area, Berber Province, Northern Sudan. Research Journal of Applied Sciences, 5: 285-302.