PRIMARY GEOCHEMICAL HALOES, EL-SID GOLD MINE, EASTERN DESERT, EGYPT

Gold mineralization in the El Sid gold mine, Eastern Desert of Egypt, occurs as fracture filling in the Neoproterozoic granitic rocks and along its contacts with serpentinites and metagabbro complexes. Zonality of the primary geochemical haloes throughout the different underground levels of the mine am studied. Trace element abundances of Au,Ag, As, Hg, Cu, Pb, and Zn in a vertical cross section revealed distinct zonality differences above and below the main auriferous quartz vein in the central part of mine (i.e. level-II). Mercury and Pb have distinct anomalous haloes only in the uppermost horizons, while Zn, As, and Ag form anomalous haloes along the lower margin of mineralization at deeper horizons. The maximum concentrations of Au and Cu are recorded in the main ore body in the central part of the mine. The Au-content in some of the bedrock and quartz vein samples collected from level-II are as high as 12.8 and 24 ppm, respectively. These are consistent with the maximum relative accumulation of trace elements calculated in the El Sid gold mine using zonality indices. The Hg/Ag zonality indices are appropriate indicators for the degree of erosion at the El Sid gold mine. The high Hg-contents at the upper-most level in the El Sid mine indicate that there has been little extensive erosion of the gold deposit. This observation is supported by the lack of Au-placers in the drainage patterns dissecting the mineralized zone.