The Evaluation of Secondary Cu, Co, Ni, Cr and Mo Dispersion Patterns in the Southeastern Egyptian Desert PDF

Keywords

sediment, surveys, geochemical

Abstract

Geochemical stream sediment surveys were carried out in the Samiuki-Hamata area of the Southeastern Egyptian Desert. Results indicate that in prospecting for Cu the fine fractions of the stream sediments (<0.075mm) are suitable for cold extraction technique, and the coarser fractions (<1 and <0.25 mm) are more suitable for spectrographical analysis. The soluble Cu ranges from 0.6 to 7% of the total Cu suggesting that mechanical dispersion of Cu is dominant and chemical dispersion plays a limited role in the development of the secondary dispersion trains and halos in this arid conditions. Spectrographical analysis of the -0.5 + 0.25, -0.25 + 0.15 and -0.15+ 0.075mm fractions of the stream sediments gave the best contrasts for Ni, Cr and Mo, respectively, indicating differences in their geochemical patterns. The reconnaissance stream sediment survey revealed a pattern of Cu distribution that is relatable to known mineral occurrences. Cr, Co and Ni are coprecipitated and are probably related to a common source material such as the mafic-ultramafic ophiolites. The Cu mineralization probably had a volcanic origin. The mineralized zones were then remobilized by late-stage Ca and Mg-bearing hydrothermal solutions associated with the rejuvenation of deep fault zones, resulting in the present association of Cu and talc mineralization within shear zones.