Hydrothermal wall rock alteration at Kurdeman gold mine area, Eastern Desert, Egypt

摘要

The shear zone-related gold mineralization of Kurdeman in the Eastern Desert of Egypt is hosted by greenschist fa-cies metavolcanic and talc-carbonate rocks of Pan-African age. The gold deposit comprises boudinaged quartz veins enveloped by alteration zones. Chlorite-sericite, carbonate-chlorite-sulfide, carbonate-sericite, and sericite constitute four distinct alteration zones which extend inwards to the mineralized quartz veins. Chlorite and carbonate-chlorite alteration zones are derived from the pre-existing talc-carbonate rocks. The geochemistry of the alteration system was statistically investigated using discriminant and factor analyses. Six factors were estimated; factors 1 and 2 are assigned to the pre-existing rock forming minerals and dominated by the rare earth elements. Throughout hydrothermal alterations, the HREE seems to be more mobile relative to the LREE. Factor 3 signifies sericitization, whereas factor 4 largely represents carbonatization and silicification, and somewhat chloritization and gold-sulfide mineralization. Factor 5 characterizes the Au-sulfide mineralization, whereas factor 6 includes Ag which separated from the Au-association due to its high mobility.