Geochemical characterization of altered rocks and element dispersion around an abandoned mining site in an arid zone: A case study of Fatira gold mine area, Eastern Desert, Egypt

Abstract

Environmental impacts related to mining are widespread due to poor waste management. Fatira abandoned gold mine area in Egypt was studied for the geochemical/mineralogical properties of alterations haloes, mine tailings, stream sediments under dry conditions and impacts to nearby environment. Results of this study indicated that stream sediments and soil-tailings mixture were derived from felsic sources, while tailings, weathered and old tailings were obtained from intermediate-felsic sources. The Pb load was much higher in weathered rocks, soil-tailings mixture and old tailings, while metals like As, Co, Cr, Cu, Ni, V, and Zn show elevated values in weathered rocks nearby Fatira mine area and in downstream sediments. The tailings have high average concentrations of heavy elements, Sr (439), Zn (389), Cu (310), and Cr (50) (in mg/kg), higher than the toxicological standard values for contaminants indicating adverse effects to the neighbouring environment, whereas, soil-tailings mixture have higher As (263), Pb (56) and Al2O3 (17 wt%) reflecting the metavolcanics and granite composition of country rocks. At lower depths of tailings, escalated concentrations of Al2O3, K2O, Na2O, and Fe2O3, and little CaO, MgO, As, Pb, Zn, Cu, and Ni are indicate variable input from intermediate rocks, grey granites, felsite dykes and pink granites. Chemically altered granites showed replacement of hornblende into actinolite, calcite, pitted ilmenite and in-situ formation of Fe-oxides/hydroxides. Low hydraulic conductivity of the rocks increased the intensity of weathering. Gypsum and goethite are recorded due to repetitive sulfides decomposition. The element enrichment that exceeds the standard toxicological values in tailings, soil-tailings mixture, weathered rocks and stream sediments have severe effects on health. Integrating the chemistry, mineralogy and microtextural analyses in the study area is required for accurate geoenvironmental forecasting that facilitate mine rehabilitation with an effective management plan.