An Assessment Of The Use Of A Cold-extraction Technique In Geochemical Exploration In North - East Algeria

Under arid or semi-arid climatic conditions, mechanical weathering predominates over chemical weathering. In this study, conducted in semi-arid climatic conditions in northeastern Algeria, a cold-extraction technique was used to analyse those chemical elements weakly bonded onto minerals surface, and considered to have been released during chemical weathering. The results were compared with those of total analysis and both data sets were used to assess the effectiveness of stream sediment samples in delineating known mineralisation and bedrock types. Dispersion trains of 1000-1300 m were found to occur, essentially in- ephemeral streams, whereas background values were found in water-bearing rivers. Known lead, zinc and copper-bearing veins as well as the chromite-bearing serpentinites were well delineated by both analytical techniques, however, the iron mineralisation could only be confirmed by the total analysis. In addition, new sulphide anomalies were outlined by both analytical techniques. It is suggested that the cold-extraction technique used may offer an acceptable and cheaper alternative to the total analysis for outlining serpentinites (cxCo and cxNi) and base-metal mineralisation (cxCu, cxPb and cxZn).