A multielement geochemical survey, based on the analysis of the minus 150 microns stream sediment grain fraction was conducted in the Collo area (N.E. Algeria). The prospected area is underlain by a basement complex including a gneiss and serpentinised peridotite; sedimentary series consisting mainly of flysch material; and post-nappe formations including a sedimentary unit, and a unit consisting mainly of an S-type granite and a monzonitic microgranite. Known mineralisation consists of As, Bi and base-metal sulphides, Fe oxides, and chromite.

The geochemical data was obtained by the total analysis (XRF) and the 3% HCI extraction analysis (AAS) of more than 200 samples. R-mode factor analysis with Varimax rotation was applied to the data with the aim of reducing the data dimensionality, the understanding of the nature of the multielement associations, and for targeting anomalous areas for follow-up work. Five factors, explaining about 70% of the variability of the data, were defined. These include 3 lithological factors, a «sulphide mineralisation factor», and a «heavy minerals factor». From this study, three target areas were outlined for further research.

Key words : Stream sediments – Geochemical survey – Total analysis – Cold-extraction analysis – R-mode factor analysis – Multielement associations – Factor score maps.