Well sediments: a medium for geochemical prospecting, an example from the Nisa region, Portugal

Abstract

Vriend, S.P., Dekkers, M.J.. Janssen, M.A. and Commandeur, J., 1991. Well sediments: a medium for geochemical prospecting, an example from the Nisa region. Portugal. In: A.W. Rose and P.M. Taufen I Editors). Geochemical Exploration ! 989. J. Geochem. Expior., 4 ! : ! 5 I- 167. Tile potential of well sediments for geochemical prospection purposes is assessed in the Nisa region Portugal ). The semiarid terrain is less suited for more conventional prospection media. The composition of well sediments is dependant on local geology. Well sediments actively interact with emerging groundwater. These influences are identified and evaluated through statistical methods, including discriminant function analysis and factor analysis. Contamination, which may bias the geochemical landscape, appears to be of minor concern. Known mineralized areas (U. Pb, Zn, Ba) show up as strong anomalies. Additional anomalies of associations of several ore-related elements are attractive targets for follow-up study. Single-element anomalies may be caused by local pollution. In general. well sediments, if available, may offer an attractive alternative to more conventional prospecting media in arid and semiarid regions.