The secondary geochemical dispersion of some selected elements around the Cravezes scheelite deposit, northeastern Portugal

Selected results of a geochemical survey using stream-sediment sampling for ore minerals are presented. The study was undertaken in the Mogadouro (Cravezes) region, northeastern Portugal in order to investigate prospecting parameters for scheelite (tungsten) mineralization within calc-silicate rocks (skarnoids).Statistical and mathematical treatment of the data obtained during prospecting aided the interpretation, particularly, factor analysis. Five factors explaining about 85% of the variability in the data, were extracted; some were characteristic lithological and mineralization factors which are still imprinted in the secondary environment. Two apparently non-correlated types of mineralization are demonstrated: a scheelite (tungsten)-tin mineralization, and a copper-lead-zinc mineralization.Anomalous patterns delineating the scheelite ore deposit are revealed by the spatial distribution of various chemical elements. This highlights the importance of some pathfinder elements which can be used for tungsten prospecting in this type of geological environment. Copper, Pb, Zn, Ni, Co, V, and Cr are suitable pathfinders for W and Sn in the Mogadouro region.