A lithogeochemical study of Lower Cretaceous shales (195 samples) from the Basque-Cantabrian region has been carried out to evaluate average values in major and trace elements. Mineralogy and chem ic al co n te n t o f m a jo r oxides reveal a tro p ic a l w ea th erin g in the source area. Lo w e r co ntents in Fe, Cu, Ni and Zn, both in shale and black shale, in comparison with rock averages reported in the literature, might be related with metal leaching processes suffered by these terrigenous sediments, compatible with ore accumulation in the urgonian limestone platforms