Contrasting geochemical features of the Central Iberian Zone shales (Iberian Massif, Spain): Implications for the evolution of Neoproterozoic - Lower Cambrian sediments and their sources in other peri-Gondwanan areas

1. Valladares, M.I.
2. Ugidos, J.M.
3. Barba, P.
4. Colmenero, J.R.