Tectonic and metallogenic significance of sedimentary manganese deposits in the eastern Cantabrian domain, Asturias, northwestern Spain

The eastern part of the Cantabrian Zone (Iberian Massif, Spain) is well known by the variety of small and medium-sized mineral occurrences of Pb-Zn-Ba-Hg, F-Ba, Cu-Co-Ni, Hg-Ba, Sb-As, Fe-Mn, etc., which have been exploited since Neolithic time. There is also a conspicuous Carboniferous Mn-Fe sedimentary deposit consisting either of small nodules in a pelitic matrix or of massive Mn (Ricacabiello Formation of Bashkirian age). Twenty-four samples of nodules and matrix and 2 samples of hydrothermal Fe-Mn have been analyzed, and trace and REE elements have shown the existence of hydrothermal and hydrogenous nodules in the formation, which was deposited in a deep-marine environment related to Late Paleozoic tectonic episodes, and also the possibility of this being the source bed for most of the rest of the epithermal deposits in the Cantabrian Zone during an intensive epoch of hydrothermal circulation in Permian time.