Contribución al conocimiento de las mineralizaciones Pb-Zn del tipo Reocín en el sector oeste de Cantabria

Abstract

The lead-zinc mineralizations from Western Cantabria are studied in this paper, mainly from a petrological and geochemical point of view. The host rocks are mesozoic dolomites which present some outstanding evidences: cavernous aspect, irregular distribution, coarsegrained, relict texture with ghosts and cloudy centers, and low geochemical content in Sr (50 ppm) and high in Mn and Fe (1200 ppm and 4%. respectively), These characteristics aIlow classify them as originated by late diagenetic dolomitization processes. The primary ores are sphalerite, galena, pyrite, marcasite , and sometimes barite. These minerals fill cavities and other open spaces, being the most important texture composed by altemating bands of sphalerite of different colour ("colloform texture") with scattered crystals of galena, pyrite, and marcasite, The general morphology is tipically stratabound and not stratiform. The secondary minerals, product of weathering, inelude smithsonite from sphalerite, cerussite from galena, and goethite from pyrite and marcasite. The characteristics of the host rocks and mineralizations show they were formed epigenetically, with existence of a source rock, migration of mineralizating solutions and deposition of them in a host rock of dolomitic character.