L'apport métallifère «direct» du volcanisme continental

Recent geochemical investigation of ash-flow revealed important quantity of base metals in form of soluble salts coating ash particles. Metallogenic speculation is made for the formation of several and different kinds of ore deposits in sediments and volcanics, marine or continental, by direct concentration of these metals transported in solution. Soil process is not always required to “filter‘ metalliferous continental volcanics and concentrate the ore.