Framework and evolution of Hercynian mineralization in the Iberian Meseta

The Hercynian cycle, starting in Late Precambrian times and terminated at the end of the Palaeozoic, is associated in the Iberian Peninsula with the deposition of a wide variety of metallic and nonmetallic mineral resources. The most famous of these are the base-metal sulphides of the Iberian Pyrite Belt (Rio Tinto and other deposits), tin and tungsten (Panasqueira), and mercury (Almadén). The depositional stage of the Hercynian cycle saw the accumulation of syngenetic mineral deposits, resulting from the interplay of palaeogeographical, sedimentary and volcanic controls. During and after the following orogenic stage, epigenetic minerals originated through magmatic activity, mostly as direct deposits from magmatic-derived fluids and also indirectly through thermal activation of existing rock. In both stages felsic magmatism was the dominant agent of mineralization, both for the more important volcanogenic and for the plutonic mineral deposits. Framework and evolution of Hercynian mineralization are defined by the geotectonic intraplate — not plate-margin – setting of the Meseta and by its palaeogeographical and structural development during the cycle, modified by regional and local factors, foremost among which are volcanic and plutonic heat and mass transfer. Metallogenetic provinces and epochs are distinguished, metallotects outlined, and possible sources for the introduced ore elements discussed.