A typological calssification of Spanish precious metals deposits

Abstract

[Abstract] Last decade's intensive exploration for precious metals in Spain led to a new understanding ofvarious types ofdeposits and prospects. A summary review of recent progress is presented, allowing the systematic (typological) classification of the Spanish precious metals deposits shown in Table 1: 19 types are defined in the framework of the Iberian Geology, their exploration significance being also considered. Hypogene deposits in the Hercynian Hesperian Massif, and epithermal gold deposits in the Neogene calc-alcaline Volcanic Province of SE Spain have been very much explored and are therefore emphasized, although their mining production is by far not to compare with the precious metals output the SWIPB (SW Iberian Pyrite Belt). In the Hesperian Massif, different metalloterts have been demonstrated to be related to attractive concentrations ofgold, bound to Hercynian shear-zones, in Galicia, in Extremadura, etc.; other concentrations (e. g., in Galicia and Asturias) are related to granite or porphyry intrusions (Salave) and skarn formations (Carlés). PGE or Platinum elements (± chromite) have been found in ophiolitic thrust complexes occurring in N Galicia, e. g. the Herbeira Massifofthe Cabo Ortegal Complex, as had been in the 1940's in Northern Portugal (Bragan\aand Morais complexes). Exploration for silver has demonstrated a small orebody in Fuenteheridos (Aracena, SW Spain), not minable under severe environmental constraints, but none ofthe classic Spanish silver producing districs (vein-Type deposits, e. g. Guadalcanal or Hiendelaencina) has recovered activity. Most ofthe EU (European Union) gold and silver production is won from only two types of deposits in the Spanish Hesperian Massif: the masive sulphides of the SWIPB, in which precious metals are won as by-products, and the related gossan deposits.