Efecto contrafuerte en las mineralizaciones de sulfuros del entorno de la Falla Sur de Río Tinto

Resum

The Rio Tinto volcanogenic massive sulfide (VMS) deposit is located in the Spanish segment of the Iberian Pyrite Belt (South Portuguese zone of the Iberian Massif) and is hosted by felsic porphyritic volcanic rocks and tuffs. The Southern Fault is the southern limit of the Rio Tinto anticline, a tight rollover during the Variscan orogeny, and together with the Northern Fault forms the VMS feeding system. In this work, we present for the first time data from 4 deep drilling cores (over 1000 m each) around the Southern Fault, which show evidence of a buttressing related transpressive deformation, that not appear in the North Fault. During the buttressing and shearing, the Rio Tinto southern limb become vertical and cataclasites and low-grade milonites are developed. Related to these processes there is a hydrothermalism under green schist metamorphism (±350ºC). The stockworks in the riolitic unit are folded, sheared, and surrounded by crenulated fine-grained sericitic-chloritic materials. The ore also presents textures such as recrystallization and overgrowth due to the deformation and related hydrothermal fluid flow circulation.