Modelling of the Río Tinto Area

Abstract

The Rio Tinto project area is located in the South Portuguese Zone, in the eastern part of the Iberian Pyrite Belt. The Iberian Pyrite Belt (IPB) is one of the world’s best-known ore provinces hosting volcanogenic massive sulphide deposit, formed in the latest Famennian (ca. 360 Ma) and subsequently folded and metamorphosed during the Variscan orogeny (330–300 Ma). The study area is located in the Rio Tinto syncline, with Carboniferous metasediments (Culm) in its core. The volcanic sedimentary complex (VSC) is overthrusted in the central part of the syncline forming the Rio Tinto anticline outcrop (an antiformal stack). The aim of this work was to construct a 3D geological model of the Rio Tinto mine area. To achieve this data compilation has been done including new geological mapping and structural interpretations, petrological and petrophysical sampling, drill hole logging, and geophysical data interpretation (gravimetric, magnetic and radiometric data). Complex surfaces were constructed using large data sets analysed by suitable geometrical techniques. The obtained 3D model shows the relationships between several lithologies, tectonic surfaces and mineralization zones, and is an example of reconstruction of complex geological units within the Iberian Pyrite Belt. In addition, in the Rio Tinto area it was possible to derive a predictive model defining four areas of high ore potential based on detailed geological field work, fracture analyses and geophysical studies related to the possible presence of massive sulphides and stockwork zones.