Rio Tinto (Iberian Pyrite Belt): a world-class mineral field reopens

Abstract

The deposits of Rio Tinto are located in the Spanish segment of the Iberian Pyrite Belt and are hosted within felsic porphyritic volcanic rocks and tuffs. The orebodies comprise a spectrum from sedimentary exhalative (San Antonio) to sub-sea floor replacement of the volcanic host rocks (Filon Norte); the two largest masses (San Dionisio and Filon Sur) are closely associated with black shale and probably formed by partial replacement of these units in an anoxic setting. Alteration associated with ore deposition is typified by marginal sericitic (white mica) alteration, and central chloritisation and silicification in a multi-phase alteration history. Structures formed during initial plate convergence may have acted as controls on ore deposition, and evidence of such controls is retained in the distribution of various elements in the sulphide deposits. Tectonism followed the mineralisation, and overprinted previous extensional events and resulted in the development of slaty cleavage in the pelitic rocks with partial remobilisation of sulphides, and tight folds with associated shearing of the southern limb.

A new 3D geological model and interpretation of structural evolution of the world-class Rio Tinto VMS deposit, Iberian Pyrite Belt (Spain)

“…Nevertheless, in the core of the Rio Tinto anticline, rhyodacitic domes and lavas dominate (Figs. 3 and 6), whilst outside this domain, including the Eduardo fault area, pyroclastic tuffs dominate (Garcia Palomero, 1980;Adamides, 2013). Some domes and plugs have been included in the map as part of the felsic sequence, but not in the 3D model because it was not possible to reconstruct them from the drill-core logs.…”

Background Conditions and Mining Pollution throughout History in the Río Tinto (SW Spain)

“…Only in the southern part of the watershed the river runs through Neogene materials, mainly marly deposits ( Figure 1). The IPB, a 230 km long by around 50 km wide strip extending from the Seville province to the southwest of Portugal, comprises three lithological groups from Devonian to Middle Carboniferous [6]: (1) the Phyllite-Quartzite Group (PQ), formed by a sequence of shales and sandstones with an estimated thickness of at least >2000 m [7], (2) the Volcano-Sedimentary Complex (VSC), which overlies the PQ group and includes a mafic-felsic volcanic sequence interstratified with shales, and (3) the Culm Group, overlying the VSC, a turbidite sequence of shales, sandstones and conglomerates.…”

“…The IPB contains one of the greatest concentrations of polymetallic massive sulphide mineralization on Earth [6], which occurs as concordant tabular bodies or lenses, commonly underlain by crosscutting stockworks in which sulphides occur in veins and as pervasive disseminations [8]. Among them, the largest individual polymetallic sulphide deposit (original reserves of 500 Mt sulphides) is the Rí o-Tinto orebody, which lies in an east-west anticline, consisting of three distinct mineralized zones: San Dionisio, San Antonio and Cerro Colorado.…”

Mineralogy and geochemistry of a clogged mining reservoir affected by historical acid mine drainage in an abandoned mining area

“…Here, metal mining has a long tradition, defining a world-class volcanogenic massive sulphide province, with more than 5000 years of mining history (Davis et al, 2000). Nowadays, several mining fields reopen and the economic interest lies on the base metals as well as precious and strategic metals as demonstrated by the intensive exploration activities (Adamides, 2013;Carvalho et al, 2011;De Oliveira et al, in press). …”