The leading role of geophysical methods in the discovery of the La Magdalena VMS deposit in the Pyrite Belt, Huelva

The La Magdalena deposit is located in the central, northern part of the IPB (Figure 1) in an area where the three main regional lithostratigraphic units of the Belt are well represented. The stratigraphic package is complicated by deformation from the different tectonic events resulting in a degree of ‘disorder’ in the units on the geological map as a result of this tectonic complexity. As a result of the tectonic deformation the oldest rocks corresponding to the PQ Group (phyllites and quartzites) appear thrusted over the VS (Volcano-sedimentary complex) in the northern limits of the prospect, but also appear as a thin band in the western half of the study area. To the south and away from the area of La Magdalena there are extensive areas of Lower Carboniferous Culm rocks, which are the youngest stratigraphic units and comprised of phyllites and greywackes. Between the Lower Carboniferous Culm in the south and the Devonian PQ in the north, the VS Complex outcrops and is well developed in the prospect area. The VS Complex comprises of mainly volcanic rocks (lavas and pyroclastics) with the rare appearance of sediments and it is in this VS sequence where many of the sulphide deposits are hosted including Aguas Tenidas, Esperanza and La Magdalena. The local geological map around La Magdalena deposit is shown in Figure 2.