Geochemical distribution in residual soils of Iberian Pyrite Belt (Spain)

Abstract

The Iberian Pyrite Belt (IPB) is a volcanic- and shale-hosted massive sulfides world-class province of the Upper Paleozoic age that includes some supergiant ore deposits with a unique mining operations history. An extensive soil (multi-element) geochemical survey in the IPB has been performed to create a geochemical database to increase the knowledge of the studied area. Both univariate and multivariate treatments have been done to manage a large amount of new data. The studied area shows higher background concentrations of several elements (e.b. Cu, Pb, Zn, Cd, Sn, In, Bi, As, or Sb) than in other terrains in Spain due to the IPB volcano-sedimentary ore deposits and their associated mining wastes. Mapping chemical elements help understand their behavior, controls and associations in natural environments. According to this, the mono-elemental contour maps show single-element distributions with geological control (e.g., Na), ore deposit control (e.g., Cu) or a mixture of both. On the other hand, multivariate analysis has been applied to reduce the large geochemical database maintaining the same information. We have chosen Factorial Analysis (FA) and obtained six factors that explain approximately 70% of the variability. Four of these factors (F1, F2, F4 and F5) show an intense geological control that improves the geological information of the IPB, while the other two (F3 and F5) show an ore deposit control. These factors allow distinguishing between different types of deposits in the IPB and help discover new possible exploration targets for future studies.