The El Indio Mine Closure Plan Effects over the Water Quality of the Upper Elqui Basin

摘要

In the Elqui Basin, volcano-sedimentary and plu-tonic rocks of calc-alkaline intermediate character dominate, along with numerous ore deposits and hy-drothermal alteration zones (Oyarzun et al, 2003; Dittmar, 2004). There are three main sub-basins: those of the Turbio, Claro and Elqui rivers (Bodini and Araya, 1998). The Turbio River receives part of its flow from the Toro River, the latter being directly affected by the presence of the El Indio District, at the head of the Elqui watershed (Figure 1). El Indio is a mining district of Tertiary age, representing a special environmental concern because of its enargitic (As-rich) character and the important presence of extensive advanced hydrothermal alteration zones that are the main natural sources of As and acid drainage in the area (Oyarzun et al., 2003).