Evaluation of the mineral exploration influence on sediment composition in the Gualaxo do Norte River Basin (MG-Brazil) based on geochemical and stratigraphic data.

Abstract

The aim of this study was to investigate the influence of mining on the geochemical composition of the alluvial sediments of the Gualaxo do Norte River Basin, located in the eastern-southeastern portion of the Quadrila ´tero Ferrı´fero (Minas Gerais State, Brazil). The analysis of the sedimentological succession was carried out using 16 stratigraphic sections (cutbanks and alluvial terraces) and analysis of 111 sediment samples for major- and trace-elements by ICP-OES. The stratigraphic analysis revealed the deposition history of the collected sediments. Anomalous concentrations of certain elements such as As and Pb were found, which are associated with stratigraphic facies with evidences of gold artisanal mining, and Fe anomalies associated with iron ore mining. The classification of the sections was possible by means of principal component analysis. From the sediment characteristics, three groups were identified: (1) those influenced by iron ore mining and gold artisanal mining; (2) those influenced by iron ore mining and (3) those with no influence of human activities.