Geologia, lavra e aproveitamento racional dos quartzitos da região de Várzea e Junco do Seridó-PB.

Abstract

The quartzite formations of Paraiba and Rio Grande do Norte states belong to the Equador Formation of Upper Proterozoic. These quartzites are explored and used as building material in the region. The objectives of this research are: to study the exploration of the quartzites in the Junco do Serido and Varzea regions of Paraiba, considering their geological characteristics; mining methods adopted and; the environmental impacts caused by mining and measures that should be taken for rational use of these rocks. Also in this work it is intended to do the geological and technological characterization of the quartzites. In field studies observations were made about structures, thickness, fracture directions and model of occurrence of quartzites. The texture and structure vary considerably in the rocks. In the Varzea region the foliations in the quartzites tend to be vertical with the thickness varying between 2-3 cm and tend to be highly fractured. In the Junco do Serido region the quartzites have horizontal foliations with 2-3 cm of thickness and fracturing tend to be less. The mining is manual and the mining efficiency varies between pits. The sterile material is piled up around the pit causing strangulation and low mining rate. The extensive vertical foliations in Varzea and extensive horizontal foliations in Junco create serious mining problems in the region. Mechanical tests were conducted to detennine the rock resistance to bending or flexion according to the standards established. The mechanical tests showed the quartzites of the region are very resistant with average values of the rupture module were above the minimum values recommended. The rock extraction varies between the mining areas caused by the foliated nature of the quartzites. The mining or extraction of the quartzites with strong foliations, high frequency in the fracture planes and high deformation make mining difficult resulting in considerable loss of rockmaterial. The environmental impact on the soil and the water in the region is minimum and the mining activities result only in damages to the landscapeand other geomorpho logic features of the region.