Structural geology applied to the underground coal mining in Araranguá (SC, Brazil)

Abstract

The underground coal mining in the carboniferous region of Santa Catarina state has a great structural control. The studied area is located in the NE portion of the Araranguá city. This research presents the structural data of the sedimentary rocks and the Barro Branco coal seam in the Mina D area through the integrated evaluation of satellite images and 100 boreholes data. The major lineaments identified in the satellite images have N30°-60°W, N60°-80°E and N30°-60°E directions. The coal seam structural contour map and the geological sections highlights the occurrence of faults which have N30°-60°W, N50°-70°E, N10°-20°W and E-W directions. The NE direction faults have regional extension and are the most influent in the structural arrangement of the area. This faults have expressive tailings (>100 m) and prevent the economic recovery of the coal in some portions of the area. The future mine galleries should be oriented parallel the main faults. The faults with NW direction is the most frequent and have minor extension and tailings (<30 m).The mining plan should consider it in order to avoid have to cross this faults. The N-S direction faults were identified in the area and presents expressive tailings (>70 m). The occurrence of inverse faults is associated with the uplift related to the intrusion of diabase sills. Stress accumulation zones can occur close to this areas and are usually related to roof instability and floor heaving. The applied methods proved to be efficient in the estimation of tectonic structures and in the preliminary evaluation of their influence on underground coal mining.