Caracterização estrutural de áreas com ocorrência de cavidades naturais em Serra Sul – Corpo S11D, Província Mineral de Carajás

Abstract

The structural characterization of the occurrence areas of natural cavities in the South Ridge – S11D shape, Carajás Mineral Province was carried out in the S11D - Eliezer Batista Mining Complex. Where the objective was to investigate and understand the influence of the local structuring in the natural underground cavities and pseudoclastic features identified in the study area. Since a large number of these features are inserted in iron ore it gives them a high economic interest. In the beginning it was visible that there are large areas of cavity concentrations within the analyzed area. Taking into account criteria such as location, data availability, local structuring and drainage network, it was possible to select and divide four concentrations of cavities, called Concentration I, Concentration II, Concentration III and Concentration IV. In the Concentration I analysis, it was observed a tendency in fracture formations in the direction NW-SE and NE-SW in the rough bundles, whereas the caves conduits follow a preferred orientation NW-SE. The Concentration II presents a structurally controlled terrain by ductile shear zone and folded zones, where the rough bundles measurements are preferably scaled to NE and the fractures present several subvertical dips with directions to NW-SE; The Concentration III presents a striking structural control through shear zones, where the rough bundles datas present preferential dips for SE and the fractures with directions NW-SE; However the Concentration IV, doesn’t present clear datas in the interpretation of this work, however, the rough bundles measurements present dips in all senses being NE the main ones, also occurs in the fracturing measurements being the dips preferentially subvertical. Through the cavities structural datas and analyzes of the low plant of the same it was possible to affirm that the cavities tend to be oriented according to the structural patterns described in the work area by Costa (2018), sometimes they orient themselves in relation to the rough bundles, sometimes by the fractures. It is also frequent in the area pseudoclastic features, which are related to lakes and abatement surfaces, these being also related to the structural geology of the area. Through a statistical study, taking data from 173 cavities presents in the study area, it was possible to determine occurrence patterns of these cavities, taking into account factors such as: Altimetry, where it was described that most of the cavities are in dimensions between 701 and 800 meters; Relief, where the plateau surfaces have the largest number of represented cavities, and the Litology, that it was possible identify the Iron Formation as having the largest number of cavities.