Geophysical analysis of natural caves in iron lithotypes in the region of Mariana, Southeastern Quadrilátero Ferrífero, Brazil


Abstract In Brazil, natural caves in iron lithotypes have increasingly been discovered in iron mining areas and its surroundings. Mining companies attempt to study them according to the Federal Decree 6640/2008 and the Normative Instruction 2/2009 of the Ministry of the Environment, which is concerned with the preservation of the Brazilian Speleological Heritage. This research is within one of those studies in which a geophysical campaign methodology is established for an attempted prospection of caves, in an area located on the north flank of Mariana's Anticlinal, Quadrilátero Ferrífero. The flank, which is sustained by iron formations from the Itabira Group and covered by the product of alteration and sedimentary redistribution, experienced extensive and compressive tectonics, generating, respectively, the main structuration in the NW-SE direction and schist thrust slices from the Nova Lima Group. Caves are mainly developed in the lithological contacts and in fault zones. In the regional stage, the methodology uses aeromagnetometric (identification of iron lithotypes, structural and statistical analysis of magnetic lineaments) and aeroradiometric (structural-geological mapping and setting of lithological contacts) methods. Results have shown some caves in lateral contact zones between lithologies, and the structural control imposed by a shear zone in the area. At the local stage, the electrical resistivity method - EL was used, dipole-dipole array, data mathematical inversion, presentation of pseudo-depth sections and tridimensional modeling. The results, in accordance with the topographic data, show the possible limits of the geometric contour and the tendency for cave deepening. However, studies of the moisture, of similar caves with different spacings, and the use of Ground Penetration Radar - GPR are suggested

Similar works

Full text


Directory of Open Access Journals

Provided original full text link
oai:doaj.org/article:e295756a579e45c5bf21614525efd981Last time updated on 6/4/2019

This paper was published in Directory of Open Access Journals.

Having an issue?

Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will take corresponding actions after reviewing your request.