Estudo Eletromagnético no Dominio da Frequência em Sequência Ultramáfica, Municipio de São Sepe - Rs

Abstract

Studies of mineral prospecting and exploration by geophysics are essential for the recognition and incorporation of new reserves, due to its low cost compared to direct methods of investigation and the possibility of covering large areas. There are several geophysical methods in mineral exploration, such as Electrical and Electromagnetic, besides Magnetometry and gamma spectrometry, because of the contrast between areas of physical properties and mineralized rocks. This paper presents the results of applying the electromagnetic method, using the technique of electromagnetic pathway, the characterization of a metamorphosed ultramafic body and chrome mineralization, located in the rural municipality of Sao Sepe (RS). The study area has gathered rocks Metamorphic Core Complex Metamorphic Complexultramafic and Vacacai. These complexes bring together a wide range of lithotypes, predominantly ultrabasic terms in the form of magnesian serpentinites and schists, with subordinate terms metabasic. The electromagnetic method in the frequency domain was effective for the objectives proposed in the work, presented a striking contrast of physical properties with low values for apparent conductivity compared to the serpentinite rocks. The apparent conductivity measurements were low for the serpentinite due to the occurrence of pyroxene and amphibole minerals which are resistive. Structural measures were essential to understanding the projection of serpentinite at depth. Understanding the results of conductivity contrast was apparent basis consistent with the structural measures, which infer the possible contours that limit the serpentinite. Introducao Desde os primordios o homem vem em busca por recursos minerais de interesse, sao feitas observacoes a respeito das relacoes entre certos tipos de mineralizacoes e determinados tipos litologicos. A partir disso foi estabelecida uma serie de associacoes entre litologias e mineralizacoes tais como: granito e cassiterita; rochas ultrabasicas e cromita. Contudo, nem todos os granitos apresentam mineralizados em estanho, e que nem todas as rochas ultrabasicas continham