Geoelectric modeling of supergenic manganese ocurrence in heliodora region, Southern Minas Gerais

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Moreira, César Augusto [UNESP]
Siqueira Reis, Samuel [UNESP]
Malagutti Filho, Walter [UNESP]
Hansen, Marco Antônio Fontoura
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This paper discusses the results of the combined application of Electric resistivity and Induced Polarization methods into a mineral occurrence of manganese of super-genic origin, characterized by oxides of manganese and iron with terrain to powdery texture, arising from weathering of spessartite contained in metasediments. From the measurements of electrical resistivity it was possible to recognize a concentric zone in 2D inversion models, with values between 73Ω.m and 380Ω.m, coinciding with the most enriched portion of the soil in oxides. The 2D inversion models for chargeability obtained near the profile of exposed soil allowed for delimitating the mineralized extension, characterized by values below 5 mV/V. The 3D modeling generated by interpolation of 2D inversion models enabled for a morphological analysis of the occurrence, characterized by a broad range (about 50 m) visible in field, but restricted to about 10 meter in depth, between horizons B and C of the soil profile. The restriction in depth can be associated to the precipitation of lixiviate metals in the alteration profile, to the interface of oxide-reduction caused by the cutting in the terrain, which provides aeration and evapotranspiration of the soil. The results reveal the potential for morphological detailing of supergenic mineralization in a fast and quick way, by the combined use of geoelectrical methods and the evaluation of data via 3D modeling.
3D modeling, Chargeability, Mineral exploration, Oxide, Resistivity
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Revista Brasileira de Geofisica, v. 34, n. 3, 2016.