O contexto lito-estrutural das mineralizações auriferas na região de Pocone-MT

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

The Poconé region represents an important gold province located in the Mato Grosso State. This province is hosted in a Neoproterozoic metasedimentary sequence, which constitute the Cuiabá Group. This research is dedicated to a detailled study of the tectonic structures of this region, and the main target is to present a descriptive and qualitative structural analysis of these structures and their relationships with the gold mineralization. The gold bearing quartz-veins are exposed on open pits, made by gold-washers. The Cuiabá Group is characterized by a psamitic and psefitic intercalations with dropstones, interpreted as a typical turbiditic sequence fed by glacial debris. The deformation had a heterogeneous, non-coaxial and progressive character. Jt has been developed at different crustalleveJs, during four distinct phases. The DI and D2 structures were deveJoped in a ductile to ductilebrittle crustal regime, caused by compressive stress-field oriented in a NW/SE direction. These two phases show coaxial and progressive evolution. The D3 structures were formed in a brittle to brittle-ductile regime and reflect a compressive stress-field oriented in a NE/SW direction. During D4, a proeminante brittle tectonic regime was formed, with an extensional character, wich was disposed in a perpendicular direction in relation to the other deformation phase stratuctures. The structural framework of the gold-mineralization is controlled by sub-vertical quartz veins, parallel to the D1 and D2 planes. The gold occurs within the quartz-veins and also disseminated in hydrothermal alteration halos at the veins margins. The intersection of these two groups of veins represents na excellent mineral "Bonanza" type deposits. The observed structures and textures in the mineralized veins reveal that gold mineralization is closed related to sulphide percolation, mainly phyrite

ASSUNTO(S)

ouro mapeamento geologico geologia estrutural

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