Mineralizações de ouro no terreno Almas-Dianópolis-TO : guias de exploração mineral

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The distribution of the main gold occurrences and deposits of the Almas-Dianópolis Terrain (TAD), firstly evinced by recognition prospecting in drainage sediments, is controlled by N35-50W/N40-60E shear zones and, less frequently, by NS-shear zones. Gold essentially occurs in quartz veins bordered by albitic, argilic and sericitic alterations associated with granitic host rock, and carbonate, chloritic, sericitic and subdued biotitic and turmalinitic alterations in banded iron formation. The geotectonic environment is that of an island arc bearing an intense TTG-type magmatism during its evolution, generating gold in local quartz veins of fault intersections or controlled by ancillary fractures in shear zones. The predominance of greenshist facies hydrothermal alteration minerals and of iron sulphide (pyrite and pyrrhotite), the magnitude of the Au/Ag ration in gold grains, are compatible with orogenic lode gold type deposits. TAD mineralizations have been probably formed during a metallogenetic event associated with Transamazonian Orogeny in the Brasilia Belt, with Brasiliano remobilization. More probably, though, mineralizations have been originated in Neoproterozoic in the western border of the São Francisco craton, during the evolution of the Brasiliano Orogeny.

ASSUNTO(S)

geologia minas e mineração tocantins geociências ouro

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