Resumo

SALADO PAZ, Natalia; FOGLIATA, Ana S; AVILA, Julio C  e  MONTENEGRO, Nicolás. Veta Esperanza Sudeste, a particular case of supergenic enrichment in the Alto de la Blenda deposit, Agua de Dionisio mining district, Catamarca Province. Rev. Asoc. Geol. Argent. [online]. 2011, vol.68, n.2, pp.185-194. ISSN 0004-4822.

Veta Esperanza Sudeste is located in the Agua de Dionisio mining district, Catamarca, belonging to the Sierras Pampeanas Occidentales morphostructural province. The stratigraphic sequence is composed of Paleozoic low grade metamorphic rocks, granites and granodiorites, Tertiary continental clastic sedimentary rocks and the Farallón Negro Volcanic Complex of Miocene age, Pliocene sandstones and tuffites and Quaternary fluvial sediments. In the mining district are disseminated and vein style deposits, among the latter, Farallón Negro and Alto de La Blenda gold-silver deposits. Veta Esperanza Sudeste is an important new discovery within the Alto de La Blenda vein system. The vein is 200m long and its thickness ranges between 0.3 and 6 m. The strike is NW with variable dips between 75° to 56° NE. The wall rock of the vein is quartz-monzonite where different hydrothermal alteration types were observed: argillization, sericitization, silicification, and propylitization. The quartz-monzonite and veins have strong supergenic alteration. The paragenesis is characterized by: (1) primary (hypogene) pyrite, galena, sphalerite, chalcopyrite, Ag sulfosalts and gold and (2) secondary (supergene) pyrolusite, psilomelane, hematitegoethite, and secondary sulphides as chalcosite and covellite. Ore grades range from 0,5 to 40 gr/tn Au and 40 to 2000 gr/tn Ag with a potential resource of approximately 400,000 tons of mineral.

Palavras-chave : Veta Esperanza Sudeste; Oxidation; Supergene enrichment.

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