Resumo

LAFONT, D; STRAZZERE, L  e  GREGORI, DA. Hydrothermal alteration temperatures and designs at Mina Angela Mine, North Patagonian Massif, Argentina. Rev. Asoc. Geol. Argent. [online]. 2003, vol.58, n.3, pp.391-402. ISSN 0004-4822.

At Mina Angela, three patterns of hydrothermal alteration were defined. A lower temperature type was generated by fluid circulation parallel to the contact between andesitic breccias and lava flows. The faults and fractures where the ore was subsequently deposited would have been closed. The second type, represented by dispersed kaolin group minerals, indicates a preponderantly descending fluid circulation and an increase in acidity. In the higher-temperature type, which is bound up with the main mineralization, the hydrothermal alteration changes from chloritic to potassic with increasing temperature and chemical changes in the fluids. The fluid circulation was typically upward.

Palavras-chave : Hydrothermal alteration; Temperatures; Angela Mine; Argentina.

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