Resumo

MAIZA, Pedro J.; MARFIL, Silvina A.; CARDELLACH, Esteve  e  ZUNINO, Juan. Geochemistryof the kaolinized zone of Estrella Gaucha mine, Province of Chubut. Rev. Asoc. Geol. Argent. [online]. 2009, vol.64, n.3, pp.426-432. ISSN 0004-4822.

Estrella Gaucha mine is situated 70 km of Alto Río Senguerr(Province of Chubut).It is a kaolin deposit hosted by sandy and conglomeratic tuffs of the ApelegFormation (Lower Cretaceous). The mineralogy of the zone is very homogeneousand it is characterized by dickite almost pure, traces of alunite and quartz.There are four alteration zones. 1) silicification; 2) zone with alunite; 3) kaolinizedzone and 4) zone with sericite - chlorite. In order to know the origin of thedeposit a mineralogical, geochemical (major and trace elements) and stableisotope study (O and H) of the kaolinized zone was carried out. Trace elementcontent and ratios of kaolin samples (P vs. S, Zr vs. Ti, Cr + Nbvs. Ti + Fe, and Ce + Y + La vs. Ba + Sr) suggest they are formedfrom hydrothermal alteration of the enclosing rocks. δ¹⁸O values ofkaolin range from +5.1 to +8.8 ‰ and D varies from -82 to -89‰.These values are compatible with fluids of hydrothermal origin.

Palavras-chave : Kaolin; Isotopes; Geochemistry; Hydrothermal alteration.

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