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Scientific article
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Evolução paragenética, textural e das fases fluidas no depósito polimetálico de Salobo, província mineral de Carajás, Pará

Publication date1995
Abstract

The Salobo polymetallic ore deposit, Pará, consists of a primary Cu (Au, Ag, Mo) mineralization, hosted by Archean iron formations. The Cu mineralization is mostly formed by bornite-chalcopyrite and bornite-calcosite disseminations, in association with magnetite-rich levels. During the tectonic-metamorphic evolution of the deposit, under high amphibolite facies conditions, the sulfide assemblage was probably represented by a Cu-rich cubic solid solution (i.s.s.). At retrograde amphibolite facies conditions, the i.s.s. originated the bornite solid solution and the tetragonal chalcopyrite. The evolution of the bornite solid solution to bornite and calcosite occurred at the greenschist facies retrograde event. Fluid inclusion studies showed that two types of fluid inclusions occur in the Salobo ore deposit: monophase carbonic inclusions (CH₄<10 mol%) and aqueous inclusions, subdivided into highly saline aqueous inclusions (34.9-52.1 wt% NaCl eq.) and low to moderate saline aqueous inclusions (1.2-21.1 wt% NaCl eq.). The carbonic fluids are interpreted as fluids generated or re-equilibrated under high amphibolite facies conditions. The saline aqueous fluids, present during the amphibolite and greenschist facies retrograde events, are probably related to the metamorphic-hydrothermal alterarions or syn- to late-tectonic granites in the study area (e.g. Salobo Velho granite) and seem to be the responsible for both Cu and Au remobilization. The isochores corresponding to the saline aqueous fluid inclusions, combined with the chlorite geothermometer, demonstrated that Cu and Au remobilization probably occurred in the range of 334º-366°C and 3.7 -1.4 Kb, co11sistent with temperatures around 350°C indicated by the compositional characteristics of Au.

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Keywords
  • Iron formations
  • Copper
  • Gold
  • Fluid inclusions
  • Archean
Citation (ISO format)
MORONA-REQUIA, Karin Cecilia, XAVIER, Roberto P., FIGUEIREDO, Bernardino. Evolução paragenética, textural e das fases fluidas no depósito polimetálico de Salobo, província mineral de Carajás, Pará. In: Boletim do Museu Paraense Emílio Goeldi. Série Ciências da Terra, 1995, vol. 7, p. 27–39.
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Article (Published version)
accessLevelPublic
Identifiers
  • PID : unige:157098
ISSN of the journal0103-4278
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