Skip to main content
Article thumbnail
Location of Repository

Precambrian Research

By Aroldo Misi and Ján Veizer

Abstract

Texto completo: acesso restrito. p.87–100The Una Group, Irecê Basin (Bahia state) is correlative with the better known Bambuí Group of the São Francisco Basin (Minas Gerais state); these basins are remnants of widespread carbonate platform that covers > 300 000 km2 of the São Francisco Craton in Brazil. The Irecê area contains a well-controlled stratigraphic succession hosting economic phosphate deposits and sulfide mineralization. Una Group strata comprise a basal siliciclastic sequence, mostly composed of glacial diamictites (Bebedouro Formation), followed by a carbonate succession that is several hundred meters thick, the Salitre Formation. An angular unconformity separates the two units. The carbonates of the Salitre Formation are characterized by 87Sr/86Sr ratios ranging between 0.70745 and 0.71776, and δ13C values ranging between −4.4 and +9.4‰ PDB. The carbonates also contain beds and nodules of barite and gypsum with highly positive δ34S values (+25.2 to +32.8‰ CDT). The ‘best preserved’ carbonate samples selected on the basis of their Mn and Sr concentrations as well as their ratios, yield 87Sr/86Sr values of 0.70745–0.70765. Comparison of these values with the secular strontium isotopic curve for the Neoproterozoic seawater suggests a 600 (to 670) Ma age for the Salitre Formation and for its correlative units in the São Francisco Basin

Topics: Brazil, Chemostratigraphy, Correlations, Isotope stratigraphy, Neoproterozoic
Year: 2013
OAI identifier: oai:agregador.ibict.br.RI_UFBA:oai:192.168.11:11:ri/8256
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://www.rcaap.pt/detail.jsp... (external link)
  • Suggested articles


    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.