Carbon-isotope and Hg stratigraphies of the Neoproterozoic Serra do Paraíso (Rio Pardo Basin) and São Desidério (Rio Preto Belt) formations, Bahia, Brazil

Abstract

The Rio Preto Basin and Rio Pardo Belt surround, respectively, the southeastern and northwestern portions of the São Francisco Craton. In this study, using carbon isotope and Hg stratigraphies, it is examined the possibility that carbonates of the Serra do Paraíso Fm. (Rio Pardo Basin) that overly diamictite/arkose of Panelinha Fm. or basement, and of the São Desidério Fm. (Rio Preto Belt), represent Neoproterozoic cap carbonates. Composite C-isotope profiles yet to be completed and refined support this hypothesis. Carbonates of the São Desiderio Fm. exhibits C-isotope pathway similar to that obtained for the upper portion of the Sete Lagoas and Lagoa do Jacaré formations of|the Bambuí Group, Minas Gerais. Hg values from carbonates of the Serra do Paraíso Fm. have been used as a proxy of volcanism intensity and CO2 buildup during snowball events