A GLACIAÇÃO STURTIANA (~750 MA), A ESTRUTURA DO RIFTE MACAÚBAS-SANTO ONOFRE E A ESTRATIGRAFIA DO GRUPO MACAÚBAS, FAIXA ARAÇUAÍ

Abstract

This paper is a contribution to the knowledge of the Sturtian glaciation (~800-750 Ma) and the gravitationalsedimentation of the Macaúbas and Santo Onofre Groups. The primary goal of this paper is: (1) todescribe glaciogenic deposits on the eastern edge of the São Francisco craton; (2) to present stratigraphic,sedimentologic and the tectonic setting of the Macaúbas-Santo Onofre rift. An extensional phase is markedby the intrusion of mafic dike swarms at 1100 – 900 Ma and alkaline rocks (750-670 Ma). The Sturtianglacial event (800-750 Ma), with formation of ice-caps in Rodinia supercontinent, is well exposed in theJequitaí area. Glaciomarine facies developed on the border of the craton grade laterally into debris-flowand turbidites. The Neoproterozoic Macaúbas – Santo Onofre rift evolved into a wide embayment limitedby normal faults and a transfer zone. The sedimentary sequence consists of the diamictites, conglomerates,sandstones,, graywackes, pelites deposited by sediment gravity flows. The Neoproterozoic Macaúbas Grouprepresents rift to drift sedimentation related to the break-up of Rodinia. Macaúbas- Santo Onofre rift isregarded as intracontinental with a limited oceanization located at southern of the basin.