C-, Sr-isotope stratigraphy of carbonate rocks from the Southern Espinhaço Ridge, Minas Gerais, southeastern Brazil

Abstract

Neoproterozoic carbonate rocks comprise different stratigraphic units in the southern part of the Espinhaço Ridge, Minas Gerais, Brazil. C, O-and Sr-isotope analyses were carried out along four selected stratigraphic sections across these formations. Sr observed in carbonate samples from the Macaúbas Group are similar to those observed in the Sr-isotope secular curve for the Neoproterozoic. Carbonate samples from the base of the Bambuí Group correlate with Ediacaran fingerprints, after the Marinoan (ca. 635 Ma) glaciation.

The Carrancas Formation, Bambuí Group: A record of pre-Marinoan sedimentation on the southern São Francisco craton, Brazil

“…All of these units belong to the Cryogenian Macaúbas Group (Pedrosa-Soares et al, 2011;Babinski et al, 2012;Fraga, 2013). Fraga et al (2014) It is widely believed that the glaciogenic Serra do Catuni Formation in the Araçuaí fold belt correlates with the Jequitaí Formation on the craton (Karfunkel and Hoppe, 1988;Uhlein et al, 1998Uhlein et al, , 1999Martins-Neto et al, 2001). Thus, we propose a similar correlation between the pre-glacial Tijucuçu sequence and the Carrancas Formation, in which the continental extension on the southern São Francisco crust may be a minor expression of the rifting at the eastern margin, and suggest that both of these units capture the Keele Peak, and hence represent the Cryogenian interglacial interval.…”

Provenance and paleogeographic reconstruction of a mesoproterozoic intracratonic sag basin (Upper Espinhaço Basin, Brazil)

“…Most of the primary structures have been obliterated by metamorphic recrystallization and deformation. Layers with stratiform stromatolites with flat and crenulated lamination (Fraga et al, 2014) occur scattered randomly throughout the massive dolostone (Fig. 6f).…”

Estratigrafia e sistemas deposicionais do Supergrupo Espinhaço e grupos Bambuí e Macaúbas

“…Metacalcários calcíticos laminados do Grupo Bambuí (Formação Sete Lagoas). Veja também Fraga (2013) e Fraga et al (2014) para descrições da rocha e dados de geoquímica isotópica.…”