Abstract
Este estudio presenta una actualización del registro isotópico de la Formación de Tamengo, parte superior del Grupo Corumbá, que se encuentra en la parte meridional del Cinturón Paraguayo. Este trabajo incluye cortes estratigráficos detallados enlazados con la geoquímica de alta resolución δ13C y δ18O de dos yacimientos mineros cercanos a Corumbá (Mato Grosso do Sul, Brasil).
Highlights
Babinski et al (2008) and Parry et al (2017) dated zircons (U-Pb method) from volcanic ash found at the upper Tamengo Formation and obtained ages of 543 ± 3 Ma and ~ 542 Ma, respectively, placing it at the late Ediacaran, close to the basal Cambrian boundary, period of outstanding climatic and evolutionary changes
Knoll et al (2006) and the Subcommission on Neoproterozoic Stratigraphy acknowledge that the δ13C chemostratigraphy can be a great tool for strata correlation and even definition of the Ediacaran chronostratigraphic limits (Xiao et al, 2016)
Several sites were observed in the vicinity of Corumbá, fresh outcrops at Corcal and Laginha Mines were selected, sampled and described for three detailed stratigraphic sections (Fig. 1) paired stable isotope geochemistry, in a scale never published for this unit before, in order to better comprehend its palaeodepositional environment
Summary
The Tamengo Formation comprises carbonate and siliciclastic rocks with highly relevant fossiliferous content of Ediacaran age. Babinski et al (2008) and Parry et al (2017) dated zircons (U-Pb method) from volcanic ash found at the upper Tamengo Formation and obtained ages of 543 ± 3 Ma and ~ 542 Ma, respectively, placing it at the late Ediacaran, close to the basal Cambrian boundary, period of outstanding climatic and evolutionary changes.The Ediacaran is marked by strong fluctuations in the carbon isotopic record, which are observed at both global and local level, and reach amplitudes greater than 10 ‰ (Grotzinger et al, 2011). The Tamengo Formation comprises carbonate and siliciclastic rocks with highly relevant fossiliferous content of Ediacaran age. The Ediacaran is marked by strong fluctuations in the carbon isotopic record, which are observed at both global and local level, and reach amplitudes greater than 10 ‰ (Grotzinger et al, 2011).
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