Abstract
This paper discusses the facies distribution of Mesozoic eolian sandstones between the Sanga do Cabral and Botucatu formations and also their contact relationships, in São Leopoldo area, State of Rio Grande do Sul (RS), southern Brazil. The main distinctive characteristics regarding these sandstones and formations are the mineralogical composition, paleocurrents and the occurrence of wet interdune deposits. These interdune deposits are characterized by frequent thin mudstone layers with mudcracks, ichnofossils and salt impressions. There are also some features that resemble plant fossils. The distinctive characteristics of these sequences to Sanga do Cabral and Botucatu formations allow us to suggest the informal name of Pedreira Sandstone, considering its type section, the Pedreira Cliff, at Sapucaia do Sul, RS.
Highlights
In São Leopoldo area, State of Rio Grande do Sul (Figure 1), between deposits of Sanga do Cabral (Late Permian – Early Triassic) and Botucatu (Jurassic - Cretaceous) formations, eolian sandstones with distinctive characteristics from the eolianites of those units are found
The depositional analysis of the Sanga do Cabral Formation suggests an increase in the region aridity, in the direction of the top of the unit, which is interrupted by the registers of the wet interdune deposits of the Pedreira Sandstone
The sedimentary structures suggest an inflow of water that, though not much significant, was enough to transform the area into a humid desert
Summary
In São Leopoldo area, State of Rio Grande do Sul (Figure 1), between deposits of Sanga do Cabral (Late Permian – Early Triassic) and Botucatu (Jurassic - Cretaceous) formations, eolian sandstones with distinctive characteristics from the eolianites of those units are found.White (1908) was the first to study the area’s stratigraphy; only in the 60’s the geological observations were systematized (Morris 1963, Fensterseifer 1979, Andreis et al 1984, Zeltzer et al 1992, Faccini & Nowatzki 1993, Nowatzki 1997).Geological sections made along federal, state and municipal roads made it possible to analyze more than the facies distribution (lithology, geometry of the beds, sedimentary structures, paleocurrents and fossils), the contact relationships between the existing units, making whenever possible, details of profiles in representative outcrops. In São Leopoldo area, State of Rio Grande do Sul (Figure 1), between deposits of Sanga do Cabral (Late Permian – Early Triassic) and Botucatu (Jurassic - Cretaceous) formations, eolian sandstones with distinctive characteristics from the eolianites of those units are found.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
