The Upper Mafra\Lower Rio do Sul sequence (Itararé Group, Permo-Carboniferous) from composite sampling by drilling in the Mafra region (State of Santa Catarina), eastern border of the Paraná Basin.

Abstract

The Permo- Carboniferous Itararé Group crops out in the Mafra area, represented by Campo do Tenente, Mafra and Rio do Sul formations; they correspond in subsurface to Lagoa Azul, Campo Mourão and Taciba formations. A composite sampling of the Group was performed through drilling of six wells, which average 60 m in depth; three of them cored the depositional sequence here designated as Upper Mafra\Lower Rio do Sul. The Upper Mafra Formation were sampled by TC-4 and BR-5 wells, and it consists of three units: the lower two are sandy, glacial-deltaic and fluvial-deltaic in origin, corresponding to a lowstand tract. The last unit is composed of two dirtyingupward successions of sandstone, diamictite and rhythmite, interpreted as deglaciation/transgressive events, and well represented in BR- 5 drilling. The Lower-Rio do Sul Formation (“Lontras Shale”) is formed by two marine units: the lower one is represented by shale and bioturbated siltstone which culminate the previous deglaciation, transgressive succession, while the upper one, sampled by SL-2 well, is formed by shale and thin, turbidite sandstone, attributed to a highstand tract.