Coarse-grained storm beds are formed by cross-bedded to symmetrically-rippled conglomerate and sandstone, followed by drape or flaser of siltstone/shale. Five examples from the Permian of Paraná Basin illustrate this type of deposit: three of them are bioclast-bearing siliciclastic rocks of Rio Bonito (Triunfo Member) and Palermo formations, while the other two are carbonate and phosphate rocks of Teresina and Corumbataí formations. The traction component at the base of coarse-grained storm beds is represented by quartzose arenite or oolitic grainstone with cavity-filling calcite cement (Palermo and Teresina formations). Most of the coarse-grained storm beds are transgressive lags intercalated in shales and fine tempestites (hummocky cross-bedded, very fine sandstones and siltstones); in one case, from subsurface, the transgressive lag occurs at the base of a prograding offshore bar. The example from Teresina Formation represents a transgressive event overlying offshore bar deposits.
Coarse-grained storm bed; traction and oscillatory processes; Permian; Paraná basin
