Storm deposited pebble and cobble-sized particles in the early Emsian of the Ponta Grossa Formation, Paraná Basin (state of Paraná, Brazil)

Abstract

Quartzite pebbles from an arenaceous siltstone with fine sand lenses have been found at two localities in the Campos Gerais region, Apucarana Sub-basin (Parana Basin), south Brazil. These pebbles were first interpreted as glacial diamictites, but their smooth surfaces and surrounding sediments indicate another origin. Two of the pebbles are associated with a small scale hummocky cross stratification in the top layer, and with laminated layers below, which is indicative of currents formed by oscillatory waves. None of the pebbles show any traces of encrustacion. The surrounding siltstone is affected by bioturbation and contain brachiopods ( Australospirifer ). Palynomorphs indicate that these storm deposits were deposited during an early Emsian maximum inundation.