Paleoichnology and palynology of Itararé Group rhythmites from Águas Claras quarry (Santa Catarina State, South of Brazil)

Abstract

This paper focuses on an integrated analysis of the paleoichnology and the palynology of the Rio do Sul siltstone-mudstone rhythmites cropping out at Águas Claras Quarry, Santa Catarina State, south of Brazil. Trace fossil assemblage is dominated by mollusk trails and perycaridean or syncaridean crustacean and merosomates trackways, preserved as undertracks. Protovirgularia isp., followed by Diplichnites gouldi and Diplopodichnus biformis are the commonest ichnospecies, but Maculichia varia and Umfolozia sinuosa are also frequent. Shallow burrows of soft-bodied animals (Cochlichnus anguineus, Hormosiroidea meandrica, and Treptichnus isp.) and arthropod resting traces (Gluckstadella cooperi) are also present. Palynological analysis carried through in the samples of the same levels where ichnofaunas are found it disclosed scarce palynological elements, with dominance of monosaccate pollen grains and opaque phytoclasts. The presence of Vittatina vittifera, Protohaploxypinus goraiensis and Illinites unicus suggests a lower Permian age, with correspondence with Protohaploxypinus goraiensis subzone base for the Vittatina costabilis zone. The dominance of Protovirgularia isp. and its presence in almost all bedding surfaces, allied with the abundance of wrinkle marks in these beddings suggest deposition in marginal marine mud flats possibly influenced by tides. The local occurrence of freshwater shallow burrows points to periodic freshwater influx into these flats, as a consequence of deglaciation pulses. Otherwise, the common occurrence of myriapod and merostomate trackways preserved as palimpsest over the aquatic suites also reveals the periodically subaerial exposure of the substrate. These data are coherent with the dominance of pollen grains and the great amount of cloudy phytoclasts, strengthening a distal positioning to the source area, with strong continental influence.

Key words: paleoichnology, palynology, Rio do Sul Formation, Itararé Group, Paraná Basin.