Estruturas de arrasto de icebergs em ritmito do Subgrupo Itarare (Neopaleozoico), Trombudo Central, SC

Abstract

A series of long, sinuous and subparallel furrows on bedding planes of rhythmites of the Itarare Subgroup (Early Permian), cropping out in the state of Santa Catarina, southern Brazil, are interpreted as icebergs scours. Troughs are associated with abundant ice-rafted clasts, pellets and mounds of dumped debris melted out from floating icebergs, and lenses of debris possibly released from grounded icebergs. Rhythmites were deposited in a sizeable, relatively deep freshwater body, at least in part as varves, during the last episode of deglaciation of the late Paleozoic glaciation. Iceberg scours are common in modern and Pleistocene glaciated shelves, but are not known fron the ancient record despite selective preservation of glaciomarine rocks. This paper presents the first detailed description of iceberg scours from pre-Pleistocene strata. -English summary