GLACIAL SCOURS OF THE CURITUBA FORMATION, BRAZIL: OCCURENCE, CHRACTERISTICS AND ORIGIN

Unique landforms of the Curituba Formation (late Paleozoic, 300 million years before present) presumed to be glacial scours (Rocha-Campos et al, 2003) were located, described and measured. The Curituba Formation is exposed in the Santa Brigida Graben in the Sergipe - Alagoas basin. Outcrops studied are located near Lagoa Seca, Bahia State and Curituba, Sergipe State, Brazil.

The outcrops studied consist predominantly of a sand - sandy diamict containing sparse clasts. At many outcrops there are abundant burms and striations, landforms that provide evidence of iceberg calving and/or a nearby-grounded glacier. The striations and burms (which also contain striations) are up to 30m in length, 3.5m wide and 40cm deep and are consistently oriented approx. N40W.

The morphology of the features analyzed is very consistent with descriptions of iceberg scours in the literature. However, the consistency of the N40W orientation is somewhat problematic. Striae of iceberg origin should vary more and there is very little evidence for grounded ice nearby (Rocha-Campos et al, 2003). Additionally, there appears to be six different stratigraphic horizons of these consistently oriented striations.

Characteristics, origin and possible explanations of these unique features will be presented. Research for this study was funded by grants from the N.S.F.-PAESMEM Program (NSF-HRD 0003111) and the University of Minnesota - Undergraduate Research Opportunities Program (UROP).

Reference: Rocha-Campos, A.C et al, 2003, Late Paleozoic landforms of glacial erosion and glacial geology on the southern flank of the Ponta Grossa arch, Paraná Basin, Brazil. Contribuições apresentadas no 3rd Latin American Congress of Sedimentology, Belém, Paraná, Brazil.