ABSTRACT

Leal, R.A.; Barboza, E.G., Bitencourt, V. Jr. Biancini da Silva, A. and Manzolli, R.P., 2016. Geological and Stratigraphic Characteristics of a Holocene Regressive Barrier in Southern Brazil: GIS and GPR Applied for Evolution Analysis. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 750–754. Coconut Creek (Florida), ISSN 0749-0208.

The observation of geological and geomorphological factors in coastal barriers to allows interpret the processes involved and the temporal trends over time. During the Holocene, the Balneário Torneiro barrier, located in the southern coast of Santa Catarina, prograded approximately 1.3 km, preserving the records of Urussanga river's system dynamics in surface and subsurface paleochannels. The presence of such features close to the boundary with the Pleistocene deposits up to the present coastline indicates that the evolutionary behavior of the barrier is progradational. The identification of superficial morphological features interpreted on the barrier such as transgressive dune sheets and beach ridges corroborates this interpretation. In subsurface, three main radar facies (RF-1, RF-2, RF-3), a surface radar (erosive surface) and a subsurface feature (SF) were identified in the Ground Penetrating Radar (GPR) profiles. Continuous to discontinuous reflectors, sub parallel with high amplitude, were interpreted as corresponding to the beach/shallow marine environment (RF-1) formed by the barrier progradation. An erosive surface in concave form truncating these reflectors, with onlap and downlap reflectors in the concave face, and truncation in the convex base, was interpreted as the base of a paleochannel. The others radar facies (RF-2 and RF-3) are related to the filling of the channel. The integrated interpretation of GIS and GPR data have allowed to interpret evolutionary characteristics at different time scales of the studied barrier sector.

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