Morphology of the Ibiraqüera dunefield, SC

MORPHOLOGY OF THE IBIRAQÜERA DUNEFIELD, SC^*

CAROLINE T. MARTINHO^** AND PAULO C.F. GIANNINI

Departamento de Geologia Sedimentar e Ambiental, Instituto de Geociências, USP, São Paulo, SP.

Presented by ANTONIO C. ROCHA-CAMPOS

The Ibiraqüera beach is located in the municipal district of Imbituba, mid-south coast of the Santa Catarina State. The active dunefield present in this beach possesses parabolic geometry and oblique position to the coastline. It begins with foredunes, that locally appear cut and destabilized by for blowouts. Towards the interior, the dunefield passes into an extensive deflation area. This area is composed by deflation plains, usually vegetated and/or flooded, gegenwalle ridges, trailing ridges and isolated parabolic dunes. The trailing ridges appear as lateral portions of transverse and barchanoid dunes. They are fixed by vegetation and left back while the rest of the dune migrates, forming straight ridges of sand, vegetated in the external part and unvegetated in the internal part. The gegenwalle ridges appear in the deflation plain as small ridges of sand (approximate height of 1 m) that possess the identical format of the barchanoid and parabolic dunes' windward limit. They form periodic sequences that record dunefield migration in the deflation area. The parabolic dunes present unvegetated sands in the main advance front (depositional lobe), trailing ridges on both sides with a deflation plain between them. In the internal part of the dunefield the deflation facies disappears, giving place to chains of transverse and barchanoid dunes. They finish in secondary advance fronts contained by the vegetation (precipitation ridges). The whole internal and frontal dunefield borders possess precipitation dunes. In old dunefields totally vegetated now, morphologic features were also recognized such as precipitation dunes and deflation plains.

In Ibiraqüera it is possible to notice that the dunefield started from the north part of the beach and migrated SW, toward the continent. The north section of the beach possesses higher sediment supply than the other sites, seeing that the foredunes in this area are not very well developed, and are buried by small transverse dunes that appear close to the beach.

The characterization of the facies of the Ibiraqüera dunefield allowed to correlate this dunefield to the typical distal or deflation facies association described by Giannini (An Acad Bras Cienc (1998) 70(3): 696). — (December 14, 2001).

Publication Dates

• Publication in this collection
  09 Oct 2002
• Date of issue
  Sept 2002