Produção Nacional
A erosão na costa leste da Ilha do Mel, Baía de Paranaguá, estado do Paraná: modelo baseado na distribuição espacial de formas deposicionais e propriedades sedimentológicas
2004; Sociedade Brasileira de Geologia; Volume: 34; Issue: 2 Linguagem: Inglês
10.5327/rbg.v34i2.1109
ISSN2317-4889
AutoresPaulo César Fonseca Giannini, Rodolfo José Angulo, Maria Cristina de Souza, Jaqueline Silveira Kogut, Marlon dos Santos Delai,
Tópico(s)Aeolian processes and effects
ResumoMel Island, a Holocene beach-ridge plain, underwent intense morphologic changes in the past 50 years, including the gradual erosion of its central istmus, from more than 150 m to less than 5m presently. The eastern side of the island is sub-parallel to a same abuting beach-ridge, which is undergoing a process of intense erosion. It is hypothesized that this beach-ridge works as a sedimentologically uniform source to the present beach. Therefore, any significative variation in the heavy minerals suite alongshore may indicate a net sediment transport direction. The results from grain size and heavy mineral studies suggest a pattern of longshore drift cell circulation, with two convergence zones, separated by a divergence zone. This pattern is consistent with field observations: the first convergence zone, in the mid-north beach, coincides with the location of a recently developed sandy cusp; the divergence zone is located close to the erosional istmus; and the second convergence zone, in the south, coincides with the site of a prograding sand spit. Therefore, the istmus erosion could be explained by the lack of sand supply to this area due to the divergent character of the longshore drift. Similarly, the sand cusp and the sand spit could be related to the sedimentary stock due to the convergent character of the longshore drift.
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