Variation in the granulometric properties of the coastal barrier of Pinheira (SC) during its progradation in the Late Holocene

Abstract

The coastal barrier of Pinheira is located in the South-Central coast of Santa Catarina State. Its morphology and stratigraphy are typical of a regressive barrier. During the Late Holocene (last 6-5 cal ka) the barrier has prograded approximately 5,500 meters. Its progradation was determined by both a sea-level fall of 2 meters and an expressive transference of sands from the adjacent continental shelf into the beach system of the barrier. In the last 3,000 meters of progradation, corresponding to the last 3 cal ka, approximately 60 foredune ridges were formed, each ridge corresponding in average to a time interval of 50 years. The study of the granulometric properties of the modern beach-dune system, and of two old foredune ridges called intermediate and inner ridges, respectively formed at 750 and 3,000 cal years BP, has demonstrated that in the last 3 ka cal these properties have not changed significantly. This behavior is being explained by the policyclic nature of the sands consumed in the progradation, and/or by a constant or even a little change on the general dynamic conditions of the beach-dune system of the Pinheira embayment.

The comparative study among the sub-environments (beach face, berm and foredune) has shown that standard deviation and skewness are potentially important sediment properties on the distinction between aeolian (foredunes) and beach (beach face) deposits.