Geomorphology and stacking patterns of the Holocene barrier in the northern Rio Grande do Sul coast

Coastal barriers can exhibit an array of stratigraphies and morphologies reflecting the drivers acting during their evolution in different temporal (secular and millennial) and spatial scales, leading to distinct stacking patterns. In this work, the Holocene coastal barrier in the northern coast of Rio Grande do Sul is investigated between Dunas Altas and Xangri-La aiming a detailed analysis of the extension and characteristics of progradational and retrogradational sectors. In order to do so, GPR sections were collected along 65 km of the barrier. A drillhole (20,45 m depth) was acquired and a morphological analysis was conducted through digital surface model (TanDEM-X). An alternation in the barrier stacking patterns was defined. Dunas Altas shows a progradational pattern. At Quintao, 6,5 km northwards, the barrier changes to a retrogradational pattern, which is maintained until South Tramandai, where it changes quickly to a progradational pattern in a 1 km stretch of coast, keeping this stacking pattern until Xangri-La. The delimitation of distinct stacking patterns contributes to the understanding of the long-term barrier behavior and supports coastal management mainly regarding the delimitation of erosive sectors.