Relative sea level and wave energy changes recorded in a micro-tidal barrier in southern Brazil

Constructional sedimentary history of coastal barriers can provide insights regarding meteorological and oceanographic processes, and relative sea-level changes. We investigated the Holocene evolution of a segment of the Rio Grande do Sul Coastal Plain in southernmost Brazil. Data were obtained from...

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Published inQuaternary research Vol. 110; pp. 13 - 25
Main Authors Santos, Natália B., Lavina, Ernesto L.C., Paim, Paulo S.G., Tatumi, Sonia H., Yee, Márcio, dos Santos, Veridiana O., Kern, Henrique P.
Format Journal Article
LanguageEnglish
Published New York, USA Cambridge University Press 01.11.2022
Subjects
Aerial photography
Altimetry
Beach profiles
Beaches
Climate change
Coastal plains
Evolution
Geology
Holocene
Radar
Research Article
Sea level
Velocity
Wave energy
Wave power
Brazil
Rio Grande do Sul Brazil
Forced regression
morphodynamics
Progradational barrier
Ground-penetrating radar
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Summary:Constructional sedimentary history of coastal barriers can provide insights regarding meteorological and oceanographic processes, and relative sea-level changes. We investigated the Holocene evolution of a segment of the Rio Grande do Sul Coastal Plain in southernmost Brazil. Data were obtained from ground-penetrating radargrams, optically stimulated luminescence dating, altimetry measurements, Google Earth imagery, and aerial photographs. These data allowed a qualitative and quantitative analysis of the beach profiles recorded in the radargrams. From which eolian, backshore/foreshore, breaker bars, and upper and lower shoreface radar facies were identified. The beach-related radar facies are recorded in twenty-eight progradational sand units (sigmoidal bodies). These units record increments of relatively steady deposition bounded by erosional surfaces produced by anomalous, high-magnitude storm events taking place about every 250 years. The upper shoreface strata include two to three breaker bars. Several pieces of evidence (number of breaker bars, upper shoreface gradient and progradation rate) suggest an alternation between dissipative and intermediate stages of barrier morphodynamics and a decrease of wave energy from 2 ka onwards. The barrier prograded during the last 7.1 ka, and initially, barrier progradation occurred because of a normal regression during a relative sea-level rise followed by a stillstand. Later, barrier progradation took place as a forced regression driven by a relative sea-level fall.
ISSN:0033-5894
1096-0287
DOI:10.1017/qua.2022.23