Sea-level fluctuations during the last 8600 years in the de la Plata river (Argentina)

Abstract

The de la Plata river, considered from the geomorphologic point of view, can be defined as a unit composed of a set of features genetically linked together which were formed as a result of the post-Last Glacial Maximum transgression. Regional stratigraphical, morphological and topographical studies carried out in the de la Plata river and surrounding areas of eastern Argentina determined that the Holocene evolution of the area was the result of processes resulting from relative sea-level fluctuations. In order to date the different stages of evolution, a curve of sea-level fluctuations was constructed after a selective choosing of samples with reliable ages supported by field geological evidence. The curve shows a rapid initial transgressive event and the maximum highstand of mean sea level at 6000 yr BP at a relative elevation of +6.5 m above present. The following regressive event was characterized by a discontinuous fall in sea level. Geomorphological evidence suggests that sea-level fall could have experienced minor changes in rate as well as moments of stability that are not shown by the curve. Short interruptions in the geological record can be explained either by the same minor changes in sea level or by a change in wave regime. Correlation of transgressive–regressive events with paleoclimatic and biogeographic information proposed that Holocene sea-level fluctuations in the de la Plata river were mainly controlled by climatic changes.