MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
Past environmental changes during the Late Holocene sea-level fall (last 2.7 Ka) at Bahía Samborombón, NE coastal plain (Argentina).
LUENGO MARIEL; FUCKS ENRIQUE; BERNASCONI EMILIANA; VILANOVA ISABEL
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
PERGAMON-ELSEVIER SCIENCE LTD
Lugar: Amsterdam; Año: 2018 vol. 85 p. 362 - 362
Here we present a reconstruction of vegetation history and environmental changes at the central zone ofBahía Samborombón during the Late Holocene sea-level regressive phase (last 2.7 Ka) corresponding to MIS 1.This study is an integrative approach based on the combination of geomorphological and micropaleontological(pollen, non-pollen palynomorphs and foraminifera) proxy data. We found agreement among the environmentalinferences from each proxy, which clearly show the evolution of the estuarine saltmarsh from an intertidal environmentunder significant marine influence towards a supratidal brackish-freshwater environment as sea-levelwas falling. The evidence of this evolution is (1) coastal progradation encompassing at least 5.7 km as revealedby relict shorelines. Saltmarsh elevation is another evidenced as a result of accretion due to fine sediments accumulationof at least 1.2 m thick. We posit based on these values, significant progradation and accumulationprocesses. (2) Plant succession, characterized by the replacement of low saltmarsh vegetation by that typical ofhigh saltmarsh; which then is associated to brackish-freshwaters plant communities in shallow water-bodies environments.(3) A gradual decrease of dinocysts and foraminifera assemblages, the latter absent during the last millenniumindicating a decrease in marine influence and the consequent lower salinity values. Bahía Samborombóncoastal plains became a regional scale character during the last 2.7 Ka due to its surface increase, turning intoone of the most extensive southeastern-South America saltmarshes, currently constituting a biosphere reserve.