INVESTIGADORES
BERNASCONI Emiliana
artículos
Título:
Past environmental changes during the Late Holocene sea-level fall (last 2.7 Ka) at Bahía Samborombón, NE coastal plain (Argentina)
Autor/es:
LUENGO MARIEL; BERNASCONI EMILIANA; VILANOVA ISABEL; FUCKS ENRIQUE
Revista:
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2018 vol. 85 p. 362 - 373
ISSN:
0895-9811
Resumen:
Here we present a reconstruction of vegetation history and environmental changes at the central zone of BahíaSamborombón during the Late Holocene sea-level regressive phase (last 2.7 Ka) corresponding to MIS 1. This studyis an integrative approach based on the combination of geomorphological and micropaleontological (pollen, nonpollenpalynomorphs and foraminifera) proxy data. We found agreement among the environmental inferences fromeach proxy, which clearly show the evolution of the estuarine saltmarsh from an intertidal environment undersignificant marine influence towards a supratidal brackish-freshwater environment as sea-level was falling. Theevidence of this evolution is (1) coastal progradation encompassing at least 5.7 km as revealed by relict shorelines.Saltmarsh elevation is another evidenced as a result of accretion due to fine sediments accumulation of at least 1.2 mthick. We posit based on these values, significant progradation and accumulation processes. (2) Plant succession,characterized by the replacement of low saltmarsh vegetation by that typical of high saltmarsh; which then isassociated to brackish-freshwaters plant communities in shallow water-bodies environments. (3) A gradual decreaseof dinocysts and foraminifera assemblages, the latter absent during the last millennium indicating a decrease in marineinfluence and the consequent lower salinity values. Bahía Samborombón coastal plains became a regional scalecharacter during the last 2.7 Ka due to its surface increase, turning into one of the most extensive southeastern-SouthAmerica saltmarshes, currently constituting a biosphere reserve.Keywords Late Holocene; Bahía Samborombón; sea-leve