Saltmarsh Evolution And Estuary Dynamics During The Last ~8800 Years In The Coastal Plain Bahía Samborombón, Argentina (35.5° S): Pollen And Stable Isotopes Analyses

ISABEL VILANOVA; INGRAM B.L.; FRANCES MALAMUD-ROAM2; WENBO YANG; ALDO R. PRIETO; MAXIMILIANO CLEDÓN

San Francisco

Conferencia; AGU FALL MEETING 3013; 2013

American Geophysical Union

We present δ13C, δ15N and C/N from organic fraction in sediments, δ13C and δ18O from biogenic carbonates and palynology for reconstructing Holocene saltmarsh and estuary evolution in Bahía Samborombón (35.5°S) Argentina over the last ~8800 years. These data derived from material collected from an outcropping section and one core at different distances from the present coastline. Additionally, we obtained modern data along saltmarsh zones. We found middle-to high marsh and the onset of an estuary ~8800?7800 cal yr BP, followed by the estuary development with highest marine input and low marsh zone ~7800?6200 cal yr BP. This estuary received progressively less marine input toward ~5050 cal yr BP, becoming atrophied ~3100 cal yr BP due to isolation from marine influence and evaporation; after that halophytic vegetation developed on Río Salado floodplain surrounded by Pampa grasslands~3100?1000 cal yr BP. The core data showed a low marsh since ~1500 cal yr BP under variable tidal influence, replaced by middle- to high marsh fully established after the construction of the channel-15 ~115 cal yr BP. The contemporary data characterizing modern saltmarsh zones resulted useful analogue, and the stable isotopes and palynology complemented well, overcoming limitations when they are used separately.