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abstracts
Tropical salt-marsh evidence for rapid sea-level changes associated with Heinrich events
Catalina González, Lydie M. Dupont
The role of sea-level as an active mechanism of rapid climate change is still under debate and new records that complement the almost exclusively marine body evidence are needed. The ecological response of intertidal tropical ecosystems can be particularly useful, since they are sensitive to environmental gradients in the sea-continent interface, and might provide valuable information on sea-level variations in the past. Centennial-millennial dynamics of tropical salt marsh vegetation are documented in the pollen record from marine core MD03-2622, Cariaco Basin, which spans the period between 63 and 29 ka. Five rapid and abrupt expansions of salt marsh vegetation are coeval with the north Atlantic Heinrich events (HEs). Within each event, a recurrent pattern –starting with species of Chenopodiaceae, followed by grasses, and subsequently by Cyperaceae species– suggests a successional process that is determined by the relationship between sea-level and community dynamics. Salt tolerant Chenopodiaceae expansions at the base of each sequence indicate hypersaline intertidal environments, which were promoted by extremely dry conditions. Rapid sea-level rise characterizes these intervals, causing erosion of marsh sediments, and continued recruitment of pioneer species. Once as sea-level drops, marsh plants are able to trap and stabilize sediments, favouring the establishment of more competitive species. The increment of marsh height reduces the extent of hypersaline environments, and allows the further establishment of mesohaline species. The Cariaco Basin palynological record is especially informative on the timing of sea-level changes during MIS 3 and their connection with HEs, supporting the idea that sea level fluctuations followed Antarctica climate variability.
Catalina González, Department of Geosciences, University of Bremen,Klagenfurter Strasse, 28359 Bremen, Germany, catalina@uni-bremen.de
Lydie M. Dupont, University of Bremen, MARUM/Department of Geosciences, 28359 Bremen, Germany
Session: F1: Climate Forcings
Download Talk:
> YSM09_OralA_Gonzalez.pdf
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