TAXONOMIC AND PALEOECOLOGICAL CHARACTERIZATION OF HOLOCENE INGRESSION IN THE BEAGLE CHANNEL (TIERRA DEL FUEGO), BASED ON DINOCYSTASSEMBLAGES AND OTHERAQUATIC PALYNOMORPHS

On the southern coast of Tierra del Fuego, Argentina, the Holocene marine ingression took place around 8,000 C-14 years BP, and it is represented by several discontinuous marine terraces along the north coast of the Beagle Channel. During the beginning of the marine incursion, the aquatic assemblages developed in Bahia Lapataia and Rio Varela localities, were characterized by a scarce participation of marine components, especially of dinoflagellate cysts. After 6,000 C-14 years BP, in Rio Ovando and Albufera Lanushuaia localities, an increase in the number of aquatic species was observed with a major participation of Peridiniales dinocysts in the associations, suggesting the establishment of marginal marine environments with low to moderate salinities and high nutrient content in the water. The analysis of the dinofiagellate cysts and other aquatic palynomorphs assemblages recorded in the marine sediments from northern coast of the Beagle Channel, indicate that the environmental conditions during the middle-late Holocene correspond to fjord (estuarine) environments close to ice fields affected by glacier meltwater discharge with anomalously low salinities. These aquatic assemblages identified have a similar composition to those observed in modem sediments of the Beagle Channel.