CONICET | Buscador de Institutos y Recursos Humanos

A foraminiferal faunal study was carried out to contribute to the knowledge of the palaeoenvironmental conditions during the late Holocene in the Beagle Channel. In that context, this foraminiferological study of a Holocene marine section from Arroyo Baliza (54º 51´S and 68º 33´W), located on the northwest coast of the channel, complements the palynological results previously documented for this site. An abundance of 40,368 predominantly calcareous individuals (10g of dry sediment for sample) was recorded throughout the sequence represented by 32 species distributed among 18 genera. The foraminiferal assemblage was dominated by Elphidium macellum (Fichtel and Moll, 1798), Elphidium alvarezianum (d´Orbigny, 1839), Cribroelphidium excavatum (Terquem, 1875) and Buccella peruviana (d?Orbigny, 1839), accompanied by Cibicides fletcheri Galloway and Wissler, 1927 and Cibicidoides dispars (d´Orbigny, 1839) in low proportion. The microplankton assemblage is characterised by a dinoflagellate cyst species diversity of 18 taxa, mainly Peridiniales over Gonyaulacales, it probably suggests inner neritic conditions, with high nutrient input in the marine environment associated with cooler and more nutrient-rich waters. The distribution of the foraminiferal species was variable throughout the sequence suggesting palaeoenvironmental changes in Arroyo Baliza between 3823-3062 14C yr BP. A gradual passage from high energy, cold and well-oxygenated marine waters towards a shallow environment with low energy, low to moderate salinity and an increasing temperature of the waters was recognized. This supports the previous palynological information from this section, which reflects an increase in number and diversity of dinocyst species suggesting marine environmental conditions during the late Holocene as it exists today in the Beagle Channel.