Abstract A foraminiferal faunal study was carried out in a Holocene marine section from Arroyo Baliza, located on the northwest coast of the Beagle Channel, to contribute to the knowledge of the palaeoenvironmental conditions during the marine Holocene event. Foraminiferal assemblage was represented by 32 species distributed among 21 genera. The assemblage was dominated by Elphidium macellum (Fichtel & Moll) Elphidium alvarezianum (d’Orbigny), Cribroelphidium excavatum (Terquem) and Buccella peruviana (d’Orbigny), accompanied by Cibicides fletcheri Galloway & Wissler and Cibicidoides dispars (d’Orbigny) in low proportion. The predominance of Peridiniales dinocysts in the marine palynomorphs assemblage, suggested inner neritic conditions with cooler and more nutrient-rich waters. The distribution of the foraminiferal species was variable throughout the section indicating palaeoenvironmental changes in Arroyo Baliza between 3499–2595 cal yr BP. A gradual passage from high energy, cold and well-oxygenated marine waters towards a shallower environment with low energy and low to moderate salinity of the waters were linked to the regressive phase. This study complements and supports the previous palynological data from this section, which reflects an increase in number and diversity of dinocyst species indicating marine environmental conditions during the late Holocene as it exists today in the Beagle Channel.

The analysis of recent benthic foraminifera from the continental shelf and San Matías Gulf is presented. Quantitative analysis was performed using methods from compositional data analysis theory. Principal Components Analysis, Cluster analysis and Geographic Information System (GIS) were used to infer a) six groups of species that respond to oceanographic conditions, four of which were related to coastal waters and the others could be influenced by the Malvinas current system; b) the relationship between 13 species and the water temperature, bottom sediments, and energetic conditions of the area c) a correlation between Cibicides dispars/Bulimina patagonica and Cibicides mckannai/Bulimina patagonica and water temperature.

Se presenta el análisis de foraminíferos bentónicos en sedimentos superficiales de un sector de la Plataforma Continental Argentina y el golfo San Matías. El estudio cuantitativo se efectuó empleando métodos de análisis estadístico de datos composicionales. Mediante el Análisis de Componentes Principales (ACP), Análisis de Agrupamiento y Sistema de Información Geográfica (SIG) se pudo inferir: a) la presencia de seis grupos de especies cuyas características responderían a las condiciones oceanográficas del lugar, cuatro de ellos indicarían el predominio del sistema de agua costera y los dos restantes, la influencia de la corriente de Malvinas; b) la vinculación entre las variaciones conjuntas que experimenta la composición de 13 especies con la temperatura del agua, las características del fondo y las condiciones energéticas en el área y c) la correlación existente entre las relaciones Cibicides dispars/Bulimina patagonica y Cibicides mckannai/Bulimina patagonica y la temperatura del agua.

Fifty species of benthic foraminifera from a core of the Argentine Continental Shelf were identified. Elphidium discoidale (d'Orbigny), Buccella peruviana campsi (Boltovskoy), Quinqueloculina patagonica d'Orbigny and Quinqueloculina seminula (Linné) were the dominant species. The association is characteristic of inner shelf environments. Qualitative and quantitative analyses allow the recognition of a lower zone with an assemblage typical of restricted environments, and an upper zone which, according to foraminifers, reflects a change towards normal marine conditions. The core was deposited during the post last glacial maximum transgression, about 10.000 yr B.P.

Se reconocen 50 especies de foraminíferos bentónicos recuperados de un testigo proveniente de la cuenca del Colorado. Predominaron Elphidium discoidale (d'Orbigny), Buccella peruviana campsi (Boltovskoy), Quinqueloculina patagonica d'Orbigny y Quinqueloculina seminula (Linné). La asociación de especies encontrada indica un ambiente marino de plataforma interna. A partir de análisis cualitativos y cuantitativos se pudieron distinguir dos tramos. En el tramo inferior se infiere un ambiente restringido, mientras que en el tramo superior se observa una tendencia al establecimiento de las condiciones marinas normales. Los sedimentos del testigo se habrían depositado durante la transgresión del último máximo glacial, hace aproximadamente 10.000 años B.P.

Qualitative, quantitative and statistic analysis on samples of surface sediments from San Matías Gulf, Río Negro Province, Argentina, reveal a relationship between the type of substrate- depth and characteristics and distribution of the benthic foraminifer Nonionella auris (d´Orbigny). The study suggests that the development of this species is favoured in low energy and deep environments with muddy substrates.

Se estudia la influencia del tipo de sedimento y la profundidad en la distribución y desarrollo del foraminífero bentónico Nonionella auris (d'Orbigny). Se analizaron muestras de sedimentos superficiales provenientes del golfo San Matías, provincia de Río Negro, Argentina. Los estudios cualitativos, cuantitativos y estadísticos realizados sugieren que sitios con mayor profundidad, mayor contenido de fango y bajo nivel de energía propiciarían el desarrollo de esta especie.