Foraminifers of the Palmer Deep region, Antarctic Peninsula, modern distribution and paleoceanography of the last 13 ky

This research focused on foraminiferal assemblages from the Antarctic Peninsula, their composition in modern and Holocene sediments dependent on environmental conditions and postmortem processes, and their utility as paleoenvironmental proxies. Additional independent proxies may be provided by chemical analysis of the shells and organic linings of benthic foraminifers in future studies as shown by reconnaissance investigations in this dissertation.; Two assemblages, living during the Austral autumn, have been recognized by the use of the vital stain Rose Bengal. The Bulimina aculeata assemblage, currently present in the Palmer Deep basins, has been proven to be robust to postmortem changes, and indicates open marine conditions during the austral summer, up-welling of Circumpolar Deep Water (CDW) and increased primary productivity in the surface waters. The Fursenkoina fusiformis assemblage seems to be opportunistic and thrives in environments that may be temporarily anoxic. These conditions seem to prevail in the Andvord drift and Gerlache Strait, recently bathed in Weddell Sea Transitional Water (WSTW), where the shallow water depth prevents deep-water circulation and hindering the oxygenation of the bottom waters. Additionally, a third assemblage is proposed in the research. It is hypothesized that the Miliammina arenacea assemblage lives during a different season of the year, since it is present only in the dead assemblages. The use of this assemblage as an indicator of hypersaline conditions, which may be generated by the formation of Saline Shelf Water (SSW), is suggested.; The derived information about ecological adaptations of modern foraminifers was used for the interpretation of Holocene environments from the study area. The results confirm that the Antarctic Peninsula has been a region of rapid and variable climate fluctuation since the Last Glacial Maximum. Four major faunal turnovers have been recognized during the latest Pleistocene. The first occurrence of benthic foraminifers at 12.8 ky BP is interpreted as the time of final disintegration of an ice shelf over the study area. A rapid increase in diversity and abundances at 11.8 ky BP is thought to indicate the beginning of the Holocene in the Antarctic Peninsula region. The onset of the mid-Holocene at 9 ky BP was accompanied by the last occurrence of the WSTW indicator F. fusiformis in the Palmer Deep. Alternating dominance of the SSW indicator M. arenacea and CDW indicator B. aculeata during the last 3.4 ky points to variable and fast changing environmental conditions. The previously observed warming over the last 50 years in the study area may thus be a part of the natural climatic variability of the Antarctic Peninsula.