INTERPRETING THE FORAMINIFERAL AND DIATOM RECORD FROM PERSEVERANCE DRIFT, NORTHWESTERN WEDDELL SEA, ANTARCTIC PENINSULA

Sediments from Perseverance Drift, northeastern Antarctic Peninsula, were analyzed for foraminiferal and diatom content to determine mid-to-late Holocene oceanographic and sea ice variability. Chronology is constrained via radiocarbon dating of biogenic calcite. The high and stable presence of benthic foraminifera Miliammina spp. through the core combined with abundant spring-blooming Chaetoceros spp., dominantly vegetative cells rather than resting spores, suggest that the region is characterized by consistently high primary productivity that was not nutrient limited. Statistical analysis delineates three foraminiferal assemblages: Miliammina spp., Globocassidulina spp., and P. bartami/P. lepida/ P. antarctica, which reflect affinities with water masses and tolerance to corrosive bottom water conditions. The interval ~3400-1800 yr BP is marked by high abundances of Globocassidulina spp. This opportunistic assemblage took advantage of the highly productive, yet non-corrosive Weddell Sea Transitional Water or Fresh Shelf Water that favored proliferation and preservation of carbonate. This Unit implies a period of ‘freshening’ of the region coinciding with an open-marine or seasonally open-marine environment during the middle-to-late Holocene Climatic Optimum (HCO). The interval 1800 yr BP to the present represents slightly colder Neoglacial conditions. Those conditions are indicated by the absence of the calcareous Globocassidulina spp. assemblage and the pronounced presence of agglutinated P. bartami/ P. lepida/ P. antarctica assemblage, along with other agglutinated species that are indicative of the presence of sea ice. Understanding the paleoenvironmental records of the region provides a perspective on the patterns, mechanisms and significance of the recent rapid regional warming in the Antarctic Peninsula. The Drift is a unique depositional environment that provides an excellent target for future coring based on the abundant carbonate material and the ~90 meter thick sediment package imaged in the 3.5 kHz record. This site holds great potential for developing a multi-proxy data set that documents the depositional and paleoclimatic conditions of the northwestern Weddell Sea through the Holocene.