HOLOCENE MARINE ENVIRONMENTAL CHANGES IN VESTFIRDIR, ICELAND: A FJORD HEAD TO MOUTH COMPARISON

This research examines paleoenvironmental changes over the last 10,000-11,000 cal yrs BP in Isafjardardjup, a 100-km long and 100-m deep fjord located in NW Iceland. Not only do the three high-resolution marine sediment cores (rates of sediment accumulation vary between 0.5 m and 5.0 m/ky) chosen for this research provide a continuous and detailed record but also provide insights to environmental changes within the fjord. The chronologies are controlled by multiple 14C AMS dates and by the Saksunarvatn tephra (10,200± cal yrs B.P.) Core B997-339 was retrieved near the fjord head and therefore is potentially strongly influenced by terrestrial run off, whereas core MD99-2266 was retrieved near the fjord mouth and is influenced more strongly by oceanic conditions associated with the Irminger Current. These two cores represent end member conditions in the fjord, whereas Core B997-441 fills the gap geographically between the fjord head and mouth sites. X-radiographs of the cores show that glacier’s descended to tidewater until ~10,000 cal yrs when IRD ceased. Cluster analysis and principal component analyses of benthic foraminiferal data show significant faunal assemblage changes, which coincide with changes in other parameters such as grain-size and sediment composition. Stable isotopic analysis of the benthic foraminifera Cibicides lobatulus and Cassidulina reniforme is being used to reconstruct paleoenvironment and paleoclimate from sites at the fjord head and mouth in order to distinguish between local changes and regional hydrographic variations related to changes in the flux of Atlantic Water.