HR: 1340h
AN: PP33B-1565    [Abstracts]
TI: A Comparison of Changes in Faunal Assemblages Over the Past 12,000 Years in Isafjardardjup, a Fjord in NW Iceland
AU: * Quillmann, U
EM: ursula.quillmann@colorado.edu
AF: INSTAAR and Department of Geological Sciences, 1560 30th Street UCB 450, Boulder, CO 80309 United States
AU: Andrews, J T
EM: john.t.andrews@colorado.edu
AF: INSTAAR and Department of Geological Sciences, 1560 30th Street UCB 450, Boulder, CO 80309 United States
AU: Jennings, A E
EM: anne.jennings@colorado.edu
AF: INSTAAR and Department of Geological Sciences, 1560 30th Street UCB 450, Boulder, CO 80309 United States
AB: This study compares faunal assemblages over the past 12,000 cal yrs in the context of changes in stable isotopic composition and sedimentology at two different sites in Isafjardardjup, a fjord in NW Iceland. Isafjardardjup (66 deg N, 23 deg W) was chosen for its high sedimentation rates and for its sensitive location to both polar atmospheric and polar oceanic fronts. Core MD99-2266 was selected to represent the outer fjord environment and Core B997-339 the inner fjord environment. Faunal assemblages have changed dramatically throughout this period. Elphidium excavatum forma clavata an opportunistic species that thrives in unstable environmental conditions, was present in large numbers at both sites during the early Holocene when land-based glaciers calved and sediments accumulated rapidly. During warmer times, Cassidulina laevigata was dominant. The outer fjord site was dominated by {Cibicides lobatulus}, an indicator of strong bottom currents. Cassidulina reniforme and E. excavatum, both indicators of cooler, arctic waters and varying salinity concentrations, are prevalent at the inner fjord site, but are not so significant at the outer fjord site. Overall, infaunal species, such as Nonion labradoricum, have dominated the inner fjord site throughout the Holocene. C. lobatulus tests, found at both locations were analyzed for stable isotopic composition, which is a function of temperature, salinity, and global ice volume. The outer fjord site shows lighter oxygen isotopes overall, suggesting warmer and/or fresher bottom waters. The oxygen isotopes at the inner fjord site lighten around 8000 cal yr BP by 0.3 per mil, a shift not recorded at the outer site. The mass accumulation rates (MAR) in the outer fjord site were ten times as high as those in the inner fjord site in the early Holocene, five times as high in the middle Holocene, and roughly the same over the past 5000 years.
DE: 1600 GLOBAL CHANGE
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1635 Oceans (1616, 3305, 4215, 4513)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005