HR: 1340h
AN: PP23B-1403    [Abstracts]
TI: A High-Resolution Study to Reconstruct Paleoclimate and Paleoceanography in Isafjardardjup, NW Iceland
AU: * Quillmann, U
EM: Ursula.quillmann@colorado.edu
AF: INSTAAR, Department of Geological Sciences, University of Colorado at Boulder, 1560 30th Street 450 UCB, Boulder, CO 80309-0450 United States
AB: Our goal is to study paleoclimatic and -oceanographic changes in Isafjardardjup, a fjord in NW Iceland. We have chosen three sites along a head to mouth transect in this fjord for a high-resolution analysis. Each site gives us an approximate 10,000-year record. The three sites are B997-339, B997-341, MD99-2266. To reconstruct paleoclimate and -oceanography, we are using three proxies: faunal assemblages, isotopes, and sediments. We are analyzing faunal assemblages, where a representative sample of about 200 benthic foraminifera per 10-cm interval is identified (1000-11,000 cal yr BP). We also are analyzing the sedimentological record. The calcareous tests of foraminifera are being used to obtain stable isotopic data. We are taking advantage of site B997-339 at the mouth of Skotufjordur (a tributary fjord located near the head of Isafjardardjup). In the upper 200 cm of this core, Cibicides lobatulus, Cassidulina reniforme, and Nonion labradoricum occur in sufficient amounts and are well-preserved, suitable for isotopic analysis. Because of vital effects, the isotopic results vary from species to species. We analyze these differences and will apply our findings to the other sites. At the other sites, we find only one or the other species well-preserved, present throughout the entire core, and in sufficient numbers for isotopic analysis. Foraminifera, which make up $>$5% of the sample (size fraction 106-1000 micron) have been statistically evaluated at a 100-yr resolution. The results show faunal changes at 100 cm and 300 cm depth. The change at 100 cm is recognizable in sedimentological data. The sand-size fraction of sediments increases in the top 100 cm of the core as the clay-size fraction decreases. Total organic carbon content increases, but the inorganic carbon contents decreases. Sedimentological changes, however, are not detected at the 300 cm level. Here the isotopic del-18O of the foraminifera Cassidulina reniforme shows a change from 3.50 to 3.05%. The del-18O of Cibicides lobatulus, an epifaunal, benthic foraminifera, at sites MD99-2266 (at the mouth of Isafjardardjup) and B997-339 for the interval between 1000-2000 cal yr BP averages 1.8%, indicating that temperature has been the main driver for isotopic results during this time interval.
DE: 3030 Micropaleontology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting