2002 Denver Annual Meeting (October 27-30, 2002)

Paper No. 15
Presentation Time: 1:30 PM-5:30 PM


CASTANEDA, Isla S., Large Lakes Observatory and Department of Geology and Geophysics, Univ of Minnesota, 10 University Drive, Duluth, MN 55812, SMITH, L. Micaela, BP America, 501 Westlake Park Blvd, Houston, TX 77079, KRISTJANSDOTTIR, Greta Bjork, INSTAAR and Geological Sciences, Univ of Colorado, Boulder, CO 80309-0450 and ANDREWS, John T., INSTAAR & Dept. Geological Sciences, Univ of Colorado, Box 450, Boulder, CO 80309, cast0150@tc.umn.edu

The N. Iceland continental shelf is a highly sensitive climatic indicator due to its location with respect to atmospheric and oceanographic fronts. In this study, we present the first light stable isotope (oxygen and carbon) records from the N. Iceland shelf. We use oxygen isotopes (planktic and benthic foraminifera) and total carbonate data from nine sediment cores to reconstruct the Holocene history of the region. Results of this study show that the Holocene history of N. Iceland consists of three main stages: 1) deglaciation of the NW Peninsula (until ~9000 BP), 2) early Holocene warming (9000-5000 BP), and 3) Neoglacial cooling (5000-0 BP). The 8.2ka calendar year cold event, which has been widely noted in the N. Atlantic, is present as only a minor isotopic event and did not have much of an effect on the N. Iceland shelf. The Holocene maximum warmth occurred between 7000-5000 BP and is indicated by light oxygen isotope values and increased total carbonate contents. Additionally, the boreal species Uvgerinia peregrina is present during this interval. U. peregrina is not found in modern assemblages from the N. Iceland shelf and its presence indicates warmer conditions. Over the past 5000 BP, the interval best documented in this study, a cooling trend towards the present has occurred. Superimposed on this overall cooling trend are a number of oscillations between relatively warm and cold intervals. Relatively warm intervals occurred at 3400-3200 BP, 2600-2550 BP, and from 1800-1200 BP. Colder periods occurred at ~3800-3600 BP, 3000-2800 BP, 2450-2300 BP, and from ~600-200 BP. Several of the relatively cold intervals in the past 5000 BP are similar in magnitude to the Little Ice Age, and during these times bottom waters on the N. Icelandic shelf cooled by up to 2 degrees Celsius. The correlation between our records and other published marine and terrestrial records indicates that changes in water temperatures and atmospheric conditions are closely linked for the region of N. Iceland.