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LATE HOLOCENE PALEOCEANOGRAPHIC VARIATIONS OF ISAFJARDARDJUP, NW-ICELAND

QUILLMANN, URSULA  INSTAAR.

This work is a high-resolution analysis of an Icelandic shelf core, as part of an effort to resolve ocean climate and environmental changes in and around the North Atlantic over the last 2000 years. High-resolution data from Core MD99-2266, retrieved from NW Icelandís inner continental shelf at the mouth of Isafjardardjup, were analyzed isotopically and sedimentologically to determine if the results can provide valid and substantial information about climatic and environmental variations during the past 2000 years, and to determine if settlement of Iceland may have caused marked changes in the record. Tests of Cibicides lobatulus, a calcareous, benthic foraminfera, were analyzed for d18O and d13C in carbonate, as possible indicators of changes in climate or environment. Five radiocarbon dates through the upper 265 cm of the core were used to correlate depth to calibrated year, which yielded a linear sedimentation rate of 7.6 years/cm.

The results of all sedimentological and isotopic analyses were cross-correlated to evaluate possible associations with one another. Features that may be associated with marine influence were higher total carbonate, higher d18O, and an increase in sand-size particles. Features that may have been associated with terrestrial influence were higher percent nitrogen, an increase in clay-size particles, and an increase in organic carbon and higher magnetic susceptibility. The interpretation of d13C remained inconclusive.

Although time-related shifts clustered around 300, 800, 1200, 1600, and 1800/1900BP, consistent with other studies that linked these periods to major climatic changes, no significant changes in the variables were found that might reflect the settlement of Iceland by humans.

This work is the preliminary study for more detailed research of Isafjardardjup. The ongoing research will be aimed at Cores B997-339, 441, and 442, which are more proxal to the fjord head and land/sea interaction. It is hoped that these cores will yield a more refined view of the Late Holocene climate and of the influence of terrestrial processes in the sedimentary record.


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