2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 11
Presentation Time: 4:00 PM


SCOTT, David B.1, SCHELL, Trecia1 and ROCHON, Andre2, (1)Department of Earth Science, Dalhousie Univ, Halifax, NS B3H 3J5, Canada, (2)Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski, 310, allée des Ursulines, Rimouski, QC G5L 3A1, Canada, tschell@dal.ca

As part of the Canadian Arctic Shelf Exchange Study (CASES) over 50 surface locations were sampled for foraminifera for the first time in 40 years in water depths ranging from 50 to 1100m. Unlike previous studies smaller size fractions (>45-63?; and above) instead of the usual >63 or 150?; above fractions were examined. Some species not previously observed here were recorded such as Elphidiella hannai, a species commonly found along the British Columbia coast and a series of large agglutinated forms including two Komokiacea species, a group not recorded before anywhere in the Arctic Ocean. One species, Ammotium cassis, only occurred near methane seeps (a mud volcano and pingo-like features) suggesting that this species might be more tolerant to methane and provide a good proxy for past methane emissions when observed down core. In the smaller size fraction (45-63 ?) there were a set of species in some places (the Amundsen Gulf) that provided evidence of deep Arctic water penetrating to depths as shallow as 150m. The smaller size fraction often had more specimens per 10cc than the 63? and above fraction but less species. There was a fairly even division between the calcareous and agglutinated forms which is the fundamental difference between the Arctic and Antarctic where the former has mostly agglutinated forms. Also because the Mckenzie Shelf has a large surface freshwater component the sedimentation rates are much higher here than the Antarctic which will provide us with high resolution records of the Holocene. Our main purpose was to be able to reconstruct the sea ice cover history in Holocene. The key to this was obtaining cores and samples where there were sufficient planktonic foraminifera which are sensitive to ice cover changes. In samples deeper than 500m there was a significant percentage of planktonics and where there was large freshwater input, there were tintinnids so that we now have two proxies for ice cover and freshwater (if there is a lot of freshwater, there isn't much ice cover). Hence we will be able to achieve our main goal of reconstructing Holocene ice cover history.