CGRG Bibliography of Canadian Geomorphology
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Author : Chang, A.S.; Hendy, I.; Cosmas, T.; and Pederson, T.F.
Date : 2006.
Title : Paleoproductivity, upwelling and glaciation histories on the Vancouver Island Margin over the last 45 kyr.
Publication : Joint Annual Meeting of the Geological Association of Canada and the Mineralogical Association of Canada. University of Quebec in Montreal (UQAM) May 14-17, 2006.
Issue :
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Abstract
A 38-m long sediment core was recovered on the Vancouver Island margin (48°58.47’ N, 127°02.14’ W) at a water depth of 1190 m. A multiproxy approach was used to determine the histories of paleoproductivity, upwelling and glaciation over the last ~45 kyr. Total N, inorganic and organic C, % opal, d15N, and d18O from the planktonic foraminiferan Globigerina bulloides were analyzed. Sedimentation rates and the abundance of ice-rafted debris (IRD) were also determined. Preliminary results indicate that productivity was higher during Marine Isotope Stage (MIS) 3 relative to the Last Glacial Maximum (LGM). Glaciers reached their maximum extent on the shelf at 19 kyr. Deterioration of the ice sheet began at 17 kyr, as indicated by an increase in IRD and sedimentation rates. During this time, there is no significant decrease in % organic C, suggesting that upwelling and productivity increased, keeping pace with sedimentation, or that there was an increase in terrestrial organic matter input, or that degradation of organic matter was minor. Productivity increased slightly from the LGM to the Bølling warm period and then decreased again during the Allerød warm period when the ice sheet had completely retreated. Productivity during the Younger Dryas cool interval increased again but to levels slightly below that of the Bølling. Higher N, organic C and opal values during the Holocene likely reflect increased upwelling and productivity, and/or better preservation of organic matter, in conjunction with greatly reduced sedimentation rates since the beginning of the Holocene. The records from the Vancouver Island Margin are compared to other upwelling sites in the northeast Pacific where large-scale productivity and glacial-interglacial intervals are found to be similar.
Bibliography of Canadian Geomorphology