HR: 0800h
AN: GP31B-0843    [Abstracts]
TI: Magnetic and Sedimentological Records of Late Pleistocene - Holocene Climate Variability from a Western Canadian Coastal Inlet
AU: Baker, J
EM: jubaker@NRCan.gc.ca
AF: Geological Survey of Canada - Pacific, P.O. Box 6000, Sidney, BC V8L 4B2 Canada
AU: * Enkin, R J
EM: renkin@NRCan.gc.ca
AF: Geological Survey of Canada - Pacific, P.O. Box 6000, Sidney, BC V8L 4B2 Canada
AU: Dallimore, A
EM: adallimore@NRCan.gc.ca
AF: Geological Survey of Canada - Pacific, P.O. Box 6000, Sidney, BC V8L 4B2 Canada
AB: Annually laminated marine sediments are potentially ideal paleoclimate recorders, particularly once proxy measurements for atmospheric, oceanographic and sedimentalogic conditions have been calibrated. In Effingham Inlet, a fiord on the southwest coast of Vancouver Island, the anoxic inner basin preserves annual varves consisting of dark terrigenous laminae related to winter precipitation, and light diatomaceous laminae related to algal blooms controlled by spring-summer sunlight and ocean productivity. The French ship Marion Dufresne, as part of the international IMAGES program, collected a continuous 40 meter long core which spans the Holocene and beyond. Since the core is continuous, paleomagnetic declination can be more accurately determined than in piecewise fitting of separate cores. The oldest dated twig is 12ka C14, and magnetic secular variation correlations extend the dating to the bottom of the core at 14ka C14. In the lower 8 metres (2000 years) of the core, magnetic properties show rapid jumps indicative of the variety of sediment sources perhaps transported by the glaciers feeding the inlet during their retreat. Throughout the rest of the core, the varve record is interupted by massive mud intervals of 1 to 50 cm thickness. Those caused by sediment slumps related to high rainfall or seismic events are identified by high magnetic susceptibility. Others, which magnetic properties indicate are reworkings of sediments already in place, are hypothesized to be caused by bottom currents related to coastal oceanographic conditions perhaps established by strong El Ni\~no periods. Variations in magnetic properties along with other paleoclimate proxies are being combined to establish annual through millennial cycles in Holocene climate on the Pacific coast.
DE: 3022 Marine sediments--processes and transport
DE: 1512 Environmental magnetism
DE: 1560 Time variations--secular and long term
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting