HR: 0800h
AN: PP51D-0637    [Abstracts]
TI: A High-Resolution Geochemical Reconstruction of Holocene and Deglacial Climate from the Eastern North Pacific.
AU: * Ivanochko, T S
EM: tivanochko@eos.ubc.ca
AF: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: Pedersen, T F
EM: sciedean@uvic.ca
AF: School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8W 3P6 Canada
AU: Calvert, S E
EM: scalvert@eos.ubc.ca
AF: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: Enkin, R J
EM: renkin@nrcan.gc.ca
AF: Paleomagnetism, Geological Survey of Canada-Pacific, Sidney, BC V8L 4B2 Canada
AU: Dallimore, A
EM: adallimore@nrcan.gc.ca
AF: Paleomagnetism, Geological Survey of Canada-Pacific, Sidney, BC V8L 4B2 Canada
AU: Southon, J
EM: jsouthon@uci.edu
AF: School of Physical Sciences, University of California, Irvine, Irvine, CA 92697 United States
AU: Soon, M
EM: msoon@eos.ubc.ca
AF: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AB: A 40 m piston core recovered from an eastern North Pacific fjord (Effingham Inlet) provides the basis for a high-resolution geochemical study of the late deglaciation and the Holocene. Using a multi-proxy approach, the transition of this inlet from a pro-glacial lake to an isolated, anoxic marine basin is reconstructed. As the Cordilleran ice sheet retreated, the pro-glacial sediments of Effingham Inlet were flooded with marine water. This transition is identified by an increase in the ratio of C_org/N and the onset of S and Mo accumulation in the sediments. Redox-sensitive trace metal contents indicate that sedimentary anoxia has been maintained in the Inlet over the last 10 kyrs: Holocene Mo/Al and U/Al ratios range between 10-29 and 1-2.7 respectively. Today, productivity in the basin is primarily diatomaceous and seasonal, coinciding with summer coastal upwelling. Recent hydrographic surveys indicate that anoxic conditions are relatively stable, but are occasionally punctuated by flushing events. But in the past, large variations in the Mo/Al and U/Al ratios suggest that significant changes in the frequency of basin flushing have occurred. Rapid and large fluctuations in productivity (based on % opal) and water column denitrification (based on δ¹⁵N) are evident throughout the Holocene. Together the trace metal, productivity and denitrification records provide an unprecedented record of Holocene rapid climate change in the eastern North Pacific.
DE: 0404 Anoxic and hypoxic environments (4802, 4834)
DE: 0424 Biosignatures and proxies
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1065 Major and trace element geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005