HR: 17:15h
AN: PP52C-06    [PDF]
TI: A Sub-Decadal Continental Margin Record of Little Ice Age-to-Modern Climate-Induced Changes in Sediment Delivery and Transport in the Gulf of Alaska
AU: * Jaeger, J M
EM: jaeger@geology.ufl.edu
AF: Geological Sciences, P.O. Box 112120 University of Florida, Gainesville, FL 32611-2120 United States
AU: Viene, W
EM: wvienn1@ufl.edu
AF: Geological Sciences, P.O. Box 112120 University of Florida, Gainesville, FL 32611-2120 United States
AU: Finney, B
EM: finney@ims.uaf.edu
AF: Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Stoner, J
EM: joseph.stoner@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309-0450 United States
AU: Evans, H
EM: geohelen@ufl.edu
AF: Geological Sciences, P.O. Box 112120 University of Florida, Gainesville, FL 32611-2120 United States
AB: The Gulf of Alaska (GOA) margin is one of the few locations on Earth where orogenic processes, glacial climate, and continental margin sedimentation can be studied and quantitatively modeled in unison. Climatic changes control glacial dynamics, erosion, and sediment/meltwater fluxes to the ocean, and GOA margin strata appear to preserve a strong record of terrestrial climate (i.e., temperature and precipitation) as well as paleoceanographic signals on seasonal to tectonic time scales. In collaboration with the GOA-NEP GLOBEC program, gravity cores were collected at key sampling sites under the influence of the climatically sensitive Alaska Coastal Current (ACC). Chronologies for the past 400-y were established using Pb-210/Cs-137, coupled with paleo-and-environmental magnetism analyzed from u-channel samples at one-cm intervals. The sedimentary paleomagnetic record is correlated to the Sitka geomagnetic observatory record for the last century and extended using the Jackson et al. 400-yr global field model. Carbon and nitrogen stable isotopes, C/N ratios and opal concentrations were analyzed to determine OM source and paleoproductivity. Proximal to large sediment sources, high ($>$1 cm/y) sediment accumulation rates vary over decadal times scales and appear to be directly tied to the amount of coastal precipitation and the corresponding strength of the ACC. Distal shelf cores have sedimentation rates that vary over longer time scales and are 2-3 x higher during glacial melting from LIA maxima. High-resolution grain size analyses and core logging of bulk density and environmental magnetic parameters including magnetic susceptibility vary at LIA, pentadecadal, and decadal time scales and are strongly correlated with variability in regional precipitation as seen in the nearby Mt. Logan ice core record. Preliminary results suggest that the amount of freshwater discharge and corresponding strength of the ACC was substantially higher during the LIA.
UR: http://web.clas.ufl.edu/users/jaeger/goapaleo.htm
DE: 3022 Marine sediments--processes and transport
DE: 4267 Paleoceanography
DE: 4808 Chemical tracers
DE: 4863 Sedimentation
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting