HR: 1400h
AN: PP43B-01    [Abstracts]
TI: Mid to Late Holocene Sediment Flux in annually laminated ocean sediments in Saanich Inlet, BC using X-ray Fluorescence and Scanning Electron Microscope
AU: * Kanamaru, K
EM: kinuyok@geo.umass.edu
AF: Climate System Research Center, Department of Geosciences, University of Massachusetts, Amherst, 611 North Pleasant Street, Amherst, MA 01003-9297, United States
AU: Francus, P
EM: pfrancus@ete.inrs.ca
AF: Institut National de la recherche Scientifique Centre Eau, Terre et Environnement, 490 rue de la couronne, Quebec, QC G1K 9A9, Canada
AU: Bradley, R S
EM: rbradley@geo.umass.edu
AF: Climate System Research Center, Department of Geosciences, University of Massachusetts, Amherst, 611 North Pleasant Street, Amherst, MA 01003-9297, United States
AB: We present high-resolution geochemical data at 200 micrometer using ITRAX core scanning X-ray fluorescence, and physical properties obtained by scanning electron microscope images of the sediment thin sections in order to reveal the depositional history during the Holocene. The core MD02-2490 has been taken from Saanich Inlet, BC, a silled fjord on southeastern Vancouver Island, as part of the IMAGES VIII (International Marine Past Global Changes Study) program. Annual laminations in Saanich Inlet are mainly couplets made of a biogenic layer and a terrigenous layer. Lamina thickness measured from 2,000 to 7,000 yr BP reveals an abrupt increase in biogenic input around 6,500 yr BP, while the annual accumulation rate is likely to be constant. During this period, the relative abundances of major and minor elements also change significantly. The spectral analysis performed on the thickness of both biogenic and terrigenous layers shows that there are strong 2-3 year and 16 year cycles around 2,000 years BP, although 2-3 year and 64 year cycles becomes stronger around 5,000 yr BP. We argue that these changes are due to changes in the climate patterns during the Holocene because they easily affect the seasonal variability of the water-column stratification at the site. We developed a high-resolution age model based on varve counts and previous work made on this core and the nearby ODP169S hole 1033 core. The differences between modeled ages and varve years range from 7 to 20 % of the varve years. Our high-resolution age-model is then used to verify if the terrigenous sediment delivery was continuous or episodic during the Holocene, and to assess the impact of abrupt climate change on depositional history in Saanich Inlet.
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4912 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4805)
DE: 4914 Continental climate records
DE: 4924 Geochemical tracers
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly