Wednesday, 29 August 2007 - 11:10 AM
3.A.B-4
Solar forcing and El Niño-Southern Oscillation (ENSO) influences on productivity cycles interpreted from a late-Holocene high-resolution marine sediment record, Adélie Drift, East Antarctic Margin
Eduard Costa1, Robert B. Dunbar1, K.A. Kryc1, D.A. Mucciarone1, S. Brachfeld2, B. Roark1, P.L. Manley3, R.W. Murray4, and Amy Leventer5. (1) Department of Geological and Environmental Sciences, Stanford University, 325 Braun Hall, Stanford, CA 94305, (2) Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, (3) Department of Geology, Middlebury College, McCardell Bicentennial Hall 427, Middlebury, VT, (4) Department of Earth Sciences, Boston University, 675 Commonwealth Ave, Boston, MA 02215, (5) Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346
JPC17B-core (26-meters long) was collected from the Adélie-Drift at 140ºE along the Pacific-sector of the Antarctic continental shelf. Sediments are laminated at scales ranging from a few millimetres to 2cm in thickness with accumulation rates on the order of 18-19 m kyr-1 based on 10-radiocarbon age-dates. Seismic data suggests the presence of up to 230 m of Holocene sediments in the drift. Opal content ranges from 45-70% by weight. Measurements of bulk sedimentary organic matter show an overall downcore enrichment of 13Corg. Ti-Ba were measured by core-scanner-XRF. Strong decadal to century-scale variability is present in all tracers. Spectral-analyses of Opal and Ti-time series show strong variance at periods of 11,22 and 110-years, that are suggestive of solar forcing as has previously been suggested for Holocene sediment sequences from the Antarctic Peninsula. Besides, Ba-time series exhibits strong variance at a period of 3-3.6-yr, consistent with possible El Niño-Southern-Oscillation (ENSO) forcing.