HR: 0800h
AN: PP11B-1469    [Abstracts]
TI: On the Physical Significance of Statistically Significant Millennial Peaks in Late Pleistocene Glacial Intervals of Marine Sediment Cores.
AU: * Obrochta, S P
EM: spo@duke.edu
AF: Duke University Division of Earth and Ocean Science, Box 90227, Durham, NC 27708 United States
AU: Crowley, T J
EM: crowley@duke.edu
AF: Duke University Division of Earth and Ocean Science, Box 90227, Durham, NC 27708 United States
AB: Multitaper and maximum entropy methods were used to determine the statistical significance and frequency, respectively, of millennial-band peaks in late Pleistocene glacial intervals of geochemical, petrological, and physical property time series generated from marine sediment cores, including ODP Site 980 and IODP Site U1308 (Reoccupied DSDP Site 609). A preliminary age model for Site U1308 was created by correlating the sediment lightness (L*) record to the Site 980 δ¹⁸O record. Marine Isotope Stages (MIS) 2-3 (Wisconsin glaciation), 6 (Penultimate glaciation), 8, 10, and 12 were analyzed as individual time series and interpolated to the average sampling resolution of each respective glacial interval. Results indicate the existence of many peaks statistically significant at a 95% or greater confidence interval within each individual glacial-interval time series. One may be tempted to accept each of these peaks as physically significant; however, the probability that a particular peak is significant by chance alone (i.e., 5% chance given a 95% confidence interval), must be considered. For example, Hyde and Crowley (2002) generated millennial-scale peaks significant at a 95% confidence interval in a 120 k.y. model run forced by white noise at a 100-year time step. Given these model results, we exercise caution in the interpretation of physical significance of peaks in the sediment core time series, placing physical significance only on peaks that consistently appear in most of the series.
DE: 3036 Ocean drilling
DE: 3270 Time series analysis (1872, 4277, 4475)
DE: 4926 Glacial
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005