Accession Number : ADA330219

Title :   A Qualitative and Quantitative Study of the Distribution of Pelagic Sediment in the Atlantic Basin

Descriptive Note : Doctoral thesis

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Webb, Helen F.

PDF Url : ADA330219

Report Date : FEB 1997

Pagination or Media Count : 427

Abstract : By numerically modeling pelagic sedimentation as a diffusive process, we study sedimentation effects in terms of stochastic parameters including seafloor RMS height, abyssal hill spacing, and slope distribution. Understanding gained allows the construction of inverse problems to obtain information about sediment distribution and basement morphology from multibeam bathymetric data. Using maximum likelihood estimation to compare slope distribution functions calculated from data to those from filtered model topographies, we estimate average sediment thickness L, basement RMS height H, and a measure of sediment mobility kappa. We invert for these parameters for 3-29 Ma seafloor from the western flank of the Mid-Atlantic Ridge (MAR) near 25 degree S, 2-45 Ma seafloor from the western flank of the MAR near 26 deg S, and 2-40 Ma seafloor from the eastern flank of the MAR near 25 deg S, and 1-38 Ma seafloor from the western flank of the MAR near 35 deg S. Variations in L allow us to constrain sediment rain rate and the corrosivity of bottom waters to calcite since the Oligocene. We hypothesize that sediment rain rates during the early and middle Miocene averaged only 10-50 % of more recent rates. Variations in H suggest correlation between tectonic setting and topographic variability. A narrow range of kappa describes intrahill sedimentation patterns.

Descriptors :   *BATHYMETRY, *SEDIMENTATION, *MIDATLANTIC RIDGE, STOCHASTIC PROCESSES, MAXIMUM LIKELIHOOD ESTIMATION, THESES, TOPOGRAPHY, SEDIMENT TRANSPORT, GEOMORPHOLOGY, SLOPE STABILITY, TECTONICS.

Subject Categories : Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE