HR: 1340h
AN: T43B-1331    [Abstracts]
TI: Effects of Seamounts and Lithospheric Structure on the Pacific Seafloor Topography
AU: * Burkholder, M
EM: Matt.Burkholder@colorado.edu
AF: University of Colorado, Dept. of Physics, University of Colorado, Boulder, CO 80309 United States
AU: Zhong, S
EM: szhong@anquetil.colorado.edu
AF: University of Colorado, Dept. of Physics, University of Colorado, Boulder, CO 80309 United States
AU: Wessel, P
EM: pwessel@hawaii.edu
AF: University of Hawaii at Manoa, Dept. of Geology and Geophysics, SOEST, University of Hawaii at Manoa, Honolulu, HI 96822 United States
AU: Ritzwoller, M
EM: ritzwoll@anquetil.colorado.edu
AF: University of Colorado, Dept. of Physics, University of Colorado, Boulder, CO 80309 United States
AU: Shapiro, N
EM: nshapiro@anquetil.colorado.edu
AF: University of Colorado, Dept. of Physics, University of Colorado, Boulder, CO 80309 United States
AB: One fundamental observation about seafloor topography is the reduced dependence on lithospheric age on relatively old seafloor (older than 70 Ma), relative to the prediction from the half-space cooling model. Understanding the origin of this deviation has been one of the central issues in geodynamics, as it has important implications for lithospheric thermal evolution and large-scale mantle dynamics. Various explanations have been proposed to be responsible for this deviation, including lithospheric reheating and erosion, mantle plumes, and statistical bias resulting from seamounts and large igneous provinces (LIP). This study focuses on the Pacific seafloor with two objectives: 1) to quantify the effects of LIPs and seamounts published by Wessel [2001] on Pacific seafloor topography and its relation to crustal age; and 2) to determine the contribution of lithospheric thermal structure as documented in a recent surface-wave seismic model to the Pacific seafloor topography. In our analyses, the topography data was analyzed by removing all 8,000 seamounts and LIPs. We find that the ocean depth vs age curve does not change significantly with the removal of seamounts and LIPs. Seamounts removed at 2 and 3 radii have an average deviation from the unfiltered topography averages of 82 and 106 meters, respectively for all ages. For ages greater than 70 Ma the deviation increases to 115 and 145 meters. However, lithospheric structure seems to have relatively large effects on seafloor topography. For the Pacific, we also construct the residual topography maps that use the half-space cooling model, the plate model, and our seismic tomography model as reference models.
DE: 8120 Dynamics of lithosphere and mantle--general
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting