Dynamic topography compared with residual depth anomalies in oceans and implications for age-depth curves

Motoyuki Kido, and Tetsuzo Seno

Earthquake Research Institute, University of Tokyo

Abstract. Ocean depth is affected by dynamic topography caused by mantle flow. Regional bathymetric deviations from the cooling plate age-depth curve, called residual depth anomalies, can therefore be used as indicators of dynamic topography in oceans. In this work, we first evaluated the oceanic residual depth anomalies. We then compute the dynamic topography for the flow induced by density perturbations converted from seismic tomography models by assuming dr/dv. We found that the predicted dynamic topography correlates with the depth anomalies when the density perturbations in the shallow part of the upper mantle were inferred from slab densities, not from tomographic models. We estimated a new age-depth curve based on depths corrected for dynamic topography. This corrected age-depth curve shows that the corrected depths for old seafloor (70--110 Ma) are a few hundred meters deeper than those uncorrected.

Geophys. Res. Lett., 21 No.8, 717-720, 1994.
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