Age, Spreading Rates and Spreading Asymmetry of the World's Ocean Crust
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We present four companion digital models of the age, age uncertainty, spreading rates and
spreading asymmetries of the world's ocean basins as geographic and Mercator grids with
2 minute resolution. The grids include data from all the major ocean basins as well as detailed
reconstructions of back-arc basins. The age, spreading rate and asymmetry at each grid node is
determined by linear interpolation between adjacent seafloor isochrons in the direction of
spreading. Ages for ocean floor between the oldest identified magnetic anomalies and
continental crust are interpolated by geological estimates of the ages of passive continental
margin segments. The age uncertainties for grid cells coinciding with marine magnetic anomaly
identifications, observed or rotated to their conjugate ridge flanks, are based on the difference
between gridded age and observed age. The uncertainties are also a function of the distance of a
given grid cell to the nearest age observation, and the proximity to fracture zones or other age
discontinuities. Asymmetries in crustal accretion appear to be frequently related to
asthenospheric flow from mantle plumes to spreading ridges, resulting in ridge jumps towards
hotspots. We also use the new age grid to compute global residual basement depth grids from
the difference between observed oceanic basement depth and predicted depth using two
alternative age-depth relationships. The new set of grids helps to investigate prominent negative
depth anomalies, which may be alternatively related to subducted slab material descending in
the mantle or to asthenospheric flow. A combination of our digital grids and the associated relative and absolute
plate motion model with seismic tomography and mantle convection model
outputs represent a valuable set of tools to investigate geodynamic problems.
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We welcome any feedback. In particular, if you have data that you would like to be included in the next version of the agegrid, please send us an email. Send email
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