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GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 9, Q04006, doi:10.1029/2007GC001743, 2008

Age, spreading rates, and spreading asymmetry of the world's ocean crust

R. Dietmar Müller

EarthByte Group, School of Geosciences, University of Sydney, Building H11, Sydney, New South Wales 2006, Australia


Maria Sdrolias

EarthByte Group, School of Geosciences, University of Sydney, Building H11, Sydney, New South Wales 2006, Australia


Carmen Gaina

Center for Geodynamics, Geological Survey of Norway, Leiv Eirikssons Vei 39, N-7491 Trondheim, Norway


Walter R. Roest

Département Géosciences Marines, Ifremer, BP 70, F-29280 Plouzané, France


Abstract

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 arc min 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 are 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 toward hot spots. 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 three 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 represents a valuable set of tools to investigate geodynamic problems.

Received 5 July 2007; accepted 16 January 2008; published 3 April 2008.

Keywords: digital isochrons; ocean floor; plate kinematic; geodynamic; seafloor spreading.

Index Terms: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 8120 Tectonophysics: Dynamics of lithosphere and mantle: general (1213); 8157 Tectonophysics: Plate motions: past (3040).

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Citation: Müller, R. D., M. Sdrolias, C. Gaina, and W. R. Roest (2008), Age, spreading rates, and spreading asymmetry of the world's ocean crust, Geochem. Geophys. Geosyst., 9, Q04006, doi:10.1029/2007GC001743.