Mantle density and dynamic topography over time

  • Model 2b of Steinberger and Calderwood (GJI, 2006) - chemically homogeneous mantle
  • Radial viscosity profile based on mineral physics and obtaining a good fit to geoid and heat flux profile
  • Scaling profile from seismic velocity to density heterogeneities based on mineral physics; anomalies in uppermost 220 km not considered
  • phase boundaries at 400 and 670 km
  • advection computed with time-dependent plate motion boundary conditions, compressible flow
  • net rotation of lithosphere but no net rotation in lower mantle
  • dynamic topography computed with free slip upper boundary, incompressible flow

  • Case 1A: Density model derived from smean (Becker and Boschi, 2002), pure backward advection (movie, present-day, 35 Ma, 70 Ma)
  • Case 1B: Density model derived from smean, modified backward advection (flow across depth 220 km, but no advection of density heterogeneities) (movie, present-day, 35 Ma, 70 Ma)
  • Case 2A: Density model derived from s20rts (Ritsema et al, 2000), pure backward advection (movie, present-day, 35 Ma, 70 Ma)
  • Case 2B: Density model derived from s20rts, modified backward advection (movie, present-day, 35 Ma, 70 Ma)
  • Case 3A: Density model derived from ngrand (Grand, 2002), pure backward advection (movie, present-day, 35 Ma, 70 Ma)
  • Case 3B: Density model derived from ngrand, modified backward advection (movie, present-day, 35 Ma, 70 Ma)