Fig. 3: Spreading boundary details.
From: Global mantle convection models produce transform offsets along divergent plate boundaries
a Non-dimensional radial heat flux at a depth of 12 km in the vicinity of a system comprised of divergent segments offset by orthogonal fractures. The snapshot shown is taken from the case depicted in parts (c) and (d) of Fig. 1, 100 Myr prior to the timing of Fig. 1d. The pink box annotated on Supplementary Fig. 4 outlines the region shown in this figure. (This region is almost diametrically opposed from that shown in Fig. 2.) Heat flux values are binned such that the interval of values spanned by each colour (from red to cyan) corresponds to an equal length time period based on a conductive heat flow model. Dimensional values, in milliWatts m−2, are obtained by multiplying the colour bar scale by 3.8. The deepest blue, corresponding to the lowest values of heat flux, delineates a convergent boundary. (Small magnitude negative values are possible in the system interior.) The white horizontal bars are of equal length and indicate the orthogonal distance to divergent boundary segments that six parcels of fluid would travel if released at the divergent boundaries at a common time. b Variation in viscosity for the region corresponding to (a). The dimensional viscosity values are obtained by multiplying the values marked on the colour bar by the reference viscosity, 4.5 × 1019 P ⋅ s. c The non-dimensional divergence of the velocity field corresponding to the region shown in (b) and the length scale applicable to all three panels. d The radial vorticity magnitude corresponding to the above panels.
