Breakup without borders: how continents speed up and slow down during rifting

 Relative plate motions during continental rifting result from the interplay of local with far‐field forces. Here, we study the dynamics of rifting and breakup using large‐scale numerical simulations of mantle convection with self‐consistent evolution of plate boundaries. We show that continental separation follows a characteristic evolution with four distinctive phases including an abrupt syn-rift increase of divergence velocity. We also find that the speed‐up during rifting is compensated by subduction acceleration or subduction initiation even in distant localities. Our study illustrates new links between local rift dynamics, plate motions and subduction kinematics during times of continental separation.

Animation A1: This animation shows mantle convection and  plate boundary evolution of a 2D model Earth. Two large continents are marked in blue and diverge with a characteristic velocity evolution. Breakup occurs at 0 My model time. The upper two panels depict the internal Earth structure in terms of viscosity and stress. The lower panel shows horizontal velocities at the surface.

Cite as:

Ulvrova, M. M., Brune, S., Williams, S. (2019): Breakup without borders: how continents speed up and slow down during rifting. - Geophysical Research Letters, 46, 3, pp. 1338-1347. doi: 10.1029/2018GL080387

Download and Resources:

Link to Paper  |  Supplementary Animation Downloads [mpg]: A1, A2, B1, C1 | Supplementary Information [pdf]