Convection models in the Kamchatka region using imposed plate motion and thermal histories

Mantle convection modelling with realistic plate histories has been limited by the availability of published gridded kinematic models. While alternative kinematic models may exist for a given region, they are not easily converted into gridded velocity models, because of the difficulty in compiling closed time-dependent plate polygons consistent with a particular plate rotation history. This problem arises because even though the location of mid-ocean ridges through time is usually well constrained, the location of subduction trenches is not always well known for the geological past.In addition, while a rigid plate may be defined as a continuous body, any two points of which have no motion relative to each other, the boundaries of plates continuously evolve. If regional plate boundaries can easily be calculated and defined over a series of time steps in a self-consistent manner, then compiling time-dependent velocity and oceanic palaeo age-grids is greatly simplified from a given plate kinematic model as input for mantle convection modelling. We present a solution to this problem for regional plate models, implemented through user-friendly open source software.We use this solution to prepare the plate motion and thermal histories for the Kamchatka region. The implications of the plate model, combined with the mantle rheology and thermal boundary conditions, is realised by slabs in the mantle. The position of these slabs can then be compared with seismic tomography images. Our convection model broadly agrees with the tomography, with slabs located under the Aleutian Basin and the Kamchatka peninsula.