TESTING ABSOLUTE PLATE REFERENCE FRAMES AND THE IMPLICATIONS FOR THE GENERATION OF GEODYNAMIC MANTLE HETEROGENEITY STRUCTURE

Absolute reference frames are a means of describing the motion of plates on the surface of the Earth over time, relative to a fixed point or "frame." Multiple models have been proposed for the Cretaceous-Tertiary period, however, estimating the robustness and limitations of each model remains a significant limitation for refining both regional and global models of plate motion as well as fully integrated and time dependent geodynamic models. Here, we use a novel approach to compare five models of absolute plate motion in terms of their consequences for forward modelled deep mantle structure since at least 140 Ma. We show that the use of hotspots, either fixed or moving, or palaeomagnetics, with or without corrections for true-polar wander, leads to significant differences in palaeo-plate velocities and palaeo-plate boundaries. We present a global comparison of the absolute reference frames in terms of mantle structure, which we have filtered for comparison to seismic tomography. At very long wavelengths hotspot models best reproduce the mantle structure. However, when geometry and the match of smaller-scale subducted slab volumes are compared, a hybrid model based on moving hotspots after 100 Ma and palaeomagnetic data before (with no corrections for true-polar wander), best reproduces the overall mantle structure of slab burial grounds, even though no single model fits best at all mantle depths.