Reference frames for plate tectonics and uncertainties

Paleomagnetic, hotspot, and mean-lithosphere frameworks are compared for the Cenozoic Era. Errors in the relative motions of plate pairs accumulate to give uncertainties in reference frames. Uncertainties in the poles of the mean-lithosphere framework are estimated to be less than 1° and for the hotspot framework 1.1°, assuming a 50 km error in location of individual hotspots. The A₉₅'s for paleomagnetic data range from 1° to 5°. With these uncertainties the differences between the paleomagnetic and mean-lithosphere coordinate systems are not found to be statistically significant, and the hotspot frame barely differs from the mean-lithosphere frame during the early Tertiary. On the other hand, the hotspot and paleomagnetic axes diverge in opposing directions in the mean-lithosphere framework, and can be distinguished. This difference can be attributed to the Pacific hotspots having more than 10° motion relative to the mean-lithosphere, whereas the African set of hotspots does not statistically differ from the mean-lithosphere frame. One possible explanation is a shift of the Pacific hotspots relative to those in the Atlantic.