Observational Test of the Global Moving Hot Spot Reference Frame

The Global Moving Hotspot Reference Frame (GMHRF) has been claimed to fit hot spot tracks better than the fixed hot spot approximation mainly because the GMHRF predicts ≈1,000 km southward motion through the mantle of the Hawaiian mantle plume over the past 80 Ma. As the GMHRF is determined by starting at present and calculating backward in time, it should be most accurate and reliable for the recent geologic past. Here we compare the fit of the GMHRF and of fixed hot spots to the observed trends of young tracks of hot spots. Surprisingly, we find that the GMHRF fits the data significantly worse (p = 0.005) than does the fixed hot spot approximation. Thus, either plume conduits are not passively advected with the mantle flow calculated for the GMHRF or Earth's actual mantle velocity field differs substantially from that calculated for the GMHRF. Plain Language Summary Hot spots are the surface manifestations of plumes of hot rock that rise from deep in the mantle. The tracks of hot spots, such as the Hawaiian island and seamount chain, have been used in two very different ways to estimate the motion of tectonic plates relative to the deep mantle. Originally, it was assumed that the hot spots are “fixed” and do not move relative to each other or relative to the deep mantle. In a later approach, termed the “Global Moving Hotspot Reference Frame” (GMHRF), the motion of each hot spot relative to the deep mantle was predicted from a calculation of the global flow of mantle rocks. The latter approach assumes that hot spot motion can be reliably calculated over the past 130 million years, but does not test its predictions using data from the trends of young hot spot chains. We compare the statistical fit of the GMHRF and fixed hot spots using data from the observed trends of young hot spot tracks. Surprisingly, we find that the GMHRF fits the data significantly worse than does the fixed hot spot approximation. Thus, simple fixed hot spots provide the more useful reference frame and some assumptions made to construct the GMHRF are incorrect. Key Points The fit of the Global Moving Hotspot Reference Frame (GMHRF) to observed geologically young trends of hot spot tracks is evaluated The data are fit significantly worse (p = 0.005) by the GMHRF than by fixed hot spots Either plume conduits do not advect passively with mantle flow or the GMHRF mantle velocity field is incorrect