New results show that the long term stability of Large Low Shear Wave Velocity Provinces (LLSVPs) on the CMB has lasted for at least 540 My

We have shown previously that ca. 15 active volcanic hot spots with parent ages as old as 134 Ma and ca. 25 Large Igneous Provinces (LIPs) with ages as old as ca. 300 Ma the (the latter rotated using a hybrid method to their locations at the times of their eruptions) lie vertically above narrow Plume Generation Zones (PGZs) on the Core/Mantle Boundary (CMB) at the margins of the Earth’s two LLSVPS. We infer that those PGZs and therefore the LLSVPs themselves have remained in their present locations, antipodal on the equator, for at least 300 My. We have now found that 80% of the eruption sites of a rotated population of ca. 1400 kimberlitic volcanic rocks with ages of < 320 My were similarly erupted above the same PGZs. A bootstrap operation (i) assuming that PGZ stability extended back to ca. 500 Ma and (ii) rotating two LIPs of ages 360 Ma and 510 Ma so that their eruption sites overlay PGZs enabled us to describe the locations of ancient continents in longitude. The strength of the idea that LLSVP stability extended back to ca. 500 Ma was then tested by rotating ca. 200 kimberlitic volcanic rock localities of known ages between 344 and 542 Ma and known present locations within the continents. Because those older kimberlites also lay over PGZs we consider that the long term stability of the two LLSVPs has been confirmed for the entire Phanerozoic. Models of mantle structure with stable LLSVPs will surely help in showing how the deep Earth behaves.