Extended Data Fig. 7: Map of West Pacific seamounts, showing Rurutu-Arago and Samoa predicted hotspot tracks (K01¹⁸ in dark shade, this study in light shade).

A) ¹⁴³Nd/¹⁴⁴Nd (red) and ²⁰⁶Pb/²⁰⁴Pb (blue) compositions of Izu-Bonin-Mariana arc volcanoes⁵² versus latitude. B) Corresponding map of the West Pacific with model reconstructions illustrating predicted locations where the Rurutu-Arago and Samoa hotspot tracks are subducted. Black numbers with white outline represent ages^31,115, while numbers in red represent likely unrelated volcanic ages, given large age difference with expected age along the hotspot track and difference in composition (pink circle³¹). New Wake region isotope data (hexagons) and a 91.3 Ma age determination provides the “missing link” that suggests that Rurutu hotspot continues through the seamounts west of Wake Island. The samples outlined with red has ¹⁴³Nd/¹⁴⁴Nd affected by phosphatization. The existing (dark blue¹⁸) APM model track for the Rurutu-Arago hotspot is devoid of major seamounts, while the new track (light blue) continues the unusual isotopic composition and morphological chain to the Izu-Bonin-Mariana trench. A similar prediction for Samoa (red: K01¹⁸; orange: updated) shows both hotspots have a corresponding unusual spike in isotopic compositions in the arc (left panel; lines represent running means), indicating prior subduction of a continuing chain of similar composition, mixing Rurutu-Arago (HIMU) or Samoa (EM2) hotspot material into the mantle wedge.