Atypical hotspot chains: evidence for a secondary melting zone below the Marquesas (French Polynesia)

The atypical age/distance to the hotspot relationships observed for the Marquesas linear chain, which present a considerable scatter, are best explained considering (1) a Pacific plate motion of 10.5 cm yr^?1 in the N115°E direction and (2) rejuvenation of volcanism in Ua Huka island. New K–Ar ages show that the main hotspot activity in Ua Huka emplaced successively shield olivine tholeiites and post‐shield alkali basalts between 3.11 ± 0.04 and 2.43 ± 0.04 Ma. Then, after a quiescence period of 1.28 ± 0.06 Myr, two small basanitic volcanoes were emplaced between 1.15 ± 0.02 and 0.763 ± 0.013 Ma. With respect to the main hotspot volcanics, their lavas originated from weaker partial melting rates of a deeper source. Field, petrologic and geochemical arguments are consistent with the existence of a secondary melting zone located c. 140 km downstream the Marquesas hotspot, which produced the rejuvenated volcanics.