Synchronous motion of the Easter mantle plume and the East Pacific Rise.

The Easter mantle plume has produced one of the longest hotspot tracks in the Pacific Ocean. While previous studies have focused on the eastern side extending across the Nazca Plate, we use Ar/Ar isotopic and geochemical data to investigate the less explored western side around the Easter Microplate. We propose a dynamic model in which a deeper (600 km-depth), less buoyant mantle exerts a westward force on the East Pacific Rise (EPR), while a more buoyant plume region drives Easter hotspot volcanism and a localised acceleration in seafloor spreading.

Slab steepening and rapid mantle wedge replacement during back-arc rifting in the New Hebrides.

The effects of the composition and angle of the subducting slab and mantle wedge flow on tectonic and magmatic processes in island arcs and associated back-arcs are poorly understood. Here we analyse the ages and compositions of submarine lavas from the flanks and the floor of the back-arc Futuna Trough some 50 km east of Tanna Island in the New Hebrides arc front. Whereas >2.

A younger and protracted emplacement of the Ontong Java Plateau.

The submarine volcanic emplacement of the Ontong Java Plateau (OJP) is the suggested cause of Ocean Anoxic Event 1a (OAE 1a). However, no precise timing and duration exists for the formation of OJP, and its connection to OAE1a relies mainly on proxies in the sedimentary record. We provide high-precision Ar/Ar data from OJP drill and dredge sites that considerably improve OJP's eruptive history.

New evidence for the Ontong Java Nui hypothesis.

The formation of the Ontong Java Nui super oceanic plateau (OJN), which is based on the model that the submarine Ontong Java Plateau (OJP), Manihiki Plateau (MP), and Hikurangi Plateau (HP) were once its contiguous fragments, could have been the largest globally consequential volcanic event in Earth's history. This OJN hypothesis has been debated given the paucity of evidence, for example, the differences in crustal thickness, the compositional gap between MP and OJP basalts and the apparent older age of both plateaus relative to HP remain unresolved. Here we investigate the geochemical and Ar-Ar ages of dredged rocks recovered from the OJP's eastern margin.