Subduction without volcanism in the Solomon Islands arc

The Solomon arc lacks subduction-associated volcanism in its eastern part. This anomalous absence arose from the collision of the submarine Ontong Java Plateau with the Solomon arc about 8 m.y. ago and a consequent flip in subduction. Collision was most forceful over the eastern half, so that the new, north-plunging slab of Indo-Australian plate remained in collisional contact with the thick oceanic crust (>40 km) and lithosphere of the Ontong Java Plateau along a face of cooled depleted refractory mantle; there is no intervening asthenospheric wedge, and therefore no magma production.