Volcanism and sedimentation in a rifting island-arc terrain: An example from Tonga, SW Pacific

Abstract

Scientific drilling of narrow sub-basins within the Lau back-arc basin system of the SW Pacific has recovered uppermost Miocene to Recent volcaniclastic sediment and pelagic nannofossil oozes. Pliocene sediment gravity flow and turbidite sands from the western Lau Basin indicate a local source for the sediment, probably intrabasinal seamount volcanoes active during the initial stages of arc rifting. Derivation of abundant material from either the remnant volcanic arc (Lau Ridge) or the new Tofua arc is ruled out by the rugged topography of the basin and the proximal nature of the facies. Sediments from the Tonga platform, adjacent to the present day Tofua arc, indicate a peak in volcanic act..