Controls on the sedimentary and subsidence history of an active plate margin: an example from the Tonga Arc (southwest Pacific)

Abstract

Provides a record of the sedimentary evolution of the active margin of the Indo-Australian Plate from late Eocene time to the present. Facies analyses of the sediments, coupled with interpretations of downhole Formation MicroScanner logs, allow the complete sedimentary and subsidence history of each site to be reconstructed. The forearc region of the Tofua Arc (Site 841) can be seen to have experienced an initial period of tectonic subsidence dating from 3.5 Ma. Subsidence has probably been gradual since that time, with possible phases of accelerated subsidence, starting at 16.2 and 10.0 Ma. The Tonga Platform (Site 840) records only the last 7.0 Ma of arc evolution. -from Author