ABSTRACT' Mainland Papua New Guinea is formed of a microcontinental /
island arc system (?Eocene - latest Oligocene Sepic arc) which in
Middle to Late Miocene times was obducted over the northward- moving Australian plate. The sedimentary and volcanic units of
this system form part of the Wogamush Group (Aure beds, Mena
beds, Omaura Formation, Movi beds, Wogamush beds, Wogamush
Formation. Nansananka Conglomerate and other correlates in- eluding cale-alkaline volcanics and carbonate beds). This Sepic
event was followed in Pliocene-Present times by the obduction
of the Finisterre-Adelbert-Oenake fore-arc or possibly oceanic
plateau. Obduction of the Sepic arc produced crustal thickening