Part 5. Plate boundary evolution in the New Guinea region: High-potash Island arc volcanics of the Finisterre and Adelbert Ranges and their tectonic significance

Abstract

The Finisterre and Adelbert Ranges consist of Cainozoic sedimentary and volcanic rocks which are exposed as a series of north-tilted fault blocks with northwesterly trend. The sequence consists of basal Eocene argillite conformably overlain by Oligocene to early Miocene volcanics (Finisterre Volcanics) which are unconformably overlain by Neogene clastic sediments and limestone. The province is distinct from the adjacent Central Highlands where upper Mesozoic to earliest Tertiary metamorphics are capped by Tertiary limestone and are overthrust by ophiolite slabs. The two provinces are separated by the Ramu?Markham Fault Zone, a major sinistral transcurrent fault.