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The continent/island-arc collision in northern Papua New Guinea

Created 17/10/2025

Updated 17/10/2025

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Recent geological mapping in the north coast ranges of Papua New Guinea has recognised a Paleogene island arc. This arc is believed to have faced southward, and formed at the northeastern boundary of the Indo-Australian plate. The arc collided with continental crust of the Indo-Australian plate to the south; collision is thought to have occurred first in the west in the Early Miocene and to have progressed eastwards. Crustal shortening on collision resulted in foreland-type folding and thrusting at the continental margin, emplacement of ophiolite allochthons from the arc-trench gap at the collision zone, and uplift and fracturing of the accreted arc. Post-collision plate adjustments are thought to include extensive trans- current faulting about the former plate boundary, southward thrusting of part of the arc (Finisterre-Huon block), and extensive faulting in a complex linear zone extending from south of Manus Island through New Ireland and the Solomon Islands. Present-day interaction between the Indo-Australian and Pacific plates is spread over a wide zone in which at least two minor plates are involved. Despite previous claims, plots of the most accurately located earthquake foci define a northward-dipping seismic zone beneath the Late Cainozoic volcanoes at the southern margin of the Bismarck Sea. We find no evidence to substantiate a reversal of arc polarity at any time after the Mid-Tertiary collision. Mid to Late Cainozoic magmatism in central Papua New Guinea appears to have been triggered by uplift inducing partial melting of mantle modified by Cretaceous subduction. The present-day northward-dipping seismic zone is believed to be a vestige of the Early Tertiary subduction zone; the hanging slab is now slowly sinking and equilibrating with the mantle. If northern New Guinea can be considered to be the type example of a continent/island-arc collision then reversal of arc polarity may not be a necessary consequence of such collisions.

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Field Value
Title The continent/island-arc collision in northern Papua New Guinea
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/en/dataset/3456a2e8-96d7-4826-be29-40518ef732cb
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        141.0,
        -12.0
      ],
      [
        156.0,
        -12.0
      ],
      [
        156.0,
        0.0
      ],
      [
        141.0,
        0.0
      ],
      [
        141.0,
        -12.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "The continent/island-arc collision in northern Papua New Guinea". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/the-continent-island-arc-collision-in-northern-papua-new-guinea