From Geoscience Australia
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Mode of emplacement of the Papuan Ultramafic Belt

Created 17/10/2025

Updated 17/10/2025

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Geological and geophysical evidence from a number of studies has established that the Papuan Ultramafic Belt is probably an overthrust sheet of oceanic crust and mantle, with a thicker crustal section than normal oceanic crust. Earlier workers have described the overthrust as the result of north-south compression produced by the northwards movement of the Australian Plate. However, left-lateral faulting of the Belt subsequent to emplacement is evident from the displacement of the main ultramafic bodies. Reconstruction of the Belt by reversing the movements along these faults suggests that the Belt was aligned north-south when originally emplaced. Theoretical cross-sections of the Belt along three profiles were constructed - assuming that is was originally aligned north-south with a shallow easterly dip, and was sheared in a northwesterly direction. The computed gravity and magnetic anomalies along these theoretical cross-sections match the observed anomalies closely. The Belt was probably emplaced 30° south of its present latitude, before the Australian Plate started to move north about 55 m.y. B.P. The thick Cretaceous crust which forms the Belt is thought to extend north under most of the western part of the Solomon Sea, and east along the Woodlark Rise where is has been subject to extensive rifting. The presently exposed part of the Belt is estimated to have been uplifted by up to 10 km.

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Additional Info

Field Value
Title Mode of emplacement of the Papuan Ultramafic Belt
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/en/dataset/d6bb662b-efc1-4af1-b820-a69eac2141d8
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        145.0,
        -10.0
      ],
      [
        152.0,
        -10.0
      ],
      [
        152.0,
        -5.0
      ],
      [
        145.0,
        -5.0
      ],
      [
        145.0,
        -10.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Mode of emplacement of the Papuan Ultramafic Belt". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/mode-of-emplacement-of-the-papuan-ultramafic-belt