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Rifting and subduction initiation history of the New Caledonia Trough, southwest Pacific, constrained by process-oriented gravity models

Created 17/10/2025

Updated 17/10/2025

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The New Caledonia Trough is a bathymetric depression 200-300 km wide, 2300 km long, and 1.5-3.5 km deep between New Caledonia and New Zealand. In and adjacent to the trough, seismic stratigraphic units, tied to wells, include: Cretaceous rift sediments in faulted basins; Late Cretaceous to Eocene pelagic drape; and ~1.5 km thick Oligocene to Quaternary trough fill that was contemporaneous with Tonga-Kermadec subduction. A positive free-air gravity anomaly of 30 mGal is spatially correlated with the axis of the trough. We model the evolution of the New Caledonia Trough as a two-stage process: (i) trough formation in response to crustal thinning (Cretaceous and/or Eocene); and (ii) post-Eocene trough-fill sedimentation. To best fit gravity data, we find that the effective elastic thickness (Te) of the lithosphere was low (5-10 km) during Phase (i) trough formation and high (20-40 km) during Phase (ii) sedimentation, though we cannot rule out a fairly constant Te of 10 km. The inferred increase in Te with time is consistent with thermal relaxation after Cretaceous rifting, but such a model is not in accord with all seismic-stratigraphic interpretations. If most of the New Caledonia Trough topography was created during Eocene inception of Tonga-Kermadec subduction, then our results place important constraints on the associated lower-crustal detachment process and suggest that failure of the lithosphere did not allow elastic stresses to propagate regionally into the over-riding plate. We conclude that the gravity field places an important constraint on geodynamic models of Tonga-Kermadec subduction initiation.

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Title Rifting and subduction initiation history of the New Caledonia Trough, southwest Pacific, constrained by process-oriented gravity models
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/fcd1739f-c40e-4b6a-893b-58971d8f4def
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 22/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
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      ],
      [
        180.0,
        -45.0
      ],
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        180.0,
        -18.0
      ],
      [
        157.0,
        -18.0
      ],
      [
        157.0,
        -45.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

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This dataset was originally found on Geoscience Australia "Rifting and subduction initiation history of the New Caledonia Trough, southwest Pacific, constrained by process-oriented gravity models". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/rifting-and-subduction-initiation-history-of-the-new-caledonia-trough-southwest-pacific-constra