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On the isostatic compensation of Australia topography

Created 16/10/2025

Updated 16/10/2025

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The depth of isostatic compensation and the strength of the lithosphere are investigated by calculating isostatic anomalies for a range of isostatic models. The models are of three-dimensional topography on a spherical earth. In all areas compensation of topography appears to be complete at the level of the lowest part of the crust. In southeast Australia the preferred isostatic model is that of Airy, with a standard sea-level crust of thickness 35-45 km. For this model, isostatic anomalies in areas measuring 0.5° x 0.5° have a low standard deviation of 90 micro m s^-2; equivalent to 80 m in elevation. The crustal thicknesses calculated from this model agree well with thicknesses found from recent seismic-refraction work. In the southeastern highlands there is evidence from physiographic studies for uniform uplift of about 1 km during the last 90 ± 30 m.y. The preferred model is for this uplift to be an isostatic response to underplating of the crust. The underplating is thought to have taken place at a constant rate since 90 m.y. ago; the underplated material is the 20 km of abnormally high velocity material that forms the basal part of the crust in this area. Away from southeast Australia no isostatic models could be found that gave small isostatic anomalies, and the best models are not consistent with crustal structure found by seismic methods. In these areas the topography varies gradually, and the gravity effect of this topography and its compensation seems to be masked by the effect of a correlation between altitude and mean crustal density. This correlation is partly the result of the lowlands usually being underlain by thicker, low-density sediments, and partly to the crust below sediments having a higher mean density in the high altitude areas.

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Field Value
Title On the isostatic compensation of Australia topography
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/20afd2bd-03f6-4640-93de-42277953ed59
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        112.0,
        -44.0
      ],
      [
        154.0,
        -44.0
      ],
      [
        154.0,
        -9.0
      ],
      [
        112.0,
        -9.0
      ],
      [
        112.0,
        -44.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "On the isostatic compensation of Australia topography". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/on-the-isostatic-compensation-of-australia-topography