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Lithospheric velocity beneath the Adavale Basin, Queensland, and the character of deep crustal reflections

Created 17/10/2025

Updated 17/10/2025

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Along a traverse across the main depression of the Devonian Adavale Basin in western Queensland, lateral variations in lithospheric velocity are predominantly displayed in the upper 15 km of the crust. In this region, Devonian sediments (up to 7 km thick) underlie the Jurassic- Cretaceous Eromanga sequence (up to 2 km thick) with only minor pockets of intervening Permo-Triassic sediments of the Cooper and Galilee Basins. P-wave velocity in t he sediments ranges from 2.0 to 5.5 km/s. Underlying the Devonian sediments is a 2- 3 km thick basement transition zone of highly folded, faulted, and sheared rocks, where metamorphic grade increases and weathering decreases with depth, and velocity increases from 5.6 to 5.85 km/s. Upper crustal basement extends to 24-25 km with velocity increasing from 5.9 km/s below the basement transition zone to 6.4 km/s above a mid-crustal horizon. Multiply refracted phases suggest the velocity gradient of 0.02 - 0.03 k s/ km in the upper crustal basement is fairly uniform a long the traverse. The increase in mid-crustal velocity from 6.4 to 6.6- 6.7 km/s is a prominent feature of the lithosphere. It marks the upper boundary of the lower crustal reflection zone evident from continuous reflection profiling. Within this zone, the velocity increases to 6.8-7. 1 km/s at the top of the crust/mantle transition zone at a depth of about 35 km. Neither the mid-crustal velocity horizon nor the Moho varies greatly in depth. The upper mantle velocity of 8.15 km/s is reached at 38- 40 km depth, the same as that measured on an east - west cross traverse. The preferred interpretation of the lower crustal velocity gradient and reflections is that they arise from extensive lower crustal magma intrusion during the formation of quasi-continental crust and that subsequent thermal events have enabled isostatic readjustment and basin formation in a compressive regime.

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Field Value
Title Lithospheric velocity beneath the Adavale Basin, Queensland, and the character of deep crustal reflections
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/81bcd62b-79a3-42f9-8975-59cd4f888ea8
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
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        141.06,
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      ],
      [
        154.33,
        -30.37
      ],
      [
        154.33,
        -21.86
      ],
      [
        141.06,
        -21.86
      ],
      [
        141.06,
        -30.37
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Lithospheric velocity beneath the Adavale Basin, Queensland, and the character of deep crustal reflections". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/lithospheric-velocity-beneath-the-adavale-basin-queensland-and-the-character-of-deep-crustal-re