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Thermal history of the Gosses Bluff impact structure, central Australia, from conodont colour-alteration indices: implications for hydrocarbon prospectivity and erosional history

Created 17/10/2025

Updated 17/10/2025

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Gosses Bluff is the remnant of a latest Jurassic asteroid or comet impact structure in the Amadeus Basin, central Australia. Conodonts have been successfully extracted from rocks exposed at the central uplift core of the impact structure, as well as from samples in petroleum exploration wells drilled into the structure. Maximum maturation of the source beds in the Early Ordovician Horn Valley Siltstone is reflected by the conodont colour-alteration index (CAl) value of 4 in Gosses Bluff No.2 well. A similar maturation level was attained by late Early Ordovician carbonates of the Stokes Siltstone, both in outcrop and drilled at shallow levels in Gosses Bluff No.1 well. A value of CAl 4 at the present surface indicates that these rocks were uplifted at least 4500m as a result of the impact. Combined with the CAl values from conodonts recovered from petroleum exploration wells to the northeast (Tyler No.1) and southeast (Palm Valley No.1 and West Waterhouse No. 1), the conodont CAl values derived from Gosses Bluff allow the construction of a palaeodepth trend, similar to the CAI-depth trend of the Appalachians and the Kidson Sub-basin of the Canning Basin. This indicates that about 500 m of rock has been eroded from above the Gosses Bluff and Tyler No. 1 well area, and that about 1700- 2800 m has been eroded from the Palm Valley and Waterhouse Range Anticlines. The CAl 4 value for the Horn Valley Siltstone, the primary rich hydrocarbon source rock in the basin, indicates that the organic matter in this formation in the Missionary Plain had reached a level of maturity equivalent to that for production of dry gas before about 140 Ma.

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Title Thermal history of the Gosses Bluff impact structure, central Australia, from conodont colour-alteration indices: implications for hydrocarbon prospectivity and erosional history
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/db4ea5c8-2da2-4206-8558-039ec59a963c
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        131.0,
        -24.7
      ],
      [
        134.5,
        -24.7
      ],
      [
        134.5,
        -23.15
      ],
      [
        131.0,
        -23.15
      ],
      [
        131.0,
        -24.7
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Thermal history of the Gosses Bluff impact structure, central Australia, from conodont colour-alteration indices: implications for hydrocarbon prospectivity and erosional history". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/thermal-history-of-the-gosses-bluff-impact-structure-central-australia-from-conodont-colour-alt