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The Arrinthrunga Formation: Upper Cambrian epeiric carbonates in the Georgina Basin, central Australia

Created 17/10/2025

Updated 17/10/2025

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The Arrinthrunga Formation (Upper Cambrian) in the Georgina Basin, central Australia, is a complex carbonate and mixed carbonate-siliciclastic sequence deposited in an extensive and intermittently emergent epeiric sea. It accumulated on a low-relief substratum in very shallow water with restricted tidal movements; these factors and a warm arid climate contributed to high salinities and the local precipitation of evaporites. Filamentous algae proliferated in the warm hypersaline shallow waters, in which grazing organisms were virtually absent, and exerted a major control on the type and distribution of carbonate lithologies. At the close of the Middle Cambrian a peloid shoal or barrier bar prograded across a broad region of shallow-marine tidal carbonates, bordered in the west by intermittently emergent algal flats. A hypersaline lagoon developed in the lee of the shoal, and a thick sequence of algal-derived peloid lime-muds was deposited. Shoaling sedimentation and intermittent emergence favoured the establishment of gypsiferous algal mats in the northwest, and, with increasing emergence, laminated algal mats colonised much of the area. A transgression of the sea then flushed the stagnant waters, and a reticulate maze of algal bioherms and interbiohermal peloid-ooid sands was established across the whole of the depositional area. Under the influence of shoaling sedimentation and a stable sea level, nearshore environments migrated laterally, and quartz-ooid shoals, intermittently emergent algal mats, and terrigenous sands prograded across the western and central portion of the sea. The progressive shallowing led to local emergence, reduced circulation, and stagnation, so that sections of the sea became isolated and halite evaporite pans were formed. A second transgression of the sea again favoured the widespread growth of algal bioherms, and prograding ooid shoals then spread out across all but the eastern portion of the depositional area. Sedimentation ended as the sea regressed, and a karst erosion surface formed on the emergent landmass.

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Field Value
Title The Arrinthrunga Formation: Upper Cambrian epeiric carbonates in the Georgina Basin, central Australia
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/d5166c75-d720-4952-bafd-612ec0bfed5d
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        134.5,
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      ],
      [
        139.5,
        -24.0
      ],
      [
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        -20.0
      ],
      [
        134.5,
        -20.0
      ],
      [
        134.5,
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      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "The Arrinthrunga Formation: Upper Cambrian epeiric carbonates in the Georgina Basin, central Australia". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/the-arrinthrunga-formation-upper-cambrian-epeiric-carbonates-in-the-georgina-basin-central-aust