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A non-marine Lower Cretaceous rift-related epiclastic volcanic unit in southern Australia: the Eumeralla Formation in the Otway Basin. Part I: Lithostratigraphy and depositional environments

Created 21/12/2025

Updated 21/12/2025

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The Early Cretaceous non-marine volcaniclastic Eumeralla Formation accumulated in a rift basin on the southern margin of Australia during the break-up of eastern Gondwana. Wireline-Iog analysis and a range of sedimentary data have helped to discriminate three major basin-wide informal lithostratigraphic units in the formation. From the base of the formation they are: Eumeralla I: siltstone/mudstone/sandstone/coal; Eumeralla II: siltstone/mudstone/thin lithic sandstone; and Eumeralia III: volcaniclastic sandstone. A fourth unit - Eumeralla IV: siltstone/sandstone/coal - occurs throughout the western Otway Basin, but is absent, probably because of erosion, from the central and eastern pans of the basin. The bases of all four lithostratigraphic units are probably diachronous. The succession of lithostratigraphic units Eumeralla I- IV is interpreted as representing coal swamps and flood plains of low-energy streams; shallow and deep freshwater lakes; channel tracts and flood plains of high-energy streams; and channel tracts, flood plains and coal swamps of low- energy streams respectively. Sedimentary facies analysis of outcropping Eumeralla II and Eumeralla III in the eastern Otway Basin confirms the interpretations for these units. The basin-wide extent of the three lower lithostratigraphic units implies that a single integrated drainage system for the entire basin was established at the onset of Eumeralla Formation deposition, and persisted at least until the late Albian. This inference is supported by the close correlation between variations in lithology and depositional environments and the Aptian- Albian sea-level changes. However, intrabasinal volcanism significantly influenced sedimentation and was probably the primary control on basin drainage.

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Title A non-marine Lower Cretaceous rift-related epiclastic volcanic unit in southern Australia: the Eumeralla Formation in the Otway Basin. Part I: Lithostratigraphy and depositional environments
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/en/dataset/33bfffc1-0429-45e5-bd2a-0d7e645105ff
Contact Point
Australian Ocean Data Network
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        112.0,
        -44.0
      ],
      [
        153.0,
        -44.0
      ],
      [
        153.0,
        -26.0
      ],
      [
        112.0,
        -26.0
      ],
      [
        112.0,
        -44.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Australian Oceans Data Network

Data Source

This dataset was originally found on Australian Oceans Data Network "A non-marine Lower Cretaceous rift-related epiclastic volcanic unit in southern Australia: the Eumeralla Formation in the Otway Basin. Part I: Lithostratigraphy and depositional environments". Please visit the source to access the original metadata of the dataset:
https://catalogue.aodn.org.au/geonetwork/srv/eng/csw/dataset/a-non-marine-lower-cretaceous-rift-related-epiclastic-volcanic-unit-in-southern-australia-the-e1