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Eastern Creek Volcanics: their geochemistry and possible role in copper mineralisation at Mount Isa, Queensland

Created 17/10/2025

Updated 17/10/2025

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New chemical analyses of relatively low-grade metabasalt from the Eastern Creek Volcanics, 120-150 km north of Mount Isa, Queensland, show them to be continental tholeiites. A 2-stage model of fractional crystallisation is proposed to explain the major and trace element variation in the suite. The uncommonly high Cu content of the metabasalt (about 200 ppm) is attributed to concentration of an immiscible sulphide phase during fractionation. Examination of all available chemical data has led to the recognition of 5 types of alteration. The Cu content is depleted in metabasalts that are anomalously enriched in K2O, MgO, or CO2, but is not affected in metabasalt enriched in CaO or Na2O. This Cu depletion supports earlier models that attribute Cu mineralisation at Mount Isa to leaching of Cu from the Eastern Creek Volcanics and its redeposition in favourable pyritic, dolomitic sediments of the Mount Isa Group. The ore localisation has been associated with brecciation and appears to depend on the juxtaposition of the Mount Isa Group and the Eastern Creek Volcanics largely by faulting.

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Field Value
Title Eastern Creek Volcanics: their geochemistry and possible role in copper mineralisation at Mount Isa, Queensland
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/91ef330c-2cd2-4268-81e4-07908b5ebb21
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
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      ],
      [
        143.0,
        -24.0
      ],
      [
        143.0,
        -18.0
      ],
      [
        138.0,
        -18.0
      ],
      [
        138.0,
        -24.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Eastern Creek Volcanics: their geochemistry and possible role in copper mineralisation at Mount Isa, Queensland". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/eastern-creek-volcanics-their-geochemistry-and-possible-role-in-copper-mineralisation-at-mount-