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Early Proterozoic migmatitic basement in the Kalkadoon-Leichhardt Belt of the Mount Isa Inlier, northwestern Queensland

Created 16/10/2025

Updated 16/10/2025

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Tightly folded migmatitic rocks, intruded by 1860 Ma granite and younger felsic and mafic dykes, are exposed in a band 95km long and up to 10km wide along the western part of the Kalkadoon-Leichhardt Belt. The migmatites are considered to represent the basement underlying Proterozoic cover rocks, the oldest of which are Ma felsic extrusives (Leichhardt Volcanics) about 1860 Ma old. The migmatites include thinly banded gneiss with mainly concordant leucosomes (metasediments), non-banded gneiss with wispy leucosomes (metavolcanics), and nebulitic granitic gneiss (meta-intrusives). Metamorphism and deformation of the migmatites took place before the intrusion of a cross-cutting granite dyke dated at 1860 ± 32 Ma by U-Pb zircon. Another U-Pb zircon age, 1850 ± 16 Ma, obtained for a migmatitic metadacite, is anomalously young, although within experimental error of a preferred migmatisation age of 1860 - 1870 Ma. Uplift rates of 2-5 mm a year are implied, to account for the inferred brief interval between migmatite formation and ensuing felsic volcanism.

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Title Early Proterozoic migmatitic basement in the Kalkadoon-Leichhardt Belt of the Mount Isa Inlier, northwestern Queensland
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/8918f9a9-9e8b-4d8f-b17a-a7d7a3fecc4a
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        138.0,
        -22.5
      ],
      [
        141.0,
        -22.5
      ],
      [
        141.0,
        -17.0
      ],
      [
        138.0,
        -17.0
      ],
      [
        138.0,
        -22.5
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Early Proterozoic migmatitic basement in the Kalkadoon-Leichhardt Belt of the Mount Isa Inlier, northwestern Queensland". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/early-proterozoic-migmatitic-basement-in-the-kalkadoon-leichhardt-belt-of-the-mount-isa-inlier-