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Regional metamorphism in the Selwyn Range area, northwest Queensland

Created 17/10/2025

Updated 17/10/2025

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The Selwyn Range, which lies at the eastern margin of the Mount Isa Inlier, consists of pelitic, psammitic, and calcareous sedimentary and basic igneous rocks, which have been intruded by granite plutons and regionally metamorphosed to amphibolite grade. Three metamorphic zones, based mainly on pelitic assemblages, have been recognised in the main prograde sequence: a lower grade (biotite) zone equivalent to uppermost greenschist/lower amphibolite facies, an andalusite-almandine-staurolite zone of amphibolite grade, and an eastern upper amphibolite grade zone (sillimanite and sillimanite-K-feldspar). Superimposed on the prograde sequence is a variable retrograde assemblage related to later folding. Regional metamorphic isograds are unrelated to the granitoids, which include both pre-tectonic or syn-tectonic and post-tectonic types. Comparisons with experimentally determined reactions and calculations from various geobarometers for higher grade rocks indicate metamorphic pressures of 3-4 kb (300-400 MPa). Cation exchange equilibria (mainly garnet-biotite) and experimentally determined dehydration reactions indicate equilibration temperatures of ~450-680°C for the prograded sequence; the staurolite and almandine isograds are estimated to be at ~550 °C, the sillimanite isograd ~600°C, and the K-feldspar isograd ~660°C.

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Field Value
Title Regional metamorphism in the Selwyn Range area, northwest Queensland
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/bfc07480-1748-4b54-9fad-98d2f77ba62b
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
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      ],
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    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Regional metamorphism in the Selwyn Range area, northwest Queensland". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/regional-metamorphism-in-the-selwyn-range-area-northwest-queensland