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An isotopic study of granitoids in the Litchfield Block, Northern Territory

Created 16/10/2025

Updated 16/10/2025

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The Litchfield Block contains a variety of granitoids, gneissic rocks, and migmatites that are intrusive into metasediments of probable Early Proterozoic age at the western margin of the Pine Creek Inlier. Isotopic data, which include U-Pb measurements on cogenetic zircon and xenotime and Rb-Sr total-rock measurements on the least metamorphosed granodiorites, show that these rocks crystallised from mantle-derived melts between 1840 Ma and 1850 Ma ago. Radiogenic Pb was lost from zircon in the early Palaeozoic (about 435 Ma), but xenotime remained a closed system until recent time. Many granitoids in the Litchfield Block have a gneissic fabric imposed during greenschist to amphibolite-grade regional metamorphism. This disturbance allowed partial isotopic re-equilibration of Rb-Sr total-rock systems, at about 1770 ± 16 Ma. As this igneous and metamorphic evolution is mirrored in other parts of the Pine Creek Inlier, the Halls Creek Inlier, and many other orogenic belts in northern Australia, its recognition and isotopic definition in the Litchfield Block further emphasise the magnitude and chronological integrity of this early Proterozoic tectonic event.

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Field Value
Title An isotopic study of granitoids in the Litchfield Block, Northern Territory
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/ddb22ee9-8192-4e5b-8c33-d94dfe2a277d
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 "An isotopic study of granitoids in the Litchfield Block, Northern Territory". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/an-isotopic-study-of-granitoids-in-the-litchfield-block-northern-territory