Noptalung, Sutthida, Sanislav, Ioan, Cocker, Helene, and Kumar, Avish (2026) Zircon U-Pb ages and Lu-Hf isotopic systematics in granites from Mt Isa Inlier − evidence of prolonged reworking of an active continental margin during the final assembly of the Nuna (Columbia) supercontinent. Precambrian Research, 432. 107965.

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Abstract

The Mount Isa Inlier, located along the eastern margin of the North Australia Craton (NAC) preserves a long history of intrusive activity linked to the assembly of the Nuna supercontinent. The intrusive rocks in the Inlier formed during six igneous events between ca. 1880 and 1490 Ma. Intrusive rocks in the south-western part of the Inlier (Dajarra region) were previously assigned ages of ca. 1680–1650 Ma without direct U-Pb geochronological constraints. New U-Pb zircon ages from granitic rocks in the Dajarra region reveal intrusive events at ca. 1860 Ma, ca. 1820–1780 Ma, ca. 1710–1690 Ma, and ca. 1670–1650 Ma corresponding to the Kalkadoon, Argylla, Wonga-Burstall and Sybella Igneous Events, respectively. These results indicate that these granites are much older than previously thought and have important implications for intrusive relationships and stratigraphic correlations. Zircon Hf isotopic compositions show negative ɛHf(t) values (+0.0 to −5.5) at ca. 1860 Ma, mixed values (−5.3 to + 8.4) at ca. 1820–1780 Ma, and unradiogenic signatures at ca. 1710–1690 Ma (−8.1 to −0.1) and ca. 1650 Ma (−5.1 to −4.3). These isotopic data indicate that the magmas were generated predominantly by internal reworking of older crust with limited juvenile input. The magmatic belts corresponding to the Kalkadoon and Argylla Igneous Events can be correlated with coeval igneous events in the NAC and the South Australia Craton (SAC) and may have formed in response to a northerly dipping subduction system located along the southern margin of the NAC. The Wonga-Burstall and the Sybella Igneous Events may have formed in response to a westward dipping subduction system developed along the eastern margin of the NAC during the final stages of Nuna assembly. The new geochronological and isotopic data presented here fill in an important gap in the magmatic history of the Mount Isa Inlier and contributes towards a more comprehensive understanding of tectonic activity along the eastern margin of the NAC and the final assembly of the Nuna supercontinent.

Item ID:	89657
Item Type:	Article (Research - C1)
ISSN:	1872-7433
Copyright Information:	© 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Date Deposited:	19 Nov 2025 02:19
FoR Codes:	37 EARTH SCIENCES > 3705 Geology > 370502 Geochronology @ 50% 37 EARTH SCIENCES > 3705 Geology > 370503 Igneous and metamorphic petrology @ 20% 37 EARTH SCIENCES > 3705 Geology > 370511 Structural geology and tectonics @ 30%
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