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

IF 2.7 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2026-01-01 Epub Date: 2025-11-10 DOI:10.1016/j.precamres.2025.107965

Sutthida Noptalung, Ioan V. Sanislav, Helen A. Cocker, Avish Kumar

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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.

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Isa Inlier山花岗岩的锆石U-Pb年龄和Lu-Hf同位素系统——努纳（哥伦比亚）超大陆最终组装期间活动大陆边缘长时间改造的证据

Isa Inlier山位于北澳大利亚克拉通（NAC）的东部边缘，保存了与努纳超大陆组合有关的悠久的侵入活动历史。河中侵入岩形成于约1880 ~ 1490 Ma之间的6次火成岩事件。Inlier西南部（Dajarra地区）的侵入岩在没有直接的U-Pb年代学约束的情况下，被确定为约1680-1650 Ma。Dajarra地区花岗质岩石的新U-Pb锆石年龄揭示了约1860 Ma、约1820-1780 Ma、约1710-1690 Ma和约1670-1650 Ma的侵入事件，分别对应于Kalkadoon、Argylla、Wonga-Burstall和Sybella火成岩事件。这些结果表明，这些花岗岩比以前认为的要古老得多，对侵入关系和地层对比具有重要意义。锆石Hf同位素组成在1860 Ma处表现为负的Hf(t)值（+0.0 ~−5.5），在1820 ~ 1780 Ma处表现为混合值（−5.3 ~ + 8.4），在1710 ~ 1690 Ma（−8.1 ~−0.1）和1650 Ma（−5.1 ~−4.3）处表现为非放射性成因特征。这些同位素数据表明，岩浆主要是由老地壳的内部改造而产生的，而年轻岩浆的输入有限。与Kalkadoon和Argylla火成岩事件相对应的岩浆带可以与NAC和南澳大利亚克拉通（SAC）的同期火成岩事件相对应，可能是在NAC南缘北倾俯冲体系下形成的。Wonga-Burstall和Sybella火成岩事件可能是Nuna组合末期沿NAC东缘发育的西倾俯冲体系的反应。本文提供的新的年代学和同位素资料填补了伊萨因利尔火山岩浆史上的一个重要空白，有助于更全面地了解南太平洋东缘的构造活动和努纳超大陆的最终组装。

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来源期刊

Precambrian Research 地学-地球科学综合

CiteScore

7.20

自引率

28.90%

发文量

325

审稿时长

12 months

期刊介绍： Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.