Reconstructing Tarim within Rodinia: Constraints from early Tonian accretionary and collisional records in the Altyn belt

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2024-11-22 DOI:10.1016/j.precamres.2024.107605

Wei Li , Jinlong Yao , Guochun Zhao , Yigui Han , Qian Liu , Donghai Zhang

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Abstract

The position of the Tarim craton within Rodinia has long been debated, with competing models varying from internal to external ones. The Altyn belt in the southeast Tarim margin preserves extensive early Neoproterozoic magmatic successions, which are possibly related to the Rodinia assembly. Thus, we here investigated the granitoids in the South Altyn belt (SAB), and present field geology, zircon U–Pb–Hf–O isotopes and H₂O contents, and whole rock geochemistry data from these granitoids. The Tula granite is dated at 914 ± 3.9 Ma, whereas the Kuoshi granites are dated at 919 ± 5.2 Ma and 927.7 ± 5.0 Ma. The Tula and Kalaqiaoka granite samples display high ACNK values that are typical of S-type granitoids, consistent with the occurrence of garnet and muscovite. In addition, the Tula granite has higher zircon δ¹⁸O (7.62 to 10.85 ‰) and lower εHf(t) (−2.4 to +0.1) values, along with lower zircon H₂O content (medium values at 102 ppmw), indicating a primary water-deficient magma generated from recycled ancient crust, with minor juvenile contribution. On the other hand, the Kuoshi granite shows high Sr (169–259 ppm), Sr/Y (17.85–19.33) and (La/Yb)_N (30–49) ratios. The Kuoshi granites are also characterized by higher MgO, lower zircon δ¹⁸O (4.15 to 9.81 ‰) and εHf(t) (−4.0 to −0.4) values, higher zircon H₂O content (medium values at 255 ppmw), as well as subduction related chemical features. These signatures suggest that the Kuoshi granitic magma might have been formed by partial melting of recycled ancient crust and juvenile crust in a subduction setting. Thus, these granitoids across the SAB reflect a transformation from water-enriched subduction setting to water-deficient syn-collisional setting at ca. 930–920 Ma. Moreover, the zircon Hf isotope evolution trend across the SAB also suggest a possible transformation from slab retreat to syn-collision at 930–920 Ma. Furthermore, the end Mesoproterozoic and early Neoproterozoic metamorphic and magmatic events in the Tarim Craton, North Qaidam-Kunlun Block, Australia and India blocks display a close affinity. Therefore, we conclude a position of the Tarim craton between QKB, Australia and North India blocks in the periphery of Rodinia, consistent with earlier paleomagnetic data.

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重建罗甸境内的塔里木：阿尔金山带早期托宁期增生和碰撞记录的制约因素

塔里木克拉通在罗迪尼亚内部的位置长期以来一直存在争议，竞争模式从内部模式到外部模式不一而足。塔里木东南边缘的阿尔金山带保留了大量新近纪早期岩浆岩系，可能与罗迪尼亚集合有关。因此，我们在此对南阿尔金山带（SAB）的花岗岩进行了调查，并提供了这些花岗岩的野外地质、锆石 U-Pb-Hf-O 同位素和 H2O 含量以及全岩地球化学数据。图拉花岗岩的年代为 914 ± 3.9 Ma，而 Kuoshi 花岗岩的年代分别为 919 ± 5.2 Ma 和 927.7 ± 5.0 Ma。图拉花岗岩和 Kalaqiaoka 花岗岩样本显示出较高的 ACNK 值，这是 S 型花岗岩的典型特征，与石榴石和黝帘石的出现相一致。此外，图拉花岗岩具有较高的锆石δ18O（7.62 至 10.85 ‰）和较低的εHf（t）（-2.4 至 +0.1）值，以及较低的锆石 H2O 含量（102 ppmw 的中等值），表明是由回收的古地壳生成的原生缺水岩浆，只有少量的幼生岩浆。另一方面，Kuoshi 花岗岩显示出较高的 Sr（169-259 ppm）、Sr/Y（17.85-19.33）和 (La/Yb)N （30-49）比率。Kuoshi花岗岩还具有较高的氧化镁、较低的锆石δ18O（4.15-9.81 ‰）和εHf（t）（-4.0--0.4）值、较高的锆石H2O含量（中等值为255 ppmw）以及与俯冲有关的化学特征。这些特征表明，郭氏花岗岩岩浆可能是在俯冲环境下，由回收的古地壳和新生地壳部分熔融形成的。因此，这些横跨SAB的花岗岩反映了在约930-920Ma时，从富水的俯冲环境向缺水的同步碰撞环境的转变。930-920 Ma。此外，整个SAB地区的锆石Hf同位素演化趋势也表明，在930-920 Ma时，可能发生了从板块退缩到同步碰撞的转变。此外，塔里木克拉通、北柴达木-昆仑地块、澳大利亚和印度地块的中新生代末期和新新生代早期的变质和岩浆事件显示出密切的亲缘关系。因此，我们断定塔里木克拉通位于北柴达木-昆仑地块、澳大利亚地块和北印度地块之间，处于罗迪尼亚的外围，这与早期的古地磁数据相一致。

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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.