The evolution of the northern margin of Gondwana, especially to the north of India and Australia, remains enigmatic. Much controversy concerns when and where the Tarim craton was amalgamated with northern Gondwana due to final closure of the North and South Altyn Oceans (two branches of the Proto–Tethys Ocean between southeastern Tarim and northern Gondwana). This study addressed these issues through systematic field-based zircon U-Pb dating and Hf-isotope analyses of early Paleozoic sedimentary rocks in the Altyn Tagh orogen. New dating results reveal depositional ages from ca. 494 to 426 Ma. Provenance tracing indicates the ca. 494–477 Ma samples were dominantly sourced from local Altyn Tagh areas to the south of the North Altyn Ocean, whereas the ca. 465–449 Ma samples are characterized by a significant increase in ca. 2.7–2.4 Ga, 2.0–1.7 Ga, and 840–780 Ma detrital zircons, indicating an augmented supply of detritus from the Tarim craton to the north of the North Altyn Ocean. This change indicates a major provenance shift from a single to multiple source regions between ca. 477 and 465 Ma, marking the timing of the final closure of the North Altyn Ocean. Zircon U-Pb and Hf-isotopic data from the ca. 444–426 Ma samples resemble those from the ca. 465–449 Ma samples, suggesting local sediment recycling related to a postcollisional regime. Considering the South Altyn Ocean and other branches of the Proto–Tethys Ocean, we infer that the entire Proto–Tethys Ocean might have been progressively closed at ca. 500–420 Ma, leading to the amalgamation of most East Asian blocks with northern Gondwana. Detrital zircon U-Pb and Hf-isotope comparisons indicate that Tarim shared a North Indian affinity with many East Asian terranes (such as North Qilian, North Qinling, South China, Indochina, South Qiangtang, etc.), rather than with Arabia-Iran or other terranes (e.g., Lhasa and Sibumasu) that were adjacent to western Australia along the northern margin of Gondwana.

中文翻译：

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Altyn Tagh造山带中的早古生代沉积岩的起源：洞察贡多瓦纳北部塔里木克拉通的古沉积，并与原特提斯洋最终封闭有关

冈瓦纳北部边缘，尤其是印度和澳大利亚北部的演化仍是一个谜。由于南北Altyn海洋（塔里木东南部和冈瓦纳北部之间的原始特提斯海洋的两个分支）最终关闭，塔里木克拉通何时与何地与冈瓦纳北部合并在一起，这引起了很多争议。这项研究通过系统地基于现场的锆石U-Pb测年和对Altyn Tagh造山带中早期古生代沉积岩的Hf同位素分析解决了这些问题。新的测年结果揭示了大约从大约成矿的沉积年龄。494至426 Ma。来源跟踪显示ca。494–477 Ma的样品主要来自北阿尔廷海洋以南的阿尔廷塔格地区。465-449 Ma样品的特征在于ca的显着增加。2.7–2.4 Ga，2.0–1.7 Ga，840-780 Ma碎屑锆石，表明从塔里木克拉通到北阿尔廷海北部的碎屑供应增加。这种变化表明主要的出处在大约2个之间从一个源区域转移到了多个源区域。477和465 Ma，标志着北阿尔丁海洋最终封闭的时机。锆石中的锆石U-Pb和Hf同位素数据 444–426 Ma的样品类似于来自约莫的样品。465-449 Ma的样本，表明与碰撞后状态有关的局部沉积物回收。考虑到南阿尔廷海和原特提斯洋的其他分支，我们推断整个原特提斯洋可能已逐渐关闭。500–420 Ma，导致大多数东亚地区与冈瓦纳北部合并。