Abstract The Paleoproterozoic is a pivotal time for understanding the geochronological framework of the Tarim Craton. Located at the southeastern margin of the Tarim Craton, the northern Altyn Tagh is the main region of exposed Paleoproterozoic magmatic and metamorphic rocks. These rocks are diverse, diachronous, and modified by multiphase tectonothermal events. In this study, we performed systematic analyses on the amphibolite, felsic gneisses, and metasedimentary rocks in the Aketashitage area, southeastern Tarim Craton, including petrography, mineral chemistry, and whole-rock geochemistry, as well as in-situ zircon U-Pb ages and Hf isotopes, to examine the Paleoproterozoic magmatic-metamorphic events in the northern Altyn Tagh. Results from our study indicate that geochemically, the amphibolite and felsic gneisses in the Aketashitage area resemble the typical bimodal associations of mafic and acidic volcanic rocks. In addition, felsic gneisses are characterized by high Sr and low Y contents, high Sr/Y and (La/Yb) N ratios, and indistinctive Eu anomalies, closely resembling high-SiO2 adakites derived from subducted basaltic slab-melt. The palimpsest textures and geochemical features of the Aketashitage metasedimentary rocks suggest that their protoliths are argillaceous rocks. The amphibolite from the study area has a metamorphic age of 1.96 Ga, and the felsic gneisses yield crystallization ages of 2.54–2.52 Ga. The major age peaks of metasedimentary rocks in the Aketashitage area, namely 2.72 Ga, 2.05 Ga, and 1.97 Ga, are remarkably consistent with the magmatic and/or metamorphic events in the same area. Furthermore, the minimum age peak of the studied metasedimentary rocks suggests a depositional age no earlier than 1.97 Ga. Geochemical and geochronological evidence from the exposed rock associations in the Aketashitage area suggest a subduction-related tectonic setting during the Paleoproterozoic. Our new data combined with the findings of previous studies indicate that Paleoproterozoic magmatism and metamorphism in the northern Altyn Tagh area are nearly synchronous, and that both are likely related to oceanic subduction.

中文翻译：

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塔里木克拉通东南部阿尔金北部变质基岩中记录的古元古代多相岩浆作用和变质作用

摘要 古元古代是认识塔里木克拉通地质年代框架的关键时期。阿尔金北部位于塔里木克拉通东南缘，是古元古代岩浆变质岩出露的主要地区。这些岩石是多样的、历时的，并受到多相构造热事件的影响。在这项研究中，我们对塔里木克拉通东南部阿克塔什塔格地区的角闪岩、长英质片麻岩和变质沉积岩进行了系统分析，包括岩石学、矿物化学和全岩地球化学，以及原位锆石 U-Pb 年龄和 Hf 同位素，以研究阿尔金北部的古元古代岩浆变质事件。我们的研究结果表明，地球化学上，Aketashitage 地区的角闪岩和长英质片麻岩类似于典型的基性火山岩和酸性火山岩的双峰组合。此外，长英质片麻岩的特点是高 Sr 和低 Y 含量，高 Sr/Y 和 (La/Yb) N 比，以及不明显的 Eu 异常，与俯冲玄武岩板片熔体产生的高 SiO2 埃达克岩非常相似。Aketashitage变质沉积岩的最复本结构和地球化学特征表明它们的原岩是泥质岩。研究区角闪岩变质年龄为1.96 Ga，长英质片麻岩结晶年龄为2.54～2.52 Ga。 Aketashitage地区变质沉积岩的主要年龄峰值为2.72 Ga、2.05 Ga和1.97 Ga，与同一地区的岩浆和/或变质事件非常一致。此外，研究的变沉积岩的最小年龄峰值表明沉积年龄不早于 1.97 Ga。来自 Aketashitage 地区裸露岩石组合的地球化学和地质年代学证据表明，古元古代期间存在与俯冲相关的构造环境。我们的新数据结合以往研究结果表明，阿尔金地区北部的古元古代岩浆作用和变质作用几乎是同步的，两者都可能与大洋俯冲有关。