Abstract Dronning Maud Land (DML) is a key area for the better understanding of the geotectonic history and amalgamation processes of the southern part of Gondwana. Here, we present comprehensive new zircon U–Pb–Hf–O, whole-rock Sm–Nd isotopic and geochemical data for late Neoproterozoic-Cambrian igneous rocks along a profile from central to eastern DML, which provides new insights into the crustal evolution and tectonics of the region. In central DML, magmatism dominantly occurred at 530–485 Ma, with 650–600 Ma charnockite and anorthosite locally distributed at its eastern periphery. In contrast, eastern DML experienced long-term and continuous granitic magmatism from ca. 650 Ma to 500 Ma. In central DML, the 650–600 Ma samples are characterized by highly elevated δ18O (7.5–9.5‰) associated with slightly negative to positive eHf(t) values (−1 to +3), indicating significant addition of high-δ18O crustal components, such as sedimentary material at the margin of the Kalahari Craton. Evolved Hf isotopic signatures (eHf(t) = −15 to −6) and moderately elevated O isotopic data (δ18O = 6–8‰) of the Cambrian granitic rocks from central DML indicate a significant incorporation of the pre-existing, old continental crust. In eastern DML, the suprachondritic Hf–Nd isotope signatures and moderate δ18O values of the late Neoproterozoic granites (650–550 Ma) from the Sor Rondane Mountains support the view that they mainly originated from crust of the Tonian Oceanic Arc Super Terrane (TOAST). The post-540 Ma granites, however, have more evolved Hf and Nd isotopic compositions, suggesting an increasing involvement of older continental components during Cambrian magmatism. Nd isotopes of the Cambrian granitic rocks in DML display an increasingly more radiogenic composition towards the east with model ages ranging from late Archean to Mesoproterozoic times, which is in line with the isotopic trend of the Precambrian basement in this region. The late Neoproterozoic (>600 Ma) igneous rocks in central and eastern DML were emplaced in two independent subduction systems, at the periphery of the eastern Kalahari Craton and somewhere within the Mozambique Ocean respectively. The accretion and assembly of the TOAST to the eastern margin of the Kalahari Craton and their collision with surrounding continental blocks was followed by extensive post-collisional magmatism due to delamination tectonics and orogenic collapse in the Cambrian. The late Neoproterozoic–Cambrian igneous rocks in DML thus record an orogenic cycle from subduction-accretion, continental collision to post-collisional process during and after the assembly of Gondwana.

中文翻译：

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Dronning Maud Land（南极东部）晚新元古代-寒武纪岩浆活动：U-Pb 锆石年代学、同位素地球化学及其对冈瓦纳大陆组装的影响

摘要 Dronning Maud Land (DML) 是更好地了解冈瓦纳大陆南部大地构造历史和合并过程的关键区域。在这里，我们提供了新元古代-寒武纪晚期火成岩的全面的新锆石 U-Pb-Hf-O、全岩 Sm-Nd 同位素和地球化学数据，这些数据沿着 DML 中部到东部的剖面，为地壳演化提供了新的见解和该地区的构造。DML中部岩浆活动主要发生在530～485 Ma，东部外围局部分布有650～600 Ma的硬长岩和斜长岩。相比之下，东部 DML 经历了来自约 650 毫安到 500 毫安。在中央 DML 中，650-600 Ma 样品的特征是 δ18O (7.5-9. 5‰) 与 eHf(t) 值略微负到正相关（-1 到 +3），表明高δ18O 地壳成分显着增加，例如喀拉哈里克拉通边缘的沉积物质。来自 DML 中部的寒武纪花岗岩的演化 Hf 同位素特征（eHf(t) = -15 至 -6）和适度升高的 O 同位素数据（δ18O = 6–8‰）表明，先前存在的古老大陆脆皮。在 DML 东部，来自 Sor Rondane 山脉的晚新元古代花岗岩（650-550 Ma）的上球粒状 Hf-Nd 同位素特征和中等 δ18O 值支持它们主要起源于托尼亚大洋弧超级地壳（TOAST）地壳的观点. 然而，后 540 Ma 花岗岩具有更多演化的 Hf 和 Nd 同位素组成，表明在寒武纪岩浆作用期间，较老的大陆成分越来越多地参与其中。DML中寒武纪花岗岩的Nd同位素显示出越来越多的放射成因成分向东，模型年龄从太古代晚期到中元古代，这与该地区前寒武纪基底的同位素趋势一致。DML 中部和东部的晚新元古代 (>600 Ma) 火成岩被置于两个独立的俯冲系统中，分别位于喀拉哈里克拉通东部的外围和莫桑比克洋内的某处。TOAST在喀拉哈里克拉通东缘的吸积和聚集以及它们与周围大陆块的碰撞之后，由于寒武纪的分层构造和造山崩塌而发生了广泛的碰撞后岩浆作用。因此，DML 中晚新元古代-寒武纪火成岩记录了冈瓦纳大陆组装期间和之后的从俯冲-增生、大陆碰撞到后碰撞过程的造山循环。