The general configuration of the main continental blocks in the Gondwana supercontinent and the Ediacaran–early Paleozoic tectonic evolution of its northern margin are widely accepted. However, reconstruction of the original positions and the question of potential separation of the Gondwana-derived crustal segments that are now included in the Variscan and Alpine orogenic belts remain controversial. The Western Carpathians, part of the Alpine–Carpathian belt, represents an important crustal segment broken-off from northern Gondwana and later incorporated into both the Variscan and Alpine collisional orogens. The earliest tectonic evolution and paleogeography of the pre-Variscan basement of the Western Carpathians remains poorly known, due to insufficient age data and intense polyphase tectonometamorphic overprints, both Variscan and Alpine. This paper provides new results of U–Pb dating and Hf isotopic analysis of detrital zircons as well as a whole-rock geochemical study from metavolcanic-sedimentary basement units of the Western Carpathians. The obtained age spectra suggest that the sedimentary succession was supplied dominantly by Ediacaran (c. 600 Ma) zircons, with a relatively minor role for Stenian–Tonian (c. 1.2–0.9 Ga) and Paleoproterozoic cratonic (c. 2.2–1.8 Ga) zircons. The mixed Hf isotopic signature (ε values ranging from −20 to +12) of the Ediacaran zircons indicates substantial mixing of mantle-derived magmas with mature crustal material, typical of continental magmatic arcs. In contrast, the mostly negative ε values (−15 to +4) of the cratonic zircons suggest recycling of an older continental crust. The presumably youngest part of the sequence is also characterised by high proportion of early Paleozoic zircons with generally negative ε values (−10 to −2). The zircon U–Pb age spectra, Hf isotopic patterns and whole-rock geochemical signatures of the studied Western Carpathians sequences are interpreted as reflecting deposition at a progressively developing Cambrian–Silurian passive margin setting. The West Carpathian data have been correlated with a comprehensive detrital zircon U–Pb age and Hf isotope data set compiled from possible source areas and other Gondwana-derived units to test the possibility of their primary linkages. These correlations indicate strong similarity in both zircon U–Pb age spectra and Hf isotopic compositions to other parts of the Ediacaran (Cadomian) continental magmatic arc. Older, cratonic sources are linked to the Saharan or East African parts of northern Gondwana, whereas the early Paleozoic detritus must represent a local volcanic source. Taken together, our new data from the Western Carpathians provide constraints for a new paleogeographic model of the northern African part of the Gondwana passive margin.

中文翻译：

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瓦里坎和阿尔卑斯碰撞所涉及的冈瓦纳被动边缘碎片的古地理：西喀尔巴阡变火山沉积基底的视角


冈瓦纳超大陆主要陆块的总体形态及其北缘埃迪卡拉纪—早古生代构造演化已被广泛接受。然而，原始位置的重建以及现在包含在瓦里斯造山带和阿尔卑斯造山带中的冈瓦纳大陆地壳部分的潜在分离问题仍然存在争议。西喀尔巴阡山脉是阿尔卑斯-喀尔巴阡山脉的一部分，代表着从冈瓦纳北部分裂出来的重要地壳部分，后来并入瓦里西亚和阿尔卑斯碰撞造山带。由于年龄数据不足和瓦里西亚和阿尔卑斯地区强烈的多相构造变质叠印，西喀尔巴阡山脉前瓦里西亚基底的最早构造演化和古地理仍然知之甚少。本文提供了碎屑锆石 U-Pb 定年和 Hf 同位素分析的新结果，以及西喀尔巴阡变火山沉积基底单元的全岩地球化学研究。获得的年龄谱表明，沉积层序主要由埃迪卡拉系（约 600 Ma）锆石提供，斯滕阶-托尼阶（约 1.2–0.9 Ga）和古元古代克拉通（约 2.2–1.8 Ga）的作用相对较小。锆石。埃迪卡拉纪锆石的混合 Hf 同位素特征（ε 值范围为 -20 至 +12）表明，地幔岩浆与成熟地壳物质大量混合，这是典型的大陆岩浆弧。相比之下，克拉通锆石的 ε 值大多为负值（−15 至 +4），表明较古老的大陆地壳发生了再循环。该序列中可能最年轻的部分还具有高比例的早期古生代锆石的特征，这些锆石的 ε 值通常为负值（−10 至 −2）。 所研究的西喀尔巴阡序列的锆石U-Pb年龄谱、Hf同位素模式和全岩地球化学特征被解释为反映了逐渐发展的寒武纪-志留纪被动边缘环境中的沉积。西喀尔巴阡山脉的数据已与从可能的源区和其他冈瓦纳衍生单元编制的综合碎屑锆石 U-Pb 年龄和 Hf 同位素数据集相关联，以测试它们主要联系的可能性。这些相关性表明，锆石 U-Pb 年龄谱和 Hf 同位素组成与埃迪卡拉纪（卡多米亚）大陆岩浆弧的其他部分非常相似。较古老的克拉通源与冈瓦纳北部的撒哈拉或东非部分有关，而早古生代碎屑必须代表当地的火山源。总而言之，我们来自西喀尔巴阡山脉的新数据为冈瓦纳被动边缘北非部分的新古地理模型提供了约束。