The Yangtze Block in South China constitutes an important Precambrian landmass in the present East Asian continent. The Neoproterozoic sedimentary successions of the Hengdan Group in the NW Yangtze Block record essential information for deciphering the Neoproterozoic tectonics along the NW margin. However, its depositional age, provenance and tectonic properties remain uncertain. Here, a combined analysis of detrital zircon U–Pb dating and geochemistry is performed on representative samples from the Hengdan Group. Concordant dating results of samples from the bottom and upper parts constrain the maximum depositional age at c. 720 Ma. Detrital zircon age patterns of samples reveal a uniformly pronounced age peak at c. 915–720 Ma, which is consistent with the magmatic pulses in domains at the NW end of the Yangtze Block. In addition, these samples display left-sloping post-Archaean Australian shale (PAAS)-normalized rare-earth element patterns and variable trace element patterns, resembling sediments accumulated in a basin related to an active continental margin geodynamic setting. Provenance analysis reveals that the main sources featured intermediate to felsic components, which experienced rapid erosion and sedimentation. These integrated new investigations, along with previous compilations, indicate that the Hengdan Group might have been deposited in a fore-arc basin controlled by subduction beneath the Bikou Terrane. Thus, such interpretation further supports proposals for subduction-related tectonics along the western margin of the Yangtze Block during the early Neoproterozoic.

中文翻译：

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华南扬子地块西北部新元古代活动边缘：来自横丹群沉积岩碎屑锆石U-Pb年代学和地球化学的新线索

华南扬子陆块是当今东亚大陆重要的前寒武纪陆块。NW扬子地块横丹群新元古代沉积序列记录了解读NW边缘新元古代构造的重要信息。然而，其沉积时代、物源和构造性质仍不确定。在这里，对来自横单组的代表性样品进行了碎屑锆石 U-Pb 定年和地球化学的联合分析。底部和上部样品的一致测年结果限制了最大沉积年龄C。720 毫安。样品的碎屑锆石年龄模式在C。915～720 Ma，与扬子地块北西端域岩浆脉冲相一致。此外，这些样品显示左倾后太古代澳大利亚页岩 (PAAS) 标准化稀土元素模式和可变微量元素模式，类似于与活跃大陆边缘地球动力学环境相关的盆地中积累的沉积物。物源分析表明，主要来源具有中长英质成分，经历了快速的侵蚀和沉积。这些综合的新调查以及以前的汇编表明，横丹群可能沉积在碧口地体下方受俯冲控制的弧前盆地中。因此，