Abstract The late Neoproterozoic (~720–541 Ma) tectonic evolution of South China may have included the development of a paleo-ocean basin (the South China Ocean Basin, SCOB) between the Yangtze and Cathaysia blocks. The Niuhe section in the Yongfu area of northern Guangxi Zhuang Autonomous Region, owing to its location on the southeastern margin of the Yangtze Block and its preservation of an alternating succession typical of both Yangtze- and Cathaysia-type deposits, provides an important window to test if this oceanic basin existed during the late Neoproterozoic. Cryogenian-Ediacaran siliciclastics in the northern Guangxi region were deposited in the intracontinental Xiang-Gui Basin. Detrital zircon assemblages from the Cryogenian Lijiapo Formation at Niuhe yield a prominent U Pb age peak of ~774 Ma, with a minor peak of ~891 Ma, indicative of provenance from the Yangtze Block to the northwest. In contrast, zircon samples from the Cryogenian Zhengyuanling Formation of the Laoshan area (Guangxi Zhuang Autonomous Region), which is located closer to the Cathaysia Block than Niuhe, yield a prominent age peak of 959–1112 Ma, consistent with a Cathaysian provenance. Furthermore, three samples of Ediacaran sandstones from Niuhe yield an age peak of ~900–1100 Ma, also demonstrating provenance from the southeast (i.e., Cathaysia). The Cathaysian provenance of Ediacaran sandstones on the southeastern margin of the Yangtze Block does not support the scenario of a broad SCOB between the Yangtze and Cathaysia blocks during the Ediacaran, and the Xiang-Gui Basin is best regarded as an immature intracontinental rift (aulacogen). Uplift of the Cathaysian Block through slab retreat on its external (southeastern) margin (i.e., the ‘top-down’ model of Rodinian breakup) may have been responsible for generation of a massive influx of siliciclastics into the Xiang-Gui Basin during the Ediacaran.

中文翻译：

---

碎屑锆石证据证明晚新元古代扬子和华夏地块的地理邻近性

摘要 华南晚新元古代 (~720-541 Ma) 构造演化可能包括在扬子地块和华夏地块之间发育古海洋盆地（华南大洋盆地，SCOB）。桂北永福地区牛河段地处扬子地块东南缘，保留了典型的扬子型和华夏型矿床交替序列，为试验提供了重要窗口如果这个洋盆存在于新元古代晚期。桂北地区低温纪—埃迪卡拉纪硅质碎屑沉积于陆内相桂盆地。来自牛河低温期李家坡组的碎屑锆石组合产生了一个显着的 U Pb 年龄峰~774 Ma，次要峰~891 Ma，表明从扬子地块到西北的物源。相比之下，位于比牛河更靠近华夏地块的崂山地区（广西壮族自治区）低温正元岭组的锆石样品产生了一个显着的 959-1112 Ma 年龄峰值，与华夏物源一致。此外，来自牛河的三个埃迪卡拉纪砂岩样品的年龄峰值约为 900-1100 Ma，也表明来自东南部（即华夏）。扬子地块东南缘埃迪卡拉纪砂岩的华夏物源不支持埃迪卡拉纪扬子地块与华夏地块之间存在广阔的SCOB情景，而香桂盆地最好被视为未成熟的陆内裂谷（aulacogen） .