The northwestern continental margin of the South China Sea, extending from the broad shelf and canyon-growth slope across the Xisha Trough, represents a relic crustal rift that eventually connects to the abyssal plain. However, the provenance and source-to-sink process of sediments in this special topography remains unclear. In this study, we present the detrital zircon U-Pb geochronology of surface sediments from the northwestern margin of the South China Sea to identify the sediment provenance, track the transport pathway, and understand the source-to-sink process in this margin. The results showed that detrital zircons exhibit a wide range of U-Pb ages from 3,062.9 to 41.5 Ma and are characterized by peaks centered on 140–154 Ma, 240–258 Ma, 425–452 Ma, and 738–991 Ma. Statistical analysis indicated that the clastic sediments on the shelf closely resemble those sourced from the Pearl River system. Conversely, sediments on the slope and abyssal plain demonstrated characteristics indicative of multiple sources, primarily originating from the Pearl River, with a minor contribution from the Red River. Further quantitative study revealed a progressive increase (from 8.2% to 43.2%) in the prevalence of Red River-derived sediments with ascending water depth on the shelf and slope, whereas sediment influx in the deepest sector remains predominantly sourced from the Pearl River. This study emphasizes the controls of topography and currents in modulating the transportation of coarse-grained and fine-grained sediments within the source-to-sink system and provides a favorable solution for reconstructing the sedimentary process in continental margins.

中文翻译：

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碎屑锆石记录了南海西北缘的物源和源汇过程


南海西北大陆边缘，从广阔的陆架和峡谷生长斜坡延伸穿过西沙海槽，代表着一个最终连接到深海平原的地壳裂谷遗迹。然而，这种特殊地形中沉积物的来源和源汇过程仍不清楚。在这项研究中，我们提出了南海西北边缘表层沉积物的碎屑锆石 U-Pb 年代学，以识别沉积物来源、跟踪运输路径并了解该边缘的源到汇过程。结果表明，碎屑锆石的 U-Pb 年龄范围较广，从 3,062.9 Ma 到 41.5 Ma，峰值集中在 140-154 Ma、240-258 Ma、425-452 Ma 和 738-991 Ma。统计分析表明，陆架碎屑沉积物与珠江水系的碎屑沉积物非常相似。相反，斜坡和深海平原上的沉积物表现出多种来源的特征，主要来自珠江，红河的贡献较小。进一步的定量研究表明，随着陆架和斜坡上水深的上升，源自红河的沉积物的普遍性逐渐增加（从8.2％到43.2％），而最深处的沉积物流入仍然主要来自珠江。本研究强调地形和水流对源-汇系统内粗粒和细粒沉积物运移的控制，为重建大陆边缘沉积过程提供了有利的解决方案。