中山大学王策团队报道了被动和活动大陆边缘沉积物从河流向海沟迁移的控制。相关论文于2024年11月12日发表于国际顶尖学术期刊《中国科学：地球科学》杂志上。

据研究人员介绍，活动大陆边缘和被动大陆边缘在沉积物搬运方面表现出显著差异。然而，量化这些特定沉积过程的机会仍然有限。南海东北部既有活动大陆边缘，也有被动大陆边缘，这为比较大型被动大陆边缘与较小但更有活力的活动大陆边缘的，相对贡献提供了独特的机会。

本研究对南海东北部海相沉积物中的碎屑锆石U-Pb年龄进行了分析，揭示了其物源及边缘搬运过程的控制。研究结果显示，从陆架到海沟，沉积物的来源各不相同。陆架的沉积物主要来自九龙河和高坪河，受控于被动边缘的地形和洋流。相比之下，海底峡谷中的沉积物主要来源于台湾岛西部的高坪河和浊水溪。定量结果表明，高坪海底峡谷与活动边缘的高坪河直接相连，为马尼拉海沟提供了约86.2%的沉积物。

根据物源结果，研究人员提出了活动边缘和被动边缘不同的沉积过程。在被动边缘，来自排水系统的沉积物进入陆架并被洋流运送，但地形的高度经常阻挡这些沉积物，使它们无法到达深海。相比之下，活动边缘以狭窄的大陆架为特征，这有助于海底峡谷和河口之间的直接连接，使重力流能够将沉积物直接带到海沟。该研究提供了对南海东北部沉积物从河流到海沟运输的理解，并强调了大陆边缘沉积物运输过程中的控制因素（洋流、地形和重力流）。

附：英文原文

Title: Controls on sediment transport from rivers to trenches in passive and active continental margins

Author: Letian ZENG, Ce WANG, David A. FOSTER, Ming SU, Heqi CUI, Junmin JIA

Issue&Volume: 2024/11/12

Abstract: Active and passive continental margins exhibit significant differences in sediment transport. However, opportunities to quantify these specific sedimentary processes remain limited. The northeastern South China Sea hosts both active and passive continental margins, offering a distinct opportunity to compare the relative contributions from a large passive continental margin with those from a smaller but more dynamic active margin. We present detrital zircon U-Pb ages from marine sediments in the northeastern South China Sea to decipher their provenance and reveal the control of transport processes in the margins. Our results show varied provenance of sediments from the shelf to the trench. In the continental shelf, sediments were primarily derived from the Jiulong and Gaoping rivers, controlled by the topography and ocean currents in the passive margin. In contrast, the sediments in the submarine canyons predominantly originated from the Gaoping and Zhuoshui rivers in western Taiwan Island. Quantitative results indicate that the Gaoping submarine canyon provided approximately 86.2% of sediments to the Manila Trench by directly linking to the Gaoping River in the active margin. Based on the provenance results, we propose a distinct sedimentary process in the active and passive margins. In passive margins, sediments from drainage systems enter the shelf and are transported by ocean currents, but topographic highs often block these sediments, preventing them from reaching the deep sea. In contrast, active margins feature narrow shelves, which facilitate direct connections between submarine canyons and river mouths, allowing gravity flows to carry sediments directly to the trenches. Our study provides an understanding of the sediments transported from rivers to trenches in the northeastern South China Sea and highlights the controls (ocean currents, dramatic topography, and gravity flows) during the sediment transport in the continental margins.

DOI: 10.1007/s11430-024-1435-0

Source: https://www.sciengine.com/SCES/doi/10.1007/s11430-024-1435-0