海洋地质与第四纪地质2026，Vol.46Issue(4)：1-13,中插1-中插2,15.DOI:10.16562/j.cnki.0256-1492.2025112802
中新世以来南海东部与西南次海盆沉积格局及其构造控制
Sedimentary differentiation and tectonic control in the eastern and southwestern sub-basins of the South China Sea since the Miocene
摘要
Abstract
To reconstruct the provenance evolution since the Middle Miocene and identify its controlling factors on sedimentation pattern in the South China Sea,the mechanisms of differential sedimentation between the eastern and southwestern sub-basins of the South China Sea were studied.Core samples from IODP Expedition 349 Sites U1431,U1433,and U1434 were used,and geochemistry of element and Sr-Nd isotope were analyzed systematically.Results reveal distinct sedimentary histories.Chemical weathering indices(CIA)indicate that the southwestern sub-basin(Site U1433)experienced persistently stronger chemical weathering than the eastern sub-basin(Site U1431)since approximately 6 Ma,highlighting a fundamental difference in source-area weathering regimes.Rare earth element signatures and La-Th-Sc systems show that sediments in the two sub-basins are derived mainly from felsic upper continental crust.However,the eastern sub-basin records a significant influx of mafic volcanic or seamount-derived materials during the Middle-Late Miocene.A major provenance reorganization occurred in～8 Ma as indicated by Sr-Nd isotopes.Following this shift,the eastern sub-basin had been dominated by northern terrigenous sources(Pearl River and Taiwan Island),whereas the southwestern sub-basin remained under the sustained influence of western sources,mostly from the Indochina Peninsula(e.g.,the Mekong River).This pivotal transition entailed a provenance change from volcanic-domination to northern terrigenous-domination in the eastern sub-basin.In contrast,the southwestern sub-basin's provenance was more sensitive to local tectonic-fluvial events(e.g.,uplift of the East Vietnam Marginal Plateau,migration of the Mekong River estuary).The observed sedimentary differentiation since the Middle Miocene fundamentally stems from differential responses of the two sub-basins to a common series of regional tectonic events.This differentiation pattern was governed by provenance shifts driven by these tectonic movements,which was further modulated by the basin topography and ocean current systems.关键词
大洋钻探/地球化学/Sr-Nd 同位素/沉积分异/南海Key words
ocean drilling/geochemistry/Sr-Nd isotope/sedimentary differentiation/South China Sea分类
海洋科学引用本文复制引用
曹海港,郭玉萍,陈雪刚..中新世以来南海东部与西南次海盆沉积格局及其构造控制[J].海洋地质与第四纪地质,2026,46(4):1-13,中插1-中插2,15.基金项目
国家自然科学基金国际(地区)合作与交流项目"南海与西伊比利亚洋陆转换带张裂-破裂过程与岩石圈结构的对比研究"(41761134051) （地区）
