Abstract A complex suite of geological information from deep-sea drilling cores can provide insights into the Cenozoic evolution of the South China Sea (SCS). Therefore, the thick sediment sequence, obtained during International Ocean Discovery Program (IODP) Expedition 368 at Site U1501 in the northern SCS, provides excellent materials to investigate the paleoceanographic and geological evolution. The generally well-preserved calcareous nannofossil assemblages allowed us to establish a high-resolution biostratigraphic framework, and revealed dramatic fluctuations in sedimentation rates during the middle Miocene through earliest Pliocene (ca. 15–5 Ma). The sedimentation rate was high during the middle Miocene, decreased dramatically before the middle/late Miocene boundary and essentially ceased afterwards, with resumption of deposition close to the late Miocene/Pliocene boundary. Sediment source analysis with diffuse reflectance spectra shows that biogenic carbonate accounts for approximately half of the bulk sediments and that the dilution effect by terrigenous sediments partially controlled the carbonate content, whereas the high sedimentation rates were fueled by both sources during the middle Miocene. The apparent 1.5-Myr-long hiatus (10.5–9 Ma) corresponds to the globally distributed “carbonate crash”, which was truncated in this region by the regionally important Dongsha Movement. The accompanying decrease in carbonate content and terrigenous materials may indicate decreased biogenic carbonate export to deep waters during the carbonate crash, possibly resulting from the progressive constriction of the Indonesian Seaway. The restricted distribution of Discoaster hamatus at this site suggests that the Dongsha Movement commenced at 9.5 Ma, younger than previously proposed.

中文翻译：

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南海北部中-晚中新世沉积速率变化及其区域地质意义

摘要 来自深海钻探岩心的一套复杂地质信息可以提供对南海新生代 (SCS) 演化的深入了解。因此，国际海洋发现计划 (IODP) 远征 368 在南海北部 U1501 站点获得的厚沉积层序列为研究古海洋学和地质演化提供了极好的材料。普遍保存完好的钙质纳米化石组合使我们能够建立高分辨率的生物地层框架，并揭示了中新世中期至上新世最早（约 15-5 Ma）期间沉积速率的剧烈波动。中中新世沉积速率高，中新世中晚期边界之前急剧下降，之后基本停止，随着靠近晚中新世/上新世边界的沉积恢复。漫反射光谱沉积物来源分析表明，生物碳酸盐约占大部分沉积物的一半，陆源沉积物的稀释作用部分控制了碳酸盐含量，而在中中新世期间，这两种来源都推动了高沉积速率。明显的 1.5-Myr-long 中断（10.5-9 Ma）对应于全球分布的“碳酸盐崩溃”，该中断在该地区被具有区域重要性的东沙运动截断。随之而来的碳酸盐含量和陆源物质的减少可能表明在碳酸盐崩溃期间向深水出口的生物碳酸盐减少，这可能是由于印度尼西亚海道的逐渐收缩造成的。