Iron geochemistry and C-S-Fe early diagenesis in sediments on South China Sea northeastern slope derived from tectonically active islands Responses to climate and environment changes

The dataset contains an age-depth model, sediment grain-size fractions, mean grain size, organic carbon contents and isotopic compositions, main elemental compositions, solid-phase reactive iron and reduced sulfur chemistry, and porewater chemistry collected from the northeastern slope of the South China Sea (SCS). These data were used to elucidate how sea-level rise and ocean current driven changes in sediment provenance from tectonically active Taiwan and Luzon islands have influenced Fe geochemistry and carbon–sulfur–iron diagenesis since the late Last Deglaciation. Results indicate that during 12.4–10.0 ka BP, marine organic carbon (OC) declined as primary productivity fell in response to rapid sea-level rise and weakening of East Asian Winter Monsoon (EAWM). During the low sea-level period before ~10 ka BP, elevated availability of degradable OC fueled sulfate reduction; however, total reduced inorganic sulfide (TRIS) remained low due to generally refractory nature of the sedimentary OC. After ~9 ka BP, bulk OC remained low, reflecting a weaker EAWM and enhanced Kuroshio intrusion driven by increased El Niño–Southern Oscillation (ENSO), with an increase in Luzon-derived sediment input in response to the intensification of Kuroshio intrusion. During the sea-level highstand after 9 ka BP, low OC and abundant reactive Fe oxides promoted dissimilatory Fe reduction, thereby suppressing sulfate reduction. After ~8.6 ka BP, enhanced input of Fe-rich volcanic material from Luzon by intensified Kuroshio intrusion represented a key mechanism for FeHR enrichment in marginal seas even under low-to-moderate chemical weathering of the source materials. Markedly high ratios of poorly reactive Fe (FePR) to FeT reflect the contribution from Luzon-derived Fe-rich detritus and/or inheritance from source materials typical of tectonically active islands in general. This study reveals coupled responses of sediment provenance, OC burial, and C–S–Fe diagenesis to sea-level and climate change, highlighting Fe-rich volcanic material in shaping Fe geochemistry and reactive Fe enrichment in oxic marginal seas.本数据集包含采自南海（South China Sea, SCS）东北部陆坡的年龄-深度模型、沉积物粒度组分、平均粒径、有机碳含量与同位素组成、主量元素组成、固相活性铁及还原硫化学特征，以及孔隙水化学数据。这些数据被用于阐明自晚末次冰消期以来，海平面上升与洋流驱动的、来自构造活跃的台湾岛与吕宋岛的沉积物物源变化，如何影响了铁地球化学与碳-硫-铁成岩作用。研究结果显示，在12.4~10.0 ka BP期间，受海平面快速上升与东亚冬季风（East Asian Winter Monsoon, EAWM）减弱影响，海洋初级生产力下降，海洋有机碳（marine organic carbon, OC）随之降低。在约10 ka BP前的低海平面时期，可降解有机碳的高可用性促进了硫酸盐还原作用，但由于沉积有机碳总体上难降解，总还原无机硫化物（total reduced inorganic sulfide, TRIS）仍处于较低水平。约9 ka BP后，总有机碳（bulk OC）维持在较低水平，这反映了东亚冬季风强度减弱以及受厄尔尼诺-南方涛动（El Niño–Southern Oscillation, ENSO）增强驱动的黑潮入侵增强；同时吕宋岛来源的沉积物输入量随黑潮入侵加剧而增加。在9 ka BP后的海平面高水位时期，低有机碳含量与充足的活性铁氧化物促进了异化铁还原作用，从而抑制了硫酸盐还原。约8.6 ka BP后，因黑潮入侵增强而输入的吕宋岛富铁火山物质增多，这即使在源区化学风化程度为中低等的情况下，仍是边缘海高反应活性铁（FeHR）富集的关键机制。低反应活性铁（FePR）与总铁（FeT）的比值显著偏高，这反映了吕宋岛来源的富铁碎屑物质的贡献，以及普遍存在的构造活跃岛弧源区物质的继承性特征。本研究揭示了沉积物物源、有机碳埋藏以及碳-硫-铁成岩作用对海平面与气候变化的耦合响应，凸显了富铁火山物质在塑造有氧边缘海铁地球化学特征与活性铁富集过程中的关键作用。