The Yangtze River Delta has experienced intricate sedimentary and environmental changes throughout the Holocene, driven by the interplay of fluvial and marine forcings. This study presents quartz optically stimulated luminescence (OSL) ages and luminescence sensitivity data from a Holocene sediment core MQ, analyzed across four grain-size fractions, ranging from silt to sand. The results reveal substantial variability in OSL ages and sensitivity among grain sizes, with the medium-grain (45–63 μm) fraction yielding the most consistent and reliable results. In contrast, finer and coarser grains tend to overestimate ages due to incomplete bleaching, with the accurate dating of coarser grains requiring more aliquots or single-grain measurements. The variability in luminescence sensitivity reflects changes in sediment provenance and depositional conditions between estuarine and deltaic environments. OSL ages indicate that the sedimentary evolution of the Yangtze River Delta progressed through distinct phases: rapid accumulation during the early Holocene (10–7 ka) driven by rising sea level and valley infilling; reduced sedimentation during the middle Holocene (7–3 ka) related to a dry climate in the catchment; and accelerated deposition in the late Holocene (3 ka–present) associated with enhanced fluvial input linked to intensified human activities. This study highlights the importance of selecting suitable appropriate grain sizes and carefully comparing different fractions in OSL analysis to reconstruct deltaic chronologies accurately. The finding that the medium-grain fraction yields more reliable OSL ages than finer and coarser fractions should be tested in similar settings elsewhere. The results provide valuable insights for future research on complex depositional environments and contribute to a better understanding of long-term environmental changes.

中文翻译：

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交叉检查不同晶粒大小的 OSL 年龄以提高三角洲环境中的时间可靠性：以长三角为例


在整个全新世，长江三角洲经历了错综复杂的沉积和环境变化，这是由河流和海洋强迫的相互作用驱动的。本研究展示了来自全新世沉积物岩芯 MQ 的石英光受激发光 （OSL） 年龄和发光敏感性数据，分析了从淤泥到沙子的四个粒度部分。结果显示，不同晶粒大小的 OSL 年龄和灵敏度存在很大差异，其中中等晶粒 （45-63 μm） 馏分产生最一致和可靠的结果。相比之下，由于漂白不完全，较细和较粗的谷物往往会高估年龄，而较粗谷物的准确年代需要更多的等分试样或单粒测量。发光敏感性的变化反映了河口和三角洲环境之间沉积物来源和沉积条件的变化。OSL 年龄表明，长江三角洲的沉积演化经历了不同的阶段：全新世早期（10-7 ka）由海平面上升和山谷填充驱动的快速积累;全新世中期 （7-3 ka） 与集水区干燥气候相关的沉积减少;以及全新世晚期 （3 ka） 的加速沉积，与与强化的人类活动相关的河流输入增强有关。本研究强调了在 OSL 分析中选择合适的晶粒尺寸并仔细比较不同馏分以准确重建 deltaic 年代学的重要性。中等颗粒馏分比较细和较粗馏分产生更可靠的 OSL 年龄的发现应该在其他地方的类似环境中进行测试。 研究结果为未来复杂沉积环境的研究提供了有价值的见解，有助于更好地理解长期环境变化。