南昌市厚田剖面末次冰期沉积的色度特征及其古环境意义

色度是古环境重建的重要指标之一，常用于黄土高原黄土古气候重建，但其在亚热带湿润区第四纪沉积中的研究十分少见且意义不明。选取鄱阳湖南岸之厚田沙地的沉积剖面为研究对象，进行了色度测试，结合光释光测年结果,将色度参数与其他气候代用指标进行对比，探讨MIS4—MIS2期间的古气候变化特征。结果表明：各色度参数曲线在剖面垂直方向上产生了较大波动，呈现出干冷→暖湿→干冷的多个冷暖震荡。其中L*值曲线的波峰段主要集中在沙丘砂层（HT6、HT4、HT1），指示MIS4阶段、MIS3b阶段和MIS2晚期阶段为干燥寒冷的气候环境，冬季风增强；a*、b*、C*和h*值曲线的波峰段主要集中在砂质古土壤层（HT5、HT3、HT2），指示MIS3c阶段、MIS3a阶段和MIS2早期阶段为温暖湿润的气候环境，夏季风增强，反映了该区域在末次冰期受冬季风和夏季风交替影响的气候演变格局。

Chromaticity characteristics of the Last Glacial sediments in Houtian section of Nanchang city and its paleoenvironmental significance

Chroma is one of the important indicators of paleoenvironment reconstruction, and is often used for paleoclimate reconstruction of the loess plateau, but its research in the Quaternary sediments in subtropical humid regions is rare and its significance is unclear. The sedimentary profile of Houtian sandy land on the south bank of Poyang Lake was selected as the research object and the chromaticity test was carried out. Combining with the results of optically stimulated luminescence (OSL), the chromaticity parameters were compared with other climatic proxies, and the paleoclimate changes during MIS2-MIS4 were discussed. Results show that the chromaticity parameter curves have large fluctuations in the vertical direction of the profile, showing multiple cold-warm oscillations from dry-cold → warm-wet → dry-cold. Among them, the peak sections of the L* (brightness) value curve are mainly concentrated in the dune sand layers of HT6, HT4, and HT1, indicating that the MIS4 stage, MIS3b stage, and early MIS2 stage, respectively, are dry and cold climate environment. The peak sections of the a*(redness), b* (yellowness), C* (saturation), and h* (hue) value curves are mainly concentrated in the sandy palaeosol layers of HT5, HT3, and HT2, representing the MIS3c stage, MIS3a stage and late MIS2 stage respectively, are warm and humid climate environment. The chromaticity index better reveals the characteristics of climate change in the Houtian area, and reflect the climate evolution pattern in the area affected by alternating winter monsoon and summer monsoon during the last glacial period.