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通过对汉江上游的野外考察,发现汉江上游郧西—郧县段第一级阶地前沿全新世土壤剖面中夹有多层古洪水滞流沉积物,选择该河段的归仙河口(GXH)剖面进行了详细野外观察,结合粒度成分和磁化率指标分析,证明它们是典型的古洪水滞流沉积物。采用石英的单片再生剂量法(SAR)获得了该剖面中9个样品的光释光年龄值。基于测定的光释光年龄、考古断代和地层对比结果,确定这四期洪水事件分别发生在距今12500-12000 a、7500-7200 a、3100-2800 a,1000-900 a。通过与汉江上游地区、国内和世界各地的多种指标气候变化记录的对比分析,进一步探讨了汉江上游郧西郧县段全新世以来发生的多期古洪水事件发生的气候背景,这一认识有助于深入理解区域洪涝灾害对全球气候变化的响应规律。
Through the field investigation in the upper reaches of the Hanjiang River, it is found that there are many layers of sediments in the Holocene soil profile in front of the first terrace of the Yunxi-Yunxian section in the upper reaches of the Hanjiang River, and the GXH section of the section A detailed field observation was carried out, which combined with the analysis of grain size composition and susceptibility indices proved that they are typical paleo-flood stagnant sediments. The light-emitting age values of nine samples in this section were obtained using quartz monolithic regeneration dosimetry (SAR). Based on the measured optical light-emitting age, archeological dating and stratigraphic contrast, it was confirmed that the four flood events occurred at 12500-12000 a, 7500-7200 a, 3100-2800 a, 1000-900 a, respectively. Through the comparative analysis of climate change records with multiple indicators in the upper reaches of Hanjiang River, China and other parts of the world, the climatic background of the multi-period ancient flood events occurring since the Holocene in Yunxi County, Upper Hanjiang River has been further discussed This will help to understand deeply the response rules of regional floods to global climate change.