摘要
细粒物质的234U／238U比值记录了颗粒自破碎以来经历的时间，具有示踪地表过程的巨大潜力。本研究应用铀同位素碎粒年龄学解析中国东部黄土堆积的物源。中国东部黄土的初始。234U／238U比值低于黄土高原黄土，指示出不同的物质来源。中国东部黄土物源具有很强的近源性，显示出明显区域特征。山东半岛及其滨海黄土主要来自黄泛平原和冰期暴露陆架的黄河沉积物。黄河沿岸黄土可能直接来自黄河河漫滩。下蜀黄土可能来自冰期阶段的长江沉积物。
The 234U/238U ratio of fine particles can record the time since the particle breaking, which has great potential in tracing the surface processes. This work applies uranium isotope comminution age to constrain the source of the loess deposits in Eastern China. Here we collected the loess samples since the Last Glacial Maximum in Eastern China, including the Shandong Peninsula and its adjacent coastal area, the lower reaches of the Yellow River and the Changjiang River. The loess deposits in Shandong Peninsula were collected from the center of the Peninsula （ QZ and XLZ profiles） , its coastal area （XBZ profile） , and the adjacent Miaodao Islands （BZ and TJ profiles）. The loess deposits in the lower reaches of the Yellow River were collected from Mangshan region, Henan Province, and Pingyin region, Shandong Province. The Xiashu loess deposits in the lower reaches of the Changjiang River were collected from four sites, Mufushan, Taishanxineun, Dagang and Laoshan, in Ningzhen region. The sediment of Yellow River and Changjiang River were also collected to compare with the loess deposits. The （ 234U//238U ） ratio of the loess deposits in Eastern China shows obvious regional characteristics. The loess deposits in the Shandong Peninsula and its adjacent coastal area show low and variable （234U/238u） values ranging from 0. 935 and 0. 944. The （234U/238U） value of Xiashu loess is relatively homogenous with a mean value of 0. 954, which is similar to that of the fresh loess deposits on the Chinese Loess Plateau （ CLP）. The loess in the lower reaches of the Yellow River show （234U/238U） values consistent with the sediments in the floodplain of the Yellow River, which are lower than that of the loess deposits on the CLP. The modern sediments of the Changjiang River show low （ 234U/238U ） values ranging from 0. 929 to 0. 942. The low initial 234U/238U ratio of the loess deposits in Eastern China indicates a dust source that is different to that of the loess on the CLP. Instead, the provenance of loess in Eastern China shows strong regional variation which is linked to the arid lands nearby. The Yellow River sediment exposed on the floodplain and the shelf during glacial times were the major source for the loess in Shandong Peninsula and its adjacent coastal area. The loess in the lower reaches of the Yellow River were blown directly from the floodplain of the Yellow River. Xiashu loess may be originated from the sediments of Changjiang River that were exposed during glacial times.
出处
《第四纪研究》
CAS
CSCD
北大核心
2017年第5期1037-1044,共8页
Quaternary Sciences
关键词
黄土
铀同位素
物源示踪
荒漠化
loess, uranium isotope, source tracing, desertification
