中国东部黄土物源铀同位素碎粒年代学研究  

DUST SOURCE OF THE LOESS DEPOSITS IN THE EASTERN CHINA CONSTRAINED BY URANIUM COMMINUTION AGE

作　　者：李高军[1] 李乐 徐树建 李徐生[3] 陈骏[1] 

机构地区：[1]南京大学地球科学与工程学院、表生地球化学教育部重点实验室,南京210023 [2]山东省水土保持与环境保育重点实验室、临沂大学资源环境学院/水土保持与环境保育研究所,临沂276005 [3]南京大学地理与海洋科学学院、地貌过程与环境实验室,南京210023

出　　处：《第四纪研究》2017年第5期1037-1044,共8页Quaternary Sciences

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 provena

关 键 词：黄土 铀同位素 物源示踪 荒漠化 

分 类 号：P597[天文地球—地球化学] P533[天文地球—地质学]