U-Pb ages of zircon grains reveal a proximal dust source of the Xiashu loess, Lower Yangtze River region, China  

作　　者：Fei Liu Gaojun Li Jun Chen 

机构地区：[1]MOE Key Laboratory of Surficial Geochemistry, Department of Earth Sciences, Nanjing University [2]Key Laboratory of Marine Ecosystem and Biogeochemistry, Second Institute of Oceanography, State Oceanic Administration

出　　处：《Chinese Science Bulletin》2014年第20期2391-2395,共5页

基　　金：supported by the National Natural Science Foundation of China(41102103,41173105 and 41321062)

摘　　要：Deciphering the eolian sources is critical to understand the paleo-significance of the Quaternary eolian deposits(the Xiashu loess)in the lower reaches of the Yangtze River.Both a local source from the fluvial sediments of the Yangtze River and a distal source from the northern deserts similar to that of the loess on the Chinese Loess Plateau(CLP)have been proposed.Recent researches show great advantages of detrital zircon ages as a source tracer for Asian dust based on the laser ablation U-Pb isotopic dating technique.This work presents the U-Pb ages of zircon grains extracted from the Xiashu loess.The results indicate that the Xiashu loess has a very different age distribution of zircon grains from that of the loess on the CLP as well as the materials in the arid lands of the Asian Interior.Instead,the zircon ages of the Xiashu loess are indistinguishable from the fluvial sediments of the Yangtze River,indicating the dominance of proximal dust source.Proximal source of the Xiashu loess implies that extensive eolian processes might have existed in the currently wet South China,possibly in response to the full glacial conditions after the middle Pleistocene transition of global climate.Deciphering the eolian sources is critical to understand the paleo-significance of the Quaternary eolian deposits （the Xiashu loess） in the lower reaches of the Yangtze River. Both a local source from the fluvial sediments of the Yangtze River and a distal source from the northern deserts similar to that of the loess on the Chinese Loess Plateau （CLP） have been proposed. Recent researches show great advantages of detrital zircon ages as a source tracer for Asian dust based on the laser ablation U-Pb isotopic dating technique. This work presents the U-Pb ages of zircon grains extracted from the Xiashu loess. The results indicate that the Xiashu loess has a very different age distribution of zircon grains from that of the loess on the CLP as well as the materials in the arid lands of the Asian Interior. Instead, the zircon ages of the Xiashu loess are indistinguishable from the fluvial sediments of the Yangtze River, indicating the dominance of proximal dust source. Proximal source of the Xiashu loess implies that extensive eolian processes might have existed in the currently wet South China, possibly in response to the full glacial conditions after the middle Pleistocene transition of global climate.

关 键 词：长江中下游地区 U-Pb年龄 中国黄土高原 下蜀黄土 锆石年龄 沙尘源 U-PB同位素 河流沉积物 

分 类 号：P425.55[天文地球—大气科学及气象学] P512.2