Methods and application of using detrital zircons to trace the provenance of loess  

作　　者：XIE Jing YANG ShiLing DING ZhongLi 

机构地区：[1]Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Science China Earth Sciences》2012年第11期1837-1846,共10页中国科学（地球科学英文版）

基　　金：supported by Young Scholars of the National Natural Science Foundation of China (Grant No.40802037);National Basic Research Program of China (Grant No.2010CB950204);Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. 80972970)

摘　　要：The composition of single-grain detrital zircons is an effective provenance indicator of loess,and sheds new light on dust formation and transportation.Here we review the features of detrital zircons and their use as a provenance indicator,including internal structure,trace element,U-Pb age spectrum and Hf isotopic compositions,and present a case study from the Horqin sandy land and its surrounding loess.The loess samples have detrital zircon age peaks in range of 2600-2300,2100-1600,and 600-100 Ma,of which the 2600-2300 Ma zircon grains mainly have positive Hf(t) values(3.4-8.7),the 2100-1600 Ma zircon grains mainly have negative Hf(t) values(10.1-6.8),and the 600-100 Ma zircon grains have a variable Hf(t) values ranging from 21 to 15.9.The detrital zircon signatures of the loess are similar to the Horqin sandy land,but clearly different from the Chinese Loess Plateau and central-western deserts,implying that the loess is transported mainly from the Horqin sandy land in the Last Glacial period.Comparing these with neighboring tectonic units,we found that zircon populations at 2600-2300,2100-1600,and 600-100 Ma with negative Hf(t) values may come from the northeast North China Craton(NCC),and those at 600-100 Ma with positive Hf(t) values may come from the east Central Asian Orogenic Belt(CAOB).It is estimated that the two sources contribute equally to the Horqin sandy land and the surrounding loess.The composition of single-grain detrital zircons is an effective provenance indicator of loess,and sheds new light on dust formation and transportation.Here we review the features of detrital zircons and their use as a provenance indicator,including internal structure,trace element,U-Pb age spectrum and Hf isotopic compositions,and present a case study from the Horqin sandy land and its surrounding loess.The loess samples have detrital zircon age peaks in range of 2600-2300,2100-1600,and 600-100 Ma,of which the 2600-2300 Ma zircon grains mainly have positive Hf（t） values（3.4-8.7）,the 2100-1600 Ma zircon grains mainly have negative Hf（t） values（10.1-6.8）,and the 600-100 Ma zircon grains have a variable Hf（t） values ranging from 21 to 15.9.The detrital zircon signatures of the loess are similar to the Horqin sandy land,but clearly different from the Chinese Loess Plateau and central-western deserts,implying that the loess is transported mainly from the Horqin sandy land in the Last Glacial period.Comparing these with neighboring tectonic units,we found that zircon populations at 2600-2300,2100-1600,and 600-100 Ma with negative Hf（t） values may come from the northeast North China Craton（NCC）,and those at 600-100 Ma with positive Hf（t） values may come from the east Central Asian Orogenic Belt（CAOB）.It is estimated that the two sources contribute equally to the Horqin sandy land and the surrounding loess.

关 键 词：loess provenance detrital zircon U-Pb age Hf isotope Horqin sandy land 

分 类 号：P54[天文地球—构造地质学] S162[天文地球—地质学]