Geochemical characteristics of rare earth elements in kaolin rock from Daqingshan coalfield

The contents of the rare earth element(REE) in 12 samples of the kaolin rocks from the Daqingshan coalfield of Inner Mongolia are detected by neutron activation analysis(NAA).The results show that the REE contents of the samples changes very greatly,the ΣREE ranges from 31.98×10^-6 to 616.3×10^-6,average 178.6×10^-6,approaching the content of NASC,and the ratios of ΣLREE/ΣHREE is 6.32-46.14,average 17.5,obviously higher than that of NASC.The Eu is medium to weak negative abnormity,and Ce weak positive abnormity.The comparative study with the contrast samples(NASC,ultrabasic rock,basalt,intermediate rock,acid rock and alkalic rock) indicats that the samples,on the REE contents,are not of the typical characteristics of sedimentogenic mudstone,and combining with the results of the rock and mineral analyses and the early study,the kaolin rocks may be formed by the intermediate,basalt or alkalic volcanic ash altered in situ.The acid medium offered by the peatification is the necessary condition that the ash transformed into the kaolin rock and the REE produced difference.