U-SERIES DATING ON LATE QUATERNARY SEDIMENTS FROM BALIKUN LAKE

The U-series component-dating method has been employed to date the sed iment core B(1)94 from Balikun Lake. Th-230/Th-232 and U-234/Th-232 ra tios in various components of the samples dissolved in different conce ntration acids were measured respectively. The results indicate that t here is a good relationship of the isotopic ratios between the solutio ns and the residues, and that uranium and thorium isotopic fractionati ons did not occur during acid leaching. Based on the U-series ages obt ained by using component-dating method, a 144-ka time sequence was est ablished corresponding to the upper 25-m interval of the B(1)94 core, which is in agreement with palaeomagnetic dating results. The fact tha t the palaeoclimatic and palaeoenvironmental record labeled with U-ser ies ages is correlative with the deep-sea delta(18)O SPECMAP also demo nstrates that the U-series component-dating method can be used to date lake sediments.