High-precision uranium-series dating of lacustrine carbonates from Daihai Lake

Ages of small aragonite samples retrieved from sediments from the Daihai La ke are determined by using the Thermal Ionization Mass Spectrometry (TIMS) technique. The ages of the samples range from (8740 +/- 601) to (10446 +/- 489) a, with a precision of 2%-3% for non-corrected dating ages and 4.7%-9. 8% for corrected ages respectively, and are consistent within the deviation range. At about 10.5 ka BP, the grain-size of the sediments coarsens sharp ly, the frequency curves of grain-size distribution show coarse grain domin ated single-double kurtosis, indicating cooling, decreased hydrodynamic con ditions and increased wind influence procedure. This fs in good agreement w ith previous results obtained from the Daihai Lake, which suggests that the climate was cold and the lake surface was shrinking. The TIMS ages of the sediments are therefore believed to be credible.