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Dating of a Shallow Ice Core from Chongce Ice Cap Using Micro-particle Content

An accurate time scale is necessary for interpretation of an ice core record.The establishment of chronology is especially difficult for sites where the conventional annual-layer counting using stable isotopes fails due to much less snow deposition.In this work,dating from the analysis of insoluble micro-particles ranging from 0.66 to 1.33 μm in diameter,in combination with the soluble Ca~2+ concentration,was applied to an ice core from a middle-sized Chongce Ice Cap,West Kunlun Mountains of China.The ice core was retrieved from the summit,6 530 m a.s.l.,of the ice cap.The dated core of 18.7 m in length represents about 2/5 of the total ice thickness at the drilling site.The assisting dating parameters include the measured net accumulation in the last 5 years prior to the drilling and the stratigraphic marker of atmospheric nuclear weapon test.Based on the combined techniques,a time scale covering the period of 1903-1992 was derived.The cumulative dating uncertainty by the bottom is estimated less than 2 years. This work suggests that the insoluble micro-particle takes an advantage in the dating of ice cores from Asian mountainous glaciers.The concentration in a certain size range( 2 μm),rather than the total concentration,is more preferable.It is significant to exclude the possible "noise" of weathered mineral dust of local sources.