关键词: 光释光测年, 晚第四纪, 毛乌素沙地, 浑善达克沙地, 沙丘固定与活化

Abstract: The loess-desert transition zone in north China is sensitive to reflect climate changes, and it is one of the key sites to investigate the history of past environmental changes. Optical stimulated luminescence dating (OSL) has been used to obtain the ages of seven profiles in Mu Us and Otindag sandlands. All the sediments are aeolian originations. Our results provide chronology constrain to active and inactive phase of sand dunes in the two sandlands during the past (60 000) years: the sand dunes are stable at 37.71 ka BP, 8.54 ka BP, 8.32 ka BP, 7.93 ka BP, 7.77 ka BP, 7.57 ka BP, 7.39 ka BP and late 2.39 ka BPin Mu Us sandland, and paleosol were developed. Whereas, the sand dunes are mobile at around 57.08 ka BP, 52.50 ka BP, 13.65 ka BP, 13.13 ka BP, 7.20 ka BP and 2.39 ka BP. In Otindag sandland, the moveable phases of sand dunes took place at 8.74~8.72 ka BP and 7.79 ka BP respectively, the inactive periods occurred at 5.69 ka BP, 4.25 ka BP, 2.75 ka BP, 1.53 ka BP, 0.71 ka BP and 0.15 ka BP to now, the sandland is dominaued by semi-stabilized sand dunes. Though the active and inactive phases in Mu Us and Otindag sandlands are not always at the same time, the changes are consistent with variations of the East Asia monsoon.Furthermore, there are two samples whose single-aliquot De values are likely scattered distribution to some extent, possibly because of heterogeneous variations in microdosimetry and biodisturbing during burial of the sediments, or there is water reworking on the aeolian deposit.

Key words: OSL dating, the later Quaternary, Mu Us sandland, Otindag sandland, active and inactive phase of sand dunes