Relic permafrost structures in the Gobi of Mongolia: age and significance

Relict permafrost structures (ice-wedge casts and cryoturbation structures) are present in the Gobi of southern Mongolia. Luminescence dates of sedime nts are presented to constrain the age of formation of permafrost structure s. These data show that there was a phase of permafrost development during the latter part of the Last Glacial (after about 22 to 15 ka) that resulted in cryoturbated sediments and ice-wedge casts. Furthermore, permafrost deg radation occurred during late Pleistocene times (13-10 ka) and was absent d uring the early Holocene. These permafrost structures mark the southernmost evidence of permafrost in northern Asia during late Quaternary times and i ndicate that the mean annual air temperature was below approximately -6 deg rees C duiing their formation. (C) 1998 John Wiley & Sons, Ltd.