RECORDS OF DEPOSITIONAL BREAKS AND ENVIRONMENTAL CHANGE AT THE ZANONGTANG SECTION OF NAM CO, TIBET SINCE 10 ka BP

Studies of sedimentary structures,more soluble and ¹⁴C dating salts,magnetic susceptibility,grain size,carbonates,and sporopollen of the Holocene Zanongtang Formation have yielded information of depositional breaks and environmental change since 10 ka BP in the Nam Co area,Tibet.The data indicate the following:since 9010-8560 a BP the climate changed from slightly cold-dry through slightly moist to relatively moist;during 4870-2350 a BP the climate changed from warm-moist to warmer-moister and then changed from the Holocene climatic optimum to relatively moist.This suggests that in the Holocene the area experienced two major climatic cycles and multiple pronounced cold-warm and dry-moist oscillations on the basis of the general trend of gradual drying.