西藏纳木错扎弄淌剖面10000年以来的沉积间断和环境变化记录

通过对西藏纳木错全新统扎弄淌组(Q^4tz)地层剖面的沉积特征观察,易溶盐、磁化率、粒度、碳酸盐、孢粉分析和^14C年代测定等综合研究表明,扎弄淌组湖相地层沉积物记录了约自10000aBP以来的沉积间断和环境变化信息。资料显示该区自9010～8560aBP以来,气候从偏冷干到偏湿再转变为轻湿;在4870～2350aBP期间,气候从暖湿到温暖湿润,又从全新世气候适宜期转变为较湿润期。表明自全新世以来该区气候在逐渐变干的总趋势的基础上,经历了两次大的气候变化旋回,有过多次明显的冷暖与干湿波动。

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 ()~(14)C 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.