西藏扎布耶湖地区三万年以来的花粉记录

A POLLEN RECORD DURING THE PAST 30000 YEARS FROM THE ZABUYE LAKE, TIBET

通过对藏北高原扎布耶湖ＺＫ＿２钻孔沉积物的花粉记录，揭示了该地区三万年以来植被和气候演变历史。３７３００－３６０００ａＢ．Ｐ．为森林草原植被，气候温湿，淡水湖时期；约３６０００－３１７００ａＢ．Ｐ．灌丛草原植被，气候冷干，湖水出现短暂咸化。３１７００－２０８００ａＢ．Ｐ．林草原植被，气候温暖湿润，湖面扩大，湖水加深时期。２０８００－１４４００ａＢ．Ｐ．荒漠植被，气候冷干，湖水咸化，湖面开始缩小，初步认为此时段为末次冰期盛冰阶。１４４００－１４０００ａＢ．Ｐ．森林草原植被，气候温暖湿润，此时段为本区冰期向冰后期转变时期。１４０００－１０７００ａＢ．Ｐ．草原植被，气候冷干。１０７００－４２００ａＢ．Ｐ．以草原植被为主，气候冷干，其中出现三次气候波动，大约１０７００，６７００和４２００ａＢ．Ｐ．推测此不同时期，在扎布耶湖周围可能有森林分布。４２００ａＢ．Ｐ．至现在，未分析样品，暂不讨论。本区是季风敏感区，三万年以来西南季风曾多次到达本区，是引起植被变化的主要原因。

Record of pollen from core ZK_2 in the Zabuye Lake,Shows a sequence of changes re-flecting the history of vegetation and climate during the past 30000 years. The forest andsteppe vegetation indicates the period from 37300 to 20800a B.P. to be interglacial andhave a stronger southwest monsoon and a higher precipitation than now. During the pe-riod about 36000 to 31700 a B.P. ,there was a small arid and cool fluctuation,showingweakened southwest wind and a lower precipitation,Vegetation of scrub and steppe wasdistributed in the area. The period of 31700-20800a B.P. had an expanding lake water,indicating warmer and wetter climate. And the vegetation became a desert type from 20800 to 14400a B.P. at the maximum of the last glaciation,and the lake water was sali-fied and shrinking,The transitional period from glacial to post-glacial may have beenaround 14400a B.P.,when abrupt changes took place in vegetation that began to reflecta strong southwest monsoon. At 10700a B.P. steppe occupied the area and cold and aridclimate appeared.But there were three humid climatic fluctuations around 10700,6700and 4200a B.P. which made some forests grow in the Zabuye Lake area.