西藏中部扎西错布晚更新世晚期微体古生物与环境变化初步研究

The Late Part of the Late Pleistocene Microfossil and Environment Change in Zaxi Lake,Middle Tibet

西藏中部扎西错布东岸T1剖面厚639cm,含6属11种介形类和1属2种以上轮藻类。据其在地层中的分布特征划分出8个生物组合,各组合间的差异表现在介形类动物群的丰度、分异度和每个种的丰度变化,根据生物属种生态特征和组合变化探讨湖区大约18653～13144aBP生态环境及气候变化情况如下:①约18653～17239aBP,湖区气候较干(冷),湖面收缩下降,湖水有一定含盐度(可能达中盐水18‰),其间有波动:18309～17809aBP,气候曾一度暖湿,湖面扩大,水质淡化;②约17239～13920aBP,气候较暖湿,水质含盐度降低,其间有气候波动,分别在16506～15213aBP和15213～13963aBP时段偏干(冷)和偏湿冷,相应地其水质含盐度增加或减小;③13920～13144aBP,气候突变,湖泊环境突然恶化,介形类灭绝,仅剩下对气候环境反应滞后的轮藻类低等植物。

The 639 cm profile T1 in Zaxicuo saline lake East shore, Middle Tibet, consists ostracod belonging to 6 genera and 2 species of stoneworts belonging to 1 genera. abundance and diversity of ostracod, 8 ostracod assemblages can be distinguished. of 11 species of According to the Environment and climate changes between about 18653 a BP and 13144 a BP was then discussed based on the ecological characteristics and assemblages of ostraeods as follow. 18653-17239 a BP, climate in the lake area was arid （cold）, and the lake surface shrinked with a little salinity （probably 18%0）; 17239-13920 a BP, the climate was generally warm and wet, with salinity lowering; 13920-13144 a BP, the environment and climate changed abruptly, and ostracods in the lake extinct, with only stoneworts, which is hysteretic to environment change, survived.