林芝地区风尘堆积及其古环境意义

Aeolian accumulation and paleoenvironmental implication in the Nyingchi region

林芝地区的黄土堆积记录着青藏高原东南部大气环流信息。选取林芝地区一黄土剖面,探讨该区域风尘堆积记录的古环境变化信息。通过AMS^(14)C限定其堆积年代,并结合粒度、磁化和色度率等指标分析,结果表明:1)林芝剖面的AMS ^(14)C年代结果介于37.6~2.4 cal.kyr BP之间,为晚更新世以来的风尘堆积物。2)有效指示了晚更新世以来林芝地区沉积环境大致从温暖到寒冷再到温暖的阶段性变化。3)与其他气候记录进行对比,显示林芝剖面的古气候环境总体上体现了全球气候环境变化的区域响应,但也存在差异性。林芝剖面变化表现出的气候波动,可能是印度季风与区域气候变化共同影响下的结果。

Loess contains rich information about atmospheric circulation and sedimentary environment.Here,based on the previous research and field investigation,we studied an aeolian accumulation section in Nyingchi area.Combined with AMS ^(14)C dating,the climate of the late Pleistocene and environmental variation in the study area was discussed based on the analysis of grain size,magnetic susceptibility and chromaticity composition.Results show:The AMS ^(14)C ages of the Nyingchi profile is from 37.6 to 2.4 cal.kyr BP,means the aeolian deposit was formed from the last Pleistocene.The sedimentary environment has changed from warm to cold,and to warm again.Compared with other climatic records,the environmental variation of the Nyingchi section was the response to global change.The climate in the Nyingchi rection was likely the result of the comprehensive action of global climate and regional environmental change.