关键词: 北疆地区, 全新世, 气候特点

Abstract: The study on the records of lacustrine deposits,peat,loess and moraines of North Xinjiang shows that the Holocene climate is different from the monsoon region.The reconstruction of Holocene environment from sedimentary facies,pollen assemblage,stable isotope(δ¹⁸O) and grain size suggests that early Holocene is warm and dry.The lakes in Tianshan and North Xinjiang occurred high levels as the glaciers melting,but the pollen records were characterized by the abundance of shrub and herb that are thrive on the arid condition.The δ¹⁸O record showed a general trend of increase and loess deposition was prevailing even if there were humid oscillations in some degree.During middle and late Holocene the climate changed from place to place,which controlled by the geography position and atmospheric circulation.In the west of Tianshan where the westerly was dominant,the arid climate lasted until Late Holocene except for an event of wind strengthening during 5 000~4 000 a B.P..In eastern Tianshan,Zungar Basin where might be effected by summer monsoon during middle Holocene,the climate fluctuated frequently.Since about 4 000 a B.P.the effective moisture of air have increased to a degree.As a result the vegetation cover increased and pollen records appeared as high density in Manasi Lake.The deciduous forest was growing during 4 000~2 000 a B.P.at surrounding mountains of Little Youerdusi Basin.The soil formation was stronger than the accumulation of loess in Yili area and northern slope of Tianshan.The δ¹⁸O curve of Manasi Lake shifted toward negative value.In Altai Mountains the climate was relative humid during middle and late Holocene compared with that of early Holocene.It is obvious that the climate and the pattern of environmental change during Holocene is very complex and the results that have made are not enough to explain the history of Holocene climate and environment change clear.Further study on the high resolution records is needed so as to understand how the climate happened,developed and evolved.

Key words: the northern Xinjiang area, Holocene, climatic characteristics