摘要
本文根据新疆地区全新世地层的年代标尺,黄土、湖泊和河流沉积物记录的环境变迁信息,以及古土壤和炭化层等所反映的古气候变化做了综合分析,对新疆地区13000年来的气候序列初步概括为:13000—10000aB.P.冷湿转凉干;10000—8000aB.P.,温干;8000—7000aB.P.,温湿;7000—6000aB.P.,暖干;6000—4000aB.P.,温湿;4000—3000aB.P.,温干;3000—2000a.B P.,凉湿;2000aB.P.至今,温干(1500aB.P.左右有凉湿的波动),与现代气候类似。
There are rich records of the climo-environment changes in late Quaternary sediments in Xinjiang region.
The Aibi lake section with 460 cm thick is a. typical profile of lacustrine sediments in Holocene; its upper part consists of three beds of brick-red silt-subsandy soil (burned beds) and two beds of grass peat and a bed of subclay; the lower is composed of three alternating beds of greenish-grey subclay and black clay (or peat). The TL age of three burned beds are 6600, 1600 B. P. and<30 a B. P. in proper order and they show three dry climatic periods. Two greenish-grey clay beds with ^(14)C age of 8 400—7 300 a and about 6 000—3 400 aB.P. reflect not only high lake level, but also warm-humid climate.
Loess in the northern piedmont of Tianshan Mrs. contains two layers of black loam with the ^(14)C age of 2 800 and 1 400 aB.P. The dune accumulation of Mosuowan section in southern Jungghariya contains some charcoal layer, two of them were formed in 2 780 and 2 460 aB.P. Black loam and charcoal layer show humid fluctuation under dry environment in late Holocene. The dune section of Damagou in southern Tarim Basin also contains two beds with charcoal, ^(14)C age of lower bed is 4 500 aB.P., similar to the paggept of Pulu sand hill in Kunlun Mrs. They indicate that a fluctuation of the relatively moister stage presented about 4 500 aB.P. in southern Xinjiang.
In the river-lake sediments section of Yuetegan in Hotan County two grey-greenlsh subclay beds reflect two periods with high lake level in Middle Holocene; the lower subclay bed was formed about 7 000 aB.P. and found with some Planorbis sp. fossils which indicate that the environment is warm-humid.
At the Pachu section in the alluvial plain of Yeerqian River a buried paleosol was dated at about 12 930 aB.P., and Corresponding to the paleosol developed in drift sheet at Luweiba ridge in Tianshan Mrs. They may be comparable with the Bolling interstadial in Europe.
The sequence of climatic change in the last 13 000 a in Xinjiang region can be summarized as: 13 000—10 000 aB.P., cool moist-cool dry; 10 000—8 000 aB.P., warm dry; 8 000—7 000 aB.P., warmer moist; 7 000—6 000 aB.P., temperate dry; 6 000—4 000 aB.P. warmer moist; 4 000—3 000 aB.P. warm dry; 3 000—2 000 aB.P., cool moister; 2 000 aB.P.-present, warm dry (in which about 1 500 aB.P. cold moist). There were four relative moist periods at least since 13 000 aB.P. in Xinjiang region. It is clear that the humidity changes are very important for the arid region of Xinjiang.
出处
《第四纪研究》
CAS
CSCD
1990年第4期363-371,共9页
Quaternary Sciences
