北疆巴里坤湖全新世环境变迁序列

HOLOCENE ENVIRONMENTAL CHANGE SEQUENCE OF BARKOL LAKE, NORTHERN XINJIANG

新疆北部巴里坤湖为内陆封闭湖泊,以其湖内岩芯为研究对象,对岩芯特征、孢粉、介形虫等多种标志进行了综合分析。结合冰川进退、湖面波动、森林线移动、树木年轮干湿变化作了对比研究。另外,也注意了全新世古季风对不同时代环境的影响。在此基础上通过_(14)C、年轮、^(210)Pb 测年所得较系统的年代数据,重建了六个暖干期(包括两个热干期)、五个冷湿期、一个暖湿期的演变序列。本区的环境演变还与国内外的资料进行了对比研究。

The Holocene sediment core of 13.6m depth was taken from the closed inland Barkol Lake in northern Xinjiang and sampled at every 5 cm interval. A comprehensive study on pair trace elements, indicatory elements, spore-pollens, ostracoda, oxygen and carbon isotopes, as well as paleomagnetism of the core was made. Combining with comparative study on the variation of glaciers, fluctuation of lake surface, migration of timberline and tree-rings, etc. and linking with systematic 14C and 210Pb datings and tree-rings, a great amount of information on the sequences of climatic stratigraphic, biological, and geochemical marks is obtained, which provides a scientific basis for reconstructing of a sequence of Holocene environmental change. The comprehensive study determines a greyish - white clayey soil layer with small smount of mirabilite and gypsum at depth of 2.51m, as the bottom of Holocene deposits with 14C dating of 12000 a B. P. The whole Holocene sediments in this core can be divided into 6 warm-dry (including 2 warm-moisture), 5 cold-moisture and 1 warm-moisture climatic periods. Thus a complete Holocene environmental change sequence is reconstructed in this paper. Fully attention also is paid to the influence of the invasion of paleomonsoon on environment of one certain period of Holocene in Barkol area and one short cold-moisture climate period of about 5000 a B. P ever found in eastern China is also discovered.In order to verify the correction of Holocene paleoclimate and paleoenvironment change, acomparative study with Holocene environmental change sequence in eastern China, southern Chile and the northern hemisphere is made and shows a better conformity with the global change. But the Holocene climatic fluctuation in Barkol area has also a distinctive regional nature. The sequence of Holocene environmental change is compliant with the inland climatic pattern with alternation of cold-moisture and warm-dry.The studies of climate and environment during the last 500 yrs show that the environmental development of eastern area of northern Xinjiang tends to warm-dry.