达连海湖泊沉积物粒度特征及其古气候意义

Grain-size characteristics of Dalian Lake sediments and its paleoclimate significance

本文选取共和盆地达连海湖泊沉积物为研究对象,在达连海湖心取得深度为4 m的浅井剖面,剖面底部年龄为3 800 a B.P.,以沉积物粒度和孢粉为环境代用指标,粗颗粒指示强水动力,细颗粒指示弱水动力,用AMS14C建立时间标尺,探讨了达连海晚全新世以来的环境演变,结果表明：①3 800~2 900 a B.P.气候半干旱;②2 900~1 500 a B.P.气候干旱;③1 500~400a B.P.气候半干旱;④ 400~0 a B.P.气候干旱。

A bts rca t：Tibet plateau , as a sensitive area of the changing global climate , is significant for the study of paleoclimate .Dalian Lake belonging to Gonghe basin which is located in the northeast of Ti-bet plateau is situated in the intersection of westerly and southwest monsoon .It is also sensitive to the climate change .The lake sediments have advantage on recording the information of the earth en-vironment changing with continuity , susceptibility and high resolution .This place is a good area to know and predict the future global climate change .A 4-meter profile in the center of Dalian Lake sediments was chosen for study .The bottom of the profile is 3 800 aB.P..Using the grain-size and pollen as environment proxies , the coarse particle represents strong water power and fine particle re-presents weak water power .Based on AMS 14 C to build the time scale of the stratum , recover the climate change in recent 4 000 years at this area .The results are follows：①From 3 800 to 2 900 aB.P., the climate was semiarid;②The climate was arid during 2 900 and 1 500 aB.P.; ③The climate was semiarid during 1 500 and 400 aB.P.;④The climate has being arid 400~0 aB.P..