内蒙古岱海湖泊沉积记录的小冰期气候环境

A Preliminary Study of Climate Change During the Little Ice Age Inferred from Lacustrine Sediments in Daihai Lake, Inner Mongolia

通过对岱海深水区沉积柱样有机碳同位素、总有机碳 ,碳酸盐含量、频率磁化率等环境代用指标的分析 ,结合剖面的岩性特征和 2 1 0 Pb定年 ,初步探讨了岱海小冰期以来气候环境演化过程 ,结果表明 :在小冰期初期 740 - 540 a BP,以冷湿气候为主 ;在 540 - 4 80 a BP为寒冷干旱气候 ,可能为小冰期盛期 ;480 - 370 a BP,气候转温和 ,以凉偏湿气候为主 ;370 - 2 2 0 a BP,凉偏干气候为主 ;2 2 0 - 1 30 a BP,为小冰期末次冷波动 ,以冷干气候为主 ;1 30 a BP左右小冰期结束 ,其后进入现代有效降水略有增加的温偏湿气候 .本文环境代用指标揭示的小冰期前期的冷偏湿气候与同期的黄河中下游地区冷偏干气候不同 ,同时其揭示的最后两次冷期与根据冰芯、树轮、历史文献重建的十年平均温度确定的 1 4 50 's- 1 51 0 's、1 790 's- 1 890

Located in the marginal belt of the southeast monsoon, Daihai Lake has always been one of the most significant areas in the paleoclimate studies. After synthesizing the environmental multi proxies, such as TOC, δ 13 C org , carbonate contents, frequency dependent susceptibility and ostracode fossils of sediment core in Daihai Lake, and combining the lithological characteristics of the sedimentary core with 210 Pb dating, the paleoclimatic evolution of this region since the beginning of the Little Ice Age(LIA) has been preliminarily reconstructed. Six stages of climate change, with fluctuation on temperature and precipitation, are divided as following: (1) In the early stage of the Little Ice Age(740-540aBP), cold and wet climate. (2) In 540-480aBP, cold and arid climate. (3) In 480-370aBP, cool and wet climate. (4) In 370-220aBP, cool and arid climate. (5) In 220-130aBP, cold and arid climate. (6) From 130aBP to present, warm and wet climate. The comparisons between climate characteristics in this region and that of other regions in China have also been carried out elementarily. Different from the cold arid climate in the middle and lower reaches of the Huanghe River during LIA, the LIA climate in Daihai Lake was cold and humid, similar to the coresponding climate in the northwestern China. The situation of precipitation during the LIA may suggest that this region belonged to transitional type between the northwest area of China and middle and lower reaches of the Huanghe River in climate change. Furthermore, the last two cold periods recorded by the lacustrine sediments in Daihai Lake (DH core) are in good agreement with two cold periods, namely 1450's-1510's and 1790's-1890's, which was inferred from ten year average temperature by tree rings, ice core and historical literature.