天山大龙池与柴达木盆地尕海过去2000年沉积记录
发布时间：2019-06-14 23:54
【摘要】：封闭、半封闭湖泊的沉积物存储着记录区域环境和气候变化的信息,是研究古气候古环境的理想材料。我国西北地区湖泊沉积恢复的过去千年气候变化研究结果表明：800-1300AD的中世纪暖期(MWP)与1500-1800AD的小冰期(LIA)普遍存在,但是区域内部的降水量与湿度的变化却存在很大的不同。本文选取位于新疆天山的大龙池110cm湖泊沉积岩芯DLC12B和青藏高原东北缘柴达木盆地尕海50cm短钻岩芯GHC1,分别恢复天山地区过去2000年和高原东北缘过去400年的环境变化历史。DLC12B采用210Pb与AMS14C两种方法建立可年代标尺,GHC1采用210Pb与137Cs建立年代。同时,对两孔岩芯样品进行了粒度、碳酸盐、磁化率、有机质及元素含量等代用指标分析测试。大龙池DLC12B孔过去近2000年的气候环境变化历史表明：193-800AD：碳酸盐含量低但却缓慢升高,指示区域由湿润逐渐转干；800-1300AD：中世纪暖期,碳酸盐含量略高于均值且无明显波动,但沉积物粒径小,显示湖泊水位较高,可能是冰川融水增加的原因；1300-1850AD期间,碳酸盐含量较高,平均粒径增大,指示冰川融水减少,水位降低。1850AD以来各个指标波动较大,显示气候的不稳定且逐渐变干。尕海沉积物碳酸盐含量可以反映区域湿度变化；而粗颗粒组分(66.91μm)主要由风力搬运入湖,其含量可以用来指示区域粉尘活动历史。区域近400年来的环境变化可分为三个阶段：1633-1750AD：其中在1650-1720AD,各指标出现一次大幅度波动,指示该时期气候环境的不稳定和干湿交替；粗颗粒组分比重大,区域风力强劲；与太阳活动进入Maunder极小期较为一致,因此推测太阳活动的变化可能是导致德令哈气候环境变化的原因之一。1750-1950AD：区域气候环境无明显波动,碳酸盐含量逐渐降低,湿度增加。1950-2010AD：各指标变动剧烈,区域虽降水增多但由于蒸发加强,湿度降低；1974AD以后粗颗粒组分急剧上升,表现出高强度尘暴事件。将大龙池与尕海的重建结果分别与当地干旱区盆地湖泊沉积孢粉及高山地区树轮重建的降水进行对比,发现：小冰期时段,大龙池湖区反映出干旱的气候特征,与同区域干旱区盆地冷湿的特征并不一致。尕海湖区与当地山区记录的气候变化趋势一致。大龙池与尕海区域在近400年来都有转湿的迹象,但二者成因却不同,这主要是由不同的地理位置及受不同的气候系统影响造成的。
[Abstract]:The sediments of closed and semi-closed lakes store the information of recording regional environment and climate change, which is an ideal material for the study of paleoclimate paleoenvironment. The results of the past millennium climate change study on lake sedimentary restoration in northwest China show that the medieval warm period (MWP) of 800-1300AD and the small ice age (LIA) of 1500-1800AD are common, but the changes of precipitation and humidity in the region are very different. In this paper, the sedimentary core DLC12B of Dalong Lake 110cm in Tianshan Mountain, Xinjiang, and the 50cm short drill core GHC1, of Gahai Basin in the northeast margin of Qinghai-Xizang Plateau are selected to restore the environmental change history of Tianshan area in the past 2000 years and the northeast margin of plateau in the past 400 years, respectively. DLC12B uses 210Pb and AMS14C to establish chronological scale, and GHC1 uses 210Pb and 137Cs to establish chronology. At the same time, the particle size, carbonate, magnetic susceptibility, organic matter and element content of the two-hole core samples were analyzed and tested. The history of climate and environment change in the Dalong Pool DLC12B hole in the past 2000 years shows that the carbonate content in 193 掳800AD is low but increases slowly, indicating that the carbonate content gradually dries from humid to dry, 800 鈮，
本文编号：2499806
[Abstract]:The sediments of closed and semi-closed lakes store the information of recording regional environment and climate change, which is an ideal material for the study of paleoclimate paleoenvironment. The results of the past millennium climate change study on lake sedimentary restoration in northwest China show that the medieval warm period (MWP) of 800-1300AD and the small ice age (LIA) of 1500-1800AD are common, but the changes of precipitation and humidity in the region are very different. In this paper, the sedimentary core DLC12B of Dalong Lake 110cm in Tianshan Mountain, Xinjiang, and the 50cm short drill core GHC1, of Gahai Basin in the northeast margin of Qinghai-Xizang Plateau are selected to restore the environmental change history of Tianshan area in the past 2000 years and the northeast margin of plateau in the past 400 years, respectively. DLC12B uses 210Pb and AMS14C to establish chronological scale, and GHC1 uses 210Pb and 137Cs to establish chronology. At the same time, the particle size, carbonate, magnetic susceptibility, organic matter and element content of the two-hole core samples were analyzed and tested. The history of climate and environment change in the Dalong Pool DLC12B hole in the past 2000 years shows that the carbonate content in 193 掳800AD is low but increases slowly, indicating that the carbonate content gradually dries from humid to dry, 800 鈮，
本文编号：2499806
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