【摘要】：封閉、半封閉湖泊的沉積物存儲(chǔ)著記錄區(qū)域環(huán)境和氣候變化的信息,是研究古氣候古環(huán)境的理想材料。我國(guó)西北地區(qū)湖泊沉積恢復(fù)的過去千年氣候變化研究結(jié)果表明：800-1300AD的中世紀(jì)暖期(MWP)與1500-1800AD的小冰期(LIA)普遍存在,但是區(qū)域內(nèi)部的降水量與濕度的變化卻存在很大的不同。本文選取位于新疆天山的大龍池110cm湖泊沉積巖芯DLC12B和青藏高原東北緣柴達(dá)木盆地尕海50cm短鉆巖芯GHC1,分別恢復(fù)天山地區(qū)過去2000年和高原東北緣過去400年的環(huán)境變化歷史。DLC12B采用210Pb與AMS14C兩種方法建立可年代標(biāo)尺,GHC1采用210Pb與137Cs建立年代。同時(shí),對(duì)兩孔巖芯樣品進(jìn)行了粒度、碳酸鹽、磁化率、有機(jī)質(zhì)及元素含量等代用指標(biāo)分析測(cè)試。大龍池DLC12B孔過去近2000年的氣候環(huán)境變化歷史表明：193-800AD：碳酸鹽含量低但卻緩慢升高,指示區(qū)域由濕潤(rùn)逐漸轉(zhuǎn)干；800-1300AD：中世紀(jì)暖期,碳酸鹽含量略高于均值且無明顯波動(dòng),但沉積物粒徑小,顯示湖泊水位較高,可能是冰川融水增加的原因；1300-1850AD期間,碳酸鹽含量較高,平均粒徑增大,指示冰川融水減少,水位降低。1850AD以來各個(gè)指標(biāo)波動(dòng)較大,顯示氣候的不穩(wěn)定且逐漸變干。尕海沉積物碳酸鹽含量可以反映區(qū)域濕度變化；而粗顆粒組分(66.91μm)主要由風(fēng)力搬運(yùn)入湖,其含量可以用來指示區(qū)域粉塵活動(dòng)歷史。區(qū)域近400年來的環(huán)境變化可分為三個(gè)階段：1633-1750AD：其中在1650-1720AD,各指標(biāo)出現(xiàn)一次大幅度波動(dòng),指示該時(shí)期氣候環(huán)境的不穩(wěn)定和干濕交替；粗顆粒組分比重大,區(qū)域風(fēng)力強(qiáng)勁；與太陽(yáng)活動(dòng)進(jìn)入Maunder極小期較為一致,因此推測(cè)太陽(yáng)活動(dòng)的變化可能是導(dǎo)致德令哈氣候環(huán)境變化的原因之一。1750-1950AD：區(qū)域氣候環(huán)境無明顯波動(dòng),碳酸鹽含量逐漸降低,濕度增加。1950-2010AD：各指標(biāo)變動(dòng)劇烈,區(qū)域雖降水增多但由于蒸發(fā)加強(qiáng),濕度降低；1974AD以后粗顆粒組分急劇上升,表現(xiàn)出高強(qiáng)度塵暴事件。將大龍池與尕海的重建結(jié)果分別與當(dāng)?shù)馗珊祬^(qū)盆地湖泊沉積孢粉及高山地區(qū)樹輪重建的降水進(jìn)行對(duì)比,發(fā)現(xiàn)：小冰期時(shí)段,大龍池湖區(qū)反映出干旱的氣候特征,與同區(qū)域干旱區(qū)盆地冷濕的特征并不一致。尕海湖區(qū)與當(dāng)?shù)厣絽^(qū)記錄的氣候變化趨勢(shì)一致。大龍池與尕海區(qū)域在近400年來都有轉(zhuǎn)濕的跡象,但二者成因卻不同,這主要是由不同的地理位置及受不同的氣候系統(tǒng)影響造成的。
[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 擄800AD is low but increases slowly, indicating that the carbonate content gradually dries from humid to dry, 800 鈮，

本文編號(hào)：2499806