A lake-level chronology based on feldspar luminescence dating of beach ridges at Tangra Yum Co (Southern Tibet)
A lake-level chronology based on feldspar luminescence dating of beach ridges at Tangra Yum Co (Southern Tibet)
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DOI：
10.1016/j.yqres.2015.03.002
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发表时间：
2015-05
影响因子：
2.3
通讯作者：
E. Rades;S. Tsukamoto;M. Frechen;Qiang Xu;L. Ding
中科院分区：
文献类型：
--
作者：
E. Rades;S. Tsukamoto;M. Frechen;Qiang Xu;L. Ding
青藏高原上的许多湖泊都表现为滨海平原，有一系列高于目前湖泊水位的滩脊。这些海滩脊标志着以前的湖泊高位，因此它们的形成年代可以重建湖泊水平的历史和环境变化。在这项研究中，我们根据17个滩脊样品的长石发光年龄，建立了青藏高原第五大湖--唐格拉-阴错的湖平面年代学。这些样本是从湖的东南和北部的两个平原上采集的，海拔范围从现在的海岸到现在的湖上方140米。利用改进的170°C后红外红外光谱协议，我们成功地将长石红外光谱信号的反常衰落降至最低，并获得了可靠的测年结果。发光年龄表明，全新世有三个不同的湖平面下降阶段：(1)从~6.4~~4.5ka的快速下降阶段(~50m)，(2)~4.5~~2.0ka的缓慢下降阶段(~20m)，(3)~2ka至今的快速下降阶段。我们的发现表明，自全新世早期以来季风活动的减少与湖泊水位的下降之间存在联系。
Many lakes on the Tibetan Plateau exhibit strandplains with a series of beach ridges extending high above the current lake levels. These beach ridges mark former lake highstands and therefore dating their formation allows the reconstruction of lake-level histories and environmental changes. In this study, we establish a lake-level chronology of Tangra Yum Co (fifth largest lake on the Tibetan Plateau) based on luminescence dating of feldspar from 17 beach-ridge samples. The samples were collected from two strandplains southeast and north of the lake and range in elevation from the current shore to 140 m above the present lake. Using a modified post-infrared IRSL protocol at 170°C we successfully minimised the anomalous fading in the feldspar IRSL signal, and obtained reliable dating results. The luminescence ages indicate three different stages of lake-level decline during the Holocene: (1) a phase of rapid decline (~ 50 m) from ~ 6.4 to ~ 4.5 ka, (2) a period of slow decline between ~ 4.5 and ~ 2.0 ka (~ 20 m), and (3) a fast decline by 70 m between ~ 2 ka and today. Our findings suggest a link between a decrease in monsoonal activity and lake-level decline since the early Holocene.