Reconstructing Glacial Retreat Using Tree Rings and Remote Sensing in the Tien Shan Mountains, China

Keywords: Dendroglaciology, Glacial moraines, Tien Shan Mountains, China, Climate, remote sensing
Session Type: Virtual Paper Abstract
Day: Monday
Session Start / End Time: 2/28/2022 03:40 PM (Eastern Time (US & Canada)) - 2/28/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 5

Abstract

Dendroglaciology can be used to interpret past glacial movement. It utilizes tree ring dating techniques on trees sampled from glacial landforms to estimate the structure’s age. As a glacier progresses, debris are pushed and molded into ridges, creating a moraine. Under warming climate and glacier retreat, new trees begin colonizing the moraine ridges, thus using the oldest tree’s age can provide a minimum estimation of the moraine’s formation age. The ecesis interval, the lag time between the formation of the moraine and tree germination, needs to be considered as well. This study will use dendroglaciological techniques to reconstruct the age of the terminal moraine in the forefield of the Xiata Glacier, in the central Tien Shan Mountains in Northwest China. Increment core samples (n=31) from seventeen Schrenk spruce (Picea schrenkiana) trees were collected from the top and outer flank of the moraine in the Xiata Glacier Valley. Manual and digital methods will be performed and compared on ring-width measurements, to test if one is more efficient than the other. To estimate the ecesis interval, time series of satellite imagery will be examined to detect the minimum time for trees’ occupation. Summing the crossdated longest chronology and the estimated ecesis interval, the hypothesis of whether the moraine is formed during the Little Ice Age can be tested and further discussed in a large context. This study will contribute to the methodology and applications of dendroglaciology to better understanding past glacier change and future ecological succession in glacial foreland in Central Asia.