Single grain pIRIR dating of glacigenic deposits in the Yuzhu Peak area of Kunlun Mountains of Tibetan Plateau revealed the glaciations during Holocene period

Abstract

The variations of glaciers in the Kunlun Mountains of the northern Tibetan Plateau are influenced by the complex interaction of the East Asia summer monsoon (EASM), Indian summer monsoon (ISM) and Westerlies, as well as human activity during the Holocene period. Consequently there is ongoing debates regarding the evolution of glaciers and the factors driving their changes. The reconstruction of glacial evolutions in these regions has been hindered by insufficient chronological data for moraines and other glacial landforms. In this study, glacial sediment samples were collected from five moraine sequences located on the southern and northern slopes of the Yuzhu Peak in the Kunlun Mountains. These poorly bleached moraine samples were dated using the single-grain quartz optically stimulated luminescence (OSL) and K-feldspar post-infrared infrared stimulated luminescence (pIRIR) dating methods. The luminescence characteristics analysis of quartz grains shows that single grain quartz OSL dating cannot be used to date Holocene moraine samples due to the low brightness of quartz OSL signals. Various tests were conducted to assess the reliability of K-feldspar pIR₅₀IR₁₇₀ dating, including anomalous fading tests, dose recovery, and residual dose tests. The K-feldspar pIR₅₀IR₁₇₀ ages, determined using the Minimum Age Model (MAM), indicate that during the early Holocene, glaciations have expanded by ∼800 m in length at ∼ 8 ka, and during the end of the Neoglacial period, they extended by ∼200 m in length at ∼ 1 ka. The strengthened ISM precipitation and northward movement of ISM boundary likely contributed to the glacial expansion in the early Holocene. During the end of the Neoglacial period, the increase in westerlies precipitation and cold events may have played a role in the advancement of glaciers.