Late Quaternary glacial history of Khentey Mountains, Central Mongolia

Abstract

Mongolian glaciers have been the subject of relatively little research, resulting in less geochronological constraint than other parts of Central Asia. The Khentey Mountains (latitude 47–51°N, longitude 105–112°E) are a typical landlocked mountain range exhibiting clear geomorphic evidence of late Quaternary glaciation. Yet, compared to western parts of Mongolia such as the Mongolian Altay, Gobi Altay, Khangay, and Khovsgol, glacial history of the Khentey Mountains is poorly understood. To address this, and permit comparison of the Khentey glacier–climate record with other alpine regions in Mongolia, we performed geomorphological mapping and cosmogenic 10Be surface‐exposure dating in two glaciated regions of the Khentey Mountains: Yestii and Khagiin Khar. Specifically, we measured 10Be in 34 samples collected from five moraine sequences, which, together with morphostratigraphy, correspond to four main glacial stages: (i) The My1 terminal moraine sequence for Yestii (21.0±4.9 ka) and the Mk1 moraine for Khagiin Khar (19.6±2.6 ka), both of which represent the Last Glacial Maximum; (ii) the Lateglacial Mk2 moraine, dated to 16.0±3.5 ka; (iii) the Mk3 moraine, dated to either 17.6±7.0 ka (Lateglacial) or 12.1±1.1 ka (Younger Dryas); and (iv) the currently undated Mk4 moraine (~2200 m a.s.l.), to which we assign a Holocene age. Our results suggest that the timing of maximum glacier extent in Mongolia was regionally variable. In the Khentey Mountains, maximum glaciation occurred during Marine Isotope Stage (MIS) 2, whereas the maximum occurred during MIS 3 in Khangay and Khovsgol and during MIS 4 in the Altay. The MIS 2 glacial maximum in the Khentey Mountains coincided with the global sea level minimum during the Last Glacial Maximum, and was followed by at least three glacial re‐advances during the Lateglacial to possibly the Holocene.

Late Pleistocene lake level, glaciation and climate change in the Mongolian Altai deduced from sedimentological and palynological archives

“…10 Be dating from moraines in the eastern part of the Khangai Mountains are reported for the Gyalgar peak (10) by Batbaatar and Gillespie (2016b), with ages between 30 and 17 ka (average 24 ka) and by Smith et al (2016) with ages of ~15 ka; for the Chuluut Gol (11), by Smith et al (2016) with ages of ~22 ka and by Poetsch (2017) with mean ages between 41 and 16 ka; for the nearby Bumbat valley (12), by Batbaatar et al (2018) with ages of ~39–31 ka; for the Egiin Davaa area (13), mean ages of 49 and 26–25 ka by Poetsch (2017); and for the Khukh Nuur (14), by Smith et al (2016) ages between 44 and 14 ka. In the Khentei Mountains (15), which are located in the northeastern part of Mongolia, Khandsuren et al (2019) reported 10 Be ages from boulders upon moraines of ~21–19 and 18–16/12 ka. Batbaatar et al (2018), who performed 10 Be dating from moraines in the Gobi Altai, reported late glacial ages (~17–13 ka) for the Ikh Bogd (16) and Holocene ages at the Gichginii range (17).…”

“…A review of the state of investigations about dating of glacial moraines in Mongolia has been published by Khandsuren et al (2019). To summarize, the MIS 2 glaciation was the most explicit stage of the last glacial period found in every mountain region of Mongolia, whereas the timing of a previous stage varies among MIS 3, 4, and late 5.…”

“…The MIS 3 glacial advance was attributed to a wet phase under cool climate conditions, whereas the MIS 2 glacial stage represents the coldest and dry period of the last glaciation (Rother et al, 2014; Batbaatar et al, 2018; Khandsuren et al, 2019). The temperature generally increased after the LGM (MIS 2; Clark et al, 2009), and the last distinct glacial advance occurred during a global cooling event around 16 ka (Khandsuren et al, 2019). However, Batbaatar et al (2018) provided evidence, based on glacial advances during wet climate periods in the Holocene, that regional glaciation is not only controlled by coldness but also by higher precipitation and seasonality of temperature.…”

“…A late glacial stage was widespread in the Mongolian mountains and is generally reported for the period between 18 and 15 ka in the beginning of the late-glacial period (LGP; 18–11.5 ka). The MIS 3 glacial advance was attributed to a wet phase under cool climate conditions, whereas the MIS 2 glacial stage represents the coldest and dry period of the last glaciation (Rother et al, 2014; Batbaatar et al, 2018; Khandsuren et al, 2019). The temperature generally increased after the LGM (MIS 2; Clark et al, 2009), and the last distinct glacial advance occurred during a global cooling event around 16 ka (Khandsuren et al, 2019).…”

Asynchronous glacial extent during the Last Glacial Maximum in Ih Bogd massif of Gobi-Altay range, southwestern Mongolia: Aspect control on glacier mass balance

“…We used cosmogenic 10 Be surface exposure dating based on the specific sampling procedure below to determine the timing of the last glacial advances in Ih Bogd massif (Khandsuren et al, 2019;Gosse and Phillips, 2001). We sampled quartz-rich granitic boulders on the moraine crests, which were not reworked and represented single, distinguishable ice-marginal positions.…”