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

Abstract

Glacial and lacustrine sediments from the Mongolian Altai provide paleoclimatic information for the late Pleistocene in Mongolia, for which only a few sufficiently studied archives exist. Glacial stages referred to global cooling events are reported for the last glacial maximum (27–21 ka) and the late glacial period (18–16 ka). Sedimentary archives from the first part of the last glacial period are infrequent. We present proxy data for this period from two different archives (88–63 and 57–30 ka). Due to the limitation of effective moisture, an increase of precipitation is discussed as one trigger for glacier development in the cold-arid regions of central Asia. Our pollen analysis from periods of high paleolake levels in small catchments indicate that the vegetation was sparse and of dry desert type between 42–29 and 17–11 ka. This apparent contradiction between high lake levels and dry landscape conditions, the latter supported by intensified eolian processes, points to lower temperatures and cooler conditions causing reduced evaporation to be the main trigger for the high lake levels during glacier advances. Rising temperatures that cause melting of glacier and permafrost ice and geomorphological processes play a role in paleolake conditions. Interpreting lake-level changes as regional or global paleoclimate signals requires detailed investigation of geomorphological settings and mountain–basin relationships.

A10Be Moraine Chronology of the Last Glaciation and Termination at 49°N in the Mongolian Altai of Central Asia

“…Taken in isolation, these particular moraine belts of the Khoton sequence were constructed coevally with decreased radiative forcing during the LGM (e.g., Marcott et al., 2019; Osman et al., 2021; Shakun et al., 2015; Tierney et al., 2020). This finding is in broad agreement with previous studies from Central Asia, demonstrating expansive mountain glaciers during the global LGM (Lehmkuhl et al., 2004, 2007, 2011, 2016; Batbaatar et al., 2018; Blomdin et al., 2016; Dong et al., 2020; Gribenski et al., 2016, 2018; Klinge et al., 2021; Yang et al., 2017). Additionally, deglaciation of the Khoton glacier after ∼18,800 years ago was underway when radiative forcing at northern latitudes generally began to increase (Figure 12).…”

“…Second, our chronology indicates that the Khoton Nuur glacier achieved a maximum extent at least as early as 35,000 years ago, nearly 10,000 years before the maximum in global ice volume, well before the lowest atmospheric CO 2 concentrations, and during a period of relatively high local summer insolation intensity (Figure 12). The Khoton Nuur chronology dovetails with other moraine chronologies that indicate extensive pre-LGM advances of Mongolian and Altai mountain glaciers (Blomdin et al, 2018;Dong et al, 2020;Gillespie et al, 2008;Gribenski et al, 2018;Klinge et al, 2021;Krivonogov et al, 2012;Lehmkuhl et al, 2011;Prokopenko et al, 2009;Rother et al, 2014). For example, a 10 Be chronology from the Otgon Tenger glacier cap in the Khangai Mountains of central Mongolia shows that moraine construction took place between and ∼46,000 and 38,000 years ago (Rother et al, 2014).…”

“…The timing and magnitude of Pleistocene glacier advances in the broader Altai have been the subject of prior investigations (Lehmkuhl et al., 2004, 2007, 2011, 2016; Blomdin et al., 2016; Dong et al., 2020; Gribenski et al., 2016, 2018; Klinge et al., 2021; Yang et al., 2017). A number of chronologies indicate that full‐glacial configurations of Central Asian mountain glaciers were achieved not only at the time of the global LGM during Marine Isotope Stage (MIS) 2 (∼29–14 ka; Lisiecki & Raymo, 2005), but also preceding the global LGM during MIS 3 (∼57–29 ka; Lisiecki & Raymo, 2005) (Batbaatar et al., 2018; Blomdin et al., 2018; Dong et al., 2020; Gillespie et al., 2008; Gribenski et al., 2016, 2018; Klinge et al., 2021; Krivonogov et al., 2012; Lehmkuhl et al., 2011; Prokopenko et al., 2009; Rother et al., 2014). Debate remains as to whether glacial advances during the local Last Glaciation were synchronous throughout Central Asia (e.g., Batbaatar et al., 2018); these issues may reflect the scarcity of well‐resolved glacial chronologies or lack of landform preservation.…”

Late Quaternary landscape evolution and paleoenvironmental implications from multiple geomorphic dryland systems, Orog Nuur Basin, Mongolia

“…For both humid pulses low Pinus pollen input points to wintery or southern air masses as moisture source. Air masses from the north during summer would cause higher pollen input from flowering Pinus trees of the taiga (Klinge et al, 2020).…”

Morphological classification and origin of lake depressions in Mongolia

“…The morphology of the depression of the Great Lakes is a glaciated super valley. Glacial drumlins forms have been preserved [33][34] in the central part of the depression.,.…”