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

Michael Klinge,Anja Zander,Ochirbat Batkhishig,Frank Lehmkuhl,Daniela Hülle,Frank Schlütz

doi:10.1017/qua.2020.67

Abstract

AbstractGlacial 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.

Highlights

The Altai Mountains are located in the northern part of central Asia within the territories of Russia, Mongolia, China, and Kazakhstan
New fading-corrected luminescence ages provide additional numerical dating for these findings. Both lakes are impounded by terminal moraines, which were formed by a large Pleistocene valley glacier flowing from the Tavan Bogd peak (4374 m asl) in a southeasterly direction
Voluminous morainic sediments of an extensive ice-marginal zone cover an intermountain tectonic basin and create a hummocky terrain around the Khurgan Nuur. These sediments incorporate large amounts of laminated glaciolacustrine clay and silt, which provide evidence for a proglacial lake. This paleolake must have existed during the late Pleistocene ice advances and glacial oscillations

Summary

Introduction

The Altai Mountains are located in the northern part of central Asia within the territories of Russia, Mongolia, China, and Kazakhstan. Two main circulation systems are controlling the climate conditions here at the border between the coldhumid Siberian taiga in the north and the arid Gobi Desert in the south (Wesche et al, 2016). Late Pleistocene lake level, glaciation and climate change in the Mongolian Altai deduced from sedimentological and palynological archives. The position, the seasonal movement, and the intensity of these two Northern Hemisphere climatic systems are responsible for the distribution of regional effective moisture conditions (Herzschuh, 2006; Rudaya et al, 2009). The vegetation pattern, the mountain glaciation, and the endorheic lake levels reflect the local conditions of effective moisture in the semihumid to arid regions of Mongolia.

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Conclusion