Lake sediments documented late Quaternary humid pulses in the Gobi Desert of southern Mongolia: Vegetation, hydrologic and paleoglaciation inferences

Reconstructing the evolutionary history of the Gobi deserts developed from alluvial sediments in arid regions has great significance in unraveling changes in both tectonic activity and climate.However,such work is limited by a lack of suitable dating material preserved in the Gobi Desert,but cosmogenic 10Be has great potential to date the Gobi deserts.In the present study,10Be in quartz gravel from the Gobi deserts of the Ejina Basin in Inner Mongolia of China has been measured to assess exposure ages.Results show that the Gobi Desert in the northern margin of the basin developed 420 ka ago,whereas the Gobi Desert that developed from alluvial plains in the Heihe River drainage basin came about during the last 190 ka.The latter developed gradually northward and eastward to modern terminal lakes of the river.These temporal and spatial variations in the Gobi deserts are a consequence of alluvial processes influenced by Tibetan Plateau uplift and tectonic activities within the Ejina Basin.Possible episodes of Gobi Desert development within the last 420 ka indicate that the advance/retreat of alpine glaciers during glacial/interglacial cycles might have been the dominant factor to influencing the alluvial intensity and water volume in the basin.Intense floods and large water volumes would mainly occur during the short deglacial periods.

Alluvial fan

Alluvial plain

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

Earth Surface Processes and Landforms (2021)

Veit Nottebaum Georg Stauch Jorien L. N. van der Wal Anja Zander Frank Schlütz

Abstract This study investigates the late Quaternary development of the sedimentary system of Orog Nuur Basin in southern Mongolia. Geomorphological archives (lacustrine sediments and beach ridges, alluvial fans, aeolian deposits, peat) recorded palaeoenvironmental change from marine isotope stage (MIS) 7 to the late Holocene. Synthesizing the variety of archives allows a better understanding of geomorphological interactions in arid regions and palaeoenvironmental implications for the area. By performing palaeoshoreline mapping and dating, we identified eight palaeolake levels resulting in a refined lake level history of Orog Nuur. The highest reliably dated shoreline is about 56 m higher than today's lake level and provides evidence for a late MIS 5 lake level between 100 and 75 thousand years (ka). Reconstructions yield a minimum volume estimate of 24.5 km 3 , delineating a lake that is 153 times larger than that of today (0.16 km 3 ). Massive lake extensions occurred also during MIS 3 and the Holocene. The geomorphological investigation reveals late MIS 5 and MIS 3 lake expansions were of similar magnitude. The palaeoenvironmental reconstruction from early Holocene archives indicates that lake expansion was caused by an increase in precipitation and meltwater inflow from the surrounding mountain systems. Afterwards, lake levels declined with some intermittent highstands during the mid‐Holocene (7–5 ka), indicating a general trend towards a lower water inflow throughout the Holocene. Palynological reconstructions of the alpine vegetation development reveal that mid‐Holocene highstands ( c . 6.5 ka and 5.5 ka) were fed by higher precipitation in the nearby Gurvan Bogd range. Mountain silts, basin silty sands, and Holocene dune deposits provide further evidence for paleoenvironmental change. As controlling factors of the sedimentary system, we identified changes in effective moisture, higher precipitation values and the contribution of meltwater. Orog Nuur Basin archives are valuable for landscape and palaeoenvironmental reconstructions and for comparisons in supraregional reconstruction approaches.

Meltwater

Holocene climatic optimum

10.1002/esp.5247

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Palaeoenvironmental and climatic changes during the Late Glacial and Holocene in the Mongolia and Baikal region: A review

Quaternary International (2021)

Fedora Khenzykhenova N. I. Dorofeyuk А. А. Shchetnikov Guzel Danukalova V. B. Bazarova

Mammoth

Steppe

Paleoclimatology

Megafauna