Palaeoecological Interpretation of a Late Holocene Sediment Sequence from the Alpine Belt of the Southern Mongolian Altai Mountains

Sven Goenster-Jordan,Brigitte Urban,Andreas Buerkert

doi:10.5334/oq.90

Abstract

The climate in the Altai Mountains is determined by two major climate systems whose dominance has varied over time, leading to significant spatio-temporal changes in temperature and precipitation during the Holocene. This study aimed at the reconstruction of the local to regional moisture and temperature conditions in an alpine belt of the southern Mongolian Altai during the Late Holocene. It thereby contributes to a more comprehensive understanding of the region’s palaeoclimate in the Holocene. Our reconstruction is based on palynological and sediment analyses as well as radiometric age determinations of samples from a 130 cm exposed soil/sediment profile within the alpine belt. Largely supported by sedimentological and geochemical observations, the pollen assemblages indicate a warm and dry period between about 2600 and 2250 cal a BP, a subsequent cold and humid phase extending to about 130 cal a BP, and a return to warm and dry conditions lasting to present. Our data support the results of recent studies on the regional climate variability and the observation of significant differences in the mode of climate changes and its temporal sequence within the Altai Mountains. Although the pollen assemblages in the profile reflected a continuous anthropo-zoogenic influence on the study site’s vegetation climatic signals were clearly detectable, underlining the indicator value of the pollen data from the Alpine sediments for regional palaeoclimatic reconstruction.

Highlights

The climate of the Altai Mountains, which are located in the center of the Eurasian continent, is dominated by westerly winds almost throughout the year (Feng et al 2017)
In view of the findings presented above, our study aimed at the reconstruction of the local to regional moisture and temperature conditions in an alpine belt of the southern Mongolian Altai Mountains during the Late Holocene
Thereby, the dark colored layers show a higher concentration of these parameters compared to the adjacent light colored layers, indicating that the color brightness of the layer is associated with the OM content (Figure 5)

Summary

Introduction

The climate of the Altai Mountains, which are located in the center of the Eurasian continent, is dominated by westerly winds almost throughout the year (Feng et al 2017). The westerlies transport warm and humid air masses mainly from Central Asia and the Atlantic Ocean to the Altai Mountains (Aizen et al 2005; Aizen et al 2006; Blyakharchuk et al 2007). This is well reflected in the distribution of precipitation in the Altai Mountains, which is higher on the western side of this range given orographic precipitation and decreases eastward on the leeward side (Feng et al 2017). During the Holocene the precipitation pattern in the Altai Mountains has been subjected to significant spatio-temporal changes (Tarasov et al 2000; Chen et al 2008; Feng et al 2017), due to shifts in the relative power between the North Atlantic system with its westerly airflows, and the Pacific system with its airflows from the east (Feng et al 2017; Zhang et al 2018) likely as a result of changes in sea surface temperature in the Atlantic and Pacific Oceans (Sun et al 2015)

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Conclusion