Aeolian dust dynamics in the Fergana Valley, Central Asia, since similar to 30 ka inferred from loess deposits

Knowledge of the interactions among atmospheric dynamics, dust emissions and climate system is essential to understand the physical mechanisms for the dust lifecycle, their role in loess formation as well as the predictions of future dust concentration. However, these issues still remain relatively...

Full description

Bibliographic Details
Published in:Geoscience Frontiers
Main Authors: Li, Yue, Song, Yougui, Kaskaoutis, Dimitris G., Zan, Jinbo, Orozbaev, Rustam, Tan, Liangcheng, Chen, Xiuling
Format: Report
Language:English
Published: CHINA UNIV GEOSCIENCES, BEIJING 2021
Subjects:
Dust dynamics
Climate
Atmospheric patterns
Loess
Ice volume
Fergana Valley
ATMOSPHERIC CIRCULATION PATTERNS
ARID CENTRAL-ASIA
INTERGLACIAL-GLACIAL CYCLE
GRAIN-SIZE DISTRIBUTIONS
LATE QUATERNARY LOESS
CHINESE LOESS
PALEOSOL SEQUENCE
MAGNETIC-SUSCEPTIBILITY
LATE PLEISTOCENE
NORTH-ATLANTIC
Geology
Geosciences
Multidisciplinary
Ice Sheet
North Atlantic
Online Access:http://ir.ieecas.cn/handle/361006/16977
https://doi.org/10.1016/j.gsf.2021.101180
Description
Summary:Knowledge of the interactions among atmospheric dynamics, dust emissions and climate system is essential to understand the physical mechanisms for the dust lifecycle, their role in loess formation as well as the predictions of future dust concentration. However, these issues still remain relatively poorly known in Central Asia (CA). The extensive loess deposits on the CA pediments provide a promising archive to explore atmospheric dust dynamics and climatic conditions in the past and their association with loess formation. This study investigates the granulometric and magnetic properties of a loess section (named Osh section) in the Fergana Valley, which provides a sensitive record of atmospheric dust dynamics since 30 ka based on radiometric (AMS C-14) dating. The frequency-dependent magnetic susceptibility (chi(fd)) and the mean grain size are used to reconstruct the broad-scale effective moisture and summer atmospheric dynamics pattern in CA, respectively. The results show that the precession forcing exerts a huge influence on the wind-regime variabilities in CA, but with different physical processes under the impact of the Northern Hemisphere ice sheet (NHIS) before and after 15 ka. The origin of the sedimentation rate variations in the Osh loess is also linked to the NHIS-modulated changes of the atmospheric circulation patterns. Either the strengthened westerlies or the increased surface roughness from higher vegetation cover in loess-deposition areas have significantly accelerated the loess accumulation. As a result, these complicated influence factors of sedimentation rate change in the Osh loess section, especially during the Holocene epoch, may hamper accessibility of the authentic dust emission flux and atmospheric dust concentration in CA. (C) 2021 ChinaUniversity of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.

Similar Items