Aeolian dust dynamics in central Asia during the Pleistocene: Driven by the long‐term migration, seasonality, and permanency of the Asiatic polar front

Abstract

Loess‐paleosol sequences preserve detailed archives of climate change, reflecting the dynamics of aeolian dust sedimentation and the paleodust content of the atmosphere. The detailed investigation of particle size distributions (PSDs) of windblown sediments is an increasingly used approach to assess the paleorecord of aeolian dust dynamics. The central Asian loess belt offers the potential to reconstruct Pleistocene atmospheric circulation patterns along an adjacent west‐east transect within interior Eurasia through granulometric studies. In this study we present the aeolian dust record of the loess sequence at Remisowka (SE Kazakhstan), which reflects a detailed signal of glacial‐interglacial climate and atmospheric dynamics in central Asia. On the basis of radiocarbon and amino acid geochronologic data, long‐term semicontinuous trends in the aeolian dust record of the Last Glacial Cycle are observed and interpreted to reveal their paleoclimate signal. In consideration of the modern synoptical atmospheric circulation patterns and aeolian dust transport in central Asia, it is likely that the observed trends reflect the long‐term migration, seasonal duration, and permanency of the polar front during the late Pleistocene. Previously published models, which focused on the reciprocal glacial‐interglacial influence of the zonal Westerlies and the Asiatic high on the aeolian dust transport in central Asia, were overly simplified and should be modified to include the major influence of the Asiatic polar front. As the polar front activity is intimately connected with the development and position of the interhemispherically active, high‐level planetary frontal zone (HPFZ), the presented data give insight to long‐term aeolian dust dynamics and climate variability of interior Eurasia, which are linked with interhemispheric climates.

Eolian dust input to the Subarctic North Pacific

“…All concentration data were corrected for the contribution of salt to the dry sample weight. For 23 of the 37 samples, grain size analyses were performed at the Bentley University Particle Size Laboratory following the method described in Machalett et al (2008). We further determined three endmember Weibull functions (EM1-EM3) that best described the observed size distributions and estimated the relative abundance of each endmember in each sample using the iterative least-square method described in McGee et al (2013).…”

Climatic imprint of the mid-latitude Westerlies in the Central Tian Shan of Kyrgyzstan and teleconnections to North Atlantic climate variability during the last 6000 years

“…Furthermore, being located at the intercept between the influences of the mid-latitude Westerlies, the Siberian Anticyclone, and partly also the Asian monsoon system (Cheng et al, 2012), the region holds information about hemispheric-scale climatic teleconnections, necessary to understand the global climate system. However, although the Tian Shan is thus of key importance for climate studies and various types of natural archives, for example, speleothems (Cheng et al, 2012), tree-rings (Esper et al, 2003), or loess sequences (Machalett et al, 2008) have been analyzed in this respect so far, knowledge about Holocene climate development and particularly hydrological changes in this region is still limited. For example, a moderate drying trend due to the gradual decline of moisture supplied by the Westerlies has been inferred for mid-latitude arid Central Asia since the Mid-Holocene from lake sediment records (Chen et al, 2008).…”

New approaches to European loess: a stratigraphic and methodical review of the past decade

“…50 ka -a careful checking of the context and the quality of the dated organic material is essential to obtain meaningful information on the age of sedimentation or soil formation [28]. Recent progress in refined chronostratigraphy of loess achieved by 14 C dating is, however, primarily based on refined sampling strategies of users, and on extension and refinement of calibration (e.g., http://www.calpal.de/). The extension of the calibration time scale to ca.…”

“…An inter-profile correlation 22 Unauthenticated Download Date | 5/11/18 7:38 PM of loess-palaeosol sequences from Central Asia and China ( Figure 5) was proposed [13] which however, needed sound geochronological support at that time. More recently the chronology of the penultimate glacial to Holocene part of the Remisowka section, SE Kazakhstan, was partly revised based on radiocarbon dating and aminostratigraphy, and the authors propose to include the major influence of the Asiatic polar front, in particular its long-term migration, seasonal duration, and permanency during the late Pleistocene in circulation models [14]. For the first time a tentative chronology of loess-paleosol sequences from north and northeast Iran, a region with extreme present day climate gradients, has been presented [15,16], as well as the first geochronological data from Late Pleistocene to Holocene sediment-soil sequences in Southern Iran (hot desert), which are now recognized as desert margin loess or loess derivates [17].…”

“…Recently, a high resolution radiocarbon-dated stacked loess chronostratigraphy of Central Europe (circum-Carpathian area) was presented ranging from the Middle Pleniglacial to the Late Glacial [28], in which the authors believe to see interstadial soils on a millennial to centennial scale. For the past >24 ka (measured through 14 C dating) a correlation is established with the high resolution loess sections at Kurtak on the Jenissei River, Siberia. Correlation with the GISP2 record suggests that there are more interstadial soils than Greenland Interstadials in the same time period (Figure 7).…”