Wind erosion in the Qaidam basin, central Asia: Implications for tectonics, paleoclimate, and the source of the Loess Plateau

Abstract

Liquid water and ice are the dominant agents of erosion and sediment transport in most actively growing mountain belts. An exception is in the western Qaidam basin along the northeastern margin of the Tibetan Plateau, where wind and windblown sand have sculpted enormous yardang fields in actively folding sedimentary strata. Here, we present observations suggesting that since the late Pliocene, wind episodically (during glacial and stadial periods) removed strata from the western Qaidam basin at high rates (>0.12-1.1 mm/yr) and may have accelerated rates of tectonic folding. Severe wind erosion likely occurred during glacial and stadial periods when central Asia was drier and the main axis of the polar jet stream was located ~10° closer to the equator (over the Qaidam basin), as predicted by global climate models. Reconstructed wind patterns, the estimated volume of Qaidam basin material removed by wind, and numerical models of dust transport all support the hypothesis that the Qaidam basin was a major source of dust to the Loess Plateau. HISTORY OF QAIDAM WIND EROSION The wind erosion that produced the modern Qaidam yardangs must be younger than late Pleistocene because lacustrine strata of this age are widely exposed in the wind-eroded part of the basin (Pan et al., 2004). However, it does not appear that

Climatic and tectonic controls on sedimentation and erosion during the Pliocene-Quaternary in the Qaidam Basin (China)

“…Active deposition occurs in saline lakes, playas, and on basin-marginal alluvial fans (Chen and Bowler, 1986;Mischke et al, 2009), although, at present, over half of the basin fl oor is actively eroding, as evidenced by the exposed bedrock and yardang fi elds that cover the northwestern part of the basin ( Fig. 1; Halimov and Fezer, 1989;Goudie, 2007;Rubin and Hesp, 2009;Kapp et al, 2011). Since at least the Eocene, however, most of the Qaidam Basin has continuously accumulated sediments, and late Paleozoic and Mesozoic sediments were locally deposited prior to the Cenozoic (e.g., Wang and Coward, 1990;Xia et al, 2001;Rieser et al, 2005;Zhuang et al, 2011b).…”

“…In addition, defl ation of the basin fl oor and formation of paleoyardangs require differential elevations of the basin fl oor, caused by uplift above active structures. The repeated occurrence of paleoyardangs within a stratigraphic section could thus be used to interpret changing climate cycles, regional wind patterns, and tectonic uplift, and they represent an under-utilized record of climate change and tectonics for comparison with other records such as the alternating loess/ paleosol stratigraphy of the Chinese Loess Plateau (Porter, 2001;Kapp et al, 2011).…”

“…Alternatively, sedimentation rate and grain-size increases could also be caused by rapid uplift along the northern margin of the Tibet-Qinghai Plateau in the absence of precipitation changes (Sun and Liu, 2000;Zheng et al, 2000;Pares et al, 2003;Fang et al, 2007;Liu et al, 2010;Suarez et al, 2011). Orographic blocking by the Tibetan Plateau is widely regarded as the major forcing mechanism for the observed global climate change between 3.6 and 2.6 Ma (Ruddiman and Kutzbach, 1989;Raymo and Ruddiman, 1992;Hsu and Liu, 2003;Li et al, 2011;Kapp et al, 2011), although direct links between tectonic uplift and climate change remain debated (Molnar, 2005). Thus, understanding the transitional time period between the Pliocene warm period and the onset of Northern Hemisphere glacial cycles at ca.…”

Comment on: Isotopic and micromorphological studies of Late Quaternary loess–paleosol sequences of the Karewa Group: Inferences for palaeoclimate of Kashmir Valley by Dar et al., 2014 (article in press)

“…The authors have done detailed field investigations but these important evidences from field are not a part of the paper, which should be added to enrich its significance, because, generally wind deposits are characterized by a variety of distinctive features (e.g. Kapp et al, 2011) which are significant in understanding their origin.…”

“…The authors have done detailed field investigations but these important evidences from field are not a part of the paper, which should be added to enrich its significance, because, generally wind deposits are characterized by a variety of distinctive features (e.g. Kapp et al, 2011) which are significant in understanding their origin.One of the important parts of this study comprises of presentation of lithologs through detailed field investigations; however all the studied sections presented are not backed by definite field evidence and data shown are often not clearly expressed. For example, in all the three studied sections A horizons are quite thick and completely devoid of carbonates but simultaneously all the B horizons contain carbonates.…”