The physics of wind-blown loess: Implications for grain size proxy interpretations in Quaternary paleoclimate studies

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• 作者：Gá ; bor Ú ; jvá ; ri^a ; ^b ; ^{ujvari.gabor@csfk.mta.hu" class="auth_mail" title="E-mail the corresponding author} ; Jasper F. Kok^c ; Gyö ; rgy Varga^d ; Já ; nos Ková ; cs^e ; ^f
• 关键词：Loess ; Grain size proxy ; Quartz ; Wind ; Aeolian dynamics ; Quaternary
• 刊名：Earth Science Reviews
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：154
• 期：Complete
• 页码：247-278
• 全文大小：3958 K

文摘

Loess deposits are recorders of aeolian activity during past glaciations. Since the size distribution of loess deposits depends on distance to the dust source, and environmental conditions at the source, during transport, and at deposition, loess particle size distributions and derived statistical measures are widely used proxies in Quaternary paleoenvironmental studies. However, the interpretation of these proxies often only considers dust transport processes. To move beyond such overly simplistic proxy interpretations, and toward proxy interpretations that consider the range of environmental processes that determine loess particle size distribution variations we provide a comprehensive review on the physics of dust particle mobilization and deposition. Furthermore, using high-resolution bulk loess and quartz grain size datasets from a last glacial/interglacial sequence, we show that, because grain size distributions are affected by multiple, often stochastic processes, changes in these distributions over time allow multiple interpretations for the driving processes. Consequently, simplistic interpretations of proxy variations in terms of only one factor (e.g. wind speed) are likely to be inaccurate. Nonetheless using loess proxies to understand temporal changes in the dust cycle and environmental parameters requires (i) a careful site selection, to minimize the effects of topography and source distance, and (ii) the joint use of bulk and quartz grain size proxies, together with high resolution mass accumulation rate calculations if possible.