Identifying eolian dust in the geological record

Abstract

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Loess‐Like Dust Appearance at 40 Ma in Central China

“…Therefore, these deposits are not classified as lithified loess (Pye, 1995), but rather interpreted as a diverse depositional environment containing a loess‐like component as well as other fluvio‐lacustrine and/or dust components (Figure 7). This interpretation is in line with recent depositional models for the Miocene Red Clay (Alonso‐Zarza et al., 2009; Liu et al., 2019; Meijer et al., 2020).…”

“…This suggests a reduction in fluvial activity rather than an increase at 40 Ma as observed in EM4. We note that the observations listed above, when considered on their own, are not strictly diagnostic of windblown transport (Meijer et al, 2020), but argue that when taken together, these observations suggest an eolian origin as the most likely. We therefore interpret the increase of EM4 as the onset of a loess-like dust component, which remains a consistent part of the sedimentary record afterward.…”

“… Depositional environment and paleovegetation of the Xining Basin during the Eocene (modified from Meijer et al., 2020). Dominant vegetation before 40 Ma is indicated in green, and after 40 Ma, in red (vegetation present throughout is colored in green with red outline).…”

“… Modern‐day topographic map (http://www.geomapapp.org) of the northeastern Tibetan Plateau showing various reported ages for the onset of loess‐like deposits (modified from Meijer et al., 2020): (1) central Loess Plateau: Z. L. Ding et al. (2001); Y.…”

Humidification of Central Asia and equatorward shifts of westerly winds since the late Pliocene

“…2), there are many stages associated with particle formation, mobilization, transport, deposition, re-mobilization, and re-deposition that may have been involved 43 . The formation of dust deposits requires a source of dust, adequate wind energy to entrain and transport the dust to the terrestrial deposition site, and conditions that favor trapping and preservation of the dust at that site 3,44,45 . The co-variation among chemical weathering proxies (Fig.…”