Magnetic fabric of Tajik loess-palaeosols as a palaeowind and process indicator

Reconstructing past wind directions is critical in constraining synoptic scale climate regimes in the geologic past. Such wider scale understanding of past climate helps frame the climatic and environmental conditions that past human populations were exposed to. This is particularly important in regions such as Сentral Asia, at the interface of a range of climate zones. Palaeolithic tools are extensively embedded within the loess-palaeosol sequences of the Khovaling Loess Plateau, Southern Tajikistan, yet little is known about the environmental conditions these hominin groups faced.

Magnetic techniques applied to loess-palaeosol sequences are particularly insightful for investigating dust transport dynamics and variations in the intensity of hydroclimate. Anisotropy of magnetic susceptibility (AMS) in particular measures the magnetic fabric, i.e., the orientation of magnetic particles in an oriented sample, which can provide insights into palaeowind directions and post-depositional processes. Here we apply AMS to three different loess-palaeosol sections of the Khovaling Loess Plateau, approximately spanning the past 1 Ma, in order to assess if this technique allows us to reconstruct palaeowind directions for this region of Central Asia.

Our results reveal the first palaeowind directions reconstructed for the Khovaling Loess Plateau. We present AMS data from three sites on the Khovaling Loess Plateau and demonstrate the potential and limitations of this data for reconstructing palaeowind directions. We investigate the question to which degree local winds, responsible for loess deposition on the Khovaling Loess Plateau, are related to broader atmospheric circulation patterns. We also explore how AMS data can be combined with other palaeoenvironmental proxies, such as frequency-dependent magnetic susceptibility as an indicator of palaeoprecipitation, and how this technique can be used to assess sediment reworking.