Résumé
A multidisciplinary team of researchers investigated a loess and paleosol sequence sampled in 2012 in NE Bulgaria near the village of Harletz. Geomorphological constraints, optical luminescence ages and sedimentological observations (Lomax et al. 2019, Antoine et al. 2019) determined that the aeolian loess sequence preserved a remarkable record, 10 meters in thickness, of the penultimate glacial period (MIS 6). The loess unit overlies a MIS 7 paleosol complex developed on alluvial deposits and transitions into a last interglacial (MIS 5) soil complex. Four incipient soils were identified in the field at the base of the MIS 6 loess unit with decreasing degrees of development upward. These incipient soils have a distinct rock magnetic signature differing from pristine parent loess material and from the highly more developed MIS 5 soil complex. A similar rock magnetic signature is observed in discrete intervals throughout MIS 6 resulting in millennial-timescale variations. A first order assumption is that the signature within the incipient soils is of a pedogenic origin. In order to resolve whether the origin of the signature observed elsewhere in the MIS 6 loess unit is also pedogenic or stemming from a different origin, for example changes in source material, a comprehensive rock magnetic analysis was conducted at both room and low temperatures. The rock magnetic data were integrated with grain size, carbon geochemical, and colour reflectance data in order to obtain coherent proxies of climate and environmental change (i.e. pedogenic activity, parent material provenance and wind dynamics) across the various discipline-based proxies. References: Antoine, P., Lagroix, F., Jordanova, D., Jordanova, N., Lomax, J., Fuchs, M., Debret, M., Rousseau, D.-D., M., Hatte, C., Gauthier, C., Moine, O. (2019) - A unique Late Saalian loess (dust) accumulation in the Lower Danube at Harletz (Bulgaria). Quaternary Science Reviews 207, 80-100. Lomax, J., Fuchs, M., Antoine, P., Rousseau, D.-D., Lagroix, F., Hatte, C., Taylor, S., Till, J., Debret, M., Moine, O., Jordanova, D. (2019). Luminescence chronology of the Harletz loess sequence, Bulgaria. Boreas 48, 179-194.