Loess sequences are a particular record of paleoenvironments and paleoclimates and show regional peculiarities. Among those, European loess sequences show the occurrence of paleosols and other pedogenic units that have been demonstrated to correspond to the Greenland Interstadials (GIS) or Dansgaard-Oeschger events (DO), for the last climate cycle (Moine et al. 2017), of GIS-like for the penultimate climate cycle (Rousseau et al. 2020).
During the last climate cycle, these paleosols developed synchronously over Europe along a wide longitude transect eastward in Ukraine (Rousseau et al., 2017). More interesting the development of these paleosols or pedogenic units, occurred during a stop of the dust deposition from the top of the most recently deposited eolian unit. Taking into consideration this point in our manuscript, we revisited the stratigraphy of the European loess sequences by considering the paleodust units, equivalent to Greenland Stadials (GS), as associating the lower loess unit and the overlying paleosol or pedogenic unit. Moreover, the close correlation that we established between the paleosols or pedogenic units with GIs, allows us to consider that the paleosol development occurred during the related GI in Greenland (Rousseau et al., 2017). Having the GI durations published by Rasmussen et al (2014), we propose therefore new timescales for the European loess sequences. Moreover, we have assigned the paleosol-loess units doublets to the corresponding Bond cycles defined by Broecker (1994). These cycles group several DO events, of increasing cold amplitude, and end with a Heinrich event that some literature interpreted as the coldest and dustiest time interval over Europe, an interpretation that we are testing in our paper.
In our manuscript, we demonstrate our new method by applying it to the reference sequence of Nussloch that we have investigated for decades. We present a revised detailed record of sedimentation and mass accumulation rates over the 60 ka to 15 ka b2k time interval (TAB. 1). We also apply our method to other key European sequences that we investigated previously at high resolution, allowing us to propose new estimates for the SR and MARs of the most recent Bond cycles, i.e. e. between GI4 and GS3 (29 to 23.2ka b2k) and between GI8 and GS5 (38.2 to 29ka b2k) (TAB. 2). We conclude the LGM as the dustiest interval with the highest values, and presenting a longitudinal pattern along the studied European transect, with the highest values westward. Another finding is that for every Bond cycle, the dustiest interval always happened in the GS prior the last ones corresponding to Heinrich stadials. Expanding the comparison with high-resolution sequences from the Chinese loess plateau (TAB. 3) for the same Bond cycles, our study shows that Europe was dustier than China. A final test of our new method is by considering the SR and MARs for the various grain size categories measured in three key reference sequences. Considering the finest grain size category, which can be assimilated as the closest the mineral aerosols, our estimates fit the dust deposition reconstructed for the LGM in Europe by Earth System models opening new perspectives for future data-model comparisons (TAB. 4).
