Source estimation of Pleniglacial Lower Danube loess based on geochemical signatures of loess-palaeosol sequences

Abstract

The source of aeolian sediments such as loess has been investigated since decades.
Reliable knowledge on potential dust sources is crucial to understand past climatic and
environmental conditions accompanying the dispersal of early modern humans (EMH) into
Europe. Provenance studies are usually performed on small sample sets and most
established methods are expensive and time-consuming. Here, we present the results of
high-resolution geochemical analyses performed on five loess-palaeosol sequences from
the Lower Danube Basin (LDB), a region, despite its importance as a trajectory for EMH,
largely underrepresented in loess provenance studies. We compare our results with
geochemical data of loess-palaeosol sequences from Austria, Hungary, Serbia, and
Ukraine. Based on published literature, we thus evaluate five plausible sedimentary
pathways for the LDB loess: 1) the Danube alluvium (DA) pathway, which constrains the
transport and re-deposition of detrital material by the Danube and its tributaries; 2) the
Carpathian Bending (CB) pathway, where sediment is mainly transported from the
Cretaceous to Neogene flysch of the Eastern Carpathian Bending; 3) the Eastern
Carpathian (EC) pathway, in which sediment is eroded from the flysch of the Outer
Eastern Carpathians, transported by rivers, and deflated by northwesterly to westerly
winds; 4) the glaciofluvial (GF) pathway, where dust is deflated from glacial outwash
plains in nowadays Ukraine, and 5) the Black Sea (BS) pathway, where dust originates
from the exposed shelf of the Black Sea. Based on geochemical data, we consider the DA
pathway to be the major sediment trajectory for loess in the LDB. Especially the sequences
located close to the Danube and the Dobrogea show similarities to sites in Central and
Northeast Hungary as well as Northern Serbia. For the northeastern part of the LDB, we
demonstrate that dust input is mainly sourced from primary material from the Eastern
Carpathians. Mineralogical estimations and geochemical data render the CB pathway as an
additional substantial source of detrital material for the loess of this area. We consider the
influence of the GF pathway in the LDB as negligible, whereas some minor influences of the
BS pathway cannot be ruled out based on geochemical data.

Resources

Bibliography

Pötter, S., Veres, D., Baykal, Y., Nett, J., Schulte, P., Hambach, U., Lehmkuhl, F. (2021): Source estimation of Pleniglacial Lower Danube loess based on geochemical signatures of loess-palaeosol sequences. – In: Frontiers in Earth Science, Vol. 9(599986), p: 1-17, DOI: 10.3389/feart.2021.600010