Meteoric 10Be as a tracer of soil redistribution rates and reconstruction tool of loess-mantled soils (SW, Poland)

Loess deposits are terrestrial archives that record progressive deposition and erosion events of varying intensities. Data on long-term erosion rates are crucial for tracking changes in the stability of a loess mantle and reconstructing the evolution of loess-enriched soils. We used meteoric Be-10 to i) define the factors responsible for its distribution along the profile, ii) determine long-term erosion rates in loess-enriched polygenetic soils characterised by illuviation processes, and iii) evaluate initial soil thickness and stability over time. Distribution of meteoric Be-10 along the soil profiles was mainly driven by its translocation with clay particles and accumulation in the illuvial horizons. However, in some cases (loess over serpentinite), the highest meteoric Be-10 content was measured in the C horizons which may be related to the longer exposure of serpentinite to meteoric Be-10 deposition before the occurrence of a major loess accumulation event. The estimated long-term erosion rates greatly depend on the assumed environmental settings and were in the range of about 0.1-3 t ha(-1) yr(-1). Based on the soil redistribution rates, we reconstructed the removed loess layer which was from a few dm to about 3 m. The results indicate four main soil evolutionary phases: a) pre-exposure of sediments to meteoric Be-10 accumulation; b) formation of thick loess mantles during the Last Glacial Maximum; c) erosion events between 21 and 11.6 ka that significantly shallowed the initial loess mantles; d) pedogenesis (with subsoil clay accumulation) in the Holocene within the thinner relicts of the former Late Pleistocene loess mantle followed by a recent and strong erosional phase due to human impact. These phases are also believed to have occurred in several other areas of Central Europe.

Automated summary

Loess deposits are important archives for studying deposition and erosion events. Long-term erosion rates are crucial for understanding loess stability and soil evolution. This study used meteoric Be-10 to analyze its distribution, determine erosion rates, and assess soil thickness and stability over time.