T03_P10

Application of ¹⁴C dating of earthworm biospheroids to investigate paleosol formation

Kertész T^1,2, Gergely V¹, Buró B¹, Molnár M¹

¹Institute for Nuclear Research, Debrecen, Hungary, ²Doctoral School of Earth Sciences, University of Debrecen, Debrecen, Hungary

¹⁴C dating of paleosols is a challenging task as ordinary soil organic matter (SOM) does not give a realistic ¹⁴C age of a soil layer. If one could not find some macrofossil remains in the discovered soil horizon then the age determination is always a matter of debate. In this study we have investigated the earthworms produced biospheroids as a possible material for soil ¹⁴C dating. Recent studies suggested that earthworms consume preferably fresh organic matter during their life in the soil, which means the products of their digestion would contain rather recent organic carbon instead of the aged carbon from the SOM fraction.

Although biospheroids are rather small (diameter < 2 mm and mass < 5 mg) pure calcite granules, AMS technique gives the possibility of their radiocarbon dating.

We have investigated 8 different recent topsoil samples collected at 5 different localities in the Hajdúság area (Hungary). Results confirmed that contemporary biospheroids mostly contain young (max age 30 years) carbon, which gives realistic (zero) age. The method was applied on buried paleobiospheroids from the 10-50 krys old paleosol profile at Süttő (Hungary). ¹⁴C ages were compared with previous OSL data too. The ¹⁴C results (29), cover a 6.1 m long section, with 10 cm resolution, and show an very consistent picture with the previous OSL results and also some with ¹⁴C ages of conventional macrofossil from the same profile. Multiple repeated measurements were performed for reproducibility. Control samples may be present in the paleoenvironmental study of later Quaternary paleosols.