Revisiting krotovina formation using luminescence dating − a case study from NE China

Abstract

Krotovinas, the infilled burrows created by small mammals through bioturbation, represent a distinct pedogenic process and provide valuable records of soil and landscape history. Traditionally, macro- and micromorphological features are analyzed to investigate the origin of burrow fills, and ages are often estimated using ¹⁴C dating. However, in some environments, morphological features can be misleading and material for ¹⁴C dating is insufficient. This study explores the potential of luminescence techniques to address these issues. We studied a Chernozem profile with typical krotovinas, forming from fluvial sediment in northeast China. Three krotovinas of different depths and colors (two black and one yellow) were sampled, along with their respective supposedly undisturbed counterparts from the surrounding soil. We conducted single-grain (SG) luminescence dating of the K-feldspar fraction and multigrain (MG) luminescence dating of both quartz and K-feldspar fractions. Significant differences in luminescence ages between samples inside and outside the krotovinas at both MG and SG levels suggest the presence of vertical bioturbation. Comparisons of SG distributions among samples indicate that the yellow krotovina at ca.70 cm was the result of upward transportation from a lower layer and was formed after the end of the Last Glacial Maximum. The two black krotovinas at ca. 80 and 160 cm are genetically linked, and probably formed in a single, rapid, simultaneous filling event occurring no earlier than 2.7 ka. This study highlights the unique role of luminescence dating in elucidating formation processes of krotovinas and the soils in which they are found.