Stratigraphic interpretation of rare earth element signatures in Pleistocene mammal bones: A case study from Kharabai site, East Siberia

A significant portion of the Quaternary mammal remains is not found in situ, which limits their biostratigraphic potential and the possibility of studying evolutionary changes. To determine stratigraphic position of such finds we used the geochemical interpretations of rare earth element relative concentrations and fractionations (REE signatures) in the faunal remains and surrounding sediments. REE signatures vary between different profile deposits due to differences in deposit sources, conditions, and REE fractionation during deposition and diagenesis. Redeposited faunal remains can retain evidence of unique REE signatures of surrounding deposits, which allows assigning such bones to their proper depositional units. This method is tested here on the material from the Kharabai site, Viluy River, Central Yakutia (63.77°N, 121.10°E). We determined that the REE signatures from the faunal remains, collected at the base of the exposure, showed a statistically significant correspondence to certain stratigraphic layers, indicating the original deposition location of these remains. Importantly, the biochronological age of the mammals, determined using their evolutionary position, was consistent with the stratigraphic position of the layers, with which they were associated using the REE signatures. This research suggests that the lower layers of the Kharabai site date to Early Middle Pleistocene, while the upper ones date to Late Pleistocene.