Perspectives of application of the 230Th/U method of geochronometry for determining the age of Quarternary fossil fauna of the Arctic region

Abstract

Perspectives of the 230Th/U method for dating the fossil bones of mammoths, widespread in sediments of the Arctic region, are considered. Determination of uranium and thorium contents in well-preserved mammoth bone samples with known radiocarbon age was carried out and the prerequisites for the 230Th/U method were tested. It was revealed that the external and middle layers of bones can be geochemical barriers that make it difficult for dissolved uranium to enter the internal layers during post-sedimentation time. Thus, the internal layers can be attributed to conditionally closed radiometric systems. In some cases, 230Th/U age of these layers is similar to radiocarbon data. 230Th/U age in the range of 100 thousand years was obtained for the sample with the direct radiocarbon age. The results suggest that using the 230Th/U method for determining the age of mammoth bones is possible under certain conditions.