Validity of radiocarbon ages of Siberian yedoma

Abstract

The ice wedges are considered as key subjects for 14C aging of yedoma, as there are no any exchange processes between the environment and the ice wedges. Syngenetic sediments contain allochthonous organic admixtures which originated at a distance from its present position. The main problem of radiocarbon dating within permafrost is the uncertain reliability of the 14C ages. To establish the age of ice wedge formation the strategy for the most authentic radiocarbon age selection for syngenetic sediments is considered on the base of a model of yedoma accumulation and distribution of reversal material by flood and aeolian transport. The re-working of organic material discussed in terms of cyclic syngenetic sedimentation of yedoma.The advantages and the complications of 14C dating of organic inclusions from ice wedges by the accelerator mass spectrometry (AMS) are discussed applying to the search of true age organic material, which is simultaneous to ice-wedge formation. Radiocarbon ages of different organic materials from the same samples are compared, it is demonstrated that the difference between ages of the fractions from the ice wedges consists of about 9 kyr in Seyaha ice-wedge complex in Yamal Peninsula and about 5 kyr in Bison yedoma, Kolyma River valley. The principle of the choice of the youngest 14C age from the set and from the layer is proposed for yedoma.