Radiocarbon dating of delta (super 18) O-delta D plots in late Pleistocene ice-wedges of the Duvanny Yar (lower Kolyma River, northern Yakutia).

Abstract

The Duvanny Yar cross-section located in the Lower Kolyma River valley of Northern Yakutia (69 degrees N, 158 degrees E, height above the Kolyma River level 55 m), has been studied and dated in detail by radiocarbon. The sequence mainly consists of sandy loam sediments with large syngenetic ice wedges. Their width at the top is 1-3.5 m. Allochthonous organic material occurs in high content, concentrating as 0.5-0.7 m lenses. Shrub fragments, twigs, and mammoth bones are accumulated in peaty layers. Through interpolation based on a series of (super 14) C dates, dating of the host sediments provides an approximate age for the ice wedges. The (super 14) C dates of various types of organic material are sometimes very close, but not all in agreement. Therefore, the dates do not accurately show the age of the delta (super 18) O and delta D plots. A new approach is developed to a (super 14) C dating strategy of syncryogenic sediments with high admixture of allochthonous organic material. The main purpose of this study is to consider detection of inversions or disturbances in the syngenetic permafrost sediment at the Duvanny Yar cross-section by (super 14) C date series. Direct accelerator mass spectrometry (AMS) dating of the ice confirmed the relatively young age of ice wedges.