The Main Elements of the Field Ice-wedge Sampling Strategies for Isotope and Radiocarbon Analysis

Abstract

The main purpose of the paper is to create an optimal strategy for field testing of wedge ice for isotope and radiocarbon analyses. The scientific significance of this task is the need for a detailed isotopic characterization of well-dated sections with ice wedges. The solution of this problem will allow us to obtain a complete isotopic and paleotemperature scenario for the Holocene and the late Pleistocene in the north of Western Siberia, northern and central Yakutia, Chukotka, and the Arctic islands. Reliable ranges of isotopic composition values will be obtained as a result of the application of an improved method of wedge ice sampling. It will give a complete picture of isotopic variations in ice wedges during a certain period of its formation in combination with the age setting of the obtained isotope data. The main provisions of the optimal strategy for field testing of wedge ice for isotope and radiocarbon analyses are formulated. The innovativeness of the proposed technique consists in comparing of oxygen isotope and deuterium curves obtained from two parallel and quasi-synchronous ice wedges exposed by a single outcrop in the yedoma and Holocene deposits. Previously, it was believed that the sampling from different ice wedges in the single outcrop would give the same results. The preliminary studies carried out by the author show that this is not always the case. At the same depths, both identical and noticeably different isotopic determinations were obtained from samples from neighboring ice wedges. Predominantly horizontal sampling from ice wedges in yedoma deposits should still be referred to as an insufficiently developed procedure, it should be supplemented by vertical sampling from ice wedges. It is possible to develop criteria for excluding older 14С dates due to admixture of allochthonous organic material as inversions with vertical sampling only. This is impossible using horizontal sampling.