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Isotopic composition of oxygen and hydrogen in ice wedges from the third marine terrace near Lorino settlement on the eastern coast of Chukotkaстатья Краткое сообщение
- Авторы: Budantseva Nadine A., Maslakov Alexey A., Vasil'chuk Alla Constantinovna, Vasil'chuk Yurij K., Kuzyakin Lev P.
- Журнал: Pangaea
- Год издания: 2024
- DOI: 10.1594/PANGAEA.965373
- Аннотация: The study's focus is on Early Holocene syngenetic ice wedges that are exposed in a polygonal peatland's outcrop in the topmost part of the third marine terrace, close to the Lorino village on Chukotka's eastern coast. The peatland accumulation near Lorino village started around 14-13 cal ka BP, at the end of the Younger Dryas, according to the radiocarbon dates that were collected. The active stage of peat accumulation ended around 10 cal ka BP. It is not unusual for peat accumulation to have started near the end of the Younger Dryas, before the Holocene's officially recognized lower limit (11.7 cal ka BP), and to have ended in the midst of the Holocene's Greenlandian stage. The reworking of ancient organic material during the erosion of the marine terrace sediments and separation of the allochthonous peat is most likely the cause of the age inversions in the peat observed along vertical profiles. In the peatland exposure, six fragments with ice wedges were studied between 2015 and 2021.The oxygen isotope data of the ice wedges under study indicate that the values of δ18O range from -15,5 to -18 ‰. The values found are consistent with data for Early Holocene ice wedges analyzed in other regions of Chukotka's eastern coast (Anadyr town, Uelen settlement), where the authors obtained δ18O values for ice wedges ranging from -16 to -19,4 ‰. This implies that the most active processes during the early Holocene were peat accumulation and ice wedge growth. For contemporary ice veinlets, the greatest δ18O values (-13,1 to -16,8 ‰) were found. All things considered, the δ2H-δ18O ratio for ice wedges shows a resemblance to the isotopic signature of winter precipitation. The Early Greenlandian stage of the Holocene had an average January air temperature that ranged from -23 to -27 °C, which is on average 3 °C colder than the current one.Measurements of the isotopic composition of oxygen and hydrogen in ice wedges were carried out in the Laboratory of Stable Isotopes of the Faculty of Geography of Lomonosov Moscow State University on a Delta-V Plus mass spectrometer using a gas-bench complex. International standards V-SMOW, GRESP, SLAP were used to calibrate the measurements. The error of determination was ±1 ‰ for δ2Н and ±0.4 ‰ for δ18O. The δ18O and δ2H values are expressed in ppm relative to VSMOW. Dexc was calculated using the formula of W. Dansgaard (Dansgaard, 1964): dexc = δ2H - 8δ18O.
- Добавил в систему: Маслаков Алексей Алексеевич