Volcanic ash layers in Lake El'gygytgyn: eight new regionally significant chronostratigraphic markers for western Beringia

• Main Authors: van den Bogaard, Christel, Jensen, B. J. L., Pearce, N. J. G., Froese, D. G., Portnyagin, Maxim V., Ponomareva, Vera V., Wennrich, V.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications (EGU) 2014
• Subjects: Arctic; Bering Sea; Pacific; Yukon; Kamchatka; Subarctic; Alaska; Beringia
• Online Access: https://oceanrep.geomar.de/id/eprint/22317/; https://oceanrep.geomar.de/id/eprint/22317/1/cp-10-1041-2014.pdf; https://doi.org/10.5194/cpd-9-5977-2013; https://doi.org/10.5194/cp-10-1041-2014

Ash layers from explosive volcanic eruptions (i.e. tephra) represent isochronous surfaces independent from the environment in which they are deposited and the distance from their source. In comparison to eastern Beringia (non-glaciated Yukon and Alaska), few Plio-Pleistocene distal tephra are known from western Beringia (non-glaciated arctic and subarctic eastern Russia), hindering the dating and correlation of sediments beyond the limit of radiocarbon and luminescence methods. The identification of eight visible tephra layers (T0–T7) in sediment cores extracted from Lake El'gygytgyn, in the Far East Russian Arctic, indicates the feasibility of developing a tephrostratigraphic framework for this region. These tephra range in age from ca. 45 ka to 2.2 Ma, and each is described and characterized by its major-, minor-, trace-element and Pb isotope composition. These data show that subduction zone related volcanism from the Kurile–Kamchatka–Aleutian–Arc and Alaska Peninsula is the most likely source, with Pb isotope data indicating a Kamchatkan volcanic source for tephra layers T0–T5 and T7, while a source in the Aleutian Arc is possible probable for Tephra T6. The location of Lake El'gygytgyn relative to potential source volcanoes (>1000 km) suggests these tephra are distributed over a vast area. These deposits provide a unique opportunity to correlate the high-resolution paleoenvironmental records of Lake El'gygytgyn to other terrestrial paleoenvironmental archives from western Beringia and marine records from the northwest Pacific and Bering Sea. This is an important first step towards the development of a robust integrated framework between the continuous paleoclimatic records of Lake El'gygytgyn and other terrestrial and marine records in NE Eurasia.