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

Abstract

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 (nonglaciated 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 ky to 2.2 My old, and each is described and characterized by its major-, minor-, trace-element and Pb isotope composition. These data show that subduction-zone-related volcan-

Tephra without Borders: Far-Reaching Clues into Past Explosive Eruptions

“…However, only one tephra from the El'gygytgyn core was tentatively correlated to the source, which permitted identification of a previously unknown M>6.5 eruption from the Karymsky eruptive center in Kamchatka (Ponomareva et al, 2013a). Specific sources of other tephras are still unknown (van den Bogaard et al, 2014). Kamchatka has the highest concentration of Quaternary calderas per unit of arc length in the world (Figure 1; Hughes and Mahood, 2008).…”

“…Eight visible tephra layers (0.5-7 cm thick) have been identified, seven of which have been ascribed to Kurile-Kamchatka, and one-possibly to the Alaska-Aleutian arc (van den Bogaard et al, 2014). This lake lies >1100 km from the closest islandarc volcano and in a location that is perpendicular or against the direction of the jet stream.…”

“…Further afield, eruptive histories are being revisited from distal tephra studies in marine, lake and peat deposits as well as in the ice caps (e.g., Shane and Hoverd, 2002;Wulf et al, 2004Wulf et al, , 2008Wulf et al, , 2012Kutterolf et al, 2008a;Kuehn and Negrini, 2010;Sulpizio et al, 2010a,b;Dunbar and Kurbatov, 2011;Abbott and Davies, 2012;Narcisi et al, 2012;Pyne-O'Donnell et al, 2012;Jensen et al, 2013;Smith et al, 2013;Davies et al, 2014;van den Bogaard et al, 2014;Bourne et al, 2015a,b;Lane et al, 2015). By now, distal tephra and cryptotephra research has been successfully undertaken in many regions including Greenland (e.g., Abbott et al, 2012;Abbott and Davies, 2012;Coulter et al, 2012;Bourne et al, 2015b); North Atlantic (e.g., Lacasse and Garbe-Schönberg, 2001;Brendryen et al, 2011;Gudmundsdóttir et al, 2012;Blockley et al, 2014;Davies et al, 2014;Griggs et al, 2014;Voelker and Haflidason, 2015); European mainland (e.g., Caron et al, 2010;Sulpizio et al, 2010a,b;Lane et al, 2011Lane et al, , 2015Lawson et al, 2012); Mediterranean (Siani et al, 2004;Wulf et al, 2004Wulf et al, , 2008Wulf et al, , 2012Paterne et al, 2008;…”

“…Indeed, in hot and humid climates tephras can weather very quickly, within tens of thousands of years (e.g., Rawson et al, 2015). Many other researchers, however, confirm that volcanic glasses in marine and lake deposits as old as millions of years are quite fresh and have meaningful geochemical characteristics (e.g., van den Bogaard et al, 2014;Straub et al, 2015). In moderate and hot and dry climates Quaternary terrestrial tephras are also well preserved and suitable for geochemical analysis (e.g., WoldeGabriel et al, 2005;Kuehn and Negrini, 2010;Westgate et al, 2011).…”

Holocene tephra from the Chukchi-Alaskan margin, Arctic Ocean: Implications for sediment chronostratigraphy and volcanic history

“…Tephra and cryptotephra occurrences are known from many terrestrial Arctic sites, including Greenland, Svalbard, and northeast Asia (e.g., Abbott and Davies, 2012;Ponomareva et al, 2013a;van den Bogaard et al, 2014;van der Bilt et al, 2017). Visible tephra layers have not been found in Arctic marine sediments, but the presence of cryptotephra in sediments from the Fram Strait connecting the Arctic and Nordic Seas (Zamelczyk et al, 2012), highlights the possibility of finding volcanic deposits in the Arctic Ocean.…”