Chronology and glass chemistry of tephra and cryptotephra horizons from lake sediments in northern Alaska, USA

• Main Authors: Monteath A, van Hardenbroek M, Davies L, Froese D, Langdon PG, Xu X, Edwards ME
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Cambridge University Press
• Subjects: Hayes; Brooks Range; Alaska
• Online Access: https://eprint.ncl.ac.uk/fulltext.aspx?url=237345/B47D46BB-812A-407C-AB76-41E2EE2B39F2.pdf&pub_id=237345

Holocene tephrostratigraphy in Alaska provides independent chronology and stratigraphic correlation in a region where reworked old (Holocene) organic carbon can significantly distort radiocarbon chronologies. Here we present new glass chemistry and chronology for Holocene tephras preserved in three Alaskan lakes: one in the eastern interior, and two in the southern Brooks Range. Tephra beds in the eastern interior lake-sediment core are correlated with the White River Ash and the Hayes tephra set H (~4200-3700 cal yr BP), while an additional discrete tephra bed is likely from the Aleutian Arc-Alaska Peninsula. Cryptotephras (non-visible tephras) found in the Brooks Range include the informally named "Ruppert tephra" (~2700-2300 cal yr BP), and the Aniakchak caldera-forming event II tephra (CFE II; ~3600 cal yr BP). A third underlying Brooks Range cryptotephra is chemically indistinguishable from the Aniakchak CFE II tephra (4070-3760 cal yr BP) and is likely to be from an earlier eruption of the Aniakchak volcano.