A new Holocene eruptive history of Erebus volcano, Antarctica using cosmogenic 3He and 36Cl exposure ages

David E.f. Parmelee, Philip R. Kyle, Mark D. Kurz, Shasta M. Marrero, Fred M. Phillips

Research output: Contribution to journalArticlepeer-review

Abstract

The ages of recent effusive eruptions on Erebus volcano, Antarctica are poorly known. Published Ar-40/Ar-39 ages of the 10 youngest "post-caldera" lava flows are unreliable because of the young ages of the flows (<10 ka) and the presence of excess Ar-40. Here we use cosmogenic He-3 and Cl-36 to provide new ages for the 10 youngest flows and 3 older summit flows, including a newly recognized flow distinguished by its exposure age. Estimated eruption ages of the post-caldera flows, assuming no erosion or prior snow cover, range from 4.52 +/- 0.08 ka to 8.50 +/- 0.19 ka, using Lifton et al. (2014) to scale cosmogenic production rates. If the older Lal (1991)/Stone (2000) model is used to scale production rates, calculated ages are older by 16-25%. Helium-3 and chlorine-36 exposure ages measured on the same samples show excellent agreement. Helium-3 ages measured on clinopyroxene and olivine from the same samples are discordant, probably due in part to lower-than-expected He-3 production rates in the Fe-rich olivine. Close agreement of multiple clinopyroxene He-3 ages from each flow indicates that the effects of past snow coverage on the exposure ages have been minimal. The new cosmogenic ages differ considerably from published Ar-40/Ar-39 and Cl-36 ages and reveal that the post-caldera flows were erupted during relatively brief periods of effusive activity spread over an interval of similar to 4 ka. The average eruption rate over this interval is estimated to be 0.01 km(3)/ka. Because the last eruption was at least 4 ka ago, and the longest repose interval between the 10 youngest eruptions is ka, we consider the most recent period of effusive activity to have ended.
Original languageEnglish
Pages (from-to)114-131
JournalQuaternary Geochronology
Volume30
Early online date5 Sep 2015
DOIs
Publication statusPublished - 1 Oct 2015

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