Hall
Chris M.
Hall
Chris M.
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ArticleNoble gas signatures in Greenland : tracing glacial meltwater sources(John Wiley & Sons, 2015-11-06) Niu, Yi ; Castro, M. Clara ; Aciego, Sarah M. ; Hall, Chris M. ; Stevenson, Emily I. ; Arendt, Carli A. ; Das, Sarah B.This study represents the first comprehensive noble gas study in glacial meltwater from the Greenland Ice Sheet. It shows that most samples are in disequilibrium with surface collection conditions. A preliminary Ne and Xe analysis suggests that about half of the samples equilibrated at a temperature of ~0°C and altitudes between 1000 m and 2000 m, with a few samples pointing to lower equilibration altitudes and temperatures between 2°C and 5°C. Two samples suggest an origin as melted ice and complete lack of equilibration with surface conditions. A helium component analysis suggests that this glacial meltwater was isolated from the atmosphere prior to the 1950s, with most samples yielding residence times ≤ 420 years. Most samples represent a mixture between a dominant atmospheric component originating as precipitation and basal meltwater or groundwater, which has accumulated crustal 4He over time.