Co-Isotopic Signature of Two Mechanisms of Basal-Ice Formation in Arctic Outlet Glaciers

Abstract

Basal ice is formed by regelation as a consequence of both pressure-melting and freezing-on at the glacier sole. A study of D/H and ¹⁸O/¹⁶O ratios in basal ice from five Arctic outlet glaciers indicates that a co-isotopic signature exists for these two mechanisms of formation. The dispersed and stratified facies of basal ice present in these glaciers are related respectively to the occurrence of regelation and to freezing-on at the glacier base. Their origin is tentatively connected with the onset of basal sliding and the zone of bed decoupling due to basal water pressure in these Arctic outlet glaciers.