Origin of stratified basal ice in outlet glaciers of Vatnajökull and Öræfajökull, Iceland
نویسندگان
چکیده
During the period 2000–2005, we collected samples of englacial ice, vent water, frazil/anchor ice and stratified basal ice from warm-based outlet glaciers of Vatnajökull and Öræfajökull, Iceland, and analysed them for H, O and D. Results of H analyses show that the stratified basal ice contains H from atmospheric thermonuclear testing and is younger than the englacial ice. Results of the O and D analyses show that frazil/anchor and stratified basal ice are both enriched by an average of 2.4% in O and 11% in D relative to vent water. These values are consistent with fractionation during partial freezing of supercooled subglacial water in an open system, one in which the remaining water is continuously removed and replenished by water of similar composition. The isotopic data and field observations do not support either a regelation or a thermal ad-freeze-on origin for the stratified basal ice.
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