Observations of debris-rich naled associated with a major glacier surge event, Disko Island, West Greenland



Glacier naled formation is associated with surge-type glaciers both during active surging and in quiescence. During the 1995–98 surge of Kuannersuit Glacier, Disko Island, West Greenland, turbid winter runoff produced an extensive naled accretion with a distinct debris-rich stratification. After surge termination the summer occurrence of naledi gradually decreased and disappeared within 5 years. The fine-grained debris was deposited on top of outwash deposits on bars and banks. Observations at the margin of surrounding glaciers revealed that only surge-type glaciers in their quiescent phase had proglacial naled assemblages, although these lacked incorporated debris. This indicates that surge-type glaciers have a significant impact on the occurrence of naledi primarily because their subglacial thermal conditions and water storage capacity allow significant winter runoff implying high hydraulic pressure on proglacial outwash plains. Copyright © 2005 John Wiley & Sons, Ltd.