Аннотация:The debris-covered ice-margins of three largely cold-based glaciers in central Spitsbergen were investigated to reconstruct their formation and degradation. Clast shapes indicate dominant englacial and supraglacial transport with a smaller subglacial component. Emplacement of material is inferred to have been through meltout along flowlines due to the relatively uniform and continuous debris cover along the glacier margins; no evidence of thrusting has been found. Degradation of all three belts is rapid and involves debris flows at unstable places—e.g., the margins of meltwater channels. Resultant exposure of underlying ice initiates or accelerates melting, thereby leading to further debris flows. Hence, once degradation starts, a self-reinforcing cycle that removes material from the glacier commences. Landform preservation potential on millennial time scales in a high-arctic, continuous permafrost environment is thus limited. This work has implications for the interpretation of Pleistocene landform associations that use modern analogues from Svalbard.
