Glacier surging as a control on the development of proglacial, fluvial landforms and deposits, Skei d ararsandur, Iceland

Glacier-hydrological processes are one of the main factors controlling prog lacial fluvial systems. It has been proposed that where jokulhlaups occur t hey play a dominant role in the evolution of proglacial outwash plains. How ever, extraordinary meltwater and sediment discharge associated with glacie r surging can also play a crucial role in the proglacial system. The interp lay of surge-related and jokulhlaup floods has been investigated at Skeioar arjokull, a jokulhlaup type-site where surging is also known to occur, allo wing the geomorphological and sedimentological effects of these events to b e differentiated. Skeioararsandur contains a spectacular assemblage of landforms and deposits associated with the 1991 surge of Skeioararjokull, The impact of the 1991 surge was felt mainly on the western half of the glacier where the ice adva nced up to 1 km between September and November. The surge limit is marked b y a push-moraine complex up to 5 m in height and 10 m in breadth. Proglacia l fluvial sediments were deposited as a series of outwash fans adjacent to the glacier, up to 400 m in diameter, as the glacier advanced during the su rge. Glaciotectonic structures associated with ice pushing inter-finger wit h undisturbed proglacial fluvial fan sediments. constraining timing of depo sition of proglacial fans to the period during and immediately following th e glacier surge. The study of landforms and sedimentary successions associated with the 1991 surge provides an excellent modern analogue for larger-scale push moraines and proglacial fans on Skeioararsandur, which are related to similar proce sses. surge-related outflows operating over timescales of months-years, tog ether with jokulhlaup flows play a major role in the creation of distinctiv e proglacial fluvial landforms and deposits. Examination of the sedimentary and landform records of areas presently subject to surging will allow the development of models which can be used to differentiate glacier surging fr om rapid glacier response to abrupt climate change. (C) 2001 Elsevier Scien ce B.V. All rights reserved.