Glacially deformed diamictons in the Karakoram Mountains, northern Pakistan

The deformation of glacial and paraglacial sediments takes many forms and occurs at several scales owing to the very variable, high-energy glacial system and the large number of juxaposed sedimentary environments. The Karakoram glaciers and adjacent Pleistocene and Recent glacial sediments provide good examples of such variability. Two main types of glacial sedimentary environments are present: Ghulkin type, consisting of ice-contact fan sedimentation dominated by glaciofluvial, debris flow and slide processes; Pasu type, characterised by roches moutonnées hummocky moraines and glaciofluvial outwash plains dominated by processes of subglacial lodgement and meltout. Glacial diamictons display structures and fabrics which arise from ice-push and subglacial shear. However, many of the structures within these diamictons cannot be explained as the result of ice-push. Rather, they relate to resedimentation by debrisslide and debris flow processes. Field study aided by laboratory work involving both optical and scanning electron microscopy of the microfabrics can help resolve the question of the mode of deposition or emplacement of these diamictons.