The relative importance of glacial and glaciofluvial transport processes at lobate glacier margins in Alaska, Svalbard and Antarctica
Lehigh University, Bethlehem, PA
2 parts (487 p.): Charts, Illus., Maps
Alaska Resources Library & Information Services: GB81 C55 1988; Rasmuson Library: ALASKA QE579 C55 1988a (microfiche); Geophysical Institute Library: THESIS NOT UAF
Detailed morphologic mapping of Neoglacial deposits and systematic provenance analysis of debris sources, debris-in-transit and proglacial deposits at lobate glaciers in Alaska, Svalbard and Antarctica have been used to determine which glacial and glaciofluvial transport processes are active at each glacier, and to estimate the relative importance of each process and debris source. These results differ in detail from glacier to glacier, depending on the local topography, the debris sources present, and the history of glacial retreat. However, several general conclusions can be drawn which apply to most of the glaciers studied. Ice-marginal and subglacial fluvial processes transport the majority ($>$90%) of debris at most of the glaciers studied. Fluvial debris is acquired from two important debris sources. Subglacial fluvial recycling of older, proglacial deposits overridden during advances of these glaciers is the most important debris transport process at many glaciers in Svalbard, and at Gulkana Glacier, in Alaska. Inwash-sourced debris, originally acquired in tributary valleys beyond the limits of the glaciers, is the dominant debris source at Maclaren Glacier and many Alaskan glaciers, and plays an important role at several of the glaciers in Svalbard. This fluvial debris is deposited directly as outwash, and is recycled during minor readvances to form push moraines and lodgment till. In contrast, supraglacial, medial moraine transport delivers only a tiny fraction ($<$10%) of the debris load at the glaciers studied. This debris is usually deposited as a thin (less than 1 clast thick) layer atop push moraines and lodgment tills, or else deposited as ablation tills and flow tills from stagnant ice blocks, downvalley from prominent medial moraines. A wide variety of englacial debris transport processes operate at many of the glaciers studied, but these processes are volumetrically unimportant except in Antarctica, where topographic and climatic conditions suppressed the activity of all other transport processes. At these glaciers, the total volume of debris transported was small, and only minor proglacial deposits have been formed. There is no evidence at the glaciers studied to support shear planes as an important debris transport mechanism.
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