TRANSPORT AGENTS AND DEPOSITIONAL ENVIRONMENTS INTERPRETED FROM QUARTZ GRAIN MICROTEXTURAL FEATURES, BERING GLACIER, ALASKA

Scanning electron microscopy (SEM) of quartz sand grain microtextural features is commonly used to interpret modes of sediment transport and the influence of post depositional weathering, with emphasis on long-term activity in uniform systems. Our investigation concentrates on the interpretation of grains that have experienced brief transportation by various agents in several environments. Sand samples were obtained from three locations in the eastern foreland of Bering Glacier, south-central Alaska. The Tsivat sand plain consists of sub-glacially derived sediment that rapidly filled an ice-contact lake at the eastern terminus. Fifteen kilometers southeast lies the Tidal site, a modern coastal bluff consisting of deflated beach sand. Lastly, samples were taken from a 30 m thick, rhythmically-bedded sand unit (Footrack Member, Weeping Peat Formation) of unknown origin. A statistical comparison of the relative abundance of microtextural features of each sample location suggests that sand within the Footrack Member and Tidal bluff originated from glacio-fluvial sediment, similar to sand of the Tsivat sand plain. These sediments then underwent further transportation and deposition by eolian processes, probably within a coastal environment. These findings are consistent with current processes and sedimentary environments.