Abstract

A semiquantitative analysis of quartz grain-surface textures is used to interpret the transport history of sands from Beaufort Sea drillcores. Within a sample, up to six types of grain are recognized. (a) highly angular grains with fresh, conchoidal fractures; (b) angular grains with conchoidal fractures modified by solution/precipitation and edge abrasion; (c) irregularly shaped, rounded grains with mechanical v-marks and linear grooves; (d) well-rounded grains with dish-shaped concavities and upturned plates; and (e) type C and D grains with large, fresh, fractured surfaces. Although most grams probably have glacial origins, only types A and B have surface features indicative of glacial processes. Other grains show modification by high-energy, subaqueous transport (type C), probably in a littoral environment, or by wind action (type D). Later fracturing of the grains (type E) may have occurred in the littoral zone or by frost action. The relative proportions of each grain type are used tentatively to distinguish sands deposited in fluvial or channel-mouth environments from sands of the littoral zone of a wave-dominated delta. The presence of aeolian grains in several assemblages provides evidence for a drier environment in the Yukon-Mackenzie Delta region during the late Wisconsinan.

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