Glacial erosion and history of Inglefield Land, northwest Greenland

Abstract. We used mapping of bedrock lithology, bedrock fractures, and lake density in Inglefield Land, northwest Greenland, combined with cosmogenic nuclide (¹⁰Be and ²⁶Al) measurements in bedrock surfaces, to investigate glacial erosion and the ice-sheet history of the northwestern Greenland Ice Sheet. The pattern of eroded versus weathered bedrock surfaces and other glacial erosion indicators reveal temporally and spatially varying erosion under cold- and warm-based ice. All of the bedrock surfaces that we measured in Inglefield Land contain cosmogenic nuclide inheritance with apparent ¹⁰Be ages ranging from 24.9 ± 0.5 to 215.8 ± 7.4 ka. The ²⁶Al/¹⁰Be ratios require minimum surface histories of ~150 to 2000 kyr. Because our sample sites span a relatively small area that experienced a similar ice-sheet history, we attribute differences in nuclide concentrations and ratios to varying erosion during the Quaternary. We show that an ice sheet history with ~900 kyr of exposure and ~1800 kyr of ice cover throughout the Quaternary is consistent with the measured nuclide concentrations in most samples when sample-specific subaerial erosion rates are between 0 and 2 x 10^-2 mm yr^-1 and subglacial erosion rates are between 0 and 2 x 10^-3 mm yr^-1. These erosion rates help to characterize arctic landscape evolution in crystalline bedrock terrains in areas away from focused ice flow.