Glacial erosion and history of Inglefield Land, northwestern Greenland

Abstract. We used mapping of bedrock lithology, bedrock fractures, and lake density in Inglefield Land, northwestern 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 combined surface burial and exposure 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 × 10−2 mm yr−1 and subglacial erosion rates are between 0 and 2 × 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.