Significant differences in late Quaternary bedrock erosion and transport: East versus West Greenland ∼70°N – evidence from the mineralogy of offshore glacial marine sediments

Abstract

ABSTRACTWe use quantitative X‐ray diffraction to determine the mineralogy of late Quaternary marine sediments from the West and East Greenland shelves offshore from early Tertiary basalt outcrops. Despite the similar basalt outcrop area (60 000–70 000 km2), there are significant differences between East and West Greenland sediments in the fraction of minerals (e.g. pyroxene) sourced from the basalt outcrops. We demonstrate the differences in the mineralogy between East and West Greenland marine sediments on three scales: (1) modern day, (2) late Quaternary inputs and (3) detailed down‐core variations in 10 cores from the two margins. On the East Greenland Shelf (EGS), late Quaternary samples have an average quartz weight per cent of 6.2 ± 2.3 versus 12.8 ± 3.9 from the West Greenland Shelf (WGS), and 12.02 ± 4.8 versus 1.9 ± 2.3 wt% for pyroxene. K‐means clustering indicated only 9% of the samples did not fit a simple EGS vs. WGS dichotomy. Sediments from the EGS and WGS are also isotopically distinct, with the EGS having higher ϵNd (−18 to 4) than those from the WGS (ϵNd = −25 to −35). We attribute the striking dichotomy in sediment composition to fundamentally different long‐term Quaternary styles of glaciation on the two basalt outcrops.