Source to sink: Statistical identification of regional variations in the mineralogy of surface sediments in the western Nordic Seas (58°N–75°N; 10°W–40°W)

Abstract

The non-clay and clay mineralogies of the < 2 mm sediment fraction from 157 seafloor samples in the western Nordic Seas is calculated by quantitative X-ray diffraction analysis. Our sample coverage includes the Iceland shelf, the ice-impacted East Greenland margin, and the Greenland, Iceland, and Irminger seas. The bedrock geology of source areas includes Precambrian basement rocks, Devonian red beds and younger marine and fluvial sediments, and large outcrops of early tertiary to recent flood basalts and other volcanic facies. Sediment erosion and transport in the area are associated with ice (sea ice and icebergs), and glacial meltwater and fluvial sediment plumes. We use Principal Component Analysis, fuzzy k-means clustering, and Discriminant Function Analysis to reduce the original 31 (minerals) × 157 (sites) matrix to more manageable 5 regional coherent clusters of sites, which are well discriminated by the weight % of six minerals, namely quartz, pyroxene, illites, magnetite and maghemite, amorphous silica (e.g. glass) and muscovite. The close spatial relationship between bedrock geology and discrete cluster membership stresses the importance of this variable and indicates that far-distant sediment transport by sea ice, icebergs, or other mechanisms, although occurring does not radically change the mineral composition of present-day sea-floor sediments. Our improved knowledge of the regional mineral assemblages allows for tracking distinct Eastern Greenland and Icelandic sources.