Geochemistry and mineralogy of modern fjord sediments, west Spitsbergen, Svalbard: implications for provenance and weathering

Arctic fjords are ideal sites for studying the recent sedimentary process that affects high-latitude coastal ecosystems. High latitude Raudfjord, Magdalenefjord, and St. Jonsfjord from the west Spitsbergen, Svalbard have been investigated to assess the source and distribution of clay minerals, weathering processes, and geochemistry of major elements. The results showed illite to be the dominant clay mineral group, followed by chlorite and kaolinite, suggesting physical rather than chemical weathering is prominent in the region, also supported by a decrease in the illite chemistry and an increase in illite crystallinity (0.18°Δ2θ). The mineralogical proxies, along with the K₂O/(Na₂O+CaO) molar ratio, chemical index of alteration (CIA), and major elements, suggested hydrolysis of plagioclase (enrichment of Ca and Na) as compared to the K-feldspar. An appreciable amount of plagioclase (21–40%) in the fjord sediment samples suggested a mostly fresh source of sediment, which was confirmed by the low Plagioclase Index of Alteration (PIA). Hydrodynamic mineralogical sorting primarily controls the inorganic geochemical composition of the fjord sediments. Our results suggest that cold and dry climate conditions and lithology significantly controlled weathering and erosion processes in high Arctic fjords. Strong physical weathering caused by glacial activities is responsible for the large availability of primary minerals and low abundance of secondary minerals in these fjords.