Weathering dynamics and micro-scale biogeomorphology in the proglacial environment of Midtre Lovénbreen, Spitsbergen

• Freshly abraded gneiss surfaces in the foreland of Arctcic glacier were studied. • Rock surface weathering rinds show rapid changes in roughness, moisture, and Fe oxidation shortly after deglaciation. • Physical weathering dominates with minimal mineral transformation despite exposure age. • Microorganisms are present at all studied sites and probably influence surface microstructure. • Spectral reflectance correlates with both abiotic and microbial variables. This study examined early-stage weathering on glacially abraded gneiss surfaces in the foreland of Midtre Lovénbreen, NW Spitsbergen, in a chronosequence spanning over a century since deglaciation. A comprehensive, interdisciplinary combination of rock surface micro-roughness, hardness, spectral reflectance, petrographic description, and microbial analysis allowed us to quantify the relationship between physical, geochemical, and biological variables that controlled the development of weathering rinds. We observed a general time-dependent increase in micro-roughness and a decrease in spectral reflectance, with the largest change between the youngest site (3 years of weathering) and the next one – site 2 (c. 40 years of weathering). Mineralogical analyses indicated a predominance of physical over chemical weathering. Microstructural features such as voids and sponge structure was more frequent at older sites. Spectral reflectance was sensitive to surface characteristics and to microbial growth, indicating remote sensing detection capacity. Our results revealed that even though time since deglaciation was a controlling factor, local micro-environmental conditions profoundly influenced weathering of gneiss. The complexity of these interaction implied that multivariate approaches were essential to unravel early landscape evolution in glacial forelands.