Size-dependent chemical depletion of sediments in glacial environments: a case study of Mandakini valley, central Himalaya, India

The size-dependent chemical maturity of sediment cycling in high-altitude glacial/periglacial environment was studied by examining the sediments of the Chorabari Glacier, Mandakini valley, central Himalaya, India. Sediments evacuated from glacial debris and periglacial area were studied through particle-size analysis, X-ray fluorescence, and X-ray diffraction of different grain-size fractions. The results suggest a clear control of grain-size fraction over chemical weathering and its attendant nutrients release from glacial substrate. Elemental indices suggest the release of nutrients is principally controlled through comminution process and sub-glacial chemical weathering of leachable minerals like feldspar, mica, and apatite. Owing to biogeochemical cycles, the release of phosphorus and calcium is predominantly controlled through apatite, organic complexes, and carbonate dissolution of aluminosilcate rocks respectively. Overall, the size-dependent chemical maturity of glacial sediments suggests a much chemically active system than previously thought. This study is explicitly important for downstream weathering tracer studies of detrital sediments.