Niveo‐aeolian sedimentation of loess and sand: An experimental and micromorphological approach

Abstract

AbstractThe concept of a ‘niveo‐aeolian influence’ on the genesis of northwest European Pleistocene aeolian sand and loess deposits has been advocated in the past both to explain the presence and the absence of lamination. Field experiments were carried out on artificially deposited alternating layers of sand and snow, and of loess and snow, to investigate the role of a niveo‐aeolian mode of deposition on resulting sedimentary structures.Field observations of sand plots revealed minor changes in surface morphology typical of denivation surfaces. The thin sections showed a characteristic porous structure. Deformations of the depositional structure and indications for erosion and redeposition were limited. However, the originally smooth aeolian sedimentary surface of the loess changed considerably. The thin sections showed also a porous, spongy structure. Indications were found for disturbances by frost action, liquefaction during melting of the snow and ice, and redeposition of loess by meltwater.The experimental results strongly suggest that sand and loess deposited as niveo‐aeolian material are characterized both by a porous structure, and that the original sedimentary structure of the sand is not affected by snowmelt, whereas loess becomes non‐laminated. Thus, the intercalation of snow during sedimentation of sand and loess does not in itself induce a laminated structure.