Quantifying the contribution of dust to alpine soils in the periglacial zone of the Uinta Mountains, Utah, USA

Profiles of alpine soils in the Uinta Mountains (Utah, USA) were investigated to determine how long-term dust deposition has influenced soil properties in this environment. Field studies were focused on four above-treeline sites, all of which were apparently beyond the reach of erosive glacial ice during the Pleistocene. Modern dust, soil A and B horizons, and local bedrock were compared in terms of major and trace element geochemistry, along with Sr and Nd isotope compositions. In all cases, soil samples are a mixture of dust and local bedrock end members, with A horizons more closely resembling dust, and B horizons more similar to bedrock. Calculations estimate that these soil profiles contain similar to 50 to 80% dust, which is effectively mixed downward into the solum by cryoturbation. Because these landscape positions were not glaciated, the total amount of dust contained within soil profiles is large relative to sites at lower elevation within the glacial limit. In addition to altering physical properties of these soil profiles, including horizonation and texture, deposition of dust rich in base cations positively influences soil fertility.