Holocene records of eolian dust deposition from high‐elevation lakes in the Uinta Mountains, Utah, USA

Abstract

ABSTRACTRadiocarbon‐dated sediment cores from subalpine lakes were used to investigate post‐glacial dust deposition in the Uinta Mountains (Utah, USA). Lake sediments were geochemically characterized with ICP‐OES, ICP‐MS and XRF core scanning. Collections from passive samplers constrain the properties of modern dust, and samples of regolith constrain properties of the local material within the watershed. Ca and Eu are more abundant in dust, whereas Ti and Zr are more abundant in local regolith. As a result, the Ca/Ti and Eu/Zr ratios are indices for the dust content of lake sediment. In all records, the dust index rises in the early Holocene as watersheds became stabilized with vegetation, reducing the influx of local material. After this point, values remained above average through the middle Holocene, consistent with an increased dust content in the sediment. Dust index values drop in the late Holocene in most lakes, suggesting a decrease in dust abundance. Generally synchronous shifts in dust index values in cores from lakes in different parts of this mountain range are evidence of enhanced dust deposition in this region during the middle Holocene, and are consistent with a variety of records for increased aridity in the south‐western USA at this time.