A ~ 13,000-Year Paleolimnological Record from the Uinta Mountains, Utah, Inferred from Diatoms and Loss-On-Ignition Analysis

Paleolimnological research in mountainous regions of the Western United States provide baseline understanding of how these lake systems will respond to ongoing climate change. Fossil diatom assemblage and loss-on-ignition data were investigated from a ∼13,000-year lake sediment core from the Uinta Mountains, northeastern Utah, USA. Results indicate the presence of three major zones of environmental change: 1) from ∼12.9–10.9 cal ka, modern lake formation began, temperatures were cool, and water was turbid; 2) from ∼10.9–3.5 cal ka conditions were warmer-than-present, and the lake stratified during the summer; and 3) beginning approximately 3.5 cal ka, temperatures decreased relative to the previous zone and the lake appears to have become increasingly alkaline. Shifts in diatom taxa relative abundances within the middle zone (ca. 8.2–6.5 and 5.0–3.5 cal ka) are probably caused by precipitation-driven decreases in alkalinity and increases in lake depth. This record reflects evolution of the lake system and suggests that currently rising temperatures will reduce ice cover and enhance lake stratification and internal nutrient cycling. Any future changes in precipitation patterns may also impact lake ecology through shifts in alkalinity and/or depth.