GSA Connects 2021 in Portland, Oregon

Paper No. 79-8
Presentation Time: 10:05 AM


MUSCOTT, Amelia1, LARSEN, Darren J.1, CRUMP, Sarah2 and WANG, Lane1, (1)Department of Geology, Occidental College, 1600 Campus Road, Los Angeles, CA 90041, (2)Department of Ecology and Evolutionary Biology, UC Santa Cruz, 1156 High St, Santa Cruz, CA 95064

Rock glaciers are common features in mountainous regions and contribute significant ice volume to the global cryosphere. Understanding how rock glaciers reacted to past climate changes is critical for identifying their climatic sensitivities and for predicting future changes to these important glacial features. The Teton Mountain Range, located in northwest Wyoming, contains numerous high-elevation alpine lakes, a few of which are situated beneath active rock glaciers. Sediment fill in these lakes marks the timing of glacier retreat at the end of the Last Ice Age (Pinedale glaciation) and preserves a continuous and datable record of subsequent landscape evolution in their catchments. Here, we analyze sediment cores collected from Omega Lake and Lake Solitude, two proximal alpine lakes at the head of Cascade Canyon in the central Tetons, that are positioned in catchments dominated by rock glacier and non-glacial processes, respectively. We evaluate and compare a suite of sedimentary indicators including bulk density, magnetic susceptibility, geochemical abundance, percent organic matter, and clastic sediment flux. Age control of the lake sediments is established using radiocarbon dating and tephrochronology. We find that deglaciation in both catchments occurred by 14,000 years ago and is followed by an increase in organic content and a decrease in sediment density, magnetic susceptibility, and clastic flux. Emerging results show that the non-glacial catchment records a trend in sediment character reflective of Holocene climate patterns. The rock glacier catchment contains higher Holocene variability, suggesting influence of the rock glacier overprinted such trends. We discuss this project in the context of natural resource management and conservation efforts to ultimately improve our understanding of future rock glacier response to climate changes and the resulting environmental impacts to sensitive alpine ecosystems in the western United States.