Investigating the influence of hydrogeomorphic setting on the response of lake sedimentation to climatic changes in the Uinta Mountains, Utah, USA
- 198 Downloads
Reader Lake and Elbow Lake, two high-altitude lakes in the Uinta Mountains of Utah, are located approximately 2 km apart, at similar elevations, and within identical vegetation communities. Loss on ignition, carbon to nitrogen ratios, biogenic silica, and sediment grain size were analyzed throughout percussion cores retrieved from both lakes to construct continuous time series spanning 14 to ca. 2 ka BP. Given the proximity of the lakes, it is assumed that both were subjected to the same climatic forcing over this time. Accordingly, the first goal of this study was to consider these two multiproxy datasets in concert to yield an integrated paleoclimate record for this region. Close inspection of the records identified discrepancies indicating that the lakes responded to climate changes in different ways despite their proximity and similar setting. Clarifying these differences and understanding why the two lakes behaved differently at certain times was the second goal of this study. Overall, the paleoclimatic records document lake formation in the latest Pleistocene following glacier retreat. Buried glacier ice at the location of Reader Lake may have persisted through the Younger Dryas. Both lakes became biologically productive ca. 11.5 ka BP, and the first appearance of conifer needles indicates that trees had replaced alpine tundra in these watersheds by 10.5 ka BP. The interval from 10 to 6 ka BP was marked by a dramatic increase in precipitation, perhaps related to enhanced monsoonal circulation driven by the insolation maximum. The two lakes recorded this event in notably contrasting ways given their differing hydrogeomorphic settings. Precipitation decreased from 6 to 4 ka BP, and low water levels and drought conditions marked the interval from 4.0 to 2.7 ka BP. The integrated paleoclimate record developed from these cores provides a useful point of comparison with other records from the region. The differences between the records from these closely spaced lakes underscore the need to consider hydrogeomorphic setting when evaluating the suitability of a lake for a paleolimnological study.
KeywordsUtah Uinta Mountains Lake sediment Geomorphology Drought Precipitation Holocene
Financial support for this project was provided by NSF-EAR 0345112 to Munroe, by the Ashley National Forest, and by the Middlebury College Senior Work Fellowship. Field and laboratory support was provided by M. Devito, N. Oprandy, B. Laabs, D. Munroe, C. Plunkett, C. Anderson, D. Berkman, B. Fisher, and C. Rodgers. J. Honke of the USGS assisted with preparing the pollen concentrates, and A. Lini of the University of Vermont assisted with C/N measurements.
- Dean WE (1974) Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: comparison with other methods. J Sediment Petrol 44:242–248Google Scholar
- Dehler CM, Sprinkel DA (2005) Revised stratigraphy and correlation of the Neoproterozoic Uinta Mountain Group, northeastern Utah. In: Dehler CM, Pederson JL, Sprinkel DA, Kowallis BJ (eds) Uinta mountain geology. Utah Geological Association Publication 33, Salt Lake City, pp 17–30Google Scholar
- Moser KA, Kimball JP (2009) A 19,000-year record of hydrologic and climatic change inferred from diatoms from Bear Lake, Utah and Idaho. In: Rosenbaum JG and Kaufman DS (eds) Paleoenvironments of Bear Lake, Utah and Idaho, and its catchment. Geological Society of America Special Paper 450, pp 229–246Google Scholar
- Mucciarone DA (2003) Stanford university stable isotope laboratory online manual. Section 6A: Biogenic silica. Available online at: http://pangea.stanford.edu/research/isotope/dam/pdf/Stanford_SIL_Online_manual.pdf
- Sampei Y, Matsumoto E (2001) C/N ratios in a sediment core from Nakaumi Lagoon, southwest Japan—usefulness as an organic source indicator. Geochem J 35:189–205Google Scholar
- Thompson RS, Whitlock CW, Bartlein PJ, Harrison SP, Spaulding WG (1993) Climatic changes in the western United States since 18,000 years B.P. In: Wright HE, Kutzbach JE, Webb T, Ruddiman WF, Street-Perrot RA, Bartlein PJ (eds) Global climates since the last glacial maximum. University of Minnesota Press, Minneapolis, pp 514–535Google Scholar