Abstracts presented at the 24th PACLIM Conference, Pacific Grove, California, USA, 19-22 April, 2009

摘要

Isotopic data from sediments from strategically selected lakes in headwater regions of the Upper Colorado River have the potential to extend our understanding of Holocene hydroclimate variations back beyond the tree-ring record. We focus on calcareous terrains where biologically productive alpine lakes have rapidly accumulating sediments that contain endogenic calcium carbonate suitable for oxygen and carbon isotope analyses with decade-to-century resolution. The White River Plateau in west-central Colorado is a limestone massif at -3000 m a.s.l. in the central Rocky Mountains. Sediment cores spanning the Holocene were collected along depth transects from Yellow Lake (39.652N, 107.453W, 3140 m a.s.l.) and Bison Lake (39.764N, 107.346W, 3255 m a.s.l.), headwater lakes of Grizzly Creek and Deep Creek respectively, both tributaries of the Upper Colorado River. The oxygen and hydrogen isotope ratios of modern lake-water, streams, springs and snow around the area indicate that both basins experience summer evaporation in addition to snow-melt and groundwater recharge. All of these factors in