Evidence of Abrupt Climate Change and the Development of an Historic Mercury Deposition Record Using Chronological Refinement of Ice Cores at Upper Fremont Glacier

Abstract

Paleoclimatic and paleoenvironmental ice-core records are not common from mid-latitude locations in the contiguous U.S.A. Although excellent paleo-records exist for the high latitudes (Hammer, 1980; Lyons et al., 1990, Dansgaard et al., 1993, Taylor et al., 1993a; Clausen et al., 1995, Alley et al., 1997, Johnsen et al., 1997, Jouzel et al., 1997, Mayewski et al., 1997, Taylor et al., 1997, White, J.W.C, et al., 1997, Zielinski et al., 1997), icecore records from polar regions may be considered proxy indicators of climatic and environmental change in the mid latitudes. Unlike polar ice cores which are more likely to preserve visual, chemical and isotopic stratigraphy with sub-annual resolution, visual stratigraphy and sub annual isotopic resolution are generally not apparent in mid-latitude ice cores. In addition, meltwater percolation can influence chemical and isotopic stratigraphy of alpine glaciers from mid-latitude ice cores by “damping” the environmental signal (Wagenbach, 1989). Despite these problems, Naftz (1993), Naftz et al., (1994), Naftz et al. (1996) and Cecil and Vogt (1997), through chemical lines of evidence, indicated that the Upper Fremont Glacier (UFG) in the Wind River Range, Wyoming, U.S.A., (43° 07’ 37” N,