ENSO-LIKE CYCLICITY IN FULL-GLACIAL (MIS-2) LAKE VARVES FROM THE WIND RIVER RANGE OF WYOMING

Varved sediments from two moraine-dammed lakes in the Wind River Range of Wyoming were analyzed for evidence of precipitation variability for more than 10,000 years of the full-to-late-glacial MIS-2 period. Spectral analysis of varve thicknesses in cores taken from Louis and Fiddlers lakes spanning the periods from ~25,000 to ~14,300 calendar years and from ~18,500 to ~15,500 calendar years BP, respectively, exhibit distinct interannual 2.3-to-3.1-year periodicity that indicates ENSO-like influence on the precipitation patterns of this region of the North American interior during the Last Glacial Maximum. Peaks in the power spectra are found for similar frequencies in both lakes, but differences in the respective catchment areas of the lakes affect details of sediment deposition and associated varve thicknesses. Our data provide the first evidence of the presence of ENSO-like forcing of precipitation-derived sedimentation patterns during the last full-glacial period into the interior of North America and may suggest a teleconnection to the late-glacial ENSO-like patterns previously reported from Lake Huron and New England.