Strontium Isotopic Signatures of the Streams and Lakes of Taylor Valley, Southern Victoria Land, Antarctica: ChemicalWeathering in a Polar Climate

Authors

W. B. Lyons, The Ohio State UniversityFollow
Carmen A. Nezat, The Ohio State University
Larry Benson, University of Colorado at BoulderFollow
Thomas D. Bullen, U.S. Geological Survey
Elizabeth Y. Graham, University of Alabama - Tuscaloosa
Jesicca Kidd, University of Alabama - Tuscaloosa
Kathleen A. Welch, The Ohio State University
James M. Thomas, Desert Research Institute

Date of this Version

2002

Citation

Aquatic Geochemistry 8: 75–95, 2002

Abstract

We have collected and analyzed a series of water samples from three closed-basin lakes (Lakes Bonney, Fryxell, and Hoare) in Taylor Valley, Antarctica, and the streams that flow into them. In all three lakes, the hypolimnetic waters have different ⁸⁷Sr/⁸⁶Sr ratios than the surface waters, with the deep water of Lakes Fryxell and Hoare being less radiogenic than the surface waters. The opposite occurs in Lake Bonney. The Lake Fryxell isotopic ratios are lower than modern-day ocean water and most of the whole-rock ratios of the surrounding geologic materials. A conceivable source of Sr to the system could be either the Cenozoic volcanic rocks that make up a small portion of the till deposited in the valley during the Last Glacial Maximum or from marble derived from the local basement rocks. The more radiogenic ratios from Lake Bonney originate from ancient salt deposits that flow into the lake from Taylor Glacier and the weathering of minerals with more radiogenic Sr isotopic ratios within the tills. The Sr isotopic data from the streams and lakes of Taylor Valley strongly support the notion documented by previous investigators that chemical weathering has been, and is currently, a major process in determining the overall aquatic chemistry of these lakes in this polar desert environment.