30 Undergraduate Geologic and Multi-disciplinary Research: Faculty Examples and Student Experiences in the Field (Posters)

Thursday, 19 May 2016
8:00 AM - 5:00 PM
Clearwater Room

STABLE ISOTOPE AND RADIOCARBON ANALYSIS OF MODERN LACUSTRINE STROMATOLITES IN GREAT SALT LAKE, UTAH

Paper number: 30-7
Program: Theme Sessions
Time: 8:00 AM – 5:00 PM

Authors

Abstract

The Great Salt Lake (GSL), a closed hypersaline lake in northern Utah, is host to numerous modern and fossil stromatolites. Because of current low lake levels, many of these stromatolites are now exposed along the northern shorelines of GSL, including Antelope Island. One stromatolite dome from Antelope Island was sampled for stable isotope geochemistry and compared with current lake water chemistry to see if the former records changes in lake water chemistry. A transect from the center to outer layers of carbonate revealed significant variations in δ13Ccarb and δ18Ocarb (δ13Ccarb ranges from 0.97 to 6.64 ‰ PDB; δ18Ocarb ranges from -4.33 to -1.19 ‰ PDB) and strong covariance between δ13Ccarb and δ18Ocarb (r=0.78). These trends are interpreted to be the result of evaporative- and residence-related effects because of the closed nature of the GSL’s hydrologic system. Additionally, organic carbon was segregated from four locations along the transect for δ13Corg and radiocarbon analyses. δ13Corg shows considerable variability as well (δ13Corg ranges from -21.71 to -25.62 ‰ PDB), possibly correlated to δ13Ccarb. Radiocarbon dates are pending and will provide temporal constraints on stromatolite formation and hydrologic changes in the GSL.

Geological Society of America Abstracts with Programs. Vol. 48, No. 6

doi: 10.1130/abs/2016RM-276249

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