Paper No. 2
Presentation Time: 1:20 PM


CORSETTI, Frank A., Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, ANDERSON, Ross Peter, Geology and Geophysics, Yale University, Kline Geology Laboratory, 210 Whitney Avenue, New Haven, CT 06511, BIRD, Jordan, Department of Microbiology, University of Tennessee, Knoxville, TN 37996, MENESKE, Maryem, Molecular Biology Genetics and Biotechnology, Istanbul Technical University, Istanbul, 34381, Turkey, STEFURAK, Elizabeth JT, Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, PETRYSHYN, Victoria A., Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095, TRIPATI, Aradhna, Department of Atmospheric and Ocean Sciences, UCLA, Los Angeles, CA 90095, STAMPS, Blake W., Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, STEVENSON, Bradley S., Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73072 and SPEAR, John R., Division of Environmental Science and Engineering, Colorado School of Mines, Golden, CO 80401-1887,

Ooids are a relatively common constituent of the sedimentary record through time (including lacustrine carbonate systems), but details of their formation remain enigmatic. We collected ooids from the Great Salt Lake in association with the International GeoBiology Summer Course in 2012 and 2013 from Antelope Island (south arm of the lake) and Spiral Jetty (north arm) in order to investigate their origin.

Petrographic investigation reveals the ooids are composed of aragonite, and display an alternating radial, concentric, and radial-concentric fabric. The delicate nature of the radial fabric is suggestive, but not conclusive, that they form currently (agitation would abrade the fabric). The nuclei are typically rod shaped micritic peloids (up to 80%) or siliciclastic mineral grains. Clumped isotopes revealed relatively warm temperatures of formation.

The clumped isotope temperatures allow us to constrain ooid formation to the warm months, given the seasonal temperature cycle in the lake (with summer surface temperatures approaching 25 degree C or more, and winter months dipping to 5 degrees C or less). We calculated the summer and winter carbonate saturation state of the lake, and while the lake is supersaturated throughout the year, it is significantly more saturated during the summer months.

The microbial community of the Spiral Jetty ooids was dominated by members of the Halobacteria, Gammaproteobacteria, and Bacteriodetes. The diversity of the surrounding water at Spiral Jetty was identical to that of the ooids. The community from the Antelope Island ooids, dominated by Bacteriodetes, Alphaproteobacteria, and Gammaproteobacteria, was distinct from that of the surrounding water, which was dominated by Halobacteria, Gammaproteobacteria, and Bacteriodetes. OTUs related to Bacteriodetes and Gammaproteobacteria in Antelope Island ooids differed from the surrounding water and Spiral Jetty ooids.

While ooid fabrics from the north arm and south arm were identical, their microbial communities differed, suggesting the variance in diversity exerts no obvious control on ooid morphology. Our results give new insight into the Great Salt Lake ooid formation, and suggest the ooids form predominantly during the warm months and the microbiota does not influence Great Salt Lake ooid formation in an obvious way.