PhD program in Earth Sciences
University of Southern California, LA.
Bio:
Olivia Piazza completed her undergraduate degree in Geological Sciences at the University of Miami where she first developed an interest in geobiology. After graduating from UM, she joined the PhD program in Earth Sciences at the University of Southern California in Los Angeles, CA. At USC, she studies the geobiology of lacustrine systems, from stromatolites as archives of paleoenvironment to the biogenicity of ooids. Her interest in Great Salt Lake includes investigating the formation of ooids utilizing modern molecular and radiometric dating tools.
Title: Ooid Formation in Great Salt Lake, UT
2:25pm - Wednesday, May 11th
Abstract: Ooids (laminated coated grains) are ubiquitous in the geologic record, but the processes that govern their formation are still poorly understood. Ooids are traditionally thought to form abiogenically, where calcium carbonate precipitates around a nucleus in an environment supersaturated with respect to calcium carbonate. Recent work on marine ooids suggests that microbial metabolism and its byproducts (e.g., proteins, extracellular polymeric substances) may enhance calcium carbonate precipitation, and has demonstrated that ooids from disparate localities shared some lipid biomarkers, suggesting a common microbiota and thus putative microbial origin. Thus, the meaning of ooids as a potential biosignature in ancient rocks remains problematic. The Great Salt Lake provides a unique opportunity to study petrographically identical ooids from two localities (North and South Arms) with distinct geochemical and biological properties. These aragonitic ooids display alternating radial, concentric, and radial-concentric fabrics. Ooids and lake water were collected from Antelope Island (South Arm) and Spiral Jetty (North Arm) for molecular and geochemical analyses. My work focuses on characterizing the microbial communities associated with the ooids at Great Salt Lake as well as dating the ooids to assess their rate of formation. This work highlights Great Salt Lake as both an important modern depositional system, and an insight into ancient lacustrine ooid formation.