Geobiological Controls on Travertine Accretion in Keane Wonder Spring, Death Valley National Park
Ruby Wang
School of the Environment
Faculty Supervisor: Yadira Ibarra
Travertine is a terrestrial carbonate that forms in thermal, calcium-rich, groundwater-fed springs. These carbonates have the potential to record valuable paleoclimate information tied to their depositional environment. Understanding the processes by which these carbonate deposits form and the factors that influence their structures can aid in calibrating and adding to existing hydroclimate records. In addition to the chemical and physical processes that take place in carbonate-forming springs, the presence of microorganisms often contributes to the structure and growth rate of travertine. Presented here are a collection of samples of ancient travertine cores and recent microbial mats from Keane Wonder Spring in Death Valley National Park. Using scanning electron microscopy and transmitted light microscopy we investigate the role of diatoms and filamentous algae at four sites of travertine accretion and crystallization in the recent microbial mats. The relative proportion of diatoms decreases with distance from the spring source, whereas filamentous algae increase with distance from the source. The ancient core samples show little petrographic evidence of microbial contribution to the carbonate microstructure. These results suggest that post-depositional changes to the travertine may alter or blur a biotic signal or that different accretion periods experience relatively more or less biotic activity.