COMPOSITION, MICROTEXTURE AND MORPHOGENESIS OF MICROBIALITES IN A MODERN COLD SPRING AT CRYSTAL GEYSER, UTAH

Located on the banks of the Green River in Eastern Utah, Crystal Geyser is a low-temperature “cold spring” that hosts a variety of columnar stromatolite forms. Rapid rates of carbonate accretion in the alkaline and saline spring environment appear to promote the passive capture and preservation of cellular and extracellular remains of microbial communities. Created as a result of petroleum exploration drilling in 1936, Crystal Geyser’s eruptions have since been fueled by the super saturation of carbon dioxide in the subsurface ground water. The relatively young age of the spring deposit provides an opportunity to observe early preservational environments and in-progress diagenetic transformations. X-ray Powder Diffraction (XRPD) and petrographic studies of spring deposits revealed that the major minerals present include aragonite, calcite, and silica (cristobalite and quartz). Additionally, the presence of poorly ordered ferrihydrite was inferred based on the colors present in hand sample and thin-sections. Optical microscopy of petrographic thin sections showed evidence for biofilm-like concentrations of fossilized cells and possible extracellular materials as well as wavy laminated microstructures reminiscent of microdigitate columnar stromatolites found in the fossil record. Results suggest that rapid chemical precipitation of the carbonate-saturated spring water effectively promotes microbial biosignature preservation, and that such environments may be good places to explore for a microbial fossil record both on Earth and Mars. Next steps in the research include applying methods to conclusively identify organic matter preservation in this oxidizing spring using a combination of UV fluorescence microscopy, SEM, and laser Raman spectroscopy.