UNDERSTANDING THE ROLE OF HYDROLOGY IN MICROBIALITE FORMATION

The formation of microbialites in lacustrine and marine settings has been debated from a sedimentological point of view for decades. The role of microbes in either passively trapping and binding carbonates or in actively providing a microenvironment to overcome kinetic barriers which then allows precipitation has more recently been the subject of laboratory experiments and field-based research. However, the role that hydrology plays in microbialite formation has largely been relegated to on-site observation of groundwater input (or lack thereof) with few measurements of water table fluctuations or heads over seasons or years. These more detailed observations are critical for evaluating water and chemical inputs that may be contributing to microbial growth or simple inorganic saturation (or dissolution) caused by mixing between lake (or marine water) and groundwater. This abstract presents case studies from Big Soda Lake, Nevada, and Lake Clifton, Australia with an emphasis on hydrological measurements both physical and chemical as a preliminary assessment of the role of hydrology in microbialite formation and as a call for further experimentation using modern microtechniques for measuring small changes in head pressures that will elucidate the contribution of hydrology to microbialite formation.