THE INFLUENCE OF ORGANIC OVERBURDEN ON KARST SPELEOTHEMS

In order to understand the pathways by which life could be sustained within the Solar System, extreme environments on Earth must first be studied to investigate how the flow of resources impacts extreme life. Within the Solar System, the icy moons of Europa and Enceladus harbor organics within interstitial lakes which may be able to sustain life. Titan’s liquid methane cycle may create caves that are karstic in nature, carved in the organic rich dunes of the surface. To determine the availability of resources on other planets, terrestrial comparisons must be available to characterize components trapped within foreign materials.

Terrestrial caves present an opportunity to examine the flow of organics in an environment that is mostly isolated from external realms yet remains within human reach. As water passes through the overburdened material, decomposed plant materials and other organics are drawn into the water. Organically laced water can further create calcite features such as flowstone that stores a record of organics from the surface. When exposed to ultraviolet light, the organically laced water and speleothems fluoresce. A portable spectrometer can be used to examine the unique color fingerprint of flowstone when exposed to ultraviolet light. Cave water has been collected and further examined to understand the fluorescence within the water itself. By freezing cave water with liquid nitrogen, cryogenic ice features, similar to what may be in Europa or Enceladus, can be created and studied, providing clues into the behaviors of organics on the icy moons of the Solar System.

Surface conditions of karst environments can alter the fluorescence of water and flowstone underground. Wind Cave National Park harbors pristine ancient water sources that contain trace materials from the Madison Aquifer. Coldwater Cave in Iowa has frequently flowing water that forms large flowstone features along the passageway. In Minnesota, Mystery Cave is a flood cave located within a secondary growth forest biome which contains calcite features from calcium-rich water. The comparison of cave environments allows for the examination of fluorescent cave water from currently flowing, old, or ancient water sources. Using primarily three different national/state park caves to form a holistic perspective, potential variables that aid in the flow of organics can be evaluated.