ELECTRON MICROPROBE ANALYSIS OF BARITE CONCRETIONS FROM KAW LAKE OKLAHOMA: IMPLICATIONS FOR MARTIAN BLUEBERRIES

In this undergraduate research project, we investigated terrestrial analogs for Martian concretions. Globular concretions from Kaw Lake in north-central Oklahoma were collected in sandy sediment; limestone is emplaced above and below the sample site. The goals of the study were to use the OSU Electron Microprobe (EMP) to image and X-Ray Element map concreted minerals to understand how they formed. Energy Dispersive Spectra were taken to identify specific elements and minerals within the samples. The concretions are zoned in Fe, Mn, and Ca. In the center of the concretions, S, Ba, Si, K, Ca and Fe are found. Minerals present in the concretions are barite, Fe-oxides, clay minerals, and calcite. We propose that barite precipitated inside a sedimentary nodule likely due to the Ba ion attraction to S species in ground water and sediment. This formed a cavity-filling concretion in sandstone. The mechanism for formation of the concretions involves minerals dissolved in solution. The concretions record fluid flow and are products of low-temperatures. For future research, a comparison of the analyses and images of the Kaw Lake concretions and EMP analyses of Utah concretions are the next step to decipher the process by which Martian Blueberries may have formed. The mechanism for the formation of the Martian concretions may involve similar interactions of sediment and groundwater as they do on Earth.