PERMIAN ENVIRONMENTAL AND BIOLOGICAL CLUES FROM FLUID INCLUSIONS IN HALITE IN THE SALT PLAIN FORMATION FORMATION AND THE CEDAR HILLS SANDSTONE OF KANSAS

The Amoco Rebecca K. Bounds #1 core of Greeley County, Kansas contains bedded halite and halite cement that offer clues about the depositional and early diagenetic history of the mid-late Permian of western equatorial Pangea. For this study, we examined bedded halite from the Salt Plain Formation and the Cedar Hills Sandstone, both of the Leonardian-Guadalupian Nippewalla Group. Observations of halite chips were made using plane transmitted, polarized, reflected, and UV light at magnifications of up to 2000x. Chevron and cumulate halite crystals host unaltered primary fluid inclusions that are remnants of Permian shallow lake water. Most primary fluid inclusions are all-liquid, but a small percentage also contain air bubbles, accidental daughter crystals, microorganisms, and/or organic compounds. Here, we report detailed fluid inclusion petrography, as well as limited freezing/melting microthermometry and laser Raman spectroscopy. Our preliminary results show that the bedded halites of the Salt Plain and Cedar Hills Sandstone formations in western Kansas formed in ephemeral acid saline lakes with complex water chemistry and extremophile microbial communities. This is consistent with depositional interpretations made for Permian-Triassic bedded halites in other cores of the Nippewalla Group from elsewhere in Kansas, as well as from cores of the Opeche Shale in North Dakota and the Mercia Mudstone in Northern Ireland.