EXCELLENT PRESERVATION OF ORGANIC AND FOSSIL PLANT MATERIALS IN BEDDED HALITE FROM MODERN WESTERN AUSTRALIAN LAKES AND THE PERMIAN NIPPEWALLA GROUP OF KANSAS

Bedded halite has traditionally been overlooked as a repository for plant fossils and other organic materials. Here, we compare evidence of plant meso- and microfossils (cuticle, tracheids, pollen grains) and suspect organic material encased in ancient and modern bedded halite. We examined bottom-growth (aka chevron) and cumulate halite collected from ephemeral acid saline Lake Brown and Twin Lake West in Western Australia and from their Permian counterparts in the Nippewalla Group of the Amoco Rebecca K. Bounds (RKB) #1 core from Greeley County, Kansas. High-fidelity environmental conditions, including depositional water depths, water temperatures, water composition, and pH, have been documented for both modern and Permian systems. However, an understanding of the vegetation associated with acid saline systems is limited. Preliminary study of these modern and Permian bedded halites has shown that they host archaea, bacteria, algae, pollen, fungi, and organic compounds, but the preservation of plant material has not been systematically assessed.

For this study, we examined thin sections of bedded halite from the Permian Salt Plain (2564-2423 ft depth) and Blaine (2053-1928 ft depth) Formations in the RKB core, as well as thin sections and chips of halite from Lake Brown and Twin Lake West. Observations were made by high-magnification (up to 2000x) plane transmitted-light microscopy with long working-distance objectives. This allows for imaging objects as small as 1 µm at depth within individual halite crystal interiors. UV-vis light microscopy at combined 330 and 385 nm wavelengths was used to determine the fluorescent response of organic material.

We found a variety of plant and other organic material in modern and Perman bedded halite, suggesting that bedded halite is a good repository for past and present plant and microbial life. Our findings show that ephemeral acid saline environments support a range of life forms. Halite should not be overlooked by geobiologists as it preserves biosignatures and aids in the search for life in terrestrial and extraterrestrial salt minerals.