Fossilized diatoms of siliceous hydrothermal deposits in Yellowstone National Park, USA

Abstract

The study of eukaryotic extremophiles is relatively novel, and, therefore, documentation of the structure and function of micro-organisms in continental hydrothermal systems globally is limited. In this study, we investigate fossil diatoms in siliceous hydrothermal deposits of the Upper Geyser and Yellowstone Lake hydrothermal basins in Yellowstone National Park, and utilize preserved diatom assemblages to infer local environmental conditions. Siliceous sinter from both the Upper Geyser Basin and Yellowstone Lake contains evidence of in-situ diatom growth within these environments. At Upper Geyser Basin, the assemblage consisted of species that could grow on moist siliceous sinter and was dominated by Rhopalodia gibberula. Diatom valves were found in various preservation states, ranging from nearly pristine to highly diagenetically altered. Diatoms collected from siliceous spires in Yellowstone Lake consisted largely of tychoplanktonic and benthic species that were almost certainly growing on the outside of the structure, with an assemblage indicative of relatively shallow, alkaline waters. What remains unclear without access to material for high-resolution dating is whether diatoms colonized the spires during hydrothermal activity or after activity ceased. Our results indicate that diatom frustules can, to some extent, survive alteration in low-temperature (<76°C) hydrothermal environments.

Keywords:

• siliceous sinter
• Bacillariophyta
• continental hydrothermal
• alkaline-chloride water
• spire

Acknowledgements

We would like to thank Dr. Shaul Hurwitz and colleagues for collecting and providing Hillside sinter material. We thank the Indiana State University Paleolimnology Laboratory for providing scanning electron microscope access, as well as light microscope use. We also extend our thank you and appreciation to Yellowstone National Park, who provided support in many ways. We would also like to thank two anonymous reviewers, as well as Scott Starratt and Michael Clynne for providing valuable feedback for improving this manuscript. USGS disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

SABRINA R. BROWN http://orcid.org/0000-0002-7101-9193

Additional information

Funding

Spire A was collected from the northern Yellowstone Lake in 1999 under permit YELL-1999-SCI-5054; Spire B and spire field sediment samples were collected from northern Yellowstone Lake in 2016 under permit YELL-2016-SCI-5054 and YELL-2016-SCI-7018. The Hillside Geyser Basin sample was collected under permit YELL-SCI-8030. This work was supported by the National Science Foundation under grants 1514814 and 1515377 awarded to coauthors Sherilyn C. Fritz, Lisa A. Morgan, and Wayne C. Shanks.