297 Caves and Karst Through Space and Time: Biogeochemistry, Climate, and Astrobiology (Posters)

We welcome submissions on the biogeochemistry, astrobiology, and historical records in of caves and karst features.

Wednesday, 22 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Secondary minerals from possible hypogene caves in Great Basin National Park and the Humboldt-Toiyabe National Forest, Nevada, USA

Paper number: 297-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Great Basin National Park and the nearby Humboldt-Toiyabe National Forest contain numerous caves that include popular tourist attractions like Lehman Caves as well as many other limestone caves. These caves contain diverse secondary mineral deposits, including sulfates, carbonates, and silicates that can provide clues to the history of cave formation. Characterizing secondary minerals throughout these caves will provide a greater understanding of the role that microorganisms could play in cave development and mineralogy, and in the case of gypsum and other sulfates, could reveal the potential influence of sulfuric acid speleogenesis. We analyzed samples from Lehman Caves and four caves in the North Snake Range, and are performing additional analyses on several others in the region. Powder X-ray diffraction (pXRD) of white crusts, speleothems, and sediments showed that most deposits were primarily calcite with trace amounts of dolomite and quartz. A few samples from cave 041709-NS-018 were composed nearly completely of gypsum with trace amounts of calcite and kaolinite, and one sample only had gypsum alone. Samples from 041709-NS-012 were entirely gypsum. Gypsum crystals were also observed in three other caves using scanning electron microscopy and energy dispersive spectroscopy. Thin section petrography is generally consistent with pXRD results, and in some places reveal fibrous textures that indicate possible recrystallization of the sulfates. Samples containing gypsum were powdered and dissolved using a gentle NaCl dissolution and barite precipitation procedure for δ34S and δ18O analysis of gypsum, which will help evaluate sulfate sources and whether these deposits were associated with sulfuric acid speleogenesis. We will discuss our results in the context of ongoing microbial community analysis, including how these and other mineral deposits in the cave might impact modern microorganisms and energy resources for cave life, as well as possible origins and speleogenetic history of caves in the region.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414167

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