HYPOGENIC KARST IN THE SNAKE RANGE, EASTERN NEVADA

Many Snake Range caves display unusual, even novel, characteristics and demonstrate no relationship with modern drainage patterns or surface features. Initially formed in a variety of heavily fractured carbonate formations by hypogenic processes, sub-aerial condensation-corrosion from both CO₂ and sulfide gases played major, and perhaps dominant, roles in speleogenesis within the Range. Thermal, deep-seated groundwaters carrying these gases travelled along faults and other fractures formed during Basin-and-Range extension and uplift. The anoxic, thermal, rising waters within buried, carbonate rocks oxidized near the top of the water table to form corrosive solutions. Gases released into the air-filled fractures and absorbed by condensate on the walls to form sulfuric and carbonic acid, likely facilitated by microbial activity, were likely even more aggressive in dissolving the passages. While deeply buried and water-filled, some caves (e.g., Crystal Ball Cave) were coated with calcite spar. As the water level dropped, mammalaries coated the walls, which were covered by folia within several meters of the water table (e.g., Burial Cave). In one cave at ~2260m asl, the folia are consistently tilted to the west, demonstrating that these sub-aqueous speleothems formed before the closure of Snake Range uplift.

After the caves drained and Basin-and-Range tectonics subsided in the region, epigenic waters deposited abundant calcite dripstone and flowstone in most the Lehman Caves passages and rooms. One stalagmite dated at 2.2 Ma (Lachniet and Crotty, 2017), suggests that the most extensive period of calcite speleothem precipitation occurred during the Pleistocene. Due to the extreme fracturing of the Pole Canyon marble host, copious shields and welts also populated the cave.

Late-stage (probably post-Pleistocene through modern day), sub-aerial condensation-corrosion processes have severely altered the cave walls and speleothems. The corrosion typically shows facing one direction of a passage while sub-aerial cave coral has formed on the other face. Lehman Caves and Burial Cave provide abundant and spectacular examples of these processes.