Interpreting the origin and evolution of ‘karst’ features from a siliceous hydrothermal terrane: A case study from the upper Geyser basin in Yellowstone National Park, USA

Abstract

The Upper Geyser Basin in Yellowstone National Park occurs over a siliceous hydrothermal terrane containing numerous hot springs and geysers. The pool and vent-conduit geometries of these hydrothermal features share a resemblance to conventional karst features known from other rock types, suggesting karst processes could be responsible for their origin and/ or evolution. Hypogene speleogenesis is a cave-forming process in which the formation of caves is decoupled from and occurs independently of surface recharge. The geologic setting for hypogene speleogenesis typically occurs at the distal end of regional groundwater systems wherein the hydrogeology is manifested by ascending fluids and/or by geochemical interactions, and whereby the source of aggressiveness occurs at or below the water table. Applying the notion of hypogene speleogenesis, we compare with it the aspects of the hydrogeology, geochemistry, geomorphology, and geological setting of the Upper Geyser Basin to determine if this process might serve as an effective mechanism for the origin and/ or evolution of these hydrothermal features. Applying karst concepts to these hydrothermal features may be significant as it could provide new insights into understanding their origin, function, and evolution.