GLACIOVOLCANIC CAVES OF THE PACIFIC NORTHWEST, USA: PLANETARY GEOMORPHOLOGICAL AND BIOLOGICAL ANALOGS

Thermal gradients between the lithosphere and the cryosphere drive the speleogenesis of glaciovolcanic caves, a physical setting existing elsewhere in the solar system. We present multi-year survey data from extensive glaciovolcanic cave systems of the Cascade Volcanic Arc, demonstrate how these caves transport heat and water, and illustrate the connection between the stability of these caves, volcanic heat flux, and climate change. Expanding these speleogenetic processes to other planets or moons requires morphodynamic models to consider the variation of gravitation, tidal forcing, atmospheric pressure, and other mineralogies of ice. For instance, glaciovolcanic cave examples in the Cascade Volcanic Arc can display low atmospheric pressure and persistent CO2 accumulations analogous to Martian lava tube and crevice environments, drawing climatological and morphological similarities. In contrast, observed cryovolcanism on Enceladus may be produced by tidal stress from Saturn, resulting in features more analogous to phreatic explosions or geysers on Earth. In settings where persistent surface temperatures are below -78°C or -182°C, such as Europa and Triton, heat flux may drive speleogenesis in accumulations of CO₂ or CH₄ ice, respectively. Applicable to all of these settings is the slow tempo of life found in dark, oligotrophic, low temperature environments on Earth, where biological cycles approach the timescales of geological processes such as glaciation and volcanism. Therefore, while glaciovolcanic caves are a compelling setting for biogeochemical cycling on other worlds, life within them may be heavily influenced by the geophysical cycles of ice and volcanic centers. Future research on the geomorphology of glaciovolcanic caves of the Pacific Northwest of the U.S. and Canada may provide critical context for the exploration of habitable zones in analogous environments by providing insight on geophysical controls on the evolution of extraterrestrial life.