VOLCANICALLY POWERED GEO/HYDROTHERMAL SYSTEMS: A CASE STUDY AT MUTNOVSKY VOLCANO, KAMCHATKA

The relationship between arc volcanoes and hydrothermal systems typically involves a stratovolcano with fumaroles at the summit and a proximal hydrothermal system(s), the latter sometimes extending outward as much as a few tens of kilometers. This association likely results from advection of magmatic aqueous fluid(s) from the magma conduit, introducing both heat and mass to meteoric water. At Mutnovsky Volcano, Kamchatka, Russia, the time scales of episodic volcanism and hydrothermal activity are consistent with this model. The 100 ka volcano has experienced four caldera-forming eruptions with nearly continuous effusive activity associated with post-caldera repositioning of the volcanic plumbing system. A 62 MWe geothermal production facility is located 10 km NNE from the active crater and geothermal production is ongoing from fluids emanating from a single fracture plane that strikes towards the volcano crater. Hydrogen and oxygen isotope data, measured in water from fumarole condensates and geothermal fluid, fall on a classic mixing line between magmatic water and local meteoric waters. Summit fumaroles, with temperatures to 620°C, emit >1000 tons/day sulfur dioxide and have a total measured thermal output of ~900 MWt, implying shallow degassing of convecting mafic magma at a rate of approximately 10 m³/sec. We are currently working to constrain the magmatic volatile history and magmatic fluid pathways, and decode their relationship with producing geo/hydrothermal fluids. Elucidating the physicochemical nature of this measured transfer of heat and mass from a magmatic to a hydrothermal system is important in the context of global geothermal development and hazard monitoring. Ultimately, the examination of the magma – hydrothermal connection at Mutnovsky will provide important new data that can be used globally to further geothermal exploration of the proximal region of continental arc volcanoes.