The Magma-Hydrothermal System at Mutnovsky Volcano, Kamchatka Peninsula, Russia

What is the relationship between the kinds of volcanoes that ring the Pacific plate and nearby hydrothermal systems? A typical geometry for stratovolcanoes and dome complexes is summit fumaroles and hydrothermal manifestations on and beyond their flanks. Analogous subsurface mineralization is porphyry copper deposits flanked by shallow Cu-As-Au acid-sulfate deposits and base metal veins. Possible reasons for this association are (1) upward and outward flow of magmatic gas and heat from the volcano’s conduit and magma reservoir, mixing with meteoric water; (2) dikes extending from or feeding towards the volcano that extend laterally well beyond the surface edifice, heating a broad region; or (3) peripheral hot intrusions that are remnants of previous volcanic episodes, unrelated to current volcanism. These hypotheses are testable through a Mutnovsky Scientific Drilling Project (MSDP) that was discussed in a workshop during the last week of September 2006 at a key example, the Mutnovsky Volcano of Kamchatka. Hypothesis (1) was regarded as the most likely. It is also the most attractive since it could lead to a new understanding of themagma-hydrothermal connection and motivate global geothermal exploration of andesitic arc volcanoes

Exploring and Modeling the Magma–Hydrothermal Regime

This special issue comprises 12 papers from authors in 10 countries with new insights on the close coupling between magma as an energy and fluid source with hydrothermal systems as a primary control of magmatic behavior. Data and interpretation are provided on the rise of magma through a hydrothermal system, the relative timing of magmatic and hydrothermal events, the temporal evolution of supercritical aqueous fluids associated with ore formation, the magmatic and meteoric contributions of water to the systems, the big picture for the highly active Krafla Caldera, Iceland, as well as the implications of results from drilling at Krafla concerning the magma–hydrothermal boundary. Some of the more provocative concepts are that magma can intrude a hydrothermal system silently, that coplanar and coeval seismic events signal "magma fracking" beneath active volcanoes, that intrusive accumulations may far outlast volcanism, that arid climate favors formation of large magma chambers, and that even relatively dry rhyolite magma can convect rapidly and so lack a crystallizing mush roof. A shared theme is that hydrothermal and magmatic reservoirs need to be treated as a single system

Inverse modeling and forecasting for the exploitation of the Pauzhetsky geothermal field

Abstract A three-dimensional numerical model of the Pauzhetsky geothermal field has been developed based on a conceptual hydrogeological model of the system. It extends over a 13.6-km 2 area and includes three layers: (1) a base layer with inflow; (2) a geothermal reservoir; and (3) an upper layer with discharge and recharge/infiltration areas. Using the computer program iTOUGH

The impact of secondary mineral formation on Na-K-geothermometer readings: a case study for the Valley of Geysers hydrothermal system (Kronotsky State Nature Biosphere Reserve, Kamchatka)

The temperature in the Valley of Geysers (Kamchatka) geothermal reservoir calculated using the feldspar Na-K-geothermometer has been steadily increasing over the past 10 years on average from 165 to 235 °C, which is close to the temperature values of a hydrothermal explosion of the steam and water mixture. For the analysis of chemical geothermometers, TOUGHREACT-simulation was used, with the help of which the previously known Na-K feldspar geothermometer was reproduced on a single-element model and new formulas were obtained for three Na-K geothermometers: zeolite, smectite, and based on volcanic glass. Data of chemical analysis for the period 1968-2018, in which the chloride ion is considered as an inert tracer of geofiltration processes, indicates that after 2007 a significant inflow of infiltration water (its mass fraction is estimated from 5 to 15 %) into the Geyser reservoir. It is assumed that the Na-K increased values of the feldspar geothermometer are not the result of the temperature increase in the Geyser reservoir, but the effect of smectite water dilution

A CO2-Driven Gas Lift Mechanism in Geyser Cycling (Uzon Caldera, Kamchatka)

Here, we report on a new geyser (named Shaman) formed in the Uzon caldera (Kronotsky Federal Nature Biosphere Reserve, Russia) in autumn 2008 from a cycling hot Na-Cl spring. The geyser is a pool-type CO2-gas lift driven. From 2012 to 2018, the geyser has shown a rather stable interval between eruptions (IBE) from 129 to 144 min with a fountain height up to 4 m, and the geyser conduit has gradually enlarged. In 2019, the Shaman geyser eruption mode significantly changed: cold water inflow from the adjacent stream was re-directed into the geyser conduit and the average IBE decreased to 80 min. We observed two eruptive modes: a cycling hot spring (June 2019) and a cycling geyser (after June 2019). Bottom-hole temperature recording was performed in the geyser conduit to understand its activity. The TOUGH2-EOS2 model was used to reproduce the obtained temperature records and estimate geyser recharge/discharge parameters in both modes. Modeling shows that a larger cold inflow into the conduit causes a switch from cycling geyser to hot cycling spring mode. It was also found that the switch to cycling geyser mode corresponds to a larger mass of CO2 release during the time of the eruption

A Modeling Study of the Role of Hydrothermal Processes in the Formation of Production Reservoirs in Volcanogenic Rocks

AbstractThe paper describes the role of hydrothermal fluid circulation in the creation of porous reservoirs bounded by low–permeability layers in volcanogenic rocks, which can accumulate fluids of different origin and phase conditions. The Rogozhnikovsky oil-bearing volcanogenic production reservoir in west Siberia, hosted in Triassic rhyolite tuffs and lavas, and the Mutnovsky high temperature geothermal reservoir hosted in recent rhyolites and andesites, are considered as benchmark examples. TOUGHREACT modeling scenarios show that formation of production reservoirs due to hydrothermal circulation may result from chemical fluid-rock interactions. The model shows short- term pressure drop conditions in the early stage of circulation (favorable for fluid migration into the reservoir), followed by reservoir self-sealing at the last stage of hydrothermal circulation (favorable for fluid trapping and formation of mineral resource deposits)

Secondary minerals in the geyserites of the Geysers Valley (Kamchatka)

Secondary minerals assemblages that are deposited from thermal solutions at the top of geysers (Velikan, Bolshoy) were investigated. It is established that assemblages are represented mainly by opal and high-silica zeolites (mordenite and heulandite). As conditions of feeding hydrothermal reservoir change, minerals of the kaolinite group and smectites may appear

Magma Fracking Beneath Active Volcanoes Based on Seismic Data and Hydrothermal Activity Observations

Active volcanoes are associated with microearthquake (MEQ) hypocenters that form plane-oriented cluster distributions. These are faults delineating a magma injection system of dykes and sills. The Frac-Digger program was used to track fracking faults in the Kamchatka active volcanic belt and fore-arc region of Russia. In the case of magma laterally injected from volcanoes into adjacent structures, high-temperature hydrothermal systems arise, for example at Mutnovsky and Koryaksky volcanoes. Thermal features adjacent to these active volcanoes respond to magma injection events by degassing CO2 and by transient temperature changes. Geysers created by CO2-gaslift activity in silicic volcanism areas also flag magma and CO2 recharge and redistributions, for example at the Uzon-Geyserny, Kamchatka, Russia and Yellowstone, USA magma hydrothermal systems. Seismogenic faults in the Kamchatka fore-arc region are indicators of geofluid fracking; those faults can be traced down to 250 km depth, which is within the subduction slab below primary magma sources

Dike model for the 2012–2013 Tolbachik eruption constrained by satellite radar interferometry observations

Abstract A large dike intrusion and fissure eruption lasting 9 months began on November 27, 2013, beneath the south flank of Tolbachik Volcano, Kamchatka, Russia. The eruption was the most recent at Tolbachik since the Great Tolbachik Eruption from 1975 to 1976. The 2012 eruption was preceded by more than 6 months of seismicity that clustered beneath the east flank of the volcano along a NW–SE trend. Seismicity increased dramatically before the eruption, with propagation of the seismicity from the central volcano conduit in the final hours. We use interferometric synthetic aperture radar (InSAR) to compute relative displacement images (interferograms) for {SAR} data pairs spanning the eruption. We use satellite {SAR} data from the Canadian Space Agency's RADARSAT-2 and from the Italian Space Agency's COSMO-SkyMed missions. Data are modeled first through a Markov Chain Monte Carlo solution for a single tensile dislocation (dike). We then use a boundary element method that includes topography to model a distributed dike-opening model. We find the best-fitting dike dips 80° to the {WNW} with maximum opening of 6–8 m, localized in the near surface and more broadly distributed in distinct regions up to 3 km beneath the surface, which varies from 1 to 2 km elevation for the eruptive fissures. The distribution of dike opening and its correspondence with co-diking seismicity suggests that the dike propagated radially from Tolbachik's central conduit