Silica nanoparticles produced by explosive flash vaporization during earthquakes

Area of Science:

• Geochemistry
• Mineralogy
• Volcanology

Background:

• Hydrothermal activity precipitates silica, forming ore deposits and shaping geothermal systems.
• Seismic activity causes pore fluid pressure fluctuations, potentially leading to flash vaporization.
• Mechanisms of quartz vein formation under extreme hydrothermal conditions are not fully understood.

Purpose of the Study:

• To investigate silica precipitation mechanisms under subcritical to supercritical conditions.
• To elucidate the formation and transformation of silica particles during flash vaporization events.

Main Methods:

• Conducted flash experiments with silica-saturated solutions.
• Simulated conditions ranging from subcritical to supercritical.
• Analyzed silica precipitation using nucleation, aggregation, dissolution, and precipitation processes.

Main Results:

• Amorphous silica nanoparticles (nano- to micron-scale) form instantaneously via nucleation and aggregation during water droplet evaporation.
• These nanoparticles rapidly transform into microcrystalline quartz through dissolution and precipitation.
• Transformation to quartz is accelerated under supercritical conditions, occurring in less than a day.

Conclusions:

• Short-lived silica nanoparticles play a crucial role in the dynamic changes of hydrothermal systems in volcanic areas.
• Understanding these nanoparticle dynamics is key to comprehending ore deposit formation and geothermal system evolution.
• The rapid phase changes of silica under extreme conditions have significant implications for geological processes.