Modeling Coupled Magma-Hydrothermal Processes at Yellowstone National Park
Abstract
The Yellowstone hydrothermal system (YHS) is one of the most active and complex magma-hydrothermal systems on Earth. The last caldera-forming eruption occurred ~640,000 years ago, and geophysical data indicate that subsequent magmatic inputs, coupled with hydrothermal heat transfer, are linked to subsequent surface uplift and subsidence. Total heat output estimates from the YHS are between 1.2 - 5.3 GW. Fournier et al (1976) used a simple heat balance argument to show that hydrothermal heat output can be derived from the latent heat and cooling of a 0.6 - 1.2 km thick magmatic sill underlying an area of ~2500 km2. This calculation does not account for complex magma-hydrothermal heat transfer that is closely linked to magma convection, crystallization, and magmatic replenishment processes in and between coupled felsic and mafic magma bodies. Fournier's simple model also does not account for heat transfer processes in the hydrothermal circulation system that are controlled, at least partly, by crustal permeability. Furthermore, existing models of YHS's heat flow do not account for growth of a conductive thermal boundary layer and its effect on hydrothermal heat output. We modify existing models of hydrothermal heat flow in the YHS to account for heat transfer, growth of a conductive thermal boundary layer, and to consider the duration that the hydrothermal system can be sustained in the absence of mass or heat replenishment to the shallow silicic magma chamber, which overlies the deeper basaltic chamber. The YHS is modeled using the NaCl-H2O FISHES code (Lewis, 2009 ), utilizing a heat transfer model that combines code modified from Liu and Lowell (2009) with additions from Huppert and Sparks (1988). Preliminary results show the importance of accounting for the conductive thermal boundary layer, which results in a 170°C cooling of the hydrothermal vent fluid over the first 10 years. This addition of a thermal boundary layer and the consideration of more complex heat transfer between model domains, suggests that frequent replenishment of the Yellowstone magma bodies is necessary to sustain the amount of heat currently measured at Yellowstone. This research will advance the understanding of the Yellowstone magmatic system.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V33D0200B
- Keywords:
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- 4302 Geological;
- NATURAL HAZARDS;
- 7280 Volcano seismology;
- SEISMOLOGY;
- 8424 Hydrothermal systems;
- VOLCANOLOGY;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY