The Effect of CO2 on Magma Chamber Growth, Longevity and Eruption Frequency

Abstract:

Volatiles have a profound effect on the behavior of volcanic systems during the growth and maturation of subvolcanic magma chambers. In silicic magma reservoirs, water is the dominant volatile species by mass and is considered to influence the thermal and mechanical behavior of magma chambers, in particular by modulating the size and frequency of eruptions. There is a growing recognition that carbon dioxide is another important factor that influences mineral phase stability and the solubility of water in the magma. However, the effect of carbon dioxide on the longevity and evolution of magma chambers remains poorly understood. We expand on previous thermal-mechanical magma chamber modeling work by Degruyter and Huber (2014) and Townsend et al. (2019) and add a statement of mass conservation for carbon dioxide and include its influence on water solubility (Liu et al., 2005) and on the phase diagram of the magma. This new model is used to illustrate the role that carbon dioxide content plays on the growth, longevity, and eruption frequency of silicic systems with various size, volatile compositions and subjected to different rates of magma recharge.