How do volatiles escape their shallow magmatic hearth?

Area of Science:

• Geochemistry and Petrology
• Volcanology and Magma Dynamics

Background:

• Volcanic eruptions are traditionally viewed as the primary pathway for volatile release from magma.
• However, a significant portion of mantle-generated magma solidifies within the crust, influencing volatile transfer.

Purpose of the Study:

• To investigate and quantify gas escape mechanisms from crystallizing magma bodies using multiscale physical modeling.
• To assess the role of intrusive magmatic processes in the global volatile budget.

Main Methods:

• Multiscale physical modeling of magma crystallization and volatile exsolution.
• Analysis of gas escape dynamics at varying crystal fractions and volatile content.

Main Results:

• Significant outgassing occurs at intermediate to high crystal fractions (40-50% crystallinity) in mature magma 'mush' states.
• Shallow, volatile-rich systems exhibit efficient gas channel formation via second boiling.
• Volcanic activity alone underestimates the total magmatic volatile flux and can yield biased volatile compositions.

Conclusions:

• Intrusive outgassing from crystallizing magma reservoirs is a dominant mechanism for volatile transfer to the surface.
• Current estimates of volatile budgets relying solely on volcanic emissions are likely incomplete and potentially inaccurate.
• Incorporating intrusive outgassing is essential for accurate modeling of volatile cycling between the mantle and Earth's surface.