Determining volcanic eruption styles on Earth and Mars from crystallinity measurements

Area of Science:

• Planetary Science
• Volcanology
• Geochemistry

Background:

• Earth and Mars exhibit diverse explosive basaltic volcanism styles.
• Differentiating phreatomagmatic eruptions (magma-water interaction) from magmatic eruptions (Strombolian, Plinian) is key to detecting past near-surface water or ice.

Purpose of the Study:

• To establish a method for distinguishing volcanic eruption styles on Mars based on groundmass crystallinity.
• To assess the implications of Martian volcanic plume dynamics on eruption style identification.

Main Methods:

• X-ray diffraction (XRD) analysis to determine groundmass or bulk crystallinity of volcanic ejecta.
• Comparison of terrestrial analogue eruption ejecta with Martian samples.
• Numerical modeling of Martian volcanic plumes to understand cooling and crystallization processes.

Main Results:

• Terrestrial phreatomagmatic ejecta show lower crystallinity (<35%) than Strombolian/Plinian ejecta (>40%) due to rapid quenching.
• Martian Plinian plumes exhibit moderate cooling, leading to 20-30% syn-eruptive crystallization, blurring style distinctions.
• Gale crater sediment crystallinity (52-54%) aligns with widespread basaltic Strombolian or Plinian volcanic ejecta on Mars.

Conclusions:

• Groundmass crystallinity, determined by XRD, serves as a viable indicator for differentiating terrestrial volcanic eruption styles.
• Martian volcanic ejecta, particularly in Gale crater, are consistent with basaltic Strombolian or Plinian activity, suggesting widespread explosive volcanism.
• The findings contribute to understanding Mars's volcanic history and the potential for past habitable environments.