Atom Probe Tomography Analysis of Exsolved Mineral Phases

Area of Science:

• Geosciences
• Volcanology
• Materials Science

Background:

• Element diffusion and thermodynamic conditions govern volcanic and metamorphic processes.
• Exsolution lamellae within host minerals record these fundamental geological events.
• Traditional microscopy methods (SEM, TEM, FIB) offer limited chemical data for lamellae analysis.

Purpose of the Study:

• To investigate the application of atom probe tomography (APT) for nanoscale analysis of exsolution lamellae.
• To examine ilmenite exsolution lamellae in titanomagnetite from Soufrière Hills Volcano ash deposits.
• To determine if APT can provide crucial chemical and spacing data for volcanic process modeling.

Main Methods:

• Utilized atom probe tomography (APT) for high-resolution, nanoscale chemical analysis.
• Analyzed ilmenite exsolution lamellae within igneous titanomagnetite.
• Quantified interlamellar spacings and diffusion profiles.

Main Results:

• Precisely measured interlamellar spacings of 14-29 ± 2 nm.
• Revealed smooth diffusion profiles, indicating no sharp phase boundaries during Fe and Ti/O exchange.
• Demonstrated APT's capability for nanoscale compositional and spacing measurements.

Conclusions:

• Atom probe tomography is a powerful novel approach for detailed lamellae analysis.
• Nanoscale lamellae data can inform models of lava dome temperature, extrusion rates, and failure.
• This research contributes to improved volcanic hazard mitigation strategies.