Deformation-induced trace element redistribution in zircon revealed using atom probe tomography

Area of Science:

• Geochemistry
• Mineral Physics
• Materials Science

Background:

• Trace elements are assumed to diffuse negligibly in pristine mineral lattices.
• Accurate geochronology and elemental monitoring using minerals like zircon depend on minimal element mobility.

Purpose of the Study:

• To investigate atomic-scale trace element mobility in zircon during crystal-plastic deformation.
• To reveal sub-micrometre-scale mechanisms governing elemental redistribution.

Main Methods:

• Atom probe tomography was employed to analyze elemental distributions at the atomic scale.
• The study focused on the role of dislocations in trace element accumulation and transport.

Main Results:

• Dislocations accumulating uranium and other trace elements were observed.
• Pipe diffusion along connected dislocation arrays facilitated continuous removal of elements like lead.
• Disconnected dislocations were found to immobilize trace elements.

Conclusions:

• Crystal-plastic deformation significantly impacts trace element redistribution in zircon.
• These findings necessitate a re-evaluation of zircon's reliability as a geochronometer under deformed conditions.
• Understanding deformation-induced mobility is crucial for both geological dating and engineering materials.