Quantifying Trace Metals in Gunflint Microfossils by 3D Correlative X-ray Nanoimaging

Area of Science:

• Geobiology
• Materials Science
• Nanotechnology

Background:

• Analyzing elemental and structural variations in materials at the nanoscale is crucial for understanding material evolution and degradation.
• Correlating chemical and structural data across mesoscale samples at the nanoscale presents significant analytical challenges.

Purpose of the Study:

• To develop and apply a nondestructive correlative workflow for nanoscale elemental and structural analysis.
• To quantify metal traces within low-Z compartments of ancient microfossils.

Main Methods:

• Combined three-dimensional nanoscale X-ray ptychographic tomography and fluorescence tomography on the same sample.
• Utilized synchrotron instruments for high-resolution data acquisition.
• Developed a workflow for trace element quantification in fossil compartments without physical subsampling.

Main Results:

• Detailed nanoscale architecture of a 1.88-billion-year-old Gunflint microfossil (Huroniospora) was revealed.
• Identified quartz crystals with nanoinclusions in the thick wall and an extracellular shell of quartz and greenalite within a chert matrix.
• Quantified trace metal concentrations (Fe, Mn) in fossil compartments with high sensitivity and precision.
• Observed organic matter comparable to modern bacterial cells.

Conclusions:

• The correlative workflow enables high-sensitivity multielement trace analysis of nanostructured mesoscopic systems.
• Metal concentrations suggest a cyanobacterial lineage and offer insights into early microbial metabolisms.
• The workflow is broadly applicable to biominerals, geobiological materials, and advanced functional materials.