Cathodoluminescence differentiates sedimentary organic matter types.

Area of Science:

• Geosciences
• Organic Geochemistry
• Microscopy

Background:

• Scanning electron microscopy (SEM) is crucial for analyzing sedimentary organic matter in geosciences.
• Current SEM methods struggle to differentiate various sedimentary organic matter types, limiting research progress.
• Understanding organic matter types is key for evaluating depositional environments, diagenesis, and fluid processes.

Purpose of the Study:

• To demonstrate that SEM-cathodoluminescence (CL) properties can identify and characterize sedimentary organic matter.
• To establish CL emission as a reliable proxy for fluorescence emission from sedimentary organic matter.
• To enable rapid differentiation of organic matter types using SEM-CL without optical microscopy.

Main Methods:

• High-resolution scanning electron microscopy (SEM) visualization.
• Cathodoluminescence (CL) imaging and intensity measurements.
• Analysis of eleven mudstone samples spanning the Paleoproterozoic to Eocene epochs.

Main Results:

• SEM-cathodoluminescence (CL) properties successfully differentiate sedimentary organic matter at low thermal maturity.
• A strong correlation was observed between sedimentary organic matter fluorescence intensity and CL intensity.
• CL emission serves as a reliable proxy for fluorescence emission, enabling visual differentiation.

Conclusions:

• Cathodoluminescence (CL) during SEM visualization can distinguish fluorescent from non-fluorescent sedimentary organic matter.
• This technique allows for rapid, visual differentiation of organic matter types, bypassing the need for optical microscopy.
• The findings offer a widely adaptable method for SEM-based geosciences studies.