Overcoming Vertical Spatial Resolution Limitations in Coupled Zircon U-Pb-Hf Analysis by Laser Ablation Split Stream
Yao Lu1, Liang-Liang Zhang1, Li Liu1
1State Key Laboratory of Geological Processes and Mineral Resources, and Institute of Earth Sciences, China University of Geosciences, Beijing, Beijing100083, China.
Analytical Chemistry
|July 28, 2026
Summary
A new laser ablation split stream (LASS) depth profiling method allows simultaneous zircon U-Pb dating and Hf isotope analysis with high spatial resolution. This technique improves the characterization of complex zircon zoning and geological processes.
Area of Science:
- Geochemistry
- Isotope Geology
- Analytical Chemistry
Background:
- Coupled in situ determination of zircon U-Pb ages and Hf isotopic compositions is crucial for understanding geological processes.
- Limited spatial resolution of existing methods hinders analysis of fine growth rims and complex zoning in zircon grains.
Purpose of the Study:
- To develop and validate a novel laser ablation split stream (LASS) depth profiling approach for simultaneous, spatially matched in situ U-Pb dating and Hf isotopic analysis of zircon.
- To enhance the vertical spatial resolution of coupled zircon U-Pb-Hf analyses.
Main Methods:
- Utilized a laser ablation split stream (LASS) technique, concurrently introducing aerosol into a Q-ICP-MS (for U-Pb) and an MC-ICP-MS (for Hf isotopes).
- Performed analyses along a single continuous ablation trajectory to ensure spatial matching of data from the same ablation volume.
- Validated the method using zircon reference materials and applied it to natural zircon samples.
Main Results:
- Achieved precisions of ≤6% for U-Pb ages and ≤0.000060 for 176Hf/177Hf ratios with a vertical spatial resolution better than 3 μm.
- Successfully characterized rim growth domains as thin as 1.8 μm.
- Obtained comparable age spectra to conventional methods and a high proportion (93%) of valid Hf isotopic data from complex natural samples.
Conclusions:
- The LASS depth profiling approach provides enhanced vertical spatial resolution for coupled zircon U-Pb-Hf analyses without sacrificing analytical precision.
- This method is a robust tool for high-resolution age-isotope investigations of complex geological processes recorded in zircon, particularly in grains with intricate zoning.
- The technique overcomes previous limitations in spatial resolution, enabling more detailed insights into crust-mantle interactions and other geological phenomena.
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