Abstract:
BACKGROUND In recent years, the in situ Hf isotopic determination method of zircon has been widely used in isotopic geochemistry, and has become an important method to explore the genesis of rocks, the source of ore-forming materials and the evolution of crust and mantle. However, for some rocks, the lack of zircon seriously hinders the restriction of formation and evolution. The development of Hf isotopic determination methods for oxide-type U-bearing accessory minerals, such as rutile, cassiterite and columbite is urgently needed.
OBJECTIVES In order to accelerate the studies of in situ Hf isotopic determination of oxide-type U-bearing minerals and their application to the geological research.
METHODS In situ Hf isotopic analysis of oxide-type U-bearing accessory minerals was reviewed with NEPTUNE multiple-collector inductively coupled plasma-mass spectrometry (MC-ICPMS) and a 193nm excimer laser ablation system.
RESULTS Combined with relevant research work in recent years, the development history of Lu-Hf isotope analysis technology for accessory minerals was briefly described, and the latest progress and existing problems in in-situ Hf isotope determination methods for oxide-type uranium-bearing minerals such as rutile, cassiterite and niobite were systematically reviewed. The current technical difficulties such as the correction strategy for isobaric interference, the lack of quality control standard samples, the lower Hf content, and the improvement of analytical sensitivity were discussed in detail.
CONCLUSIONS The low Hf content of oxide-type U-bearing accessory minerals requires a larger spot diameter. The femtosecond laser has the characteristics of fine and uniform grain size of the ablation samples. The combination of femtosecond laser and MC-ICPMS (fs-LA-MC-ICPMS) can reduce the spot diameter and improve the spatial resolution, which is the development direction of in situ Hf isotope analysis of oxide-type U-bearing accessory minerals in the future.
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