In situ Hf isotope analysis of cassiterite by LA-MC-ICP-MS: protocol and applications

Abstract

We report the laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) ¹⁷⁶Hf/¹⁷⁷Hf ratios for cassiterite of a known age and demonstrate that the ¹⁷⁶Hf/¹⁷⁷Hf ratios can be measured accurately and reproducibly with adequate precision for cassiterite with Hf contents around 100 μg g⁻¹. Although cassiterite only has minor rare earth elements (REEs), corrections for Yb and Lu interferences are required as they may affect the determination of the ¹⁷⁶Hf/¹⁷⁷Hf ratios. Among the investigated samples, Rond-A has a homogeneous Hf isotopic composition. We recommend cassiterite sample Rond-A as a primary reference material for in situ Hf isotope analysis. The Kard sample has a homogeneous Hf isotopic composition and is suitable as a primary reference material once its Hf isotopic composition has been confirmed by solution-based MC-ICP-MS. Samples BB#7, 19MP, and 19GX showed minor variations in their Hf isotopic compositions and, therefore, can only be used as secondary reference materials.