New insights into mantle metasomatism using in-situ isotopic analysis

The development of the multi-collector ICP-MS has provided a wider range of isotopic systems (e.g. Li, Mg, Fe, Cu, Hf, Tl) that can used to place constraints on the timing of mantle metasomatism and better characterize metasomatic processes. Associated with the application of these isotopic systems has been the parallel development of in-situ isotope analysis using a laser ablation microprobe attached to the mass spectrometer. The in-situ capabilities allow for the first time the investigation of the scale of isotopic variation due to metasomatism and raises questions over the validity of whole-rock measurments. In-situ analysis also allows the isotopic data to be interpreted within a microstructural context and in the framework of geochemical data from other microanalytical techniques.