Iron isotope measurement development and application of the method to fractionation in Archaean and post Archaean ores

摘要

Using new multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) techniques, the isotopic behaviour of iron is being gradually characterised in a wide variety of systems (e.g. Zhu et al.). This contribution details the development of the iron isotope method and its application to the study of banded iron formation (BIF) and ore deposit samples of different ages (Table 1). Samples are processed using a standard two step HF-HClO_4 + HNO_3 acid dissolution procedure for silicate bearing samples, and HNO_3 dissolution for metallic samples. Iron is then separated from matrix elements using anion exchange chromatography (Fig. 1), which results in 100 percent iron recovery. Measurements are undertaken on a single-focusing Micromass IsoProbe MC-ICP-MS using Faraday detectors and a desolvating nebuliser.