Cl, Br and I in igneous standard rocks

Radiochemical neutron activation analysis (RNAA) and isotope dilution mass spectrometry (IDMS) are applied to the determination of Cl, Br and I in igneous standard rocks. Seventeen different standard samples of igneous rocks distributed by the Geological Survey of Japan (GSJ) and by the Association National de la Recherche Technique (ANRT) in France were investigated. The Cl contents range from 10 to 1000 ppm, Br from 0.05 to 2.5 ppm, and I from 5 to 100 ppb. In this study, four standard samples for Cl, eight for Br, and six for I were newly determined. The analytical results between RNAA and IDMS are in good agreement within one standard deviation. The halogen contents are found to be well correlated for Cl and Br, but less clearly for I. Halogens generally are enriched in rhyolites in the volcanic rock series while they are depleted in plutonic rock series, especially in granite.