gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1994.58A.1.59 Lead Isotope Systematics in Sulphides from Modern Hydrothermal Vents: A Comparison of Mid Ocean and Back Arc Settings (Pacific) Bortnikov N. S. Vikentyev V. Chernyshov I. V. Agapova A. A. IGEM, Russian Academy of Sciences, 35 Staromonetny per., Moscow 109017 Russia 8 1994 58A 1 107 108 Copyright © 1994, The Mineralogical Society 1994