Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

The distribution of TABS (Te, As, Bi, Sb, and Sn) in magmatic sulphide ore deposits have been neglected despite their critical role in forming platinum-group minerals (PGM). Investigating the primary processes controlling the TABS distribution is a challenge as TABS are generally volatile, present at low levels, and mobile with alteration. Magmatic sulphide ore bodies in the Noril’sk mining district (Siberia, Russia) offer an exceptional opportunity to investigate the behaviour of TABS during fractional crystallisation of sulphide liquids and PGM formation as the primary features of the ore bodies have been relatively well preserved. We show that the distribution of Pt, Pd, and TABS is controlled by their partitioning behaviour during sulphide liquid fractional crystallisation, prior to PGM formation. In Cu-poor massive sulphides the PGM formed as the result of exsolution from sulphide minerals, whereas in Cu-rich massive sulphides the PGM formed by crystallisation from late-stage fractionated liquids.