In-situ Isotopic and Chemical Study of Pyrite from Chu-Sarysu (Kazakhstan) Roll-front Uranium Deposit

Philippe Lach (1) , Michel Cathelineau (1) , Marc Brouand (2) , Nicolas Fiet (2)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 AREVA MINES [Courbevoie]

Pyrite is common in roll-front type uranium deposit in Chu-sarysu basin, Kazakhstan. Combined in-situ microstructural, isotopic and chemical analysis of pyrite indicates variation in precipitation conditions and in fluid composition. Broad-scale δ34S heterogeneity indicates a complex multi-facet evolution. First generation authigenic framboïdal aggregates are biogenic as demonstrated by the lowest δ34S values of -48‰ to -28‰. The latest generation pyrites are probably hydrothermal with greater δ34S variation (-30‰ to +12‰). This hydrothermal pyrite commonly displays variable enrichment of several trace elements especially As, Co and Ni. Strong variation in δ34S values and variable trace element enrichment is interpreted in terms of continuous variations in fluid composition.

Keywords: SIMS; LA-ICP-MS; traces elements; sulfur isotopy; pyrite; uranium; roll-front

Domains: Sciences of the Universe [physics]; Earth Sciences

Philippe Lach, Michel Cathelineau, Marc Brouand, Nicolas Fiet. In-situ Isotopic and Chemical Study of Pyrite from Chu-Sarysu (Kazakhstan) Roll-front Uranium Deposit. Procedia Earth and Planetary Science, 2015, 13, pp.207 - 210. ⟨10.1016/j.proeps.2015.07.049⟩. ⟨hal-03699892⟩