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TitreLA-ICP-MS trace-element study of pyrite from massive sulphide deposits of the Bathurst Mining Camp, Canada: Determination of volatile trace-element contents in pyrite and its application as a vectoring tool for the exploration of VMS deposits
AuteurSoltani Dehnavi, A; Lentz, D R; McFarlane, C R M; McClenaghan, S H
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37, 2014 p. 260
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140518
RéunionGAC-MAC 2014; Joint annual meeting of Geological Association of Canada and Mineralogical Association of Canada; Fredericton; CA; mai 21-23, 2014
Documentpublication en série
Mediaen ligne; numérique
SNRC21O/01; 21O/02SE; 21O/02NE; 21O/07SE; 21O/07NE; 21O/08; 21O/09; 21O/10SE; 21O/10NE; 21P/04; 21P/05; 21P/12
Lat/Long OENS -66.6667 -65.5000 47.7500 47.0000
Sujetsgîtes volcanogènes; sulfures; gîtes sulfureux; analyses des éléments en trace; induction électromagnétique; analyse par spectromètre de masse; méthodes analytiques; Camp minier de Bathurst; géochimie; minéralogie
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
Pyrite is a ubiquitous refractory sulphide mineral in massive sulphide deposits. It typically hosts minor elements, such as Cu, Ni, As, and Co, as well as many other trace elements, such as Au, Ag, Pb, Zn, Sb, Se, Te, Hg, Tl, and Bi. Pyrite can, therefore, be treated as an effective scavenger of metals from ore-forming fluids. In this study, texturally-controlled in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is used to measure volatile trace-elements (As, Cd, Hg, In, Sb, Tl), in pyrite from the massive sulphide deposits of the Bathurst Mining Camp (BMC), eastern Canada. Texturally, pyrite can be categorized as pre-deformational (primary and pseudo-primary), syn-deformational (ductile and brittle), and post-deformational (late-recrystallization and annealing textures) in nature. LA-ICP-MS results indicate that all forms of pyrite are arsenian in nature, ranging from 2.2 ppm to 2.58%. The arsenian pyrite also contains elevated concentrations of Sb, Tl, Au, and Hg, whereas In and Cd were not found in significant concentrations within pyrite forms. The LA-ICP-MS data, coupled with petrographic (textural) observations, suggests a relationship between the textural setting and grain size of pyrite and their trace-element composition. The enrichment of volatile trace-elements is typically linked to pre-deformational pyrite, which are anhedral, colloform, spongy (corroded-diseased cores), and mostly fine grained (<200 ?m). This suggests that metamorphism and syn-deformational processes have not had a major effect on the redistribution of these elements. Alternatively, some deposits with primary enrichment in Au, Sb, Hg, and Tl, such as Louvicourt, also have high volatile trace element contents in late recrystallized pyrite forms. Consequently, the refractory nature of pyrite and its ability to scavenge trace elements may provide a record of both the primary style of mineralization, as well as secondary recrystallization, deciphering the metamorphic and deformational evolution of massive sulphide deposits of the BMC. Moreover, this powerful technique can reveal whether these trace elements are accommodated in the pyrite structure by lattice substitution and (or) by nano-inclusions of other minerals. Data for single-spot LA-ICP-MS analyses of pyrite show that elevated contents of As, Sb, Tl, and Hg in pyrite occur via lattice substitution, supported by the absence of spikes in the laser-ablation time-series data. Finally, vertical metal zonation exists in the deposits studied to date and indicate that, As, Sb, Tl, and Hg are systematically enriched toward the top of the massive sulphide intervals. Hence, based on the distribution of volatile trace-elements in texturally distinct pyrite, the potential of developing sulphide mineral composition (pyrite) as an exploration vectoring tool is proposed.