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Detecting magmatic-derived fluids using pyrite chemistry: example of the Chibougamau area, Abitibi Subprovince, Québec

Mathieu Lucie. (2019). Detecting magmatic-derived fluids using pyrite chemistry: example of the Chibougamau area, Abitibi Subprovince, Québec. Ore Geology Reviews, 114,

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URL officielle: https://doi.org/10.1016/j.oregeorev.2019.103127

Résumé

Magmatic fluids are an important carrier of precious and base metals in many mineralized systems (porphyry deposits, intrusion-related gold systems – IRGS, volcanogenic massive sulfides – VMS). Recognizing magmatic inputs is essential for understanding metallogenic processes and for developing accurate exploration models, and the importance of fluids exsolved from magmas remains a source of much debate for some contexts, such as IRGS and orogenic gold deposits. This study aims to identify magmatic fluids in the Chibougamau area (northeastern corner of the Neoarchean Abitibi Subprovince, Canada), using pyrite chemistry. This is achieved by comparing the chemistry of pyrites recovered from the Cu-Au magmatic-hydrothermal (porphyry) systems of the Chibougamau area to “background” compositions, i.e., the chemistry of pyrites from weakly mineralized rocks from the same area. Analyses of quantitative laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are processed in three distinct manners to better evaluate the trace elements controlled by silicates, oxides, sulfides, and sulfosalt inclusions and the trace elements that are structurally bound to pyrite. Detailed investigation of the trace element content of pyrite indicates that most elements are controlled by silicate inclusions, some reflect the composition of the host rock, others correlate with the mineralizing style, and only Te and Bi are discriminant of the porphyry systems of the Chibougamau area. Tellurium is structurally bound to pyrite or forms telluride nanoparticles in the study area, while the distribution of Bi is controlled by galena and chalcopyrite inclusions, and pyrite chemistry is interpreted using absolute Te values and Bi ratios (Bi/Pb and Bi/Cu). This study provides insight into the Cu-Au magmatic-hydrothermal systems of the Chibougamau area. It also has implications for the way pyrite chemistry can be used to probe for magmatic fluids in other mineralized contexts.

Type de document:Article publié dans une revue avec comité d'évaluation
Volume:114
Version évaluée par les pairs:Oui
Date:Novembre 2019
Sujets:Sciences naturelles et génie > Sciences naturelles > Sciences de la terre (géologie, géographie)
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Unité d'enseignement en sciences de la Terre
Mots-clés:pyrite chemistry, Te-Bi, porphyry deposit, magmatic-hydrothermal systems, Abitibi Subprovince, fluid signature, chimie de la pyrite, gisement de porphyre, systèmes magmatiques-hydrothermaux, sous-province de l'Abitibi, signature fluide
Déposé le:17 oct. 2019 00:19
Dernière modification:17 oct. 2019 21:36
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