View in EDS

Constraints on the Origin and Metal Fertility of the Archean Mooshla Intrusive Complex (MIC), Doyon–Bousquet–LaRonde Mining District, Abitibi Greenstone Belt, Québec, Canada: Accessory Mineral Composition, Thermobarometry, and Geochronology

Saved in:

Bibliographic Details
Title:	Constraints on the Origin and Metal Fertility of the Archean Mooshla Intrusive Complex (MIC), Doyon–Bousquet–LaRonde Mining District, Abitibi Greenstone Belt, Québec, Canada: Accessory Mineral Composition, Thermobarometry, and Geochronology
Authors:	Neyedley, Kevin¹ (AUTHOR), Hanley, Jacob J¹ (AUTHOR), Mercier-Langevin, Patrick² (AUTHOR), Crowley, James L³ (AUTHOR), Tsay, Alexandra⁴ (AUTHOR), Zajacz, Zoltán⁴ (AUTHOR), Fayek, Mostafa⁵ (AUTHOR), Sharpe, Ryan⁵ (AUTHOR)
Source:	Journal of Petrology. Mar2026, Vol. 67 Issue 3, p1-39. 39p.
Subject Terms:	Magmatism, Archaean, Structural geology, Geothermometry, Greenstone belts, Gold mining, *Geological time scales
Geographic Terms:	Québec (Province), Canada
Abstract:	The Mooshla Intrusive Complex (MIC) is an Archean, low-Al, polyphase tonalite–trondhjemite–quartz diorite–gabbroic magmatic body located in the Doyon–Bousquet–LaRonde mining camp of the Abitibi greenstone belt, Québec, Canada. The MIC is spatially and temporally associated with numerous gold-rich volcanogenic massive sulfide (VMS), epizonal intrusion-related Au ± Cu, and shear zone-hosted orogenic gold and/or remobilized VMS deposits. The igneous units are grouped into two distinct stages, the tholeiitic to transitional Mouska stage and the transitional to calc-alkaline Doyon stage. Using a combination of petrography, high-precision zircon U–Pb geochronology, accessory mineral thermometry, and zircon trace element compositions from the different phases comprising the MIC, this study provides new constraints on the pressure–temperature–time and compositional evolution of this magmatic system. The results demonstrate that individual phases crystallized over a relatively short time scale and likely in distinct magmas gestating (in chambers or during transcrustal migration) at deep levels within the crust (~700–800 °C; ~0.5–0.9 GPa, 15–30 km), at slightly cooler and shallower conditions than expected tonalite–trondhjemite–granodiorite (TTG) magma generation. The entire intrusive complex formed over a maximum period of ~1.44 Ma, with the formation of the Mouska and Doyon stages overlapping within a ~1 Ma window. This indicates a rapid change in tectonic setting from a relatively mature back-arc rift- to arc-dominated environment, early in the magmatic evolution of the MIC magmas. Based on distinct zircon trace element ratios and ranges associated with individual MIC lithologies multiple, broadly coeval magma chambers were required at depth. Processes documented at the level of near-seafloor emplacement in this geological setting do not fully capture the duration and compositional complexity of deep crustal magmatic processes that can be directly involved in the magmatic contributions of metals to Au-rich VMS and intrusion-related deposit styles in the Doyon–Bousquet–LaRonde mining camp and other similar environments in Archean terranes. [ABSTRACT FROM AUTHOR]
Database:	Energy & Power Source

Description
Abstract:	The Mooshla Intrusive Complex (MIC) is an Archean, low-Al, polyphase tonalite–trondhjemite–quartz diorite–gabbroic magmatic body located in the Doyon–Bousquet–LaRonde mining camp of the Abitibi greenstone belt, Québec, Canada. The MIC is spatially and temporally associated with numerous gold-rich volcanogenic massive sulfide (VMS), epizonal intrusion-related Au ± Cu, and shear zone-hosted orogenic gold and/or remobilized VMS deposits. The igneous units are grouped into two distinct stages, the tholeiitic to transitional Mouska stage and the transitional to calc-alkaline Doyon stage. Using a combination of petrography, high-precision zircon U–Pb geochronology, accessory mineral thermometry, and zircon trace element compositions from the different phases comprising the MIC, this study provides new constraints on the pressure–temperature–time and compositional evolution of this magmatic system. The results demonstrate that individual phases crystallized over a relatively short time scale and likely in distinct magmas gestating (in chambers or during transcrustal migration) at deep levels within the crust (~700–800 °C; ~0.5–0.9 GPa, 15–30 km), at slightly cooler and shallower conditions than expected tonalite–trondhjemite–granodiorite (TTG) magma generation. The entire intrusive complex formed over a maximum period of ~1.44 Ma, with the formation of the Mouska and Doyon stages overlapping within a ~1 Ma window. This indicates a rapid change in tectonic setting from a relatively mature back-arc rift- to arc-dominated environment, early in the magmatic evolution of the MIC magmas. Based on distinct zircon trace element ratios and ranges associated with individual MIC lithologies multiple, broadly coeval magma chambers were required at depth. Processes documented at the level of near-seafloor emplacement in this geological setting do not fully capture the duration and compositional complexity of deep crustal magmatic processes that can be directly involved in the magmatic contributions of metals to Au-rich VMS and intrusion-related deposit styles in the Doyon–Bousquet–LaRonde mining camp and other similar environments in Archean terranes. [ABSTRACT FROM AUTHOR]
ISSN:	00223530
DOI:	10.1093/petrology/egag022