TTG plutonism in the Archean Abitibi greenstone belt, Superior craton: geodynamic and metallogenic perspectives

• The trace element and major element compositions of TTGs are used as proxies for their melting depth, crystallization depth, and metallogenic potential. • The typological mapping of TTGs in the Abitibi region indicates an early lithotectonic partitioning of the Neoarchean crust. • Three distinct lithotectonic domains are identified based on the evolution of crustal thickness prior to and during the onset of tectonism. • Understanding the early crustal architecture provides valuable insights for discriminating the metallogenic potential of VMS and intrusion-related deposits. This study of the Abitibi greenstone belt (Quebec, Canada) relies on TTG (tonalite, trondhjemite, and granodiorite) composition to investigate the spatiotemporal evolution of the Archean crust and evaluate its metallogenic significance. Trace element signatures (e.g., La/Yb, Sr/Y, Eu/Eu*, Nb, Ta) of 32 dated TTG intrusions is analyzed using the FI-FII-FIII fertility typology developed for felsic volcanic rocks, which links mineral systems to melting depth and crustal architecture. Crystallization depths estimated from normative felsic mineralogy correlated with melting depth and showed a crustal thickness increase during incipient tectonics. The spatiotemporal distribution of TTG types indicates an early partitioning of the Abitibi crust into three distinct domains. The Northeastern Abitibi is characterized by FI types, early crustal thickening, and arc-like settings. These geological characteristics are favorable for porphyry-type deposition within syn-volcanic shallow plutons (e.g., the Chibougamau camp) or Windfall-like intrusion-related gold mineralization within syn-tectonic, LILE-enriched intrusions crystallized at deeper levels, possibly below the brittle crust. The southern volcanic zone is dominated by FIII and FIIb types, consistent with thin-crust, high–heat flux environments linked to the major volcanogenic massive sulfide camps. Finally, the western North Volcanic Zone exhibits an intermediate crustal thickness response and a transition from FII to FI types, associated with syn-tectonic crustal thickening; punctual occurrences of FIII-type intrusions occur, which indicate trenches or thermal corridors prospective for volcanogenic massive sulfides. This research emphasizes the utility of TTG geochemistry as a proxy for crustal processes and mineral potential. It demonstrates that TTG compositional variability offers a robust framework for reconstructing Archean crustal evolution and guiding metallogenic models.