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The Neoarchean Pukaskwa batholith consists of pre-, syn-, and post-tectonic phases emplaced over an interval of 50 million years. Pre-tectonic phases are broadly synvolcanic and have a high-Al tonalite-trondhjemite-granodiorite (TTG) affinity interpreted to reflect derivation by partial melting of basaltic crust at lower crustal or upper mantle depths. Minor syn-tectonic phases slightly post-date volcanism and have geochemical characteristics suggesting some involvement or interaction with an ultramafic (mantle) source component. Magmatic emplacement of pre- and syn-tectonic phases occurred in the midcrust at paleopressures of 550-600 MPa and these components of the batholith are thought to be representative of the midcrust underlying greenstone belts during their development. Subsequent to emplacement of the syntectonic phases, and likely at approximately 2680 Ma, the Pukaskwa batholith was uplifted as a structural dome relative to flanking greenstone belts synchronously with ongoing regional sinistral transpressive deformation. The driving force for vertical tectonism is interpreted to be density inversion (Rayleigh-Taylor-type instabilities) involving denser greenstone belts and underlying felsic plutonic crust. The trigger for initiation of this process is interpreted to be an abrupt change in the rheology of the midcrust attributed to introduction of heat from the mantle attendant with slab breakoff or lithospheric delamination following the cessation of subduction. This process also led to partial melting of the intermediate to felsic midcrust generating post-tectonic granitic phases at approximately 2667 Ma. We propose that late density inversion-driven vertical tectonics is an inevitable consequence of horizontal (plate) tectonic processes associated with greenstone belt development within the Superior Province. Le batholite neeoarcheeen de Pukaskwa comprend des phases pre-, syn- et post-tectoniques mises en place durant une peeriode de 50 Ma. Les phases pre-tectoniques sont largement synvolcaniques et elles ont une affinite Al et TTG (<>) elevee qui est interpretee comme etant le reflet de la derivation par fusion partielle d'une croflte basaltique a des profondeurs de croflte inferieure ou de manteau superieur. Des phases syntectoniques mineures sont leegerement plus tardives que le volcanisme et elles ont des caracteristiques geochimiques qui suggerent une certaine implication ou interaction avec une composante de source ultramafique (manteau). La mise en place magmatique des phases pre;- et syntectoniques a eu lieu dans le milieu de la croflte a des paleeopressions de 550-600 MPa et ces composantes du batholite seraient representatives des ceintures de roches vertes sous-jacentes, au centre de la croflte durant leur deeveloppement. Apres la mise en place des phases syntectoniques, et probablement vers 2680 Ma, le batholite de Pukaskwa a ete souleve en dome structural par rapport aux ceintures de roches vertes de part et d'autre, et ce, de maniere synchrone avec la deformation transpressive regionale senestre en cours. La force motrice derriere le tectonisme vertical serait une inversion de densite (instabilitees de type Rayleigh-Taylor) impliquant les ceintures de roches vertes plus denses et la croflte felsique plutonique sous-jacente. Le declencheur pour l'initiation de ce processus est interprete comme etant un changement abrupt dans la rheologie de la croflte moyenne attribue a l'introduction de chaleur du manteau auxiliaire a la rupture de la dalle ou a la delamination lithospherique suivant la cessation de la subduction. Ce processus a aussi mene a une fusion partielle de la croflte moyenne intermediaire a felsique generant des phases granitiques post-tectoniques vers 2667 Ma. Nous proposons que la tectonique verticale poussee par l'inversion de densite tardive soit une consequence inevitable des processus tectoniques horizontaux (plaques) associesau developpement de ceintures vertes dans la Province du Superieur. [Traduit par la Redaction], Introduction Large, intermediate to felsic plutonic complexes of batholithic dimensions are a major component of the Superior Province and Archean cratons in general, but are poorly understood compared to the [...]

Abstract: A combined U-Pb and field mapping study of the Island Lake greenstone belt has led to the recognition of three distinct supracrustal assemblages. These assemblages record magmatic episodes at [...]

Abstract: Evidence for both vertical and horizontal movement is well preserved in the Cross Lake greenstone belt in the northwestern Superior Province. The vertical movement components are concentrated in high-strain [...]