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Numerical models offer powerful insights into tectonic processes, especially when their validity can be tested against geological and geophysical observations from natural orogenic belts. Here we explain some of the criteria for success in integrating orogenic models with data, using examples from the Grenville Orogen. Model designs must be simplified by comparison with nature to illuminate the first-order processes that control orogenic evolution, which limits the extent to which model results can reproduce geological observations. For the western Grenville Orogen, observed variations in geological properties are represented by lower crustal blocks with strength decreasing from the exterior to the interior of the model. GO-series models with this design reproduce the first-order crustal architecture of the Georgian Bay and Montréal – Val d’Or Lithoprobe transects. Both constant-convergence and stop-convergence models produce similar geometries, but only stop-convergence models produce normal-sense shear zones like those observed. EGO-series models, incorporating an initial weak zone bounded by stronger lower crustal blocks, predict exhumation of high-pressure rocks as observed in the eastern Grenville Orogen, although other aspects of these model results are not as successful. The single most important test of a geodynamic model is its ability to integrate diverse and independent observations in a self-consistent manner. Other criteria include consistency with crustal-scale geometry and structural and metamorphic histories. By these criteria, the present models account reasonably well for the syn- and post-convergent evolution of the western Grenville Orogen, but further work is required to produce a fully satisfactory model for the eastern end of the system. Plusieurs modèles numériques offrent des aperçus révélateurs de processus tectoniques, surtout lorsqu’ils peuvent être validés par rapport à des observations géologiques et géophysiques de ceintures orogéniques naturelles. Dans cet article, nous expliquons quelques critères pour réussir l’intégration de modèles orogéniques avec les données, en utilisant des exemples de l’orogène de Grenville. Les conceptions des modèles doivent être simplifiées par rapport à la nature afin de souligner les processus de premier ordre qui contrôlent l’évolution de l’orogène, ce qui limite l’étendue selon laquelle les résultats des modèles peuvent reproduire les observations géologiques. En ce qui concerne la partie ouest de l’orogène de Grenville, les variations observées dans les propriétés géologiques sont représentées par des blocs de la croûte inférieure dont la puissance décroît de l’extérieur vers l’intérieur du modèle. Les modèles de séries de l’orogène de Grenville conçus de cette manière reproduisent l’architecture de premier ordre de la croûte des transects Lithoprobe de la baie Georgienne et de Montréal – Val-d’Or. Les modèles de convergence constante et de convergence par à-coups produisent des géométries similaires, mais seuls les modèles par à-coups produisent des zones de cisaillement distensif comme celles observées. Les modèles des séries de l’orogène de Grenville oriental, incorporant une zone initiale faible limitée par des blocs plus forts de la croûte, exhument les roches de haute pression tel qu’observé dans l’orogène de Grenville oriental, bien que d’autres aspects des résultats de ces modèles ne soient pas aussi réussis. La vérification la plus importante d’un modèle géodynamique est sa capacité d’intégrer des observations diverses et indépendantes d’une manière autoconsistante. D’autres critères comprennent la conformité avec la géométrie à l’échelle de la croûte et les historiques de structure et de métamorphisme. Selon ces critères, les modèles actuels tiennent raisonnablement compte de l’évolution syn- et post-convergente de l’orogène de Grenville occidental mais il faudrait plus de travaux pour établir un modèle pleinement satisfaisant pour l’extrémité est du système. [ABSTRACT FROM AUTHOR]

The Kisseynew domain within the central Trans-Hudson orogen constitutes a high-temperature (T) and low- to medium–pressure (P) metasedimentary belt characterized by uniform peak metamorphic conditions of 750 ± 50 °C and 5–6 kbar (1 kbar = 100 MPa). To investigate the thermal evolution of the Kisseynew domain 1-dimensional thermal modelling was conducted for a range of thermal parameters, including the effects of exhumation and incorporating current information about the crustal architecture. The results show that tectonic thickening of the sedimentary pile to ~40 km, consistent with present-day thickness estimates and erosional levels, is capable of producing enough crustal heating to melt the base of the sedimentary pile, advect heat to shallower crustal levels, and produce the observed P–T conditions. Deep-seated mantle heat sources, though not excluded, are not required. [ABSTRACT FROM AUTHOR]

A three-dimensional model of the regional crustal architecture of the western Trans-Hudson Orogen, based on the interpretation of 590 km of deep-sounding seismic reflection data and a comparable length of existing seismic reflection information, is presented. The seismic images identify the regional geometry of the basal detachment zone (Pelican thrust) that separates juvenile allochthonous terranes from the underlying Archean microcontinent (Sask craton). The Sask Craton is inferred to have a minimum spatial extent of over 100 000 km2 with an associated crustal root that extends for 200 km along strike. During terminal collision, complete convergence of the Rae–Hearne and Superior continental blocks was precluded by the presence of the Sask Craton, resulting in the preservation of anomalous amounts of oceanic and associated sedimentary juvenile material. Along regional tectonic strike, consistency of crustal structure across the Rae–Hearne margin – Reindeer zone boundary is established. Several phases of tectonic development, including multistage subduction and continent–continent collision, are inferred for the western margin of the orogen. A bright, shallow (2–3.5 s two-way traveltime) band of reflectivity (Wollaston Lake reflector) imaged over ~150 000 km2 area is inferred to be a large post-orogenic mafic intrusion. A highly reflective, well-defined and structurally disturbed Moho discontinuity is mapped throughout the western Trans-Hudson Orogen. The present-day crustal architecture of the western Trans-Hudson Orogen is described in terms of the tectonic evolution within the region. [ABSTRACT FROM AUTHOR]

A correlation chart showing the evolution of the Manitoba–Saskatchewan segment of the Paleoproterozoic Trans-Hudson Orogen (THO) has been constructed based on available geochronological and isotopic data. Geological, petrological, geochemical, and structural data have also been incorporated into the correlation chart to provide finer detail and to allow comparison of specific tectonic events. The chart also emphasizes that the bounding Archean cratons (Superior, Hearne, Sask) have been significantly affected by Paleoproterozoic events, and it is hoped that this chart will also facilitate comparison with other Paleoproterozoic orogens in North America and beyond. [ABSTRACT FROM AUTHOR]