Density, temperature, and rheological models for the southeastern Canadian Cordillera: implications for its geodynamic evolution
Two-dimensional density, temperature, and rheological models are constructed for a 350 km northeast-trending transect of the southeastern Canadian Cordillera. All models highlight several major physical differences between foreland and hinterland lithosphere. Significant features of the density model are the presence of an anomalously low-density (3.10 × 103 kg∙m−3) layer, with a maximum thickness of 12 km, beneath the Moho in the hinterland; the similar densities of the Monashee Terrane and the cratonic crust of the foreland; and an increase in crustal thickness beneath the Southern Rocky Mountain Trench. The temperature model shows steeper gradients and higher Moho temperatures beneath the hinterland than beneath the foreland. In the rheological model the hinterland is characterized by a thin, brittle, upper crust beneath which the entire lithosphere is hot, weak, and ductile. In contrast, the foreland is composed of a thick, brittle, upper crust, with an additional brittle zone in the upper mantle. The...