The Thermal Regime of NW Canada and Alaska, and Tectonic and Seismicity Consequences

NW Canada and Alaska are the continuation of North American Cordillera through Mexico, western USA Canada. I show that they have similar thermal regimes control tectonics seismicity. first summarize multiple constraints to crust upper mantle temperatures then discuss some consequences. There bimodal characteristic most subduction zones: cool forearc, uniformly hot backarc (Yukon Composite Terrane Southern Brooks Range, Mackenzie Mountains), stable cratonic backstops (Arctic Canadian Shield). The main as follows: (a) Heat flow measurements, (b) Temperature-dependent velocities seismic attenuation, (c) topographic elevations; isostasy, (d) Depth temperature lithosphere-asthenosphere boundary (LAB), (e) Origin depth craton kimberlite xenoliths, (f) Geochemically inferred source recent volcanic rocks. (g) magnetic Curie temperature, (h) extent lithosphere is thin, LAB at 50–85 km ∼1,350°C ± 25°C. Moho 35 850°C 100°C compared areas 400°C–500°C. consequences include following: Thin weak accommodates pervasive tectonic deformation indicated by wide-spread seismicity GPS-defined motions, in contrast regions; Weak lower flattens allows detachment thrusting over cold strong Arctic Shield. This article provides a model for how estimate deep from constraints.