Fig. 3: Mantle conversions beneath the Cordillera-craton transition.

a Laurentia Lithosphere-Asthenosphere Boundary (LLAB) depth perturbations from the regional average. Colored solid lines delineate the surface traces of three different profiles; seismic stations share color conventions with the corresponding profile line. The region shaded in gray is the Cordillera-craton boundary zone, estimated from recent tomographic models and thermal boundary definitions (e.g., refs. ^6,7,8,9,28). Regions numbered from 1 to 3 denote the Cordillera, craton, and Cordillera-craton transition zone, respectively. b–d S receiver functions (black-shaded) superimposed on shear velocities from surface wave tomographic inversions^10,79. Thin, solid white lines indicate 1.2% and 0.1% perturbations in velocity. Surface elevation (grey-shaded polygons) and Bouguer gravity¹¹¹ (blue lines) are plotted on top of each profile. The LLAB is denoted by a horizontal pink line at each station, and measurements from all stations are subsequently interpolated (linearly) using thick, white dashed lines.