CLIMBING UP THE WALLS: OROGEN-SCALE INVERTED BARROVIAN METAMORPHISM DURING OBLIQUE CONVERGENCE ALONG A REACTIVATED SUTURE ZONE, NORTHERN CORDILLERA
The new data reveal: 1) peak pressures of ~1.0-0.7 GPa and temperatures of 600-650°C from the structurally highest sample; 2) decreasing age of syn-deformational monazite growth structurally downward through the inverted metamorphic gradient from 64-56 Ma; and 3) consistent thermochronology indicating cooling through 500-400°C by ca. 50 Ma of all four samples. The data support a scenario wherein the VCsz formed by non-coaxial flow that progressively incorporated footwall material during prograde metamorphism and rapid uplift of high-grade gneisses in the hangingwall. Based on the metallogenic history, structural evolution, plutonic history, tectonic role of the VCsz, and new strike-slip restorations of Alaska, we correlate the VCsz with the western metamorphic belt of the Coast shear zone, thereby creating a >1750 km long zone of inverted metamorphism along the largest accretionary suture preserved in the Phanerozoic record of North America.