A 1200-km-long Eocene metamorphic-plutonic belt in the northwestern Cordillera: evidence from southwest Yukon

Distinctive regional Eocene metamorphic-plutonic units of the Coast Belt in southwestern Yukon match similar units in southeastern Alaska and British Columbia, and possibly in the eastern Alaska Range, and together form a belt originally >1200 km long. The final high-grade metamorphic event in the Aishihik and Kluane assemblages between the Ruby Range batholith and the Denali fault zone occurred in latest Paleocene to early Eocene time. Structural, petrologic, and geochronologic evidence indicates that metamorphism occurred during a major period of west-southwest-vergent deformation and metamorphism. The final phase of consumption of the Kula plate at approximately 43 Ma may be linked to the culmination of metamorphism, intrusion, and deformation along the early Cenozoic Cordilleran margin.