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 Be lt in southwestern Yukon match similar units in southeastern Alaska an d British Columbia, and possibly in the eastern Alaska Range, and toge ther form a belt originally > 1200 km long. The final high-grade metam orphic event in the Aishihik and Kluane assemblages between the Ruby R ange batholith and the Denali fault zone occurred in latest Paleocene to early Eocene time. Structural, petrologic, and geochronologic evide nce indicates that metamorphism occurred during a major period of west -southwest-vergent deformation and metamorphism. The final phase of co nsumption of the Kula plate at approximately 43 Ma may be linked to th e culmination of metamorphism, intrusion, and deformation along the ea rly Cenozoic Cordilleran margin.