Genetic links among fluid cycling, vein formation, regional deformation, and plutonism in the Juneau gold belt, southeastern Alaska

Gold-bearing quartz vein systems in the Juneau gold belt formed within a 160-km-long by 5- to 8-km-wide zone along the western margin of the Coast Mountains, Alaska. Vein systems are spatially associated with shear zones adjacent to terrane-bounding, mid-Cretaaceous thrust faults. Analysis of vein orientations and sense of shear data define a stress configuration with greatest and least principal axes oriented subhorizontally with northeast-southwest trends and subvertically, respectively. This local stress configuration is compatible with the far-field plate configuration during Eocene time. Isotopic ages of vein formation indicate that fluid cycling occured between 56.5 and ≥52.8 Ma, and are consistent with a genetic link between veining and a change in plate motion in early Eocene time. -from Authors