Active folding of Arctic Alaska driven by Yakutat microplate subduction?

Arctic Alaska’s eastern Brooks Range and coastal plain host large earthquakes and active folds, but the rates and drivers of deformation in this setting—over 1000 km north of the Yakutat−North American plate boundary—have been elusive. We show that 101−105-yr-averaged deformation rates decay northward across Alaska from near-plate-rates above the Yakutat microplate flat-subduction zone to the eastern Brooks Range, where GPS velocities accord with ≤1 mm/yr of distributed NNE-trending seismic left shear. On the adjacent coastal plain, we estimate ∼0.4−1.6 mm/yr late Quaternary shortening across the kinematically compatible Marsh Creek anticline. Moho depth and lower-lithosphere temperature models imply that the crust may transfer Yakutat microplate strain >1000 km north along compatible stress directions via faulting, lower crustal detachment, and distributed seismic deformation to drive active folding of the Arctic coastal plain. Oppositional Chersky−Gakkel−Atlantic plate boundary forces may buttress and/or amplify the Yakutat-driven deformation.