A plutonic brother from another magma mother: Disproving the Eocene Foraker-McGonagall pluton piercing point and implications for long-term slip on the Denali Fault

The Denali Fault is an active strike-slip fault system responsible for the highest topography in North America, yet there are conflicting constraints on the fault's Cenozoic slip history. The long-term slip rate constraint of the eastern Denali Fault is similar to 400 km since 57 Ma. In apparent conflict, the long-term slip rate of the western Denali Fault is 38 km since 38 Ma based on the reconstruction of the Foraker and McGonagall plutons. Tests of the genetic relationship of the plutons with bulk rock geochemical and paired U-Pb and Hf zircon analysis suggest a disparate origin. The McGonagall pluton, despite having a lower SiO2, has lower epsilon(Hf) values inconsistent with chemical and isotopic variations between the two being the result of contamination. The Denali Fault is a highly strain partitioned system, but the amount of Cenozoic slip dispersed east to west is likely significantly less than the previous similar to 360 km constraint.