Deformation between the highly oblique Yakutat–North American plate boundary and the Eastern Denali fault

Abstract

Abstract This study investigates the spatial and temporal pattern of rock exhumation inboard of the highly oblique Yakutat–North American plate boundary. We aim to quantify how far deformation is transferred inboard of the Fairweather transform plate boundary and across the Eastern Denali fault. We present new detrital apatite and zircon fission track data from 27 modern drainages collected on both sides of the Eastern Denali fault and from the Alsek and Tatshenshini River catchments that drain the mountainous region between the Fairweather fault and the Eastern Denali fault. By integrating our data with published bedrock and detrital geochronology and thermochronology, we show that exhumation reaches much farther inboard (>100 km) of the Fairweather fault than farther north in the St. Elias syntaxial region (<30 km). This suggests that the entire corridor between the Fairweather and Eastern Denali faults exhumed since mid-Miocene time. The Eastern Denali fault appears to be the backstop, and late Cenozoic exhumation northeast of the fault is very limited.