Long distance plutonic relationships demonstrate 33 million years of strain partitioning along the Denali fault
Sean P. Regan, Jeffrey A. Benowitz, Trevor S. Waldien, Mark E. Holland, Sarah M. Roeske, Paul O’Sullivan, Paul W. Layer
Abstract
Abstract We identify two piercing point pairs along a ~500 km transect of the arcuate strike‐slip Denali fault to document long‐term slip partitioning. Geochemical and isotopic similarity between Foraker and Panorama‐Schist Creek‐Nenana Plutons suggest ~155 km of right‐lateral displacement on the western Denali fault since 37 Ma at a rate of ~4.2 mm/year. The eastern Denali fault Maclaren‐Cottonwood Terrane geochronology correlation establishes ~305 km of displacement on the eastern Denali fault since 33 Ma at a rate of ~9.2 mm/year. The ratio of Pleistocene‐Holocene slip rates between the western (5.3 mm/year) and eastern (12.9 mm/year) Denali fault is 0.41 and our new constraints yield a Late Eocene‐Holocene ratio of 0.46. Hence, we interpret that the overall arcuate geometry of the Denali fault master strand was established by 33 Ma. We infer that the persistent long‐wave geometric stability of the Denali fault and other highly slip partitioned fault systems are related to long‐term highly oblique transpressive environs.