Downloaded from http://sp.lyellcollection.org/ by guest on October 1, 2021 Persistent long-term (c. 24 Ma) exhumation in the Eastern Alaska Range constrained by stacked thermochronology JEFF A. BENOWITZ1*, PAUL W. LAYER2 & SAM VANLANINGHAM3 1Geophysical Institute, University of Alaska Fairbanks, PO Box 755940, Fairbanks, AK 99775, USA 2College of Natural Science and Mathematics, University of Alaska Fairbanks, PO Box 755940, Fairbanks, AK 99775, USA 3Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK 99775, USA *Corresponding author (e-mail:
[email protected]) Abstract: To address Miocene–present episodic v. persistent exhumation, we utilize a simple graphical procedure that vertically stacks spatially diverse K-feldspar 40Ar/39Ar multi-domain dif- fusion (MDD) models from the length of the approximately 100 km-long high-peak region of the Eastern Alaska Range. We supply additional constraints with 40Ar/39Ar mica dating because the higher closure-temperature-window places limits on the initiation of rapid Eastern Alaska Range exhumation. We also provide a broad 40Ar/39Ar K-feldspar minimum closure age data set to add more detail on spatial patterns in the regional exhumation history for the Eastern Alaska Range. We find that rapid and persistent exhumation has occurred in the Eastern Alaska Range since about 24 Ma at a long-term rate of approximately 0.9 km/Ma, but that this rapid exhumation is spatially variable through time. Onset of rapid Eastern Alaska Range exhumation is coincident with the initiation of rapid exhumation in SW Alaska, the Western Alaska Range and the Chugach– Saint Elias Range at around 25 Ma, implying a region-wide deformational response to a change in tectonic forcing.