Skip to main content
U.S. flag

An official website of the United States government

Spatial variations in focused exhumation along a continental-scale strike-slip fault: The Denali fault of the eastern Alaska Range

January 1, 2011

40Ar/39Ar, apatite fission-track, and apatite (U-Th)/He thermochronological techniques were used to determine the Neogene exhumation history of the topographically asymmetric eastern Alaska Range. Exhumation cooling ages range from ~33 Ma to ~18 Ma for 40Ar/39Ar biotite, ~18 Ma to ~6 Ma for K-feldspar minimum closure ages, and ~15 Ma to ~1 Ma for apatite fission-track ages, and apatite (U-Th)/He cooling ages range from ~4 Ma to ~1 Ma. There has been at least ~11 km of exhumation adjacent to the north side of Denali fault during the Neogene inferred from biotite 40Ar/39Ar thermochronology. Variations in exhumation history along and across the strike of the fault are influenced by both far-field effects and local structural irregularities. We infer deformation and rapid exhumation have been occurring in the eastern Alaska Range since at least ~22 Ma most likely related to the continued collision of the Yakutat microplate with the North American plate. The Nenana Mountain region is the late Pleistocene to Holocene (~past 1 Ma) primary locus of tectonically driven exhumation in the eastern Alaska Range, possibly related to variations in fault geometry. During the Pliocene, a marked increase in climatic instability and related global cooling is temporally correlated with an increase in exhumation rates in the eastern Alaska Range north of the Denali fault system.

Publication Year 2011
Title Spatial variations in focused exhumation along a continental-scale strike-slip fault: The Denali fault of the eastern Alaska Range
DOI 10.1130/GES00589.1
Authors J.A. Benowitz, P.W. Layer, P. Armstrong, S.E. Perry, Peter J. Haeussler, P.G. Fitzgerald, S. VanLaningham
Publication Type Article
Publication Subtype Journal Article
Series Title Geosphere
Index ID 70036537
Record Source USGS Publications Warehouse