Early Pleistocene climate-induced erosion of the Alaska Range formed the Nenana Gravel

By: , and 



The Pliocene-Pleistocene transition resulted in extensive global cooling and glaciation, but isolating this climate signal within erosion and exhumation responses in tectonically active regimes can be difficult. The Nenana Gravel is a foreland basin deposit in the northern foothills of the Alaska Range (USA) that has long been linked to unroofing of the Alaska Range starting ca. 6 Ma. Using 26Al/10Be cosmogenic nuclide burial dating, we determined the timing of deposition of the Nenana Gravel and an overlying remnant of the first glacial advance into the northern foothills. Our results indicate that initial deposition of the Nenana Gravel occurred at the onset of the Pleistocene ca. 2.34 Ma and continued until at least ca. 1.7 Ma. The timing of initial deposition is correlative with expansion of the Cordilleran ice sheet, suggesting that the deposit formed due to increased glacial erosion in the Alaska Range. Abandonment of Nenana Gravel deposition occurred prior to the first glaciation extending into the northern foothills. This glaciation was hypothesized to have occurred ca. 1.5 Ma, but we found that it occurred ca. 0.39 Ma. A Pleistocene age for the Nenana Gravel and marine oxygen isotope stage 10 age for the oldest glaciation of the foothills necessitate reanalysis of incision and tectonic rates in the northern foothills of the Alaska Range, in addition to a shift in perspective on how these deposits fit into the climatic and tectonic history of the region.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Early Pleistocene climate-induced erosion of the Alaska Range formed the Nenana Gravel
Series title Geology
DOI 10.1130/G49094.1
Volume 49
Issue 12
Year Published 2021
Language English
Publisher Geological Society of America
Contributing office(s) Geosciences and Environmental Change Science Center
Description 5 p.
First page 1473
Last page 1477
Country United States
State Alaska
Other Geospatial Alaska Range
Google Analytic Metrics Metrics page
Additional publication details