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

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dc.contributor.authorSortor, Rachel N.en
dc.contributor.authorGoehring, Brent M.en
dc.contributor.authorBemis, Sean P.en
dc.contributor.authorRuleman, Chester A.en
dc.contributor.authorCaffee, Marc W.en
dc.contributor.authorWard, Dylan J.en
dc.date.accessioned2022-05-05T13:00:54Zen
dc.date.available2022-05-05T13:00:54Zen
dc.date.issued2021-12-01en
dc.description.abstractThe 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 Al-26/Be-10 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.en
dc.description.adminPublic domain – authored by a U.S. government employeeen
dc.description.notesWe thank Denny Capps, Mike Frothingham, Keir Nichols, and Chandler Powers for assistance with sample collection. We thank Adrian Bender, Julie Brigham-Grette, Mike Taylor and one anonymous reviewer for their thoughtful insight, which greatly improved the manuscript. Field work travel was funded in part by a Geological Society of America Graduate Student Research Grant. We thank the staff of PRIME Lab (Purdue University, Indiana, USA) for 10Be and 26Al analyses and the Louisiana State University Wetland Biogeochemistry Laboratory (Louisiana, USA) for inductively coupled plasma-optical emission spectrometry (ICP-OES) analyses. Additional support was provided by a Tulane University Lavin Bernick Faculty Grant to B. Goehring.en
dc.description.sponsorshipGeological Society of America Graduate Student Research Grant; Tulane University Lavin Bernick Faculty Granten
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1130/G49094.1en
dc.identifier.eissn1943-2682en
dc.identifier.issn0091-7613en
dc.identifier.issue12en
dc.identifier.urihttp://hdl.handle.net/10919/109812en
dc.identifier.volume49en
dc.language.isoenen
dc.publisherGeological Society of Americaen
dc.rightsPublic Domain (U.S.)en
dc.rights.urihttp://creativecommons.org/publicdomain/mark/1.0/en
dc.subjectDenudationen
dc.subjectRecorden
dc.subjectLoessen
dc.titleEarly Pleistocene climate-induced erosion of the Alaska Range formed the Nenana Gravelen
dc.title.serialGeologyen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

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