Sponsor
Publication of this article in an open access journal was funded by the Portland State University Library’s Open Access Fund.
Published In
Frontiers in Earth Science
Document Type
Citation
Publication Date
3-26-2021
Subjects
Paleoclimate -- Oregon, Biogeography -- Oregon Coast Range
Abstract
We characterize the topographic evolution of the Pacific Northwest, United States, during the Cenozoic. New paleosol carbonate stable isotope (δ18O) results from central Oregon are presented, along with published proxy data, including fossil teeth, smectites, and carbonate concretions. We interpret a polygenetic history of Cascade Mountain topographic uplift along-strike, characterized by: 1) Steady uplift of the Washington Cascades through the Cenozoic due long-term arc rotation and shortening against a Canadian buttress, and 2) Uplift of the Oregon Cascades to similar-to-modern elevations by the late Oligocene, followed by topographic stagnation as extension developed into the Neogene. Since the Miocene, meteoric water δ18O values have decreased in Oregon, possibly due to emergence of the Coast Range and westward migration of the coastline. Spatial variability in isotopic change throughout the Pacific Northwest suggests that secular global climate change is not the primary forcing mechanism behind isotopic trends, though Milankovitch cycles may be partly responsible for relatively short-term variation.
Rights
Copyright © 2021 McLean and Bershaw. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Locate the Document
DOI
10.3389/feart.2021.624961
Persistent Identifier
https://archives.pdx.edu/ds/psu/35454
Citation Details
McLean, A., & Bershaw, J. (2021). Molecules to Mountains: A Multi-Proxy Investigation Into Ancient Climate and Topography of the Pacific Northwest, USA. Frontiers in Earth Science, 9, 624961. https://doi.org/10.3389/feart.2021.624961