Oxygen isotope evidence for the late Cenozoic development of an orographic rain shadow in eastern Washington, USA

Abstract

Research Article| April 01, 2005 Oxygen isotope evidence for the late Cenozoic development of an orographic rain shadow in eastern Washington, USA Akinori Takeuchi; Akinori Takeuchi 1Department of Geology, Washington State University, P.O. Box 642812, Pullman, Washington 99164-2812, USA Search for other works by this author on: GSW Google Scholar Peter B. Larson Peter B. Larson 1Department of Geology, Washington State University, P.O. Box 642812, Pullman, Washington 99164-2812, USA Search for other works by this author on: GSW Google Scholar Geology (2005) 33 (4): 313–316. https://doi.org/10.1130/G21335.1 Article history received: 09 Nov 2004 rev-recd: 03 Dec 2004 accepted: 03 Dec 2004 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Akinori Takeuchi, Peter B. Larson; Oxygen isotope evidence for the late Cenozoic development of an orographic rain shadow in eastern Washington, USA. Geology 2005;; 33 (4): 313–316. doi: https://doi.org/10.1130/G21335.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Topographic development of the southern Washington Cascade Range and its influence on regional climate on the leeward side of the range for the past 15.6 m.y. are evaluated, using oxygen isotope ratios (δ18O) of ancient meteoric water recorded in authigenic smectites. The δ18O values of authigenic smectites from paleosols and altered tuffs on the east side of the range exhibit a temporal and continuous decrease of ∼3‰–4‰ from 15.6 Ma to the present. Taking into account a regional temperature change in eastern Washington since the middle Miocene, the calculated δ18O values of regional meteoric water show a negative shift of ∼3.5‰–4.5‰ over the same interval. Such a decrease is similar to the change in the δ18O values of modern precipitation from the coastal side to a region downwind of the Washington Cascades. This negative shift of the calculated δ18O values on the east side of the range is best explained by the development of a rain shadow due to the tectonic rock uplift of the Cascades during the late Cenozoic. Based on the empirically calculated relationship between change in elevation and change in the δ18O value of precipitation, paleorelief of the southern Washington Cascades since 15.6 Ma is estimated to be ∼1.2–1.7 km. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.