Physical and chemical constraints on the evolution of the Columbia River basalt

Research Article| August 01, 1984 Physical and chemical constraints on the evolution of the Columbia River basalt P. R. Hooper P. R. Hooper 1Department of Geology, Washington State University, Pullman, Washington 99164 Search for other works by this author on: GSW Google Scholar Geology (1984) 12 (8): 495–499. https://doi.org/10.1130/0091-7613(1984)12<495:PACCOT>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation P. R. Hooper; Physical and chemical constraints on the evolution of the Columbia River basalt. Geology 1984;; 12 (8): 495–499. doi: https://doi.org/10.1130/0091-7613(1984)12<495:PACCOT>2.0.CO;2 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 Physical and chemical constraints require that Columbia River basalt flows were fed from a large (>700 km3) magma reservoir near the crust-mantle boundary and prohibit significant crystal fractionation or crustal assimilation between reservoir and surface. Demonstrable fractionation of plagioclase + olivine ± pyroxene in the reservoir largely obviates the need for an unusual iron-rich pyroxenite source. Variation of Sr and Nd isotope ratios with age in the main series of Columbia River basalt and variation in such incompatible trace-element ratios as Ba/P suggest lower crustal assimilation at the top of the reservoir combined with crystal fractionation. However, decoupling between isotope ratios and incompatible element ratios implies two separate processes in addition to crystal fractionation, of which lower crustal assimilation may be one. The other process may involve the participation of a vertically heterogeneous mantle resulting from metasomatism in the continental lithosphere. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.