Preeruption history of the Grande Ronde Formation lavas, Columbia River Basalt Group, American Northwest: Evidence from phenocrysts

Research Article| April 01, 2004 Preeruption history of the Grande Ronde Formation lavas, Columbia River Basalt Group, American Northwest: Evidence from phenocrysts Sedelia Rodriguez Durand; Sedelia Rodriguez Durand 1Department of Earth Sciences and Florida Center for Analytical Electron Microscopy, Florida International University, Miami, Florida 33199, USA Search for other works by this author on: GSW Google Scholar Gautam Sen Gautam Sen 1Department of Earth Sciences and Florida Center for Analytical Electron Microscopy, Florida International University, Miami, Florida 33199, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Sedelia Rodriguez Durand 1Department of Earth Sciences and Florida Center for Analytical Electron Microscopy, Florida International University, Miami, Florida 33199, USA Gautam Sen 1Department of Earth Sciences and Florida Center for Analytical Electron Microscopy, Florida International University, Miami, Florida 33199, USA Publisher: Geological Society of America Received: 11 Aug 2003 Revision Received: 03 Dec 2003 Accepted: 04 Dec 2003 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2004) 32 (4): 293–296. https://doi.org/10.1130/G20109.1 Article history Received: 11 Aug 2003 Revision Received: 03 Dec 2003 Accepted: 04 Dec 2003 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 Sedelia Rodriguez Durand, Gautam Sen; Preeruption history of the Grande Ronde Formation lavas, Columbia River Basalt Group, American Northwest: Evidence from phenocrysts. Geology 2004;; 32 (4): 293–296. doi: https://doi.org/10.1130/G20109.1 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 Basaltic andesite lavas belonging to the Grande Ronde Formation constitute ∼87% of the Columbia River Basalt Group. Although these lavas are chemically evolved, they generally contain <5% phenocrysts. Two hypotheses have been proposed to explain this observation. The first hypothesis suggests that Grande Ronde lavas were near-primary melts generated by large-scale melting of eclogite from the inferred Yellowstone plume. The alternative hypothesis proposes that Grande Ronde magmas were extremely hydrous and rose rapidly from the mantle such that the dissolved water kept the magmas close to their liquidi. We present new information on textures and mineral chemistry of phenocrysts in two well-characterized field sections through the Grande Ronde Formation. The new data lead us to conclude that at least some of the Grande Ronde primary magmas were highly hydrous; however, they all underwent extensive fractionation, magma mixing, and degassing in a shallow intrusive network prior to eruption as lava. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.