Physical evolution of Grande Ronde Basalt magmas, Columbia River Basalt group, north-western USA

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dc.contributor.author Caprarelli, Graziella en_US
dc.contributor.author Reidel, Stephen en_US
dc.date.accessioned 2009-06-26T04:11:12Z
dc.date.available 2009-06-26T04:11:12Z
dc.date.issued 2004 en_US
dc.identifier 2004001189 en_US
dc.identifier.citation Caprarelli Graziella and Reidel Stephen 2004, 'Physical evolution of Grande Ronde Basalt magmas, Columbia River Basalt group, north-western USA', Springer, vol. 80, no. 1-2, pp. 1-25. en_US
dc.identifier.issn 0930-0708 en_US
dc.identifier.other C1 en_US
dc.identifier.uri http://hdl.handle.net/10453/696
dc.description.abstract In this paper we present what is, to the best of our knowledge, the first comprehensive study of clinopyroxenes and plagioclases contained in the flows of the Grande Ronde Basalt member of the Columbia River Basalt Group (northwestern USA). The rocks have MgO(wt%)<6%, and trace amounts of Cr and Ni. About 56% of extracted solid containing normative clinopyroxene and plagioclase explains the liquid line of descent from the more mafic sample (MgO wt%=5.89) to the most evolved. The most ubiquitous phases in the basalts are plagioclase and augite. Ilmenite and magnetite are accessories in all rocks. Olivine is present in small amount only in one sample (RT 89-7). Based on principles of Ca?Na plagioclase?liquid exchange, estimates of pre-eruptive magmatic water are < 2.4thinspwt%. From clinopyroxene?liquid equilibria, calculated pressures and temperatures of ascending magmas are between 1thinspatm and 0.617thinspGPa, and 1068thinsp?C and 1166thinsp?C, respectively. Compositions of magnetite?ilmenite pairs and olivine?clinopyroxene?oxide assemblages yield post-eruptive oxygen fugacities of DeltaNNO=?1.923, and one pre-eruptive value of DeltaNNO=? 2.455. A simple model of asthenospheric melting and magma ponding in the lower crust fits the physical parameters. en_US
dc.publisher Springer en_US
dc.relation.isbasedon http://dx.doi.org/10.1007/s00710-003-0017-1 en_US
dc.title Physical evolution of Grande Ronde Basalt magmas, Columbia River Basalt group, north-western USA en_US
dc.parent Mineralogy and Petrology en_US
dc.journal.volume 80 en_US
dc.journal.number 1-2 en_US
dc.publocation Vienna, Austria en_US
dc.identifier.startpage 1 en_US
dc.identifier.endpage 25 en_US
dc.cauo.name SCI.Environmental Sciences en_US
dc.conference Verified OK en_US
dc.for 040300 en_US
dc.personcode 960836 en_US
dc.personcode 0000020529 en_US
dc.percentage 100 en_US
dc.classification.name Geology en_US
dc.classification.type FOR-08 en_US


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