Original paper

Basalts of Oregon (U. S. A.) and their Geotectonic Environment, III. Petrochemistry of Tertiary and Quaternary Continental Basalts of Eastern Oregon

Loeschke, Jörg

Neues Jahrbuch für Mineralogie - Abhandlungen Band 144 Heft 3 (1982), p. 268 - 290

58 references

published: Sep 1, 1982

BibTeX file

ArtNo. ESP154014403004, Price: 29.00 €

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Abstract

As part of a series of studies of interrelations between basic volcanism and crustal structure at the northwestern continental margin of the United States (Loeschke, 1979 a, b), a review of chemical compositions of continental basalts of eastern Oregon is given here. This study is based on 60 chemical analyses of Miocene continental lava flows (Columbia River basalt, Steens Mountain basalt), and of Pliocene to Quaternary continental lava flows and cinder cones. The major and trace element analyses (Zr, Y, Sr, Rb, Ni, Cr) show that continental basalts are very heterogeneous in their chemical composition and that some continental basalts of eastern Oregon have chemical affinities to oceanic basalts. A comparison of SiO2, TiO2, MgO, CaO, K20, P2OS, Sr, and Rb average values reveals that there are significant differences in the average compositions of continental basalts of eastern Oregon, basic volcanic rocks of the active continental margin of the Oregon Cascades, and oceanic basalts of the Oregon Coast Range.

Keywords

Continental basaltlava flowscinder conesplateau basaltclassificationmajor elementstrace-element analysesTiZrYSrRbNiCrbasaltic compositioncontinental marginactive marginsoceanic basaltNeogeneQuaternaryOregon