Volcanism and Tectonism in the Columbia River Flood-Basalt Province

The occurrence of interstitial granite-glass in all formations of the Columbia River Basalt Group and its petrogenetic implications
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Published:January 01, 1989
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CiteCitation
R. St J. Lambert, I. K. Marsh, V. E. Chamberlain, 1989. "The occurrence of interstitial granite-glass in all formations of the Columbia River Basalt Group and its petrogenetic implications", Volcanism and Tectonism in the Columbia River Flood-Basalt Province, Stephen P. Reidel, Peter R. Hooper
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Almost all Columbia River Basalt Group (CRBG) flows contain a residuum that consists of two phases, one chlorophaeite-rich and one a granite-glass. The chlorophaeite includes types that vary from irregular aggregates to polycrystalline spherules and drop-shaped inclusions of two major types occurring totally within the unaltered granite-glass. The granite-glass is usually isotropic but may be cryptocrystalline. The average analysis for our samples from Wanapum Basalt flows is SiO2, 76.1 percent; Al2O3, 12.5 percent; FeO(T), 1.7 percent; MgO, 0.6 percent; CaO, 0.4 percent; Na2O, 2 percent; K2O, 6 percent; and TiO...