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Origin of high-alumina basalt, andesite, and dacite magmas

January 1, 1964

The typical volcanic rocks of most island arcs and eugeosynclines, and of some continental environments, are basalt, andesite, and dacite, of high alumina content. The high-alumina basalt differs from tholeiitic basalt primarily in having a greater content of the components of calcic plagioclase. Laboratory data indicate that in the upper mantle, below the level at which the basaltic component of mantle rock is transformed by pressure to eclogite or pyroxenite, the entire basaltic portion probably is melted within a narrow temperature range, but that above the level of that transformation plagioclase is melted selectively before pyroxene over a wide temperature range. The broad spectrum of high-alumina magmas may represent widely varying degrees of partial melting above the transformation level, whereas narrow-spectrum tholeiite magma may represent more complete melting beneath it.

Citation Information

Publication Year 1964
Title Origin of high-alumina basalt, andesite, and dacite magmas
Authors W. Hamilton
Publication Type Article
Publication Subtype Journal Article
Series Title Science
Series Number
Index ID 70010683
Record Source USGS Publications Warehouse
USGS Organization