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Article: Igneous rock associations 8. Arc magmatism II: geochemical and isotopic characteristics.(Series)
- Article from:
- Geoscience Canada
- Article date:
- March 1, 2007
- Author:
CopyrightCOPYRIGHT 2007 Geological Association of Canada. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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SUMMARY
Geochemical and isotopic data provide insights into the origin and evolution of magmatism found at destructive plate margins. Tholeiitic magmas are dominant in the early stages of oceanic island-arc genesis and calc-alkalic magmas are most common in mature oceanic arcs and in continental arcs where they may range from basalt to rhyolite in composition, including voluminous intermediate (andesitic) rocks. Experiments suggest that calc-alkalic mafic magmas are formed by melting of a hydrated mantle wedge and undergo low pressure fractional crystallization under near-[H.sub.2]O saturated conditions. Intermediate to felsic magmas are derived in a wide variety ...