Petrogenesis of Silicic Rocks from the Króksfjördur Central Volcano, NW Iceland

Calc-alkaline dacites are found in the Tertiary Kroksfjordur central volcano besides the more typical tholeiitic dacites and rhyolites characteristic of Icelandic rift zones. It is clear that these calc-alkaline dacites are not subduction related, but their chemistry and petrography are definitely c...

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Bibliographic Details
Published in:Journal of petrology 1992-12, Vol.33 (6), p.1345-1369
Main Authors: JÓNASSON, K., HOLM, P. M., PEDERSEN, A. K.
Format: Article
Language:English
Subjects:
Crystalline rocks
Earth sciences
Earth, ocean, space
Exact sciences and technology
Igneous and metamorphic rocks petrology, volcanic processes, magmas
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Summary:Calc-alkaline dacites are found in the Tertiary Kroksfjordur central volcano besides the more typical tholeiitic dacites and rhyolites characteristic of Icelandic rift zones. It is clear that these calc-alkaline dacites are not subduction related, but their chemistry and petrography are definitely calc-alkaline. They are much lower in Fe and higher in Ca and Al than other rocks from Iceland with comparable silica percentages. They are significantly depleted in the high field strength elements (HFSE, e.g., Nb, Zr, Y, and heavy rare earth elements), and some of them contain hydrous phases or their relics. The anhydrous phase assemblage and relatively high Fe content of the tholeiitic silicic rocks indicate generation at shallow depths (PH2o
ISSN:0022-3530
1460-2415
DOI:10.1093/petrology/33.6.1345