Petrology of mugearite-hawaiite: Early extrusives in the 1973 Heimaey eruption,Iceland |
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| Authors: | SP Jakobsson AK Pedersen JG Rönsbo L Melchior Larsen |
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| Institution: | 1. Museum of Natural History, P.O. Box 5320, Reykjavik, Iceland;2. Mineralogisk Museum, University of Copenhagen, Østervoldgade 5–7, Denmark;3. Mineralogisk Institut, University of Copenhagen, Østervoldgade 5–7, Denmark;4. Petrologisk Institut, University of Copenhagen, Østervoldgade 5–7, Denmark |
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| Abstract: | Rocks which erupted during the first few weeks are described and chemical analyses of rocks and microprobe analyses of minerals are presented. An outline of the eruption history and of the geology of the area is given. A gradational change in chemistry from mugearitic to hawaiitic composition is recorded. Xenoliths of hypersthene gabbro not cognate with magma were discovered in the mugearite. One xenolith has reacted with the mugearite magma at depth to form pargasitic hornblende and kaersutite. It is argued that the magma reacted with the xenoliths at a total pressure well below 8–9 kbar and at a gas pressure higher 1 kbar. |
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