Fig. 1.1 Iceland is an elevated plateau in the middle of the North Atlantic, situated at the junction between the Reykjanes and Kolbeinsey Ridge segments. Also shown: the axis of the Mid-Atlantic Ridge (heavy solid line), the North Atlantic basalt plateau (black) and their submarine equivalents (grey). The line with the dots shows the position of the Iceland mantle plume from 65 million years to the present day.
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Fig. 1.2 The principal elements of the geology in Iceland, outlining the distribution of the major geological subdivisions, including the main fault structures and volcanic zones and belts. RR, Reykjanes Ridge; RVB, Reykjanes Volcanic Belt; WVZ, West Volcanic Zone; MIB, Mid-Iceland Belt; SISZ, South Iceland Seismic Zone; EVZ, East Volcanic Zone; NVZ, North Volcanic Zone; TFZ, Tjörnes Fracture Zone; KR, Kolbeinsey Ridge; ÖVB, Öræfi Volcanic Belt; and SVB, Snæfellsnes Volcanic Belt. Letters enclosed by filled black circles indicate axes of anticlines and synclunes refered to in the text, where B and H indicate the Borgarfjörður and Hreppar anticlines and S and H the Snæfellsnes and Víðidalur synclines.
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Fig. 1.5 Distribution of active volcanic systems among volcanic zones and belts in Iceland: 1. Reykjanes, 2. Krýsuvík, 3. Brennisteinsfjöll, 4. Hengill, 5. Hróðmundartindur, 6. Grímsnes, 7. Geysir, 8. Prestahnjúkur, 9. Hveravellir, 10. Hofsjökull, 11. Tungnafellsjökull, 12, Vestmannaeyjar, 13. Eyjafjallajökull, 14. Katla, 15. Tindfjöll, 16. Hekla-Vatnafjöll, 17. Torfajökull, 18. Bárðarbunga-Veiðivötn, 19. Grímsvötn, 20. Kverkfjöll, 21. Askja, 22. Fremrinámur, 23. Krafla, 24. Þeistareykir, 25. Öræfajökull, 26. Esjufjöll, 27. Snæfell, 28. Ljósufjöll, 29. Helgrindur, 30. Snæfellsjökull. The large open circle indicates the approximate centre of the Iceland mantle plume. Dotted line shows the northern limits of the East Volcanic Zone, whereas the hachured line indicates the boundary between the active and propagating rift segments of the zone.
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Fig. 6. (a) The main structural elements of a volcanic system. Abbreviations: c, crustal magma chamber; ds, dyke swarm; cv, central volcano; fs, fissure swarm; fe, fissure eruption. (b) Injection and growth of a dyke feeding an eruption during a rifting episode. The numbers indicate the growth sequence of the dyke rising through the crust in a major eruption episode.
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