Geologic Setting
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Geologic Setting. - Iceland “Tertiary Formation” is part of the North Atlantic Igneous Province - magmatic activity began around ~61 Ma - continental flood basalts from 61-56 Ma found from Baffin Island, W & E Greenland, N Ireland, and Scotland.

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Geologic Setting

- Iceland “Tertiary Formation” is part of the North Atlantic Igneous Province

- magmatic activity began around ~61 Ma

- continental flood basalts from 61-56 Ma found from Baffin Island, W & E Greenland, N Ireland, and Scotland

Source: “Origin of the Iceland hotspot and the North Atlantic Igneous Province”, Korenaga, 2004, http://www.mantleplumes.org/


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Icelandic Rift Zones

- WVZ and NVZ (western and northern volcanic zones) represent the current mid-ocean ridge track

- EVZ is propagating to the south

- SISZ = south Iceland seismic zone, connects WVZ and EVZ

- EVZ represents a juvenile ridge zone; eventually the mid-ocean ridge will jump from the WVZ to the EVZ

Source: “Tertiary Volcanism in Iceland”, Harðarson et al., Jökull, 2008.


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Icelandic Hot Spot Track

- Greenland, Iceland, Faeroe “ridge” represents a hot-spot trail

- proto-Iceland may have been formed off the east coast of Greenland (hot spot reached East Greenland coast between 40-35 Ma)

- connected by a trail of small islands or a land bridge (supported by paleobotanical evidence, Grimmson et al. 2007)

Source: “The Faeroe-Iceland-Greenland Aseismic Ridge and the Western Boundary Undercurrent”, P. R. Vogt, Nature, Sep. 1972


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Icelandic Volcanoes

Tertiary = 16 to 3.3 Ma

Plio-Pliestocene = 3.3 to 0.78 Ma

Upper Pliestocene = 0.78 Ma to 15000 yr BP

Holocene = 15000 yr BP to present

-- tertiary volcanoes = open, unfilled circles

-- Plio-Pliestocene = crossed, unfilled circles

-- active volcanoes = brown, filled circles

Source: “Tertiary Volcanism in Iceland”, Harðarson et al., Jökull, 2008.


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Volcanic Hazards

plinian eruption of Hekla in 1947

(plume reached 28 km)

lava and tephra deposits covering

a small town by Eldfell eruption in

1973

a jökulhlaup glacial outwash plain

destroying a section of the ring road

(Highway 1)

Source: “Volcanic Hazards in Iceland”, Gudmundsson et al., Jökull, 2008.


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Volcanic Hazards

-- tephra fallout isopach map

-- fallout of >10 cm can cause roof cave-ins

-- can cause problems with farming (as in 1619, 1873, 1903 eruptions of Grimsvötn)

-- historical eruptions have had plumes from 8-15 km

-- map of historical and prehistoric lavas

-- pyroclastic flows are not common, although the subplinian Hekla eruption in 2000 produced flows up to 5 km from the vent

Source: “Volcanic Hazards in Iceland”, Gudmundsson et al., Jökull, 2008.


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Jokülhlaups

-- jokülhlaups: glacial outwash floods

-- can be caused by geothermal activity or by volcanic eruption-- 1 to 1.5 hours to notify and evacuate areas

-- water depth exceeding 1 meter and flow velocities > 1 m/s

-- 300,000 m3/s of material discharged

Source: “Volcanic Hazards in Iceland”, Gudmundsson et al., Jökull, 2008.


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