Post on 01-Jan-2016
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Iceland: What we know and what we don’t
Gillian R. Foulger
Durham University, U.K.
Rift to Ridge ‘07 meeting, 28-29 June 2007National Oceanography Centre, Southampton
Invited keynote talk
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What we know and what we don’t is person-dependent
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Is Iceland hot?
• T = 93˚C (Ribe et al., 1995)
• T = 0-200˚C (Foulger et al., 2000)
• T = 70-190˚C (Herzberg et al., 2007)
• T = 270˚C (Langmuir et al., 1992)
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Is the Iceland “hotspot” a spot?
Centre of “the” Iceland plume
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• “How does a hotspot influence the
development of an oceanic basin…”
• How does breaking the law affect crime?
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Other plume diagnostics
• Precursory uplift
• Initial LIP
• Time-progressive volcanic chain
• Deep mantle seismic anomaly
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Upliftcontemporaneous, fast, permanent
Jones (2005)
0-200 m0 - 200 m
500-800 m
400-900 m 420-620 m
180-425 m
0-100 m
380-590 m
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LIPNot one, but two
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• Iceland LIP started ~ 30 Ma• Area = ~ 500,000 km2
LIP # 2
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Time-progressive chain
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Seismic anomaly
Ritsema et al. (1999)model of Bijwaard & Spakman (1999)
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Now I’ve got that off my chest, let’s turn to some problems
1. Complex spreading
2. An Easter-type trapped microplate?
3. Composition of the crust and mantle
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1. Complex spreading
• How?
• Why?
• What is the way forward?
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1. Complex spreading
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1. Complex spreading
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1. Complex spreading
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2. A trapped microplate beneath Iceland
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3. Composition of crust and mantle
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3. Composition of crust and mantle
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3. Composition of crust and mantle
IcelandShelf
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3. Composition of crust and mantle
• mantle-lowercrust ~ 100 kg/m3
• Composition unknown• Source of Icelandic lavas partly recycled
surface materials– crust?– lithosphere?– how much? ~ 10%? (Sobolev et al., 2007)– where does microplate fit in?
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• “To summarise the current state of
knowledge…”
• We know a lot, but understand little
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http://www.mantleplumes.org/Resources
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