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Iceland: What we know and what we don’t

Rift to Ridge ‘07 meeting, 28-29 June 2007 National Oceanography Centre, Southampton Invited keynote talk. Iceland: What we know and what we don’t. Gillian R. Foulger Durham University, U.K. What we know and what we don’t is person-dependent. Is Iceland hot?. D T = 93˚C (Ribe et al., 1995)

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Iceland: What we know and what we don’t

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  1. Rift to Ridge ‘07 meeting, 28-29 June 2007 National Oceanography Centre, Southampton Invited keynote talk Iceland: What we know and what we don’t Gillian R. Foulger Durham University, U.K.

  2. What we know and what we don’t is person-dependent

  3. Is Iceland hot? • DT = 93˚C (Ribe et al., 1995) • DT = 0-200˚C (Foulger et al., 2000) • DT = 70-190˚C (Herzberg et al., 2007) • DT = 270˚C (Langmuir et al., 1992)

  4. Centre of “the” Iceland plume Is the Iceland “hotspot” a spot?

  5. “How does a hotspot influence the development of an oceanic basin…” • How does breaking the law affect crime?

  6. Other plume diagnostics • Precursory uplift • Initial LIP • Time-progressive volcanic chain • Deep mantle seismic anomaly

  7. 400-900 m 420-620 m 380-590 m 180-425 m 0-100 m 500-800 m 0 - 200 m 0-200 m Upliftcontemporaneous, fast, permanent Jones (2005)

  8. LIPNot one, but two

  9. LIP # 2 • Iceland LIP started ~ 30 Ma • Area = ~ 500,000 km2

  10. Time-progressive chain

  11. Seismic anomaly Ritsema et al. (1999) model of Bijwaard & Spakman (1999)

  12. Now I’ve got that off my chest, let’s turn to some problems • Complex spreading • An Easter-type trapped microplate? • Composition of the crust and mantle

  13. 1. Complex spreading • How? • Why? • What is the way forward?

  14. 1. Complex spreading

  15. 1. Complex spreading

  16. 1. Complex spreading

  17. 2. A trapped microplate beneath Iceland

  18. 3. Composition of crust and mantle

  19. 3. Composition of crust and mantle

  20. 3. Composition of crust and mantle Iceland Shelf

  21. 3. Composition of crust and mantle • Dr 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?

  22. “To summarise the current state of knowledge…” • We know a lot, but understand little

  23. Resources http://www.mantleplumes.org/

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