title: Continental crust beneath southeast Iceland.
abstract: The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume.
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway; Geological Survey of Norway, Geodynamics, N-7491 Trondheim, Norway; School of Geosciences, University of Witwatersrand, Wits 2050, South Africa; t.h.torsvik@geo.uio.no.
authors.forename: Trond H
authors.initials: TH
authors.lastname: Torsvik
authors.affiliation: Vestfonna Geophysical, N-8310 Kabelvåg, Norway;
authors.forename: Hans E F
authors.initials: HE
authors.lastname: Amundsen
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway; Natural History Museum, University of Oslo, N-0318 Oslo, Norway.
authors.forename: Reidar G
authors.initials: RG
authors.lastname: Trønnes
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway;
authors.forename: Pavel V
authors.initials: PV
authors.lastname: Doubrovine
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway;
authors.forename: Carmen
authors.initials: C
authors.lastname: Gaina
authors.affiliation: Department of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 3GP, United Kingdom;
authors.forename: Nick J
authors.initials: NJ
authors.lastname: Kusznir
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway; Helmholtz Centre Potsdam, GeoForschungsZentrum, Section 2.5 Geodynamic Modelling, D-14473 Potsdam, Germany;
authors.forename: Bernhard
authors.initials: B
authors.lastname: Steinberger
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway; Geosciences, University of Oslo, N-0316 Oslo, Norway;
authors.forename: Fernando
authors.initials: F
authors.lastname: Corfu
authors.affiliation: School of Geosciences, University of Witwatersrand, Wits 2050, South Africa;
authors.forename: Lewis D
authors.initials: LD
authors.lastname: Ashwal
authors.affiliation: Core to Crust Fluid Systems/Geochemical Evolution and Metallogeny of Continents, Macquarie University, Sydney, NSW 2109, Australia; and.
authors.forename: William L
authors.initials: WL
authors.lastname: Griffin
authors.affiliation: Centre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway;
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Werner
authors.affiliation: Physics of Geological Processes, University of Oslo, N-0316 Oslo, Norway.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Jamtveit
keywords: continental crust; geochemistry; geology; plate reconstructions; plumes
references.citation: Nature. 2000 Feb 3;403(6769):530-4
references.pmid: 10676958
references.citation: Nature. 2007 Aug 9;448(7154):684-7
references.pmid: 17687322
references.citation: Nature. 2010 Jul 15;466(7304):352-5
references.pmid: 20631796
references.citation: Nature. 2010 Aug 12;466(7308):853-6
references.pmid: 20703304
references.citation: Proc Natl Acad Sci U S A. 2014 Jun 17;111(24):8735-40
references.pmid: 24889632
references.citation: Nature. 2008 May 1;453(7191):89-93
references.pmid: 18451860