Náttúrufræðingurinn - 2012, Síða 111

111
Tímarit Hins íslenska náttúrufræðifélags
Heimildir
1. Walker, G.P.L. 1975. Excess spreading axes and spreading rate in Ice-
land. Nature 255. 468–470.
2. Árni Hjartarson 2009. Central volcanoes as indicators for the spread-
ing rate in Iceland. Bls. 323–330 í: Studies in Volcanology: The legacy
of George Walker (ritstj. Þorvaldur Þórðarson, Guðrún Larsen, Row-
land, S.K. & Ármann Höskuldsson). Special Publications of IAVCEI 2.
Geological Society, London.
3. Þóra Árnadóttir, Halldór Geirsson & Jiang, W. 2008. Crustal deformation
in Iceland: Plate spreading and earthquake deformation. Jökull 58. 59–74.
4. DeMets, C., Gordon, R.G., Argus, D.F. & Stein, S. 1994. Effect of recent
revisions to the geomagnetic reversal time scale on estimates of current
plate motions. Geophysical Research Letters 21. 2191–2194.
5. Martin, E., Paquette, J.L., Bosse, V., Ruffet G., Tiepolo, M. & Olgeir
Sigmarsson 2011. Geodynamics of rift-plume interaction in Iceland as
constrained by new 40Ar/39Ar and in situ U-Pb zircon ages. Earth and
Planetary Science Letters 311. 28–38.
6. Moorbath, S., Sigurðsson, H. & Goodwin, R. 1968. K-Ar ages of the oldest
exposed rocks in Iceland. Earth and Planetary Science Letters 4. 197–205.
7. Kristján Geirsson 1993. Pétrologie d’une série tholéiitique complète : le
volcan central de Fagridalur. Doktorsritgerð, Université Pierre et Marie
Curie, Paris VI. 217 bls.
8. Guðmundur Pálmason 1973. Kinematics and heat flow in a volcanic rift
zone, with application to Iceland. Geophys. J.R. Astr. Soc. 33. 451–481.
9. Guðmundur Pálmason 1986. Model of crustal formation in Iceland and
application to submarine mid-ocean ridges. Bls. 87–97 í: The Geology
of North America. The Western North Atlantic Region (ritstj. Vogt, P.R.
& Tucholke, B.E.). Geological Society of America, Boulder, CO.
10. Jancin, M., Young, K.D., Voight, B., Aronson, J.L. & Kristján Sæmunds-
son 1985. Stratigraphy and K/Ar ages across the west flank of the
northeast Iceland axial rift zone, in relation to the 7 Ma volcano-tecton-
ic reorganization of Iceland. Journal of Geophysical Research 90.
9961–9985.
11. Olgeir Sigmarsson 2011. Hvítserkur: fjall sem myndaðist í setskál.
Glettingur 21. 20–23.
12. Kristján Sæmundsson 1974. Evolution of the Axial Rifting Zone in
Northern Iceland and the Tjörnes Fracture Zone. Geological Society of
America Bulletin 85. 495–504.
13. Kristján Sæmundsson 1979. Outline of the geology of Iceland. Jökull
29. 7–28.
14. Haukur Jóhannesson 1980. Jarðlagaskipan og þróun rekbelta á Vestur-
landi. Náttúrufræðingurinn 50. 13–31.
15. Bott, M.H.P. 1985. Plate tectonic evolution of the Iceland transverse ridge
and adjacent regions. Journal of Geophysical Research 90. 9953–9960.
16. Foulger, G.R. 2006. Older crust underlies Iceland. Geophysical Journal
International 165. 672–676.
Póst- og netföng höfunda/Authors’ addresses
Olgeir Sigmarsson
Jarðvísindastofnun Háskólans, Öskju, Sturlugötu 7, IS-101 Reykjavík.
Laboratoire Magmas et Volcans,
Université Blaise Pascal og CNRS,
5 rue Kessler, 63038 Clermont-Ferrand, Frakkland
olgeir@raunvis.hi.is
Erwan Martin
Institut des Sciences de la Terre de Paris,
Université Paris 6, 75005, Paris, France.
erwan.martin@upmc.fr
Jean-Louis Paquette og Valerie Bosse
J.L.Paquette og V.Bosse@opgc.univ-bpclermont.fr
Kristján Geirsson
Umhverfisstofnun,
Suðurlandsbraut 24,
IS-108 Reykjavík
kristjan@umhverfisstofnun.is
Um höfundana
Olgeir Sigmarsson (f. 1958) lauk doktorsprófi í jarðefna-
fræði frá Blaise Pascal háskólanum í Clermont-Ferrand,
Frakklandi 1990. Hann starfar við Vísindastofnun Frakk-
lands (Centre National de la Recherche Scientifique) og
Jarðvísindastofnun Háskólans.
Erwan Martin (f. 1979) lauk doktorsprófi í jarðefnafræði
frá Blaise Pascal háskóla, Clermont-Ferrand, Frakklandi
2006. Hann kennir nú við Parísarháskóla.
Jean-Louis Paquette vinnur við Vísindastofnun Frakk-
lands og Blaise Pascal háskólann í Clermont-Ferrand,
Frakklandi.
Valerie Bosse vinnur við Blaise Pascal háskólann í
Clermont-Ferrand, Frakklandi.
Kristján Geirsson (f. 1968) lauk doktorsprófi í berg- og
steindafræði við Pierre et Marie Curie háskólann í París,
Frakklandi 1993. Hann starfar á Umhverfisstofnun.
the NIRZ half spreading rate has been
between 0.7 and 1.1 cm/yr as revealed
by linear correlation between age and
longitude. The excess width of Iceland
can thus not be explained by faster
spreading rate in the past. This ~200 km
‘excess’ of crust must take into account
the eastward relocation of the rift zone
and corresponding older crustal cap-
ture over the course of Iceland’s geo-
logical history.
The need for rift relocations and
crustal capture to explain the width of
Iceland strongly suggests that during
rift/plume interaction the mantle
plume plays an active role. It forces the
active rift zone to be frequently relo-
cated by rift jumps above its center,
leaving inactive rift zones as older syn-
clines in the geological record. This re-
sults in an eastward position of the rift
zone in Iceland relative to the North
Atlantic ridge.