Seismic model of Iceland's crust

Павленкова, Н. И.; Zverev, S. M.

doi:10.1007/bf01764327

Cited by 17 publications

(8 citation statements)

References 4 publications

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“…There has been a long debate concerning the thickness of the Icelandic crust. Some [ Palmason , 1971; Gebrande et al , 1980; Beblo and Bjornsson , 1978, 1980; Flovenz , 1992, 1993; Björnson et al , 2005] argue for a thin, hot crust while others [ Båth , 1960; Zverev et al , 1976; Pavlenkova and Zverev , 1981; Bjarnason et al , 1993; Menke and Levin , 1994; White et al , 1996; Staples et al , 1997; Darbyshire et al , 1998, 2000a, 2000b; Du and Foulger , 1999, 2001; Du et al , 2002; Weir et al , 2001; Kaban et al , 2002; Foulger et al , 2003; Schlindwein , 2006] argue for a thick, cold crust. Receiver function studies have also been applied in both Greenland and Iceland to decipher the crustal parameters and in turn elucidated the evolution and nature of the crust and lithosphere [ Darbyshire et al , 2000a; Du and Foulger , 1999, 2001; Du et al , 2002; Schlindwein , 2006].…”

Section: Introductionmentioning

confidence: 99%

Crustal structure of Iceland and Greenland from receiver function studies

Kumar¹,

Kind²,

Priestley³

et al. 2007

J. Geophys. Res.

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[1] We used data from both permanent and temporary seismic networks on Iceland and Greenland to investigate the crustal thickness by partly reinterpreting earlier data (P receiver functions) and adding S receiver functions to better constrain the results. We obtained good conversions from the Moho and also crustal multiples in both Iceland and Greenland. The central ice covered part of Greenland has an average crustal thickness of 40 km, typical for a craton. At the edges of Greenland the crustal thickness decreases to 30-40 km. On the east coast of Greenland, where the track of the Iceland plume is thought to have affected the lithosphere, the crustal thickness is only 24-26 km. In contrast to previous studies, we find that the crustal thickness in the east and the northwest coastal regions of Iceland is more than 40 km, similar to beneath the active volcanic region. In the southwest region of Iceland and along the mid-ocean ridge, the crustal thickness is only 25 km or less. Also in contrast to earlier receiver function interpretations, which deduced a broad crust-mantle transition zone for Iceland, we find indications for a normal, sharper Moho beneath a number of sites.

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Section: Introductionmentioning

confidence: 99%

Crustal structure of Iceland and Greenland from receiver function studies

Kumar¹,

Kind²,

Priestley³

et al. 2007

J. Geophys. Res.

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“…Different authors have come to quite different conclusions, especially regarding the thickness and the thermal state of the crust. In principle two different models of the Icelandic crust have been put forward, the thin and hot crust model (Pálmason 1971; Gebrande et al 1980; Beblo & Björnsson 1978, 1980; Flóvenz 1992, 1993) and the thick crust model (Båth 1960; Zverev et al 1976; Pavlenkova & Zverev 1981; Bjarnason et al 1993; Menke & Levin 1994; White et al 1996; Darbyshire et al 1998, 2000a,b; Weir et al 2001). These models are based on different interpretations of seismic data, with or without the aid of magnetotelluric, heat flow and gravity data.…”

Section: Introductionmentioning

confidence: 99%

Nature of the crust-mantle transition zone and the thermal state of the upper mantle beneath Iceland from gravity modelling

Kaban¹,

Flóvenz²,

Pálmason³

2002

Geophysical Journal International

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Summary Gravity data from Iceland and its surroundings are analysed and modelled with respect to seismic data. A Bouguer gravity map of Iceland is recomputed based on admittance between the topography and the gravity and with corrections for glacial ice sheets. From seismic data and with the help of relations between the residual topography and the depth to seismic boundaries we construct maps of the main seismic boundaries, including the Moho. By inversion calculations we recomputed these maps, assuming different density values for Seismic Layer 4 to fit the observed gravity field. We found that the average density of Layer 4 has to be in the range 3050–3150 kg m−3 in order to fit both seismic and gravity data. Thus we conclude that Layer 4 is a transition zone between the mantle and the oceanic crust in Iceland. Furthermore by assuming that the upper‐mantle density variations necessary to compensate for the gravity effect of crustal layers, are caused by thermal variations in the upper mantle, we calculate the depth to the 1200 °C isotherm to be at 30–50 km depth below Iceland but rising up to less than 20 km below parts of the volcanic zone in Northern Iceland. We conclude that the temperature within the Seismic Layer 4 is close to 600 °C at its top, increasing to approximately 950 °C at its bottom (Moho), which makes a widespread layer of partially molten material within Layer 4 unlikely. By use of cross spectral analysis of the gravity field and the external topographic load at short wavelengths, we conclude that the elastic plate thickness in Iceland can hardly exceed 6 km. In addition we point out that the residual isostatic anomalies have circular forms east of the eastern volcanic zone but are near parallel to the ridge axis on the western side. This form of the anomalies may be caused by pressure from the eastward moving mantle plume below the eastern volcanic zone.

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“…Even early on, this 'hot-crust' model of Iceland had it critics. In particular, Zverev et al (1976) and Pavlenkova & Zverev (1981) argued for a much thicker (30 km) and cooler (< 600 "C) crust, on the basis of the 1972 NASP long-range refraction profile. More recent seismic data have corroborated this idea.…”

Section: Introductionmentioning

confidence: 99%

Reinterpretation of the RRISP-77 Iceland shear-wave profiles

Menke

Brandsdóttír

Einarsson

et al. 1996

Geophysical Journal International

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S U M M A R YTwo shear-wave profiles, E and G, collected during the 1977 Reykjanes Ridge Iceland Seismic Experiment have played an important role in models of the Icelandic crust. They were originally interpreted as indicating very low shear-wave velocities and abnormally low shear-wave quality factors in the 10-15km depth range. These attributes, which are indicative of near-solidus temperatures, were used to support the hypothesis that the crust of Iceland is relatively thin (10-15 km) and underlain by partially molten material. More recent seismic data, however, contradict this hypothesis and suggest that the crust is thicker (20-30 km) and cooler. A re-examination of the RRISP-77 data indicates that the low shear-wave velocities are artefacts arising from source static anomalies (in the case of profile G) and misidentification of a secondary shear phase, S,S, as S (in the case of profile E). Furthermore, the attenuation occurs at ranges when rays from the shots pass near the Askja (profile E) and Katla and Oraefajokull (profile G) volcanoes. It may therefore have a localized source, and not be diagnostic of Icelandic crust as a whole. This new interpretation of the RRISP-77 shear-wave data is consistent with models having a thick, cold crust.

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Seismic model of Iceland's crust

Cited by 17 publications

References 4 publications

Crustal structure of Iceland and Greenland from receiver function studies

Crustal structure of Iceland and Greenland from receiver function studies

Nature of the crust-mantle transition zone and the thermal state of the upper mantle beneath Iceland from gravity modelling

Reinterpretation of the RRISP-77 Iceland shear-wave profiles

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