MAGNUS--A Seismological Broadband Experiment to Resolve Crustal and Upper Mantle Structure beneath the Southern Scandes Mountains in Norway

Weidle, Christian; Maupin, Valérie; Ritter, Joachim; Kværna, Tormod; Schweitzer, Johannes; Balling, Niels; Thybo, Hans; Faleide, Jan Inge; Wenzel, F.

doi:10.1785/gssrl.81.1.76

Cited by 38 publications

(32 citation statements)

References 20 publications

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“…That study also outlined a P-wave low-velocity uppermost mantle below most of southern Norway, an area also characterized by low S-wave velocities, as shown by both S-wave traveltime tomography (Wawerzinek et al 2013) and surface wave analysis (Weidle & Maupin 2008;Maupin 2011;Köhler et al 2012). The above studies with results for southern Norway included data from the MAGNUS project (Weidle et al 2010) and formed part of the TopoScandiaDeep project (for a review see Maupin et al 2013), a component of the TOPOEUROPE program. Some recent continent-scale models also show velocity contrasts in southern Scandinavia for both P and S waves (Jakovlev et al 2012;Zhu et al 2012;Rickers et al 2013), although they generally have lower resolution than the above studies.…”

Section: Previous Studiesmentioning

confidence: 99%

Upper-mantleP- andS-wave velocities across the Northern Tornquist Zone from traveltime tomography

et al. 2015

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S U M M A R YThis study presents P-and S-wave velocity variations for the upper mantle in southern Scandinavia and northern Germany based on teleseismic traveltime tomography. Tectonically, this region includes the entire northern part of the prominent Tornquist Zone which follows along the transition from old Precambrian shield units to the east to younger Phanerozoic deep sedimentary basins to the southwest. We combine data from several separate temporary arrays/profiles (276 stations) deployed over a period of about 15 yr and permanent networks (31 stations) covering the areas of Denmark, northern Germany, southern Sweden and southern Norway. By performing an integrated P-and S-traveltime analysis, we obtain the first high-resolution combined 3-D V P and V S models, including variations in the V P /V S ratio, for the whole of this region of study. Relative station mean traveltime residuals vary within ±1 s for P wave and ±2 s for S wave, with early arrivals in shield areas of southern Sweden and later arrivals in the Danish and North German Basins, as well as in most of southern Norway. In good accordance with previous, mainly P-velocity models, a marked upper-mantle velocity boundary (UMVB) is accurately delineated between shield areas (with high seismic mantle velocity) and basins (with lower velocity). It continues northwards into southern Norway near the Oslo Graben area and further north across the Southern Scandes Mountains. This main boundary, extending to a depth of at least 300 km, is even more pronounced in our new S-velocity model, with velocity contrasts of up to ±2-3 per cent. It is also clearly reflected in the V P /V S ratio. Differences in this ratio of up to about ±2 per cent are observed across the boundary, with generally low values in shield areas to the east and relatively higher values in basin areas to the southwest and in most of southern Norway. Differences in the V P /V S ratio are believed to be a rather robust indicator of upper-mantle compositional differences. For the depth interval of about 100-300 km, thick, depleted, relatively cold shield lithosphere is indicated in southern Sweden, contrasting with more fertile, warm mantle asthenosphere beneath most of the basins in Denmark and northern Germany. Both compositional and temperature differences seem to play a significant role in explaining the UMVB between southern Norway and southern Sweden. In addition to the main regional upper-mantle velocity contrasts, a number of more local anomaly features are also outlined and discussed.

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Section: Previous Studiesmentioning

confidence: 99%

Upper-mantleP- andS-wave velocities across the Northern Tornquist Zone from traveltime tomography

et al. 2015

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“…We apply our analysis to seismological data recorded by the temporary MAGNUS network between September 2006 and June 2008 (Weidle et al, 2010), by the temporary DANSEIS network from April 2008 to June 2008, by the temporary CALAS stations (Medhus et al, 2009) and by permanent stations in the study area (Fig. 1).…”

Section: Measurement Of Travel Time Residualsmentioning

confidence: 99%

“…Our residual measurement procedure and the frequencydependence of the crustal corrections are illustrated using data from a network in southwestern Scandinavia (Weidle et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Measuring and crust-correcting finite-frequency travel time residuals – application to southwestern Scandinavia

Kolstrup

Maupin

2015

Solid Earth

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Abstract. We present a data-processing routine to compute relative finite-frequency travel time residuals using a combination of the Iterative Cross-Correlation and Stack (ICCS) algorithm and the Multi-Channel Cross-Correlation method (MCCC). The routine has been tailored for robust measurement of P-and S-wave travel times in several frequency bands and for avoiding cycle-skipping problems at the shortest periods. We also investigate the adequacy of ray theory to calculate crustal corrections for finite-frequency regional tomography in normal continental settings with nonthinned crust. We find that ray theory is valid for both P and S waves at all relevant frequencies as long as the crust does not contain low-velocity layers associated with sediments at the surface. Reverberations in the sediments perturb the arrival times of the S waves and the long-period P waves significantly, and need to be accounted for in crustal corrections. The data-processing routine and crustal corrections are illustrated using data from a network in southwestern Scandinavia.

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“…;Svenningsen et al, 2007). During this study the land stations of Profile 1 were deployed as an extension of the SE-NW trending profile across southern Norway in the Magnus Rex experiment (Weidle et al, 2010). The hydrocarbon exploration activity provides extensive documentation of the upper sedimentary section of the Mid-Norwegian Margin.…”

Section: Introductionmentioning

confidence: 99%

Crustal structure across the Møre margin, mid-Norway, from wide-angle seismic and gravity data

et al. 2014

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The Møre Margin in the NE Atlantic represents a dominantly passive margin with an unusual abrupt transition from high alpine topography onshore to a deep sedimentary basin offshore.In order to study this transition in detail, three ocean bottom seismometer profiles with deep seismic reflection and refraction data were acquired in 2009; two dip-profiles which were extended by land stations, and one tie-profile parallel to the strike of the Møre-Trøndelag Fault Complex. The modelling of the wide-angle seismic data was performed with a combined inversion and forward modelling approach and validated with a 3D-density model.Modeling of the geophysical data indicates the presence of a 12-15 km thick accumulation of sedimentary rocks in the Møre Basin. The modeling of the strike profile located closer to land shows a decrease in crustal velocity from north to south. Near the coast we observe an intracrustal reflector under the Trøndelag Platform, but not under the Slørebotn Sub-basin.Furthermore, two lower crustal high-velocity bodies are modeled, one located near the Møre Marginal High and one beneath the Slørebotn Sub-basin. While the outer lower crustal body is modeled with a density allowing an interpretation as magmatic underplating, the inner body has a density close to mantle density which might suggest an origin as an eclogized body, formed by metamorphosis of lower crustal gabbro during the Caledonian orogeny. The difference in velocity and extent of the lower crustal bodies seems to be controlled by the Jan 2 Mayen Lineament, suggesting that the lineament represents a pre-Caledonian structural feature in the basement.

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MAGNUS--A Seismological Broadband Experiment to Resolve Crustal and Upper Mantle Structure beneath the Southern Scandes Mountains in Norway

Cited by 38 publications

References 20 publications

Upper-mantleP- andS-wave velocities across the Northern Tornquist Zone from traveltime tomography

Upper-mantleP- andS-wave velocities across the Northern Tornquist Zone from traveltime tomography

Measuring and crust-correcting finite-frequency travel time residuals – application to southwestern Scandinavia

Crustal structure across the Møre margin, mid-Norway, from wide-angle seismic and gravity data

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