Crustal Transect across the Lofoten Volcanic Passive Continental Margin, N. Norway, Obtained by Use of Ocean Bottom Seismographs, and Implications for Its Evolution.

Kodaira, Shuichi; Mjelde, Rolf; Sellevoll, Markvard A.; Hirschleber, H. B.; Iwasaki, Takaya; Kanazawa, Toshihiko; Shimamura, Hideki

doi:10.4294/jpe1952.43.729

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…10), and the lower crustal variation around the lower crustal reflector beneath the Bivrost lineament is also interpreted to indicate an increase in the volume of the intrusions. This southwestward increase of intrusions along the northern Norwegian margin is believed to be in accord with a southwestward increase in the influence of the Iceland hot spot (KODAIRA et al, 1996). It should be noted that the transition from the ''pure continental'' lower crust in Lofoten to the intruded lower crust in the Vo *ring Basin is not believed to represent a sharp boundary; it most likely changes gradually as in the model shown by MJELDE et al (1996a).…”

Section: Crystalline Crustmentioning

confidence: 60%

“…Figure 10 also shows a fence diagram along and across the Vo *ring and Lofoten margins inferred from the results of the 1988 and 1992 OBS studies of the Lofoten and Vo *ring margins. The crustal structure across the Lofoten and Vo *ring margins has been thoroughly discussed by MJELDE et al (1993MJELDE et al ( , 1996aMJELDE et al ( , 1997, KODAIRA et al (1996). This section mainly discusses the crustal variation along the Vo *ring-Lofoten margins based on the structure of Line 1, Line 1-N and L8 (Fig.…”

Section: Crystalline Crustmentioning

confidence: 99%

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Structure of a Volcanic Continental Margin Derived from Ocean-bottom Seismographic Data: The Northern Vøring Margin, off Norway

Kodaira

Mjelde

Shiobara

et al. 1998

Pure appl. geophys.

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This paper presents a crustal model derived from an Ocean Bottom Seismograph (OBS) study along the northern Vo *ring margin off Norway. The profile was acquired to map the crustal structure in the northernmost part of the Vo *ring Basin, and to link crustal models of the Lofoten and central Vo *ring Basin obtained by previous OBS studies. The Vo *ring margin, as well as the Lofoten margin to the north, was created by continental breakup between Norway and Greenland in late Paleocene-early Eocene. The rifting and continental breakup process were accompanied by intense extrusive and intrusive magmatic activities. The OBS data provide the whole crustal structure along the northern Vo *ring margin, in the area where the deep crustal structure cannot be resolved by conventional multichannel reflection data due to sill intrusions in the sedimentary sequence. The shallow part of the crustal model is characterized by up to 10 km thick sediments, a sequence of flood basalts and sill intrusions. The P-wave velocities in the flood basalts and sill intrusions are estimated to 5.0 km/s and 4.7-5.8 km/s, respectively. The model indicates an abrupt thickening of the upper crystalline crust from 3 km in the NE, to about 10 km towards the SE, with velocities of 6.0-6.2 km/s. The lower crustal velocities are not well resolved due to lack of clear refraction arrivals from the lower crust. However, the observed amplitude versus offsets are best explained by a model with a change in lower crustal velocities from 6.8 to 7.2 km/s beneath the Bivrost lineament. The modelling infers the presence of a lower crustal reflector beneath the lineament, which represents the landward continuation of the Bivrost lineament. Reflection arrivals from the Moho reveal a Moho depth of 23 km in the middle of the profile and 18-20 km in the northeastern part of the profile. A 370 km long crustal section from the central part of the Vo *ring Basin to the Lofoten margin, obtained by the results of this study and previous OBS studies, shows a simple thinned continental crust on the Lofoten margin, and a high velocity lower crust underlying an upper crust of varying thickness in the Vo *ring Basin. The transition between these structures is situated beneath the Bivrost lineament in the lower crust, and beneath the basement high about 40 km south of the lineament in the upper crust.

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Section: Crystalline Crustmentioning

confidence: 60%

Section: Crystalline Crustmentioning

confidence: 99%

Structure of a Volcanic Continental Margin Derived from Ocean-bottom Seismographic Data: The Northern Vøring Margin, off Norway

Kodaira

Mjelde

Shiobara

et al. 1998

Pure appl. geophys.

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“…Although extensive studies have been carried out to determine the crustal thickness and velocity structure of the Norwegian continental margin (e.g. Chroston & Brooks 1989; Planke et al 1991; Mjelde et al 1992; Kodaira et al 1995, 1998), very little work appears to have been undertaken on the lithospheric structure (especially the upper mantle) of the margin and Norwegian Sea area. Until now, surface wave studies have been impractical since most of the earthquake events that occur in the vicinity of this region are small ( M < 5.0) .…”

Section: Introductionmentioning

confidence: 99%

Transitional continental-oceanic structure beneath the Norwegian Sea from inversion of surface wave group velocity data

Midzi

Singh

Atakan

et al. 1999

Geophysical Journal International

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We have analysed the fundamental mode of Love and Rayleigh waves generated by 12 earthquakes located in the mid-Atlantic ridge and Jan Mayen fracture zone. Using the multiple filter analysis technique, we isolated the Rayleigh and Love wave group velocities for periods between 10 and 50 s. The surface wave propagation paths were divided into five groups, and average group velocities calculated for each group. The average group velocities were inverted and produced shear wave velocity models that correspond to a quasi-continental oceanic structure in the Greenland-Norwegian Sea region. Although resolution is poor at shallow depth, we obtained crustal thickness values of about 18 km in the Norwegian Sea area and 9 km in the region between Svalbard and Iceland. The abnormally thick crust in the Norwegian Sea area is ascribed to magmatic underplating and the thermal blanketing effect of sedimentary layers. Maximum crustal shear velocities vary between 3.5 and 3.9 km s−1 for most paths. An average lithospheric thickness of 60 km was observed, which is lower than expected for oceanic-type structure of similar age. We also observed low shear wave velocities in the lower crust and upper mantle. We suggest that high heat flow extending to depths of about 30 km beneath the surface can account for the thin lithosphere and observed low velocities. Anisotropy coefficients of 1-5 per cent in the shallow layers and >7 per cent in the upper mantle point to the existence of polarization anisotropy in the region.

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Variation of Icelandic and Hawaiian magmatism: evidence for co-pulsation of mantle plumes?

Mjelde

Faleide

2009

Mar Geophys Res

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Crustal Transect across the Lofoten Volcanic Passive Continental Margin, N. Norway, Obtained by Use of Ocean Bottom Seismographs, and Implications for Its Evolution.

Cited by 6 publications

References 21 publications

Structure of a Volcanic Continental Margin Derived from Ocean-bottom Seismographic Data: The Northern Vøring Margin, off Norway

Structure of a Volcanic Continental Margin Derived from Ocean-bottom Seismographic Data: The Northern Vøring Margin, off Norway

Transitional continental-oceanic structure beneath the Norwegian Sea from inversion of surface wave group velocity data

Variation of Icelandic and Hawaiian magmatism: evidence for co-pulsation of mantle plumes?

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