| 1. |
- Berthelsen, A., et al.
(author)
-
Recording marine airgun shots at offsets between 300 and 700 km
- 1991
-
In: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 18:4, s. 645-648
-
Journal article (peer-reviewed)abstract
- This paper demonstrates that - under favorable conditions - by using multichannel recording and subsequent stacking of adjacent records marine airgun shots have been detected at offset distances up to 700 km, the maximum offset at which the authors attempted to record data.^Besides a powerful airgun array, a low noise environment at the recording site and the elimination of static shifts are the prerequisites to obtain refracted and reflected arrivals from the crust and upper mantle at such large offsets.^Primary arrivals detected at offsets between 400 and 700 km image the upper mantle from 70 to about 120 km depth.^Stacking of neighboring shots and/or receivers successfully increases the signal-to-noise ratio, if the traces have been corrected for offset differences, which requires knowledge of the apparent phase velocities.^The data presented here were collected in autumn 1989 during the BABEL Project on the Baltic Shield.
|
|
| 2. |
- Hobbs, R. W., et al.
(author)
-
Integrated seismic studies of the Baltic shield using data in the Gulf of Bothnia region
- 1993
-
In: Geophysical Journal International. - 0956-540X .- 1365-246X. ; 112:3, s. 305-324
-
Journal article (peer-reviewed)abstract
- In the autumn of 1989 a co-operative experiment involving 12 research institutions in northwestern Europe collected 2268 km of deep seismic reflection profiles in the Gulf of Bothnia and the Baltic Sea. the 121 litre airgun array used for this profiling was also recorded by 62 muiticomponent land stations to provide coincident refraction surveys, fan-spreads, and 3-D seismic coverage of much of the Gulf of Bothnia. We thus have potentially both high-resolution impedance contrast images as well as more regional 3-D velocity models in both P- and S-waves. In the Bothnian Bay a south-dipping, non-reflective zone coincides with the conductive Archaean-Proterozoic boundary onshore in Finland. Between the Bothnian Bay and Bothnian Sea observed reflectivity geometries and velocity models at Moho depths suggest structures inherited from a 1.9Ga subduction zone; the upper crust here appears to have anomalously low velocity. Within the Bothnian Sea, reflectivity varies considerably beneath the metasedimentary/granitoid rocks of the Central Svecofennian Province (CSP) and the surrounding metavolcanic-arc rocks. Numerous dipping reflectors appear throughout the metavolcanic crust, whereas the CSP has little reflectivity. Wide-angle reflections indicate that the metasedimentary crust of the Bothnian Basin is 10 km thicker than the neighbouring Svecofennian subprovinces. Near the Åland archipelago Rapakivi granite plutons exhibit bright reflections, a contrast to the usual non-reflective plutons elsewhere in western Europe. Additional dipping reflections deep in the crust of this area may support models of rifting and crustal thinning during emplacement of the 1.70-1.54 Ga Rapakivi granites. Coeval gabbroic/anorthositic magmatism may explain the high reflectivity and high velocity of these plutons. the c. 1.25 Ga mafic sills and feeder dykes of the Central Scandinavian Dolerite Group also produce clear reflections on both near- and far-offset seismic sections. Continued modelling will produce better velocity models of the crust and better constrained contour maps of crustal thickness in this part of the Baltic shield.
|
|
| 3. |
- Öhlander, Björn, et al.
(author)
-
Delineation and character of the Archaean-Proterozoic boundary in northern Sweden
- 1993
-
In: Precambrian Research. - 0301-9268 .- 1872-7433. ; 64:1-4, s. 67-84
-
Journal article (peer-reviewed)abstract
- Before the deposition of a Proterozoic cover and the repeated Proterozoic reworking of the older rocks, the presently exposed Archaean areas in northern Sweden formed part of a coherent craton. In the present study, we have used Sm---Nd isotopic analyses of Proterozoic granitoids and metavolcanics to delineate the Archaean palaeoboundary. In a regional context, the transition from strongly negative εNd(t) values in the northeast to positive values in the southwest is distinct, and approximately defines the border of the old craton. The Archaean palaeoboundary extends in a WNW direction, and is subparallel to the longitudinal axis of the Skellefte sulphide ore district but it is situated ≈ 100 km farther to the north. The ≈ 1.9 Ga old granitoids on the two sides of the palaeoboundary were all formed in compressional environments, but those situated to the north have higher contents of LILE and LREE at similar contents of Si. This indicates that they were generated in an area with thicker crust and supports the location of the Archaean-Proterozoic palaeoboundary. There is no simple correlation between the Archaean palaeoboundary, as defined by the isotopic results, and any of the major fracture systems as interpreted from regional geophysical measurements. Reflection seismic work indicates that juvenile volcanic-arc terrains to the south have been thrust onto the Archaean craton. Possible thrust faults have been identified from aeromagnetic measurements. Rifting of the Archaean craton created a passive margin ≈ 2.0 Ga ago. Spreading shifted to convergence with subduction beneath the Archaean continent ≈ 1.9 Ga ago. Subsequently, the resulting juvenile volcanic arc collided with the old continent, and the Archaean palaeoboundary as existing today was formed by a collision characterized by overthrusting. The boundary then was disturbed by later deformation predominantly along NNE-trending fracture systems.
|
|
| 4. |
- Bock G., Roberts R.G., Kissling E., Achauer A., Alingahi J., Bruneton M., Friedrich W., Grad M. Guterch A., Hjelt S-E., Hyvönen T., Ikonen J-P., Komminaho K., Korja A, Heikkinen P., Kozolovaskaya E., Nevsky M.V., Pavlenkova N., Pedersen H., Plomerova J.
(author)
-
Seismic probing of Archean and Proterozoic Lithosphere in Fennoscandia.
- 2001
-
In: EOS Transactions American Geophysical Union. - : American Geophysical Union. ; 82, s. 621,628-629
-
Journal article (peer-reviewed)
|
|
| 5. |
- SVEKALAPKO Seismic Tomography Working Group (SSTWG): G. Bock, U. Achauer, A. Alinaghi, J. Ansorge, M. Bruneton, W. Friederich, M. Grad, A. Guterch, S.-E. Hjelt, T. Hyvönen, J.-P. Ikonen, E. Kissling, K. Komminaho, A. Korja, P. Heikkinen, E. Kozlovskaya, M
(author)
-
Seismic probing of Fennoscandian Lithosphere
- 2002
-
In: EOS, Trans. Am. geophys. Un.. ; 82:621, s. 628-629
-
Journal article (peer-reviewed)
|
|
| 6. |
- Bruneton, M., V. Farra, H. A. Pedersen & the SVEKALAPKO Seismic Tomography Working Group, (G. Bock, U. Achauer, A. Alinaghi, J. Ansorge, M. Bruneton, W. Friederich, M. Grad, A. Guterch, S.-E. Hjelt, T. Hyvönen, J.-P. Ikonen, E. Kissling, K. Komminaho, A.
(author)
-
Non-linear surface wave phase velocity inversion based on ray theory.
- 2002
-
In: Geophys. J. Int. ; 151, s. 583-596
-
Journal article (peer-reviewed)
|
|
| 7. |
- Burke, S. R., et al.
(author)
-
Analysis of the foam-forming of non-woven lightweight fibrous materials using X-ray tomography
- 2021
-
In: SN Applied Sciences. - : Springer Nature. - 2523-3963 .- 2523-3971. ; 3:2
-
Journal article (peer-reviewed)abstract
- Abstract: Foam-forming has in the past predominantly been used to create two-dimensional sheet-like fibrous materials. Allowing the foam to drain freely and decay under gravity, rather than applying a vacuum to remove it rapidly, we can produce lightweight three-dimensional fibrous structures from cellulose fibres, of potential use for thermal and acoustic insulation. μCT scanning of the fibrous materials enable us to determine both void size distributions and also distributions of fibre orientations. Through image analysis and uniaxial compression testing, we find that the orientation of the fibres, rather than the size of the voids, determine the compressive strength of the material. The fibrous samples display a layering of the fibres perpendicular to the direction of drainage of the precursor liquid foam. This leads to an anisotropy of the compressive behaviour of the samples. Varying the initial liquid fraction of the foam allows for tuning of the compressive strength. We show an increase in over seven times can be achieved for samples of the same density (13 kg.m-3). Graphic abstract: [Figure not available: see fulltext.]. © 2021, The Author(s).
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
