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- Simancas, J.F., et al.
(författare)
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The seismic crustal structure of the Ossa-Morena Zone and its geological interpretation
- 2004
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Ingår i: Journal of Iberian Geology. - 1698-6180 .- 1886-7995. ; 30, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- The IBERSEIS deep reflection seismic experiment has provided a crustal image of the Variscan orogen of southwest Iberia. A brief presentation of the entire seismic profile is given, and then the Ossa-Morena Zone (OMZ) and its boundaries are considered. The crust of the OMZ is shown to be divided into an upper crust, characterized by dominantly NE-dipping reflectivity, and a poorly reflective lower crust. The reflectivity of the upper crust has good correlation with the geological cross-section constructed from surface mapping. In the seismic image, the upper crustal geological structures are seen to merge in the middle crust. Nevertheless, the OMZ middle crust is not a mere detachment level, as it shows very unusual features: it appears as a band of strong reflectivity and irregular thickness (the Iberian Reflective Body, IRB) that we interpret as a great sill-like intrusion of basic rocks. The boundaries of the OMZ are considered sutures of the orogen, and their geometrical features, as deduced from geological mapping and the seismic image, are in accordance with the transpressional character of the Variscan collision recorded in SW Iberia. The present Moho is flat, obliterating the root of the orogen.
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| 2. |
- Kashubin, A., et al.
(författare)
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A footprint of rainfall on land seismic data repeatability at the CO2 storage pilot site, Ketzin, Germany
- 2011
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Two vintages of land time-lapse seismic data were acquired in 2005 and in 2009 at the Ketzin CO2 storage site in Germany. The datasets showed some differences in frequency content, signal-to-noise ratio and refraction statics despite that they were acquired with the same equipment and during the same seasons. The spatial variations in the data appeared to show good correlation with the difference in precipitation during the campaigns. These observations provide a ground for estimation of spatially varying operators that may be used in pre-stack or post-stack cross-equalization corrections of the time-lapse datasets. © 2011 Society of Exploration Geophysicists.
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| 4. |
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| 5. |
- Kashubin, S., et al.
(författare)
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Crustal structure of the Middle Urals based on seismic reflection data
- 2006
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Ingår i: European Lithosphere Dynamics. - London : Geological Society. - 1862392129 ; , s. 427-442
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- EUROPROBE-related seismic reflection surveys in the Middle Urals, Russia (latitude 56-62°) since 1993 have led to an increased understanding of the crustal structure and tectonic evolution of this region. A 400 km long profile now extends from the foreland basin in the west well into the West Siberian Basin in the east. Bivergent structures characterize the upper crust of the Uralide orogen, whereas the middle and lower crust generally contain gently west-dipping reflections. A crustal root is imaged down to almost 60 km beneath the exposed Urals. Below the foreland and the West Siberian Basin the lower crustal reflectivity is pronounced and the Moho lies at a depth of 40-45 km. Below the foreland on the recently acquired Serebrianka-Beriozovka profile, two sets of late arriving (20-25 s) reflections are present. One set reflects from a zone in the mantle at about 60-70 km depth that strikes ENE and dips about 45° to the SSE. The other set may represent imbricated lower crust. Major events during the Palaeozoic tectonic evolution of the Middle Urals were: continental and oceanic rifting (Late Cambrian to Early Ordovician); development of a passive continental margin (Mid-Ordovician to Mid-Carboniferous); intra-oceanic subduction below the Tagil arc (Silurian to Devonian); east-dipping subduction of the Baltica plate (Silurian to Early Devonian); possible subduction reversal with formation of the Alapaevsk island arc and the Krasnoturjinsk-Petrokamensk active continental margin (Devonian to Early Carboniferous); active building of a mountain belt and intrusion of collision-related granitic plutons (Carboniferous to Permian).
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| 6. |
- Simancas, J. F., et al.
(författare)
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Crustal structure of the transpressional Variscan orogen of SW Iberia : SW Iberia deep seismic reflection profile (IBERSEIS)
- 2003
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Ingår i: Tectonics. - : AGU. - 0278-7407 .- 1944-9194. ; 22, s. 1062-
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Tidskriftsartikel (refereegranskat)abstract
- IBERSEIS, a 303 km long (20 s) deep seismic reflection profile, was acquired across the Variscan belt in SW Iberian Peninsula. The acquisition parameters were designed to obtain a high-resolution crustal-scale image of this orogen. The seismic profile samples three major tectonic terranes: the South Portuguese Zone, the Ossa-Morena Zone, and the Central Iberian Zone, which were accreted in Late Paleozoic times. These terranes show a distinctive seismic signature, as do the sutures separating them. Late strike-slip movements through crustal wedges are apparent in the seismic image and have strongly modified the geometry of sutures. The upper crust appears to be decoupled from the lower crust all along the seismic line, but some deformation has been accommodated at deeper levels. A sill-like structure is imaged in the middle crust as a 1–2 s thick and 175 km long high-amplitude conspicuous reflective band. It is interpreted as a great intrusion of mafic magma in a midcrustal decollement. Taking into account surface geological data and the revealed crustal architecture, a tectonic evolution is proposed for SW Iberia which includes transpressional collision interacting during Early Carboniferous with a mantle plume. The Moho can be identified along the entire transect as subhorizontal and located at 10 to 11 s, indicating a 30–35 km average crustal thickness. Its seismic signature changes laterally, being very reflective beneath the South Portuguese Zone and the Central Iberian Zone, but discontinuous and diffuse below the Ossa Morena Zone.
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| 8. |
- Kashubin, Artem S., et al.
(författare)
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The Krasnouralsky profile in the Middle Urals, Russia : a tomographic approach to vintage DSS data
- 2009
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Ingår i: Tectonophysics. - : Elsevier BV. - 0040-1951 .- 1879-3266. ; 472:1-4, s. 249-263
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Tidskriftsartikel (refereegranskat)abstract
- The Middle Urals region has been widely studied with geophysical methods over the past decades. An integrated program is in progress to summarize this knowledge, including modern reprocessing of controlled-source seismic data. This work is devoted to the Krasnouralsky DSS profile. We applied modern tomography inversion algorithms in 2D and 2.5D on first break traveltime picks from an archive catalogue. A number of initial models and various smoothing constraints were used to investigate the influence of starting models on the final model. Robustness and uncertainty of the recovered models were estimated with hypothesis testing and checkerboard tests. The recovered velocity structure shows a thicker crust below the contact of the West Uralian Zone and the Central Uralian Zone and below the Tagil–Magnitogorsk Zone. Deep high velocity anomalies on both sides of this zone are interpreted as crustal thinning or alteration of the crust by intrusions of mantle material. Our results suggest that it is worthwhile reinterpreting DSS traveltime data with modern inversion techniques.
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