Proterozoic–Archean boundary in the mantle lithosphere of eastern Fennoscandia as seen by seismic anisotropy

Plomerová, Jaroslava; Babuška, Vladislav; Vecsey, Luděk; Kozlovskaya, Elena; Raita, Tero; Sstwg,

doi:10.1016/j.jog.2005.10.008

Cited by 35 publications

(38 citation statements)

References 19 publications

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“…The traveltimes of the first arrivals of refracted P and S waves for all shots are compared in Figure 4. Small differences in traveltimes of first arrivals between vertical and horizontal components visible on Figure 4a suggest week anisotropy in the crust and upper mantle beneath the FENNIA profile, which agrees with the results by Plomerová et al [2006]. Surface waves, very well visible on seismic record sections were interpreted by Grad and Luosto [1994].…”

Section: P and S Wavefieldsupporting

confidence: 85%

Crust‐mantle boundary in the central Fennoscandian shield: Constraints from wide‐angle P and S wave velocity models and new results of reflection profiling in Finland

2007

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[1] Our paper presents analysis of the crust-mantle boundary in the central Fennoscandian shield based on new P and S wave two-dimensional velocity models of the SVEKA'81, SVEKA'91 and FENNIA wide-angle reflection and refraction profiles and on results of a new seismic reflection experiment in Finland (Finnish Reflection Experiment (FIRE)). In this area, the crust is extremely thick (50-60 km), and the Moho boundary is difficult to detect using methods based on interpretation of P waves only (near vertical profiling and wide-angle experiments). However, the S wave reflections from the Moho boundary (SmS) are frequently more pronounced in wide-angle data than the P wave reflections (PmP). In order to infer the crust-mantle transition, we developed new P and S wave velocity models using reprocessing of the old data and compared them to record sections of collocated reflection profiles and to published values of V p and V p /V s for the main types of lower crustal and upper mantle rocks. On the basis of the lateral variations of V p , V p /V s , and reflectivity in the lower crust and upper mantle, three main types of the crust-mantle boundary were distinguished. The first type corresponds to eclogitized lower crust that overlies peridotitic upper mantle. In this case, the Moho coincides with the lithological crust-mantle boundary. The second type corresponds to lower crust composed of mafic garnet granulites overlying the peridotitic upper mantle, for which the Moho and the lithologic crust-mantle boundary coincide as well. The third type corresponds to the mafic garnet granulites underlain by a layer of eclogitic upper mantle. In the latter case, the lithological crust-mantle boundary is deeper than the Moho.Citation: Janik, T., E. Kozlovskaya, and J. Yliniemi (2007), Crust-mantle boundary in the central Fennoscandian shield: Constraints from wide-angle P and S wave velocity models and new results of reflection profiling in Finland,

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Section: P and S Wavefieldsupporting

confidence: 85%

Crust‐mantle boundary in the central Fennoscandian shield: Constraints from wide‐angle P and S wave velocity models and new results of reflection profiling in Finland

2007

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“…The anisotropy vectors (Plomerova et al 2006) seem to coincide with the suggested palaeoplate movement directions (Lahtinen et al 2005). The high velocity anomaly (70-150 km in depth) has the shape of a saddle with the long axis (250 km) in NE-SW direction and the short axes (120 km) in NW-SE direction.…”

Section: The Mode Of Extensionmentioning

confidence: 77%

“…The Fennoscandian shield is underlain by thick lithosphere with anomalously high P-and S-wave velocities and large lateral variations in velocities and anisotropy (Alinaghi et al 2003;Bruneton et al 2004;Plomerova et al 2006). The anisotropy vectors (Plomerova et al 2006) seem to coincide with the suggested palaeoplate movement directions (Lahtinen et al 2005).…”

Section: The Mode Of Extensionmentioning

confidence: 99%

A case study of lateral spreading: the Precambrian Svecofennian Orogen

Korja

Kosunen

Heikkinen

2009

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We have studied the crustal structures of the Palaeoproterozoic Svecofennian (c. 1.9 Ga) Orogeny with the help of large scale seismic reflection surveys (FIRE 1-3), preliminary structural field work and geological and geophysical databases. The central part of the orogen is occupied by the Central Finland Granitoid Complex, which comprises two suites of granitoid rocks and associated mafic and volcanic rocks. The complex and the surrounding supracrustal belts are cut and deformed by numerous shear zones and faults; here divided into six groups. The most prominent reflections are usually shear zones or faults on outcrops. The granitoid complex is interpreted as a deep, lower-level section of an old core complex, where the younger granitoid intrusions form the basins and older granitoid intrusions and associated volcanic rocks form the horsts. The upper-middle crust detachment zone is exposed at the northeastern edge of the complex and middle crust is exposed in the migmatitic domes at northern and western margins.The seismic reflection sections display a frozen image of orogenic thickening and lateral spreading. The decoupling of the upper, middle and lower crust during spreading resulted in the formation of layered superstructure-infrastructure of the crust.

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“…Similarly to the most of large passive seismic experiments in Europe (e.g., CALIXTO, EIFEL, PASSEQ, RETREAT), this paper aims at presenting first results on seismic anisotropy of the mantle lithosphere obtained from the LAPNET array body-wave data processed in 3-D. The results are robust enough with general consequences for tectonic development of cratonic provinces and are supposed to fill a gap in studies of velocity structure of the upper mantle beneath northern Fennoscandia (e.g., Sandoval et al, 2004;Pedersen et al, 2006;Plomerová et al, 2006Plomerová et al, , 2008Vecsey et al, 2007;Eken et al, 2010).…”

Section: With Amentioning

confidence: 97%

Domains of Archean mantle lithosphere deciphered by seismic anisotropy – inferences from the LAPNET array in northern Fennoscandia

Plomerová¹,

Vecsey²,

Babuška³

2011

Solid Earth

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Abstract.An international LAPNET array (2007-2009, http://www.oulu.fi/sgo-oty/lapnet) of the POLENET/LAPNET sub-project of the POLENET-IPY consortium, related to seismic and geodetic studies in the Arctic regions, consisted of about 60 broadband seismic stations located on the territory of northern Finland and adjacent parts of Sweden, Norway and Russia. We analyze relative P-wave travel-time deviations evaluated for a subset of 90 teleseismic events recorded by the LAPNET array and show examples of lateral variations of shear-wave splitting to demonstrate variability of fabrics of the Archean mantle lithosphere. The initial results clearly demonstrate the Archean mantle lithosphere consists of domains with consistent fabrics reflecting fossil anisotropic structures. 3-D self-consistent anisotropic models with inclined symmetry axes accommodate two independent sets of body-wave anisotropic observations. Individual domains are delimited by boundaries (sutures), where the anisotropic parameters change. The results obtained from the LAPNET array fill a gap in structural studies of the upper mantle beneath northern Fennoscandia.

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Proterozoic–Archean boundary in the mantle lithosphere of eastern Fennoscandia as seen by seismic anisotropy

Cited by 35 publications

References 19 publications

Crust‐mantle boundary in the central Fennoscandian shield: Constraints from wide‐angle P and S wave velocity models and new results of reflection profiling in Finland

Crust‐mantle boundary in the central Fennoscandian shield: Constraints from wide‐angle P and S wave velocity models and new results of reflection profiling in Finland

A case study of lateral spreading: the Precambrian Svecofennian Orogen

Domains of Archean mantle lithosphere deciphered by seismic anisotropy – inferences from the LAPNET array in northern Fennoscandia

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