scholarly journals Crustal and upper mantle seismic structure of the Svalbard Archipelago from the receiver function analysis

2015 ◽  
Vol 36 (2) ◽  
pp. 89-107 ◽  
Author(s):  
Monika Wilde−Piórko
Keyword(s):  
Upper Mantle ◽  
Barents Sea ◽  
Receiver Function ◽  
Function Analysis ◽  
Seismic Station ◽  
Receiver Functions ◽  
Seismic Velocities ◽  
Seismic Structure ◽  
Svalbard Archipelago ◽  
The North

Abstract Receiver function provides the signature of sharp seismic discontinuities and the information about the shear wave (S−wave) velocity distribution beneath the seismic station. This information is very valuable in areas where any or few reflection and/or refraction studies are available and global and/or regional models give only rough information about the seismic velocities. The data recorded by broadband seismic stations have been analysed to investigate the crustal and upper mantle structure of the Svalbard Archipelago. Svalbard Archipelago is a group of islands located in Arctic, at the north−western part of the Barents Sea continental platform, which is bordered to the west and to the north by passive continental margins. The new procedure of parameterization and selection of receiver functions (RFs) has been proposed. The back−azimuthal sections of RF show a strong variation for the HSPB and KBS stations. Significant amplitudes of transversal component of RF (T−RF) for the HSPB station indicate a shallow dipping layer towards the southwest. The structure of the crust beneath the SPITS array seems to be less heterogeneous, with very low amplitudes of converted phase comparing to the KBS and HSPB stations. Forward modelling by trial−and−error method shows a division of the crust into 3-4 layers beneath all stations and layering of the uppermost mantle beneath the SPITS array and the HSPB stations. The thickness of the mantle transition zone is larger for western part of archipelago and smaller for eastern part comparing to iasp91 model.

The Crustal Structure of the Eastern Marmara Region Using Receiver Function Analysis

2020 ◽  
Author(s):  
Pınar Büyükakpınar ◽  
Mustafa Aktar
Keyword(s):  
Fault Zone ◽  
Receiver Function ◽  
Function Analysis ◽  
Joint Inversion ◽  
Crustal Thickness ◽  
Receiver Functions ◽  
Gradual Transition ◽  
Marmara Region ◽  
The North ◽  
Receiver Function Analysis

<p>This study focuses on the crust of the Eastern Marmara in order to understand of how much the structure is influenced by the tectonic history and also by the activity of the NAF. Recent studies have claimed that the crustal thickness varies significantly on the north and south of the NAF, which is assumed to indicate the separation line between Eurasian and Anatolian Plates. The present study aims to reevaluate the claim above, using newly available data and recently developed tools. The methods used during the study are the receiver function analysis and surface wave analysis. The first one is more intensively applied, since the second one only serves to introduce stability constraint in the inversions. Data are obtained from the permanent network of KOERI and from PIRES arrays.  The main result of the study indicates that the receiver functions for the stations close to the fault zone are essentially very different from the rest and should be treated separately. They show signs of complex 3D structures of which two were successfully analyzed by forward modeling (HRTX and ADVT). A dipping shallow layer is seen to satisfy the major part of the azimuthal variation at these two stations. For the stations off the fault on the other hand, the receiver functions show a more stable behavior and are analyzed successfully by classical methods. CCP stacking, H-k estimation, single and joint inversion with surface waves, are used for that purpose. The results obtained from these totally independent approaches are remarkably consistent with each other. It is observed that the crustal thickness does not vary significantly neither in the NS, nor in the SW direction. A deeper Moho can only be expected on two most NE stations where a gradual transition is more likely than a sharp boundary (SILT and KLYT). The structural trends, although not significant, are generally aligned in the EW direction.  In particular, a slower lower crust is observed in the southern stations, which is possibly linked to the mantle upwelling and thermal transient of the Aegean extension. Otherwise neither the velocity, nor the thickness of the crust does not imply any significant variation across the fault zone, as was previously claimed.</p>

scholarly journals Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 957-970 ◽  
Author(s):  
R. Kind ◽  
X. Yuan ◽  
J. Mechie ◽  
F. Sodoudi
Keyword(s):  
United States ◽  
Upper Mantle ◽  
Receiver Function ◽  
Rocky Mountain ◽  
Receiver Functions ◽  
Western United States ◽  
Small Scale ◽  
Rift System ◽  
The North ◽  
Central United States

Abstract. We used more than 40 000 S-receiver functions recorded by the USArray project to study the structure of the upper mantle between the Moho and the 410 km discontinuity from the Phanerozoic western United States to the cratonic central US. In the western United States we observed the lithosphere–asthenosphere boundary (LAB), and in the cratonic United States we observed both the mid-lithospheric discontinuity (MLD) and the LAB of the craton. In the northern and southern United States the western LAB almost reaches the mid-continental rift system. In between these two regions the cratonic MLD is surprisingly plunging towards the west from the Rocky Mountain Front to about 200 km depth near the Sevier thrust belt. We interpret these complex structures of the seismic discontinuities in the mantle lithosphere as an indication of interfingering of the colliding Farallon and Laurentia plates. Unfiltered S-receiver function data reveal that the LAB and MLD are not single discontinuities but consist of many small-scale laminated discontinuities, which only appear as single discontinuities after longer period filtering. We also observe the Lehmann discontinuity below the LAB and a velocity reduction about 30 km above the 410 km discontinuity.

scholarly journals Lithospheric and sublithospheric deformation under the Borborema Province of northeastern Brazil from receiver function harmonic stripping

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 893-905 ◽  
Author(s):  
Gaelle Lamarque ◽  
Jordi Julià
Keyword(s):  
Lithospheric Mantle ◽  
Seismic Anisotropy ◽  
Receiver Function ◽  
Seismic Station ◽  
Atlantic Coast ◽  
Shear Zones ◽  
Receiver Functions ◽  
Azimuthal Anisotropy ◽  
Northeastern Brazil ◽  
Borborema Province

Abstract. The depth-dependent anisotropic structure of the lithosphere under the Borborema Province in northeast Brazil has been investigated via harmonic stripping of receiver functions developed at 39 stations in the region. This method retrieves the first (k=1) and second (k=2) degree harmonics of a receiver function dataset, which characterize seismic anisotropy beneath a seismic station. Anisotropic fabrics are in turn directly related to the deformation of the lithosphere from past and current tectonic processes. Our results reveal the presence of anisotropy within the crust and the lithospheric mantle throughout the entire province. Most stations in the continental interior report consistent anisotropic orientations in the crust and lithospheric mantle, suggesting a dominant northeast–southwest pervasive deformation along lithospheric-scale shear zones developed during the Brasiliano–Pan-African orogeny. Several stations aligned along a northeast–southwest trend located above the (now aborted) Mesozoic Cariri–Potiguar rift display large uncertainties for the fast-axis direction. This non-azimuthal anisotropy may be related to a complex anisotropic fabric resulting from a combination of deformation along the ancient collision between Precambrian blocks, Mesozoic extension and thermomechanical erosion dragging by sublithospheric flow. Finally, several stations along the Atlantic coast reveal depth-dependent anisotropic orientations roughly (sub)perpendicular to the margin. These results suggest a more recent overprint, probably related to the presence of frozen anisotropy in the lithosphere due to stretching and rifting during the opening of the South Atlantic.

scholarly journals Broadband Seismic Deployments for Imaging the Upper Mantle Structure in the Lützow-Holm Bay Region, East Antarctica

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Masaki Kanao ◽  
Yusuke Usui ◽  
Tomofumi Inoue ◽  
Akira Yamada
Keyword(s):  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Receiver Function ◽  
Tectonic Stress ◽  
Receiver Functions ◽  
East Antarctica ◽  
Mantle Structure ◽  
Passive Seismic ◽  
Regional Tectonic ◽  
Break Up

Broadband seismic deployments have been carried out in the Lützow-Holm Bay region (LHB), Dronning Maud Land, East Antarctica. The recorded teleseismic and local events are of sufficient quality to image the structure and dynamics of the crust and mantle of the terrain. Passive seismic studies by receiver functions and shear wave splitting suggest a heterogeneous upper mantle. Depth variations in topography for upper mantle discontinuities were derived from long period receiver function, indicating a shallow depth discontinuity at 660 km beneath the continental area of LHB. These results provide evidence of paleo upwelling of the mantle plume associated with Gondwana break-up. SKS splitting analysis anticipated a relationship between “fossil” anisotropy in lithospheric mantle and past tectonics. Moreover, active source surveys (DSSs) imaged lithospheric mantle reflections involving regional tectonic stress during Pan-African and succeeding extension regime at the break-up. By combining the active and passive source studies of the mantle structure, we propose an evolution model of LHB for constructing the present mantle structure.

Structure of the crust and upper mantle of the Great Slave Lake shear zone, northwestern Canada, from teleseismic analysis and gravity modelling

2003 ◽  
Vol 40 (9) ◽  
pp. 1203-1218 ◽  
Author(s):  
David W Eaton ◽  
Jacqueline Hope
Keyword(s):  
Shear Zone ◽  
Upper Mantle ◽  
Receiver Function ◽  
Function Analysis ◽  
Crustal Material ◽  
S Wave ◽  
Crust And Upper Mantle ◽  
Fast Axis ◽  
Great Slave Lake ◽  
Basic Features

The Great Slave Lake shear zone (GSLsz) exposes lower crustal rocks analogous to deep-seated segments of modern strike-slip fault zones, such as the San Andreas fault. Extending for 1300 km beneath the Western Canada Sedimentary Basin to the southern margin of the Slave Province, the GSLsz produces one of the most prominent linear magnetic anomalies in Canada. From May to October 1999, 13 three-component portable broadband seismograph stations were deployed in a 150-km profile across a buried segment of the shear zone to investigate its lithospheric structure. Splitting analysis of core-refracted teleseismic shear waves reveals an average fast-polarization direction (N49°E ± 19°) that is approximately parallel to the shear zone. Individual stations near the axis of the shear zone show more northerly splitting directions, which we attribute to interference between regional anisotropy in the upper mantle (fast axis ~N60°E) and crustal anisotropy within the shear zone (fast axis ~N30°E). At the location of our profile, the shear zone is characterized by a 10-mGal axial gravity high with a wavelength of 30 km, superimposed on a longer wavelength 12-mGal low. This gravity signature is consistent with the basic features of the crustal model derived from receiver-function analysis: a Moho that dips inward toward the shear-zone axis and a mid-crustal zone with high S-wave velocity (ΔVs = 0.6 ± 0.2 km/s). The axial gravity high may be related to uplift of deeper crustal material within the shear zone, or protolith-dependent compositional differences between the shear zone and surrounding wall rocks.

Receiver function analysis reveals layered anisotropy in the crust and upper mantle beneath southern Peru and northern Bolivia

2019 ◽  
Vol 753 ◽  
pp. 93-110 ◽  
Author(s):  
Neta Bar ◽  
Maureen D. Long ◽  
Lara S. Wagner ◽  
Susan L. Beck ◽  
George Zandt ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Receiver Function ◽  
Function Analysis ◽  
Crust And Upper Mantle ◽  
Southern Peru ◽  
Receiver Function Analysis

Moho Topography and Velocity/Density Model for the Hedmarken area, Eastern Norway, using Receiver Function Analysis and Rj-McMC

2020 ◽  
Author(s):  
Claudia Pavez ◽  
Marco Brönner ◽  
Odleiv Olesen ◽  
Arne Bjørlykke
Keyword(s):  
Receiver Function ◽  
Function Analysis ◽  
Seismic Station ◽  
Velocity Model ◽  
Density Model ◽  
Local Velocity ◽  
Anomalous Density ◽  
Receiver Function Analysis ◽  
Mohorovičić Discontinuity ◽  
Eastern Norway

<p>A Receiver Function Analysis was carried out in the Mjøsa area, Eastern Norway, in order to better image this tectonically complex area, understand the crustal contrasts and complement geological analysis that were made previously in the area. For this, we used seismic traces received for seven broadband stations from the NORSAR permanent array. The H-K (depth vs Vp/Vs) stacking procedure and a Reversible jump Markov chain Monte Carlo (Rj-McMC) inversion were developed independently. The first analysis allows us to obtain a model with the Mohorovicic discontinuity values under each seismic station and the average Vp/Vs crustal ratio. With the inversion, it was possible to develop a 1D local velocity model. Applying the Nafe-Drake relationship, a 2D density model was obtained and tested against observed gravity. Results indicate the presence of a low anomalous density layer that is located to the NNW of the study area, which is probably related to low-density meta-sediments in the Åsta Basin located above the basement. A main crustal fault is also indicated from the density model, spatially coinciding with faults grown during the Sveconorwegian orogenic process.</p><p> </p>

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