Sedimentary basin exploration with receiver functions: Seismic structure and anisotropy of the Dublin Basin (Ireland)

Geophysics ◽  
2017 ◽  
Vol 82 (4) ◽  
pp. KS41-KS55 ◽  
Author(s):  
Andrea Licciardi ◽  
Nicola Piana Agostinetti
Keyword(s):  
Seismic Anisotropy ◽  
Sedimentary Basin ◽  
Structural Data ◽  
Receiver Functions ◽  
Seismic Structure ◽  
S Wave ◽  
Low Velocity ◽  
Velocity Models ◽  
Sonic Log ◽  
Anisotropic Layers

Teleseismic receiver functions (RFs) were used to investigate the seismic structure of the southern margin of the Dublin Basin, a potential geothermal site. Through an inversion-based approach, the elastic properties and seismic anisotropy of sedimentary basin units were examined, using data from a linear array of closely spaced seismic stations. Our results were compared with sonic logs and lithostratigraphies from two nearby boreholes, NGE1 and NGE2 and colocated active seismic data. Including a high-frequency RF (up to 8 Hz) allowed us to compute S-wave velocity models with a vertical resolution [Formula: see text]. The results indicated the presence of a subvertical lateral discontinuity in [Formula: see text], in correspondence with the main basin-bounding fault (Blackrock-Newcastle Fault [BNF]). North of this discontinuity, a shallow low-velocity layer thickens (from 0.7 to 1.0 km thick) toward the inner basin, in agreement with the geometry of the shallowest reflector found by active seismics. A good correlation was also found between the sonic log at NGE1 and our velocity model. Station DB02 showed an increase in [Formula: see text] at a depth of approximately 0.7 km and a decrease in [Formula: see text] at approximately 1.4 km in depth. Two velocity jumps with matching polarities were also observed in the NGE1 sonic log at the contact between the Upper and Lower Calp formations (positive jump, 688 m deep), and between a calcarenite and a sandstone layers (negative jump, 1337 m deep). Moreover, the main velocity contrasts in our model agree with the major lithostratigraphic boundaries inferred from borehole-drilled samples. Two juxtaposed anisotropic layers are identified close to the BNF. Directions of the slow axis of anisotropy are consistent with the borehole structural data. From these observations, the presence of aligned open cracks within the sandstones, possibly fluid-filled, was inferred up to a depth of 2.3 km in the vicinity of the BNF.

Crustal anisotropy beneath northeastern Tibetan Plateau from the harmonic decomposition of receiver functions

2019 ◽  
Vol 220 (3) ◽  
pp. 1585-1603
Author(s):  
Zhenxin Xie ◽  
Vadim Levin ◽  
Qingju Wu
Keyword(s):  
Tibetan Plateau ◽  
Seismic Anisotropy ◽  
Receiver Function ◽  
Flow Direction ◽  
Receiver Functions ◽  
Low Velocity ◽  
Northeastern Tibetan Plateau ◽  
Harmonic Decomposition ◽  
Anisotropic Layers ◽  
Qilian Orogen

SUMMARY A uniformly spaced linear transect through the northeastern Tibetan Plateau was constructed using 54 stations from ChinaArray Phase II. We used a set of colocated earthquakes to form receiver function beams that were then used to construct a 2-D image of main converting boundaries in our region and to investigate lateral changes in main impedance contrasts along the transect. The image revealed obvious mid-crustal low-velocity zones beneath the Qilian Orogen and the Alxa Block. We developed a new procedure that uses harmonically decomposed receiver functions to characterize seismic anisotropy, and that can determine both the orientations of symmetry axes and their type (fast or slow). We tested our technique on a number of synthetic models, and subsequently applied it to the data from the transect. We found that: (1) within the upper crust the orientations of slow symmetry axes are nearly orthogonal to the strike directions of faults, and thus anisotropy is likely caused by the shape preferred orientation of fluid-saturated cracks or fractures and (2) together with the low-velocity zones revealed from receiver functions stacks, anisotropic layers in the middle-to-lower crust could be explained by the crustal channel flow that was proposed for this region by previous studies. The shear within the boundary layers of crustal flow forms anisotropy with symmetry axes parallel to the flow direction.

Mapping crustal structure of the Nechako–Chilcotin plateau using teleseismic receiver function analysis,

2014 ◽  
Vol 51 (4) ◽  
pp. 407-417 ◽  
Author(s):  
H.S. Kim ◽  
J.F. Cassidy ◽  
S.E. Dosso ◽  
H. Kao
Keyword(s):  
Wave Velocity ◽  
Crustal Structure ◽  
Velocity Structure ◽  
Receiver Function ◽  
Function Analysis ◽  
Crustal Thickness ◽  
Receiver Functions ◽  
S Wave ◽  
Low Velocity ◽  
Velocity Models

This paper presents results of a passive-source seismic mapping study in the Nechako–Chilcotin plateau of central British Columbia, with the ultimate goal of contributing to assessments of hydrocarbon and mineral potential of the region. For the present study, an array of nine seismic stations was deployed in 2006–2007 to sample a wide area of the Nechako–Chilcotin plateau. The specific goal was to map the thickness of the sediments and volcanic cover, and the overall crustal thickness and structural geometry beneath the study area. This study utilizes recordings of about 40 distant earthquakes from 2006 to 2008 to calculate receiver functions, and constructs S-wave velocity models for each station using the Neighbourhood Algorithm inversion. The surface sediments are found to range in thickness from about 0.8 to 2.7 km, and the underlying volcanic layer from 1.8 to 4.7 km. Both sediments and volcanic cover are thickest in the central portion of the study area. The crustal thickness ranges from 22 to 36 km, with an average crustal thickness of about 30–34 km. A consistent feature observed in this study is a low-velocity zone at the base of the crust. This study complements other recent studies in this area, including active-source seismic studies and magnetotelluric measurements, by providing site-specific images of the crustal structure down to the Moho and detailed constraints on the S-wave velocity structure.

scholarly journals Lithosphere–asthenosphere boundary beneath the Sea of Japan from transdimensional inversion of S-receiver functions

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takeshi Akuhara ◽  
Kazuo Nakahigashi ◽  
Masanao Shinohara ◽  
Tomoaki Yamada ◽  
Hajime Shiobara ◽  
...  
Keyword(s):  
Sea Of Japan ◽  
Receiver Functions ◽  
The Sea Of Japan ◽  
Detailed Knowledge ◽  
Ocean Bottom ◽  
S Wave ◽  
Low Velocity ◽  
Lithospheric Thickness ◽  
Velocity Models ◽  
Back Arc

AbstractThe evolution history of the Sea of Japan back-arc basin remains under debate, involving the opening of sub-basins such as the Japan and Yamato Basins. Detailed knowledge of the lithospheric structure will provide the key to understanding tectonic history. This study identifies the lithosphere–asthenosphere boundary (LAB) beneath the Sea of Japan back-arc basin using S-receiver functions (S-RFs). The study area, including the Japan and Yamato Basins, has been instrumented with broadband ocean-bottom seismometers (OBSs). S-RFs from these OBSs show negative Sp phases preceding the direct S arrivals, suggesting the LAB. The S-RFs also show abnormally reduced amplitudes. For further qualitative interpretation of these findings, we conduct transdimensional Bayesian inversion for S-wave velocity models. This less-subjective Bayesian approach clarifies that the low-velocity seafloor sediments and damped deconvolution contribute to the amplitude reduction, illuminating the necessity of such considerations for similar receiver function works. Inverted velocity structures show a sharp velocity decrease at the mantle depths, which we consider the LAB. The obtained LAB depths vary among sites: ~ 45 km beneath the Japan and Yamato Basins and ~ 70 km beneath the Yamato Rise, a bathymetric high between the two basins. The thick lithosphere beneath the Yamato Rise most likely reflects its continental origin. However, the thickness is still thin compared to that of eastern Asia, suggesting lithosphere extension by rifting. Notably, the Japan and Yamato Basins show a comparable lithospheric thickness, although the crustal thickness beneath the Yamato Basin is known to be anomalously thick. This consistency in the lithospheric thickness implies that both basins undergo similar back-arc opening processes.

scholarly journals Lithosphere–asthenosphere Boundary Beneath the Sea of Japan From Transdimensional Inversion of S Receiver Functions

2021 ◽  
Author(s):  
Takeshi Akuhara ◽  
Kazuo Nakahigashi ◽  
Masanao Shinohara ◽  
Tomoaki Yamada ◽  
Hajime Shiobara ◽  
...  
Keyword(s):  
Sea Of Japan ◽  
Receiver Functions ◽  
The Sea Of Japan ◽  
Detailed Knowledge ◽  
Ocean Bottom ◽  
S Wave ◽  
Low Velocity ◽  
Lithospheric Thickness ◽  
Velocity Models ◽  
Back Arc

Abstract The evolution history of the Sea of Japan back-arc basin remains under debate, involving the opening of sub-basins such as the Japan and Yamato Basins. Detailed knowledge of the lithospheric structure will provide the key to understanding tectonic history. This study identifies the lithosphere–asthenosphere boundary (LAB) beneath the Sea of Japan back-arc basin using S-receiver functions (S-RFs). The study area, including the Japan and Yamato Basins, has been instrumented with broadband ocean-bottom seismometers (OBSs). S-RFs from these OBSs show negative Sp phases preceding the direct S arrivals, suggesting the LAB. The S-RFs also show abnormally reduced amplitudes. For further qualitative interpretation of these findings, we conduct transdimensional Bayesian inversion for S-wave velocity models. This less-subjective Bayesian approach clarifies that the low-velocity seafloor sediments and damped deconvolution contribute to the amplitude reduction, illuminating the necessity of such considerations for similar receiver function works. Inverted velocity structures show a sharp velocity decrease at the mantle depths, which we consider the LAB. The obtained LAB depths vary among sites: ~45 km beneath the Japan and Yamato Basins and ~70 km beneath the Yamato Rise, a bathymetric high between the two basins. The thick lithosphere beneath the Yamato Rise most likely reflects its continental origin. However, the thickness is still thin compared to that of eastern Asia, suggesting lithosphere extension by rifting. Notably, the Japan and Yamato Basins show a comparable lithospheric thickness, although the crustal thickness beneath the Yamato Basin is known to be anomalously thick. This consistency in the lithospheric thickness implies that both basins undergo similar back-arc opening processes.

scholarly journals Velocity structure and radial anisotropy of the lithosphere in southern Madagascar from surface wave dispersion

2020 ◽  
Vol 224 (3) ◽  
pp. 1930-1944 ◽  
Author(s):  
E J Rindraharisaona ◽  
F Tilmann ◽  
X Yuan ◽  
J Dreiling ◽  
J Giese ◽  
...  
Keyword(s):  
Receiver Functions ◽  
Dispersion Curves ◽  
Eastern Coast ◽  
Small Scale ◽  
Seismic Structure ◽  
Lithospheric Thickness ◽  
Velocity Models ◽  
Phase Velocities ◽  
Maximum Value ◽  
Radial Anisotropy

SUMMARY We investigate the upper mantle seismic structure beneath southern Madagascar and infer the imprint of geodynamic events since Madagascar’s break-up from Africa and India and earlier rifting episodes. Rayleigh and Love wave phase velocities along a profile across southern Madagascar were determined by application of the two-station method to teleseismic earthquake data. For shorter periods (<20 s), these data were supplemented by previously published dispersion curves determined from ambient noise correlation. First, tomographic models of the phase velocities were determined. In a second step, 1-D models of SV and SH wave velocities were inverted based on the dispersion curves extracted from the tomographic models. As the lithospheric mantle is represented by high velocities we identify the lithosphere–asthenosphere boundary by the strongest negative velocity gradient. Finally, the radial anisotropy (RA) is derived from the difference between the SV and SH velocity models. An additional constraint on the lithospheric thickness is provided by the presence of a negative conversion seen in S receiver functions, which results in comparable estimates under most of Madagascar. We infer a lithospheric thickness of 110−150 km beneath southern Madagascar, significantly thinner than beneath the mobile belts in East Africa (150−200 km), where the crust is of comparable age and which were located close to Madagascar in Gondwanaland. The lithospheric thickness is correlated with the geological domains. The thinnest lithosphere (∼110 km) is found beneath the Morondava basin. The pre-breakup Karoo failed rifting, the rifting and breakup of Gondwanaland have likely thinned the lithosphere there. The thickness of the lithosphere in the Proterozoic terranes (Androyen and Anosyen domains) ranges from 125 to 140 km, which is still ∼30 km thinner than in the Mozambique belt in Tanzania. The lithosphere is the thickest beneath Ikalamavony domain (Proterozoic) and the west part of the Antananarivo domain (Archean) with a thickness of ∼150 km. Below the eastern part of Archean domain the lithosphere thickness reduces to ∼130 km. The lithosphere below the entire profile is characterized by positive RA. The strongest RA is observed in the uppermost mantle beneath the Morondava basin (maximum value of ∼9 per cent), which is understandable from the strong stretching that the basin was exposed to during the Karoo and subsequent rifting episode. Anisotropy is still significantly positive below the Proterozoic (maximum value of ∼5 per cent) and Archean (maximum value of ∼6 per cent) domains, which may result from lithospheric extension during the Mesozoic and/or thereafter. In the asthenosphere, a positive RA is observed beneath the eastern part Morondava sedimentary basin and the Proterozoic domain, indicating a horizontal asthenospheric flow pattern. Negative RA is found beneath the Archean in the east, suggesting a small-scale asthenospheric upwelling, consistent with previous studies. Alternatively, the relatively high shear wave velocity in the asthenosphere in this region indicate that the negative RA could be associated to the Réunion mantle plume, at least beneath the volcanic formation, along the eastern coast.

scholarly journals Seismic Structure of Local Crustal Earthquakes beneath the Zipingpu Reservoir of Longmenshan Fault Zone

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Haiou Li ◽  
Xiwei Xu ◽  
Wentao Ma ◽  
Ronghua Xie ◽  
Jingli Yuan ◽  
...  
Keyword(s):  
Fault Zone ◽  
Three Dimensional ◽  
P Wave ◽  
The Tibetan Plateau ◽  
Seismic Structure ◽  
Infiltration Depth ◽  
Low Velocity ◽  
Longmenshan Fault Zone ◽  
Velocity Models ◽  
Longmenshan Fault

Three-dimensional P wave velocity models under the Zipingpu reservoir in Longmenshan fault zone are obtained with a resolution of 2 km in the horizontal direction and 1 km in depth. We used a total of 8589 P wave arrival times from 1014 local earthquakes recorded by both the Zipingpu reservoir network and temporary stations deployed in the area. The 3-D velocity images at shallow depth show the low-velocity regions have strong correlation with the surface trace of the Zipingpu reservoir. According to the extension of those low-velocity regions, the infiltration depth directly from the Zipingpu reservoir itself is limited to 3.5 km depth, while the infiltration depth downwards along the Beichuan-Yingxiu fault in the study area is about 5.5 km depth. Results show the low-velocity region in the east part of the study area is related to the Proterozoic sedimentary rocks. The Guanxian-Anxian fault is well delineated by obvious velocity contrast and may mark the border between the Tibetan Plateau in the west and the Sichuan basin in the east.

Geodynamic processes of the continental deep subduction: constraints from the fine crustal structure beneath the Pamir Plateau

2020 ◽  
Author(s):  
Wei Li ◽  
Yun Chen ◽  
Ping Tan ◽  
Xiaohui Yuan
Keyword(s):  
Spatial Configuration ◽  
Spline Interpolation ◽  
Joint Inversion ◽  
Receiver Functions ◽  
Crustal Material ◽  
Seismic Zone ◽  
S Wave ◽  
Low Velocity ◽  
Crust And Upper Mantle ◽  
Intermediate Depth

<p>The Pamir plateau, located north of the western syntaxis of the India­–Eurasia collision system, is regarded as one of the most possible places of the ongoing continental deep subduction. Based on a N-S trending linear seismic array across the Pamir plateau, we use the methods of harmonic analysis of receiver functions and the cubic spline interpolation of surface wave dispersions to coordinate their resolutions, and perform a joint inversion of these datasets to construct a 2-D S-wave velocity model of the crust and uppermost mantle. A spatial configuration among the intermediate-depth seismicity, Moho topography, and low-velocity zone(LVZ)s within the crust and upper mantle is revealed. The intermediate-depth seismic zone is enclosed in a mantle LVZ which extends upward to the crustal root and connects with a lower crustal LVZ in the northern Pamir. Just above it, another crustal LVZ is collocated with a Moho uplift. These results not only further confirm the deep subduction of the Asian lower continental crust beneath the Pamir plateau, but also indicate the importance of the metamorphic dehydration of the subducting continental crustal material in the genesis of the intermediate-depth seismicity and crustal deformation.</p>

Lithospheric structure of the Arabian Shield from joint inversion of P- and S-wave receiver functions and dispersion velocities

2015 ◽  
Vol 65 (2) ◽  
pp. 239-255 ◽  
Author(s):  
Abdullah M. Al-Amri
Keyword(s):  
Green's Functions ◽  
Velocity Structure ◽  
Green’S Functions ◽  
Joint Inversion ◽  
Receiver Functions ◽  
Gulf Of Aqaba ◽  
Arabian Shield ◽  
S Wave ◽  
Velocity Models ◽  
Seismic Networks

Abstract New velocity models of lithospheric thickness and velocity structure have been developed for the Arabian Shield by three tasks: 1) Computing P-Wave Receiver Functions (PRFs) and S-Wave Receiver Functions (SRFs) for all the broadband stations within the Saudi seismic networks. The number of receiver function waveforms depends on the recording time window and quality of the broadband station. 2) Computing ambient noise correlation Green’s functions for all available station pairs within the Saudi seismic networks to image the shear velocity in the crust and uppermost mantle beneath the Arabian Peninsula. Together they provided hundreds of additional, unique paths exclusively sampling the region of interest. Both phase and group velocities for all the resulting empirical Green’s functions have been measured and to be used in the joint inversion. 3) Jointly inverted the PRFs and SRFs obtained in task 1 with dispersion velocities measured on the Green’s functions obtained in task 2 and with fundamental-mode, Rayleigh-wave, group and phase velocities borrowed from the tomographic studies to precisely determine 1D crustal velocity structure and upper mantle. The analysis of the PRFs revealed values of 25-45 km for crustal thickness, with the thin crust next to the Red Sea and Gulf of Aqaba and the thicker crust under the platform, and Vp/Vs ratios in the 1.70-1.80 range, suggesting a range of compositions (felsic to mafic) for the shield’s crust. The migrated SRFs suggest lithospheric thicknesses in the 80-100 km range for portions of the shield close to the Red Sea and Gulf of Aqaba and near the Arabian Gulf. Generally, the novelty of the velocity models developed under this paper has consisted in the addition of SRF data to extend the velocity models down to lithospheric and sub-lithospheric depths.

scholarly journals Preliminary Results of Regional P and S Wave Tomography at Seram, Indonesia

2021 ◽  
Vol 873 (1) ◽  
pp. 012066
Author(s):  
P A Subakti ◽  
M I Sulaiman ◽  
D Y Faimah ◽  
I Madrinovella ◽  
I Herawati ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Shallow Depth ◽  
Double Difference ◽  
S Wave ◽  
Low Velocity ◽  
Seismicity Pattern ◽  
Velocity Models ◽  
Event Distribution ◽  
Wave Tomography ◽  
Subduction System

Abstract The Seram Trough is located in the northern part of Indonesia and has a complex tectonic setting. The uniqueness of these regions lies in the U-shape subduction system. Several models have been proposed in this region, such as one subduction system that has been rotated 90° or 180°, two subduction systems, and one subduction that having a slab roll-back that causes extension systems. In this study, we try to invert velocity and seismicity using double-difference tomography with the target of better imaging the sub-surface structure in the region. We use data catalogue collection from the Indonesian Agency of Meteorology, Climatology, and Geophysics. The length of data is 4 years from January 2015 to December 2019 from 16 permanent stations. Earthquake relocations show a focused hypocenter distribution at shallow depth, and we interpreted some of these shallow depth events are related to the magmatic activity. Event distribution also displays a steep angle of seismicity pattern that represents the dipping subduction slab. Inverted Tomography models show a band of faster velocity models that dip from North to South, suggesting a subductions slab. We also observe a possibility of a tear in the slab from the seismicity pattern and tomogram model. The slower velocity perturbation is seen at shallow depth that may associate with magmatic and frequent shallow seismicity. A possibility of partial melting is also seen with low-velocity zone at a depth of 70 km next to the fast dipping velocity.

Crust-Mantle Kinematics in and around the Hellenic Arc Elucidated by Local Shear Wave Splitting and Receiver Function Analyses

2021 ◽  
Author(s):  
Derya Keleş ◽  
Tuna Eken ◽  
Judith M. Confal ◽  
Tuncay Taymaz
Keyword(s):  
Seismic Anisotropy ◽  
Receiver Function ◽  
Receiver Functions ◽  
Data Sets ◽  
S Wave ◽  
Uppermost Mantle ◽  
Hellenic Arc ◽  
Wave Splitting ◽  
Harmonic Decomposition ◽  
Local Shear

<p>The fundamental knowledge on seismic anisotropy inferred from various data sets can enhance our understanding of its vertical resolution that is critical for a better interpretation of past and current dynamics and resultant crustal and mantle kinematics in the Hellenic Trench and its hinterland. To investigate the nature of deformation zones, we perform both local S-wave splitting (SWS) measurements and receiver functions (RFs) analysis. Our preliminary findings from the harmonic decomposition technique performed on radial and tangential RFs suggest relatively more substantial anisotropic signals in the lower crust and uppermost mantle with respect to upper and middle crustal structure in the region. Apparent anisotropic orientations obtained from RFs harmonic decomposition process show several consistencies with those discovered from local SWS measurements at selected stations. The actual anisotropic orientation for the structures, however, requires further modelling of the receiver functions obtained.</p>

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