Fluid-filled porosity of magmatic underplates from joint inversion of P and S receiver functions

Vinnik, Lev; Oreshin, Sergey; Makeyeva, Larissa; Dündar, Süleyman

doi:10.1093/gji/ggx067

Cited by 3 publications

(4 citation statements)

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“…According to results along the coincident refraction seismic profile, V p is normal for this part of the area, although it is significantly higher further to the west. This unusual V p / V s could indicate the presence of fluids in the lower crust (Kennedy & van Soest, ; Vinnik et al, ).…”

Section: Discussionmentioning

confidence: 99%

Crustal Structure in Central‐Eastern Greenland From Receiver Functions

et al. 2019

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The crustal structure in the interior of Greenland is largely unknown because of its remote location below the up to 3.4‐km‐thick ice sheet. We present a model of the crustal velocity structure in central‐eastern Greenland based on simultaneous inversion of P and S receiver functions for data acquired at 23 broadband stations between the coast and the center of the ice sheet. The area is believed to mainly include Precambrian basement and includes a part covered by Tertiary volcanic rocks and some sedimentary basins. Our results show a westward deepening Moho from less than 20 km at the coast to 50 km below central Greenland. Crustal S wave velocities are generally 3.75 km/s through the whole crust which may be relatively small for Precambrian areas, and Vp/Vs is generally around 1.73, although slightly higher in central Greenland. In the coastal area we observe anomalously low velocities at the top of the crust. In the volcanic area south of Scoresbysund Fjord this layer has very high Vp/Vs (>2), which indicates a high mafic content and the presence of water‐filled cracks in the basaltic material. In the north, outside the volcanic area, Vp/Vs is normal and the low‐velocity layer probably is instead related to the presence of sedimentary basins. At stations in the center of our study area we find low Vs and high Vp/Vs in the lower crust. Based on the Moho topography, our results do not support Airy type isostasy as explanation of the high topography in eastern Greenland.

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Section: Discussionmentioning

confidence: 99%

Crustal Structure in Central‐Eastern Greenland From Receiver Functions

et al. 2019

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“…Согласно эмпирическому соот-ношению между пористостью и отношением ско-ростей [Peacock et al, 2011], отношение скоростей 2.0 соответствует пористости около 2 %. Ранее вы-сокие оценки отношения скоростей в нижней коре были получены тем же методом для трех станций на территории Сибирского кратона [Vinnik et al, 2017]. Повышенные значения отношения скоро-стей были получены на территории БРЗ при срав-нении скоростей продольных и поперечных волн [Krylov et al, 1991].…”

Section: обсуждение результатовunclassified

“…1 -Siberian сraton; 2 -boundaries of the Baikal rift zone; 3 -main Cenozoic basins: M -Mondy, T -Tunka, ЮБ -South Baikal, ЦБ -Central Baikal, СБ -North Baikal, Бр -Barguzyn, BA -Upper Angara; 4-6 -faults: 4 -normal, 5-thrust, 6 -strike-slip. нас действовать иначе; метод и предыдущий опыт решения этой задачи описаны в статье [Vinnik et al, 2017]. Этот метод связан с совместным обращением приемных функций продольных и поперечных волн.…”

Section: Introductionunclassified

Crust and Mantle of the Baikal Rift Zone From P- And S-Wave Receiver Functions

Vinnik

Oreshin

Tsydypova³

et al. 2017

Geodin. tektonofiz.

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Abstract:We have obtained P-wave and S-wave receiver functions for 10 broadband seismograph stations in the Baikal rift zone (BRZ) and inverted them for seismic velocity models of the crust and upper mantle. The thinnest crust (30-35 km) is found in the Baikal basin, the thickest in the East Sayan uplift (45-50 km). Intermediate values (40 km) are found in the BRZ at distances around 100 km from Lake Baikal. A high (at least 1.8) Vp/Vs ratio is observed in the middle and lower crust. It exceeds 2.0 at some stations. In our opinion, the highest Vp/Vs ratios are due to fluid-filled porosity with a high pore pressure. The seismic lithosphere -asthenosphere boundary (LAB) is manifested by a shear velocity drop from 4.5 km/s to 4.0-4.2 km/s. Beneath the Baikal basin, the LAB is located at a depth not more than 50 km, and the S velocity drop is maximal (10 %). A similar structure is found outside the basin, underneath a segment of the East Sayan uplift. At other locations in the BRZ, a typical depth of the LAB varies from 80 to 90 km. Having considered changes in the depth of the 410 km seismic discontinuity, we cannot find any evidence of an elevated temperature of a hypothetical thermal plume beneath the BRZ.Key words: сrust; Vp/Vs ratio; fluid-filled porosity; mantle; mantle plume; lithosphere -asthenosphere boundary GEODYNAMICS & TECTONOPHYSICS P U B L I S H E D B Y T H E I N S T I T U T E O F T H E E A R T H ' S C R U S T S I B E R I A N B R A N C H O F R U S S I A N A C A D E M Y O F S C I E N C E S R e c e n t G e o d y n a m i c s RESEARCH ARTICLEReceived: August 13, 2017 Revised: September 20, 2017 Recommended by K.Zh. Seminsky Accepted: October 18, 2017For citation : Vinnik L.P., Oreshin S.I., Tsydуpova L.R., Mordvinova V.V., Kobelev M.M., Khritova M.A., Tubanov Ts.A., 2017. Crust and mantle of the Baikal rift zone from P-and S-wave receiver functions.

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“…Although S-wave receiver functions (SRF) have been used previously to image deeper discontinuities within the Earth (e.g. Farra & Vinnik 2000;Zhou et al 2000;Vinnik et al 2017), they have not been used as routinely as PRF because of their lower frequencies.…”

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confidence: 99%

Crustal structure variations in south-central Mexico from receiver functions

Rodríguez-Domínguez

Pérez‐Campos

Montealegre-Cázares

et al. 2019

Geophysical Journal International

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Summary Mexico has a complex geological history that is typified by the distinctive terranes that are found in the south-central region. Crustal thickness variations often correlate with geological terranes that have been altered by several processes in the past, for example aerial or subduction erosion, underplating volcanic material or rifting but few geophysical studies have locally imaged the entire continental crust in Mexico. In this paper, the thickness of three layers of the crust in south-central Mexico is determined. To do this, we use P- and S-wave receiver functions (RF) from 159 seismological broad-band stations. Thanks to its adaptive nature, we use an empirical mode decomposition (EMD) algorithm to reconstruct the RFs into intrinsic mode functions (IMF) in order to enhance the pulses related to internal discontinuities within the crust. To inspect possible lateral variations, the RFs are grouped into quadrants of 90°, and their amplitudes are mapped into the thickness assuming a three-layer model. Using this approach, we identify a shallow sedimentary layer with a thickness in the range of 1–4 km. The upper-crust was estimated to be of a few kilometers (<10 km) thick near the Pacific coast, and thicker, approximately 15 km in central Oaxaca and under the Trans-Mexican Volcanic Belt (TMVB). Close to the Pacific coast, we infer a thin crust of approximately 16 ± 0.9 km, while in central Oaxaca and beneath the TMVB, we observe a thicker crust ranging between 30 and 50 km ± 2.0 km. We observe a crustal thinning, of approximately 6 km, from central Oaxaca (37 ± 1.9 km) towards the Gulf of Mexico, under the Veracruz Basin, where we estimate a crustal thickness of 31.6 ± 1.9 km. The boundary between the upper and lower crust in comparison with the surface of the Moho do not show significant variations other than the depth difference. We observe small crustal variations across the different terranes on the study area, with the thinnest crust located at the Pacific coast and Gulf of Mexico coast. The thickest crust is estimated to be in central Oaxaca and beneath the TMVB.

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Fluid-filled porosity of magmatic underplates from joint inversion of P and S receiver functions

Cited by 3 publications

References 31 publications

Crustal Structure in Central‐Eastern Greenland From Receiver Functions

Crustal Structure in Central‐Eastern Greenland From Receiver Functions

Crust and Mantle of the Baikal Rift Zone From P- And S-Wave Receiver Functions

Crustal structure variations in south-central Mexico from receiver functions

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