Crustal Structure beneath Mexico from Receiver Functions

Espíndola, Víctor Hugo; Quintanar, Luis; Espíndola, J. M.

doi:10.1785/0120160152

Cited by 13 publications

(29 citation statements)

References 28 publications

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“…Interestingly enough, this abrupt change in the Moho depth occurs just above where Dougherty and Clayton () propose the existence of a plate tear and it encompasses the same ∼50‐ to 75‐km‐wide zone where they observe a sharp decrease in intraslab seismicity (Figure ). The crustal thickness measurements inferred from this study are, in general, consistent with previous experiments in the area (Espíndola et al, ; Molina‐Garza & Urrutia‐Fucugauchi, ; Urrutia‐Fucugauchi & Flores‐Ruiz, ). However, using a fixed velocity contour to define the Moho can be problematic if other physical processes that are altering the crust's chemistry are present.…”

Section: Resultssupporting

confidence: 91%

“…Coupled with this feature is an extremely sharp topographic gradient that connects the volcanic arc high peaks with the Veracruz basin (altitude drops ∼5,000 m over a horizontal distance of just 120 km; Figure ). Crustal thickness measurements derived from gravity data (Molina‐Garza & Urrutia‐Fucugauchi, ; Urrutia‐Fucugauchi & Flores‐Ruiz, ) and receiver functions (Espíndola et al, ) indicate that a simple isostasy compensation model is insufficient to explain the thickness difference between these two regions. Furthermore, the presence of the nearby late Miocene Anegada High submarine volcanic complex (Ferrari et al, ) and the active Los Tuxtlas Volcanic Field (LTVF) (Nelson et al, ) marks an interruption of arc volcanism that is thought to be associated with the steepening and rollback motion of the slab.…”

Section: Introductionmentioning

confidence: 99%

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Imaging the Eastern Trans‐Mexican Volcanic Belt With Ambient Seismic Noise: Evidence for a Slab Tear

2018

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The eastern sector of the Trans‐Mexican Volcanic Belt (TMVB) is an enigmatic narrow zone that lies just above where the Cocos plate displays a sharp transition in dipping angle in central Mexico. Current plate models indicate that the transition from flat to steeper subduction is continuous through this region, but the abrupt end of the TMVB suggests that the difference in subduction styles is more likely to be accommodated by a slab tear. Based on a high‐resolution shear wave velocity and radial anisotropy model of the region, we argue that a slab tear within South Cocos can explain the abrupt end of the TMVB. We also quantify the azimuthal anisotropy beneath each seismic station and present a well‐defined flow pattern that shows how mantle material is being displaced from beneath the slab to the mantle wedge through the tear in the subducted Cocos plate. We suggest that the toroidal mantle flow formed around the slab edges is responsible for the existence of the volcanic gap in central Mexico. Moreover, we propose that the temperature increase caused by the influx of hot, less dense mantle material flowing through the tear to the Veracruz area may have significant implications for the thermomechanical state of the subducted slab and explain why the intermediate‐depth seismicity ends suddenly at the southern boundary of the Veracruz basin. The composite mantle flow formed by the movement of mantle material through the slab tears in western and southern Mexico may be allowing the Cocos plate to roll back in segments.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Imaging the Eastern Trans‐Mexican Volcanic Belt With Ambient Seismic Noise: Evidence for a Slab Tear

2018

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“…Estimations of crustal thickness in Oaxaca by Espíndola et al (2017) are directly compared with our results due to the similarity of the processes. However, their results seem to overestimate the crustal thickness.…”

Section: Moho Discontinuitymentioning

confidence: 95%

“…Ferrari et al (2012) compiled the crustal thickness using the receiver functions results from the Meso-American Subduction Experiment (MASE, Pérez-Campos et al 2008), the Mapping the Rivera Subduction Zone array (MARS, Yang et al 2009) and the Veracruz-Oaxaca profile (VEOX, Melgar & Pérez-Campos 2011) along with the gravimetric data of Urrutia-Fucugauchi & Flores-Ruiz (1996). Espíndola et al (2017), determined the crustal structure under each of the broad-band seismic stations of the Mexican National Seismological Service Network. In most of these studies, the crustal structure is limited to determining the depth of the Mohorövičić discontinuity (Moho).…”

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confidence: 99%

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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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