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Published December 2019 | Supplemental Material + Published
Journal Article Open

Crustal structure variations in south-central Mexico from receiver functions

Abstract

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.

Additional Information

© 2019 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 September 30. Received 2019 September 23; in original form 2019 April 11. Published: 03 October 2019. Data and Resources: Broad-band data from the permanent SSN and UV networks is available by request http://www.ssn.unam.mx/doi/networks/mx/). Data from station POCC of CENAPRED should be requested to Ing. Gilberto Pescina (gilberto@cenapred.unam.mx). Data from OxNet is available since mid-2006 to early 2012 at http://tlalocnet.udg.mx/. Data from MASE and VEOX experiments are available from the IRIS Data Management Center, http://service.iris.edu/fdsnws/dataselect/1/. Data from Los Humeros network should be requested to Instituto de Ingeniería, UNAM (www.iingen.unam.mx/, JLermoS@iingen.unam.mx); data from GECO network can be requested to PI X. Pérez-Campos (xyoli@igeofisica.unam.mx) and will be open on 2021. Topography grids were provided by Amante & Eakins (2009). This work was supported by Universidad Nacional Autónoma de Mexico through project UNAM-PAPIIT IN105816, and Consejo Nacional de Ciencia y Tecnología (Conacyt) through project 177676. SSN data was obtained by the Servicio Sismológico Nacional (México), station maintenance, data acquisition and distribution are possible thanks to its personnel. This work is also partly based on seismic data generated from OxNet through an NSF +++Grant EAR-1246944 to M. Brudzinzki. We thank the personnel involved in operation and maintenance of all the stations used in this work. We especially thank Antonio de Jesús Mendoza Carvajal (SSN), and Jorge Real Pérez (Instituto de Geofísica, UNAM) for installing and maintaining the GECO stations and Oscar Díaz-Molina and Luis Salazar-Tlaczani (Instituto de Geofísica, UNAM) for the OxNet operations. We also thank Francisco Córdoba-Montiel (UV), Javier Lermo-Samaniego (Los Humeros) and Gilberto Castelán-Pescina (CENAPRED) for providing data used on this project. We thank the Academic Writing UNAM-Canada program for their assistance in the elaboration of this paper. M. Rodríguez-Domínguez had a Conacyt graduate scholarship. Figs 1, 2 and 6 were made using the Generic Mapping Tools version 4.5.9 (www.soest.hawaii.edu/gmt; Wessel & Smith 1998). Finally, we thank the editor Prof Frederik Simons, Dr Luca Ferrari and an anonymous reviewer for their valuable comments that improved this paper.

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August 22, 2023
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