An Evaluation of Proposed Mechanisms of Slab Flattening in Central Mexico

Skinner, Steven M.; Clayton, Robert W.

doi:10.1007/s00024-010-0200-3

Cited by 36 publications

(26 citation statements)

References 77 publications

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“…Earthquakes are located within the high‐velocity and low‐attenuation slab. The cause of flat subduction in central Mexico is not well understood [ Skinner and Clayton , 2011], and this study does not indicate a mechanism for the flattening.…”

Section: Discussionmentioning

confidence: 79%

Structure of central and southern Mexico from velocity and attenuation tomography

Chen¹,

Clayton²

2012

J. Geophys. Res.

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[1] The 3D V p , V p /V s , P-and S-wave attenuation structure of the Cocos subduction zone in Mexico is imaged using earthquakes recorded by two temporary seismic arrays and local stations. Direct P wave arrivals on vertical components and direct S wave arrivals on transverse components from local earthquakes are used for velocity imaging. Relative delay times for P and PKP phases from teleseismic events are also used to obtain a deeper velocity structure beneath the southern seismic array. Using a spectral-decay method, we calculate a path attenuation operator t* for each P and S waveform from local events, and then invert for 3D spatial variations in attenuation (Q p À1 and Q s À1 ). Inversion results reveal a low-attenuation and high-velocity Cocos slab. The slab dip angle increases from almost flat in central Mexico near Mexico City to about 30 in southern Mexico near the Isthmus of Tehuantepec. High attenuation and low velocity in the crust beneath the Trans-Mexico Volcanic Belt correlate with low resistivity, and are probably related to dehydration of the slab and melting processes. The most pronounced high-attenuation, low-V p and high-V p /V s anomaly is found in the crust beneath the Veracruz Basin. A high-velocity structure dipping into the mantle from the side of Gulf of Mexico coincides with a discontinuity from a receiver functions study, and provides an evidence for the collision between the Yucatán Block and Mexico in the Miocene.

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Section: Discussionmentioning

confidence: 79%

Structure of central and southern Mexico from velocity and attenuation tomography

Chen¹,

Clayton²

2012

J. Geophys. Res.

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“…Numerous ideas have been proposed to explain flat‐slab subduction. Possible hypotheses include a high rate of convergence, young slab age, increased slab buoyancy due to overthickened oceanic crust, the hydration of the mantle wedge, slab suction forces, and the hydration of the oceanic slab mantle [e.g., Stevenson and Turner , 1977; Tovish et al , 1978; Pilger , 1981; Cross and Pilger , 1982; McGeary et al , 1985; Cloos , 1993; Gutscher et al , 2000b; van Hunen et al , 2002; Kopp et al , 2004; van Hunen et al , 2004; Guillaume et al , 2009; Skinner and Clayton , 2010; Gans et al , 2011]. While recent receiver function work in the region suggests that the oceanic crust is moderately overthickened and contributes to the buoyancy of the slab, it is unlikely that this provides all of the necessary buoyancy to maintain flat‐slab subduction [ Gans et al , 2011].…”

Section: Discussionmentioning

confidence: 99%

Shear wave velocities in the Pampean flat‐slab region from Rayleigh wave tomography: Implications for slab and upper mantle hydration

et al. 2012

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[1] The Pampean flat-slab region, located in central Argentina and Chile between 29 and 34 S, is considered a modern analog for Laramide flat-slab subduction within western North America. Regionally, flat-slab subduction is characterized by the Nazca slab descending to $100 km depth, flattening out for $300 km laterally before resuming a more "normal" angle of subduction. Flat-slab subduction correlates spatially with the track of the Juan Fernandez Ridge, and is associated with the inboard migration of deformation and the cessation of volcanism within the region. To better understand flat-slab subduction we combine ambient-noise tomography and earthquake-generated surface wave measurements to calculate a regional 3D shear velocity model for the region. Shear wave velocity variations largely relate to changes in lithology within the crust, with basins and bedrock exposures clearly defined as low-and high-velocity regions, respectively. We argue that subduction-related hydration plays a significant role in controlling shear wave velocities within the upper mantle. In the southern part of the study area, where normal-angle subduction is occurring, the slab is visible as a high-velocity body with a low-velocity mantle wedge above it, extending eastward from the active arc. Where flat-slab subduction is occurring, slab velocities increase to the east while velocities in the overlying lithosphere decrease, consistent with the slab dewatering and gradually hydrating the overlying mantle. The hydration of the slab may be contributing to the excess buoyancy of the subducting oceanic lithosphere, helping to drive flat-slab subduction.

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“…Furthermore, the ''normal'' mineral assemblage in the dipping oceanic crust beneath southern Mexico based on our seismic observation makes the case in central Mexico unique and unusual. The origin of the flat subduction in central Mexico is not clear (Skinner and Clayton, 2010), and the presence of hydrous mantle mineral, talc, in the upper oceanic crust beneath central Mexico may provide a clue to complicated slab dynamics in the past, which lead to the current configuration.…”

Section: Southern Mexicomentioning

confidence: 99%

Distribution of hydrous minerals in the subduction system beneath Mexico

Kim

Clayton

Jackson

2012

Earth and Planetary Science Letters

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

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An Evaluation of Proposed Mechanisms of Slab Flattening in Central Mexico

Cited by 36 publications

References 77 publications

Structure of central and southern Mexico from velocity and attenuation tomography

Structure of central and southern Mexico from velocity and attenuation tomography

Shear wave velocities in the Pampean flat‐slab region from Rayleigh wave tomography: Implications for slab and upper mantle hydration

Distribution of hydrous minerals in the subduction system beneath Mexico

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