Xyoli Pérez-Campos, YoungHee Kim, Allan Husker, Paul M. Davis, Robert W. Clayton,. Arturo Iglesias, Javier F. Pacheco, Shri K. Singh, Vlad Manea, Micael ...
Reconstructing of Flat Slab Subduction and Detachment beneath Central Mexico Vlad Manea1,2 and Michael Gurnis2 1-Computational Geodynamics Laboratory, Centro de Geociencias, Juriquilla, UNAM, Mexico 2-Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125
Recent tomographic images beneath Central Mexico revealed a perfectly flat slab segment extending several hundreds of km inland [PerezCampos et al., 2008]. Also, the flat slab in not in direct contact with the overlying crust, and a low velocity layer decouples the two plates. Here we present a 3D geodynamic model tailored to realistic paleoreconstruction back to 35 Ma. Using a tracer technique described in details by Manea and Gurnis [2007], the models incorporate a low viscosity wedge and channel down to 300 km. Time-dependent dynamic models are solved using the finite element package CitcomS from CIG. The computations are performed within a spherical domain (r=1300 km, θ= 57°, ϕ=57°). The position of plate boundaries is imposed and set using the GPlates software. The modeling results show that the subduction system in Central Mexico entered into flat slab regime at ~15 Ma. Later, at ~10 Ma, the slab started to break off and by ~5 Ma is completely detached. In Central Mexico the propagation of slab detachment is expressed by a short (2–3 m.y.), eastward-migrating pulse of mafic volcanism that took place from ca. 11.5 to ca. 5 Ma to the North of the present TransMexican Volcanic Belt [Ferrari, 2004]. The onset of flat slab (from volcanic rock dating, Ferrari et al., 1999) took place 17-12 Ma. Our models predict both, the onset of flat slab around 15 Ma and the slab detachment at ~10 Ma.
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Figure. Temperature evolution and the onset of flat slab (~15 Ma) and slab detachment (~10 Ma) in Central Mexico. References Ferrari, L., López-Martinez, M., Aquirre-Díaz, G., and Carrasco-Núñez, G., Space-time patterns of Cenozoic arc volcanism in central México: from the Sierra Madre Occidental to the Mexican Volcanic Belt. Geology, vol. 27, no. 4, pp. 303-306, 1999. Ferrari, L., Slab detachment control on mafic volcanic pulse and mantle heterogeneity in central Mexico, Geology, vol. 32, no. 1, pp. 7780, 2004. Manea, V.C., and Gurnis, M., Subduction zone evolution and low viscosity wedges and channels, Earth and Planetary Science Letters, vol. 264, issues 1-2, pp. 22 – 45, 2007. Xyoli Pérez-Campos, YoungHee Kim, Allan Husker, Paul M. Davis, Robert W. Clayton, Arturo Iglesias, Javier F. Pacheco, Shri K. Singh, Vlad Manea, Micael Gurnis, Flat Slab Subduction in the Vicinity of Mexico City, Geophysical Research Letter, doi:10.1029/2008GL035127, 2008.
