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The Cretaceous-Cenozoic major lithologic units and structures of the Sierra Madre del Sur are well known. The Laramide orogeny is generally considered as the cause of the contractile structures, but the details about the migration, kinematics, and intensity of deformation are poorly known. Furthermore, the deformation events responsible for the post-Laramide strike-slip and normal faults have not been identifi ed. In this paper, we document the migration of the deformation events that occurred in southern Mexico from Maastrichtian to Miocene time. We identify different groups of structures representing three successive deformation events, based on the geometry, age, and kinematics of tectonic structures. Deformation migrated from west to east. The fi rst event, corresponding to the Laramide orogeny, occurred during Late Cretaceous time in the Guerrero-Morelos Platform and ended in the middle Eocene in the east within the Veracruz basin. The Oaxacan fault system, which bounds the Acatlan-Oaxacan block to the east, records Laramide shortening. From six structural sections, we interpret the juxtaposition of the Oaxacan complex against the mylonite belt of the Sierra de Juarez, with subsequent uplift of the eastern border of the Oaxacan complex and, fi nally, the gravitational overriding of the sedimentary cover in a radial centripetal arrangement. The second event produced strike-slip faulting during NE-SW horizontal shortening from Eocene to Oligocene time. The third event produced normal and strike-slip faults, indicating NE-SW horizontal extension during Oligocene-Miocene time. Major structures produced during these three deformation events are roughly distributed in an arcuate pattern bounding the block formed by the Acatlan and Oaxacan complexes. Based on this pattern and the relatively less deformed Mesozoic rocks within the Acatlan-Oaxacan block, we interpret that most of the deformation resulted from the impingement of this block on thinner crustal domains adjoining the block.

otros tres límites, este, oeste y sur están formados por sistemas de fallas regionales en los que se ha documentado actividad cenozoica. El límite este lo forma el sistema de fallas Taxco-San Miguel de Allende cuya edad de actividad varía de norte a sur de Oligoceno en la región central (San Luis Potosí) a Mioceno hacia el límite sur (San Miguel de Allende). El límite sur lo forma la falla del Bajío cuya actividad documentada abarca del Oligoceno al Mioceno medio, al igual que el graben de Aguascalientes que constituye la parte sur del límite poniente de la Mesa Central. Hay una gran estructura que constituye el límite de las regiones norte y sur de la Mesa Central y buena parte de su límite occidental. Ese gran sistema de fallas denominado San Luis-Tepehuanes muestra evidencias de actividad durante el Eoceno y Oligoceno, y se puede documentar actividad Plioceno-cuaternaria solamente en su porción NW. Los yacimientos minerales, en especial epitermales, que se conocen en la Mesa Central están localizados, en su gran mayoría, sobre las trazas de esos grandes sistemas de falla. La información disponible permite establecer que esas estructuras ejercieron un control para el emplazamiento de rocas volcánicas, hipabisales y depósitos minerales a lo largo de sus trazas, sin que se pueda precisar los mecanismos por los que se dio ese control.

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