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.

No abstract

No abstract

No abstract

During Pangea breakup, several Jurassic extensional to transtensional basins were developed all around the world. The boundaries of these basins are major structures that accommodated continental extension during Jurassic time. Therefore, reconstructing the geometry of Jurassic basins is a key factor in identifying the major faults that produced continental attenuation during Pangea breakup. We reconstruct the tectono-sedimentary evolution of the Jurassic Tlaxiaco Basin in southern Mexico using sedimentologic, petrographic, and U-Pb geochronologic data. We show that the northern boundary of the Tlaxiaco Basin was an area of high relief composed of the Paleozoic Acatlán Complex, which was drained to the south by a set of alluvial fans. The WNW-trending Salado River–Axutla fault is exposed directly to the north of the northernmost fan exposures, and it is interpreted as the Jurassic structure that controlled the tectono-sedimentary evolution of the Tlaxiaco Basin at its northern boundary. The eastern boundary is represented by a topographic high composed of the Proterozoic Oaxacan Complex, which was exhumed along the NNW-trending Caltepec fault and was drained to the west by a major meandering river called the Tlaxiaco River. Data presented in this work suggest that continental extension during Pangea breakup was accommodated in Mexico not only by NNW-trending faults associated with the development of the Tamaulipas–Chiapas transform and the opening of the Gulf of Mexico, but also by WNW-trending structures. Our work offers a new perspective for future studies that aim to reconstruct the breakup evolution of western equatorial Pangea.