GEODINAMIC EVENTS DURING THE TECTONIC AND STRATIGRAPHIC EVOLUTION OF THE SISTEMA CORDILLERANO IN THE ZACATERA AND ISTMO DE TEHUANTEPEC, SOUTHEASTERN, MEXICO

The Zacatera is located towards the eastern part of Oaxaca, in the central part of the called Itsmo de Tehuantepec, southeastern México. In this area, outcrop igneous, sedimentary and metamorphic rocks. The basement is represented by Paleozoic igneous and metamorphic rocks. The Mesozoic of the Todos Santos, Mogoñé, el Porvenir, Potrerillo, Paso de Buques y El Grupo Sierra Madre overly these rocks. The “Complejo Ramos Millán” and the “Metamórfico del Cretácico Superior” represent the metamorphic units of Upper Cretaceous.

The sedimentation and the environmental conditions were as a result of the tectonic evolution since Upper Triassic to Upper Cretaceous and it is represented from alluvial fans with volcanic material supply of the Todos Santos Formation, to calcareous-siliciclastic Cretaceous sedimentation of subtidal shallow marine semi-restricted platform.

In the late Cretaceous to the Oligocene-Miocene, a tectonic deformation of the basement as well as the Mesozoic sedimentary cover took place. This deformation gave place to the presence of cataclastic metamorphic rocks from the preexistent igneous and sedimentary units represented by the “Complejo Ramos Millán” and “Cretácico Superior Metamórfico” respectively. The strongest tectonic deformation occurred during the Miocene that led to the displacement of the Macizo de Chiapas towards the northeast and the folding and the final structural configuration of the Sierra de Chiapas.

The understanding of the tectonic evolution of this region of the Sistema Cordillerano in the Istmo de Tehuantepec is very important to define the regional dynamics of the tectonic plates of southern Mexico and the Caribbean region. Finally, the tectonic evolution is related with the geologic evolution of the Golfo de Tehuantepec, Chiapas and Guatemala.