One of the most spectacular ranges in southern Mexico is the Sierra Madre de Oaxaca, or Cuicateco terrane. For many decades, the geology of this terrane has been very poorly known despite its critical location between two continental blocks with Grenvillian affinities: Oaxacan Complex to the west and Guichicovi Complex to the east. This map constitutes the first systematic project improving the understanding of the geology of an entire tectonostratigraphic terrane; it covers an area about 45 × 15 km, elongated in a NNW direction and located in the western border of the Cuicateco terrane. The western front of the Cuicatecan mountain range is marked by the Oaxaca fault, a long-lived tectonic boundary that separates the Mesozoic crust constituting the main part of the Cuicateco terrane (proto-oceanic basin) from Precambrian granulites of the Oaxacan Complex in the west. The Late Cretaceous-Paleocene tectonic inversion of the former Early Cretaceous Cuicatecan basin, partly bottomed by oceanic crust, resulted in the imbrications of basement and cover units that are noticeably expressed by multiple thrust faults and folds with top-to-the east kinematics.

1 color plate (approx. 36″ by 40″)