The pre-Mesozoic metamorphic basement of Mexico, 1.5 billion years of crustal evolution

The pre-Mesozoic metamorphic geology of Mexico is summarized in this review through the integral analysis of 11 deep orogenic systems composed altogether of more than 20 individual metamorphic complexes that span in age from the Paleoproterozoic (Statherian) to the middle Permian (Roadian, probably extending into the earliest Triassic). Although cropping out in relatively small to very small areas and dispersed throughout the country, their geologic register holds key aspects for the tectonic history of the Earth, which includes the assembly and disruption of the three supercontinents that populated our planet in Proterozoic-Paleozoic times, namely Columbia (Nuna), Rodinia, and Pangea, including the corresponding bordering oceans. Major processes of modem plate tectonics that represent collisional, accretionary, and slab-related orogenic events involving continents and microcontinents, as well as island arcs and oceanic basins, marked the geologic architecture of the Mexican pre-Mesozoic basement, which is essentially composed of lithologies that range from very high pressure eclogites and very high temperature granulites, to those formed at much lower temperatures in the blueschist and greenschist metamorphic facies, or were reworked by partial melting of the deep crust. The secular paleogeographic position and interactions of Mexico with major cratons such as Laurentia, Gondwana and Baltica throughout this time, resulted in a mosaic of tectonostratigraphic terranes, whose correlation with their possible conjugate tectonic systems in other continental plates has proved to be extremely difficult to achieve; consequently, models explaining the origin of evolution of all these orogenic terranes are naturally diverse and controversial. This contribution attempts for the first time to construct a modem geologic synthesis of Mexico dealing with the tectonic evolution of the pre-Mesozoic lithospheric foundations of the country.