Late Cretaceous to Oligocene overlapping plutonic magmatism episodes in the eastern Mesa Central province of Mexico

• Published in: International geology review 2022-03, Vol.64 (5), p.675-697
• Main Authors: Díaz-Bravo, Beatriz A., Barboza-Gudiño, José R., Ortega-Obregón, Carlos, Morales-Gámez, Miguel
• Format: Article
• Language: English
• Subjects: Apatite; arc migration; Biotite; Carbonates; Cooling; Cooling rate; Cretaceous; Eocene; farallon plate; flat-slab subduction; Geochronology; Geochronometry; Igneous rocks; inland magmatism; Isotopes; laramide orogeny; Lava; Magma; Mesa Central Province; mexican crust; Oligocene; Palaeocene; Paleocene; Plutons; Radiometric dating; Rocks; Statistical analysis; Statistical methods; Subduction; Subduction (geology); Subduction zones; Triassic; u-Pb ages; Volcanic rocks; Zircon
• ISSN: 0020-6814; 1938-2839
• DOI: 10.1080/00206814.2021.1871866

Several plutonic bodies are distributed along the northern and eastern margins of the Mesa Central province, intruding mainly clastic and carbonate sedimentary sequences from the Triassic and Cretaceous. In this work, U-Pb ages in zircon and apatite have been obtained using the LA-ICPMS technique in samples from six of these plutons and some possibly related volcanic rocks. In general, intrusive rocks are porphyritic, suggesting a relatively shallow intrusion and are mostly monzogranite to quartz-monzodiorite in composition, displaying biotite and amphibole. According to the geochronological results, the plutonic rocks can be divided into two groups; a group that varies in age from Campanian-Maastrichtian limit up to Paleocene, and a second group that essentially corresponds to the Oligocene, specifically the Rupelian. Unfortunately, the geochronological data on apatites were not conclusive to establish a trajectory or cooling rate and the ages obtained in this mineral phase for several of these bodies are very similar to the age of zircons, which suggests a relatively rapid cooling, very probably associated with shallow depths of emplacement. The statistical analysis of obtained and published ages suggests two periods of significant magmatic activity that occurred essentially during the Late Cretaceous (Campanian) and during the late Eocene (Bartonian and Priabonian). Notably, the plutonic bodies, particularly those of the group of ancient granites (Paleocene-Late Cretaceous) are very far from the ancient subduction zone to which they have been associated, in addition to being spatially close to plutonic rocks of the Eocene and Oligocene. In this sense, the traditional model of magmatic migration originated by the flat subduction of the Farallon plate is not very consistent, so it will be necessary to evaluate or reconsider the geodynamic evolution associated with magmatism for this region, in view to these new data and to those that could be generated later.