ABSTRACT
Sandstone petrography, zircon and apatite U-Pb geochronology, and apatite geochemistry of Early Cretaceous siliciclastic turbidites interbedded with basalt (Chivillas Formation) in the southern Sierra Madre Oriental, Mexico, indicate local provenance from westerly basement sources. Three main detrital populations were observed in both the zircon and apatite geochronology: Meso–Neoproterozoic, Carboniferous–Permian, and Early Cretaceous. Apatite Sr/Y vs light rare earth element discrimination diagrams indicate that most Precambrian grains have affinity with high-grade metamorphic rocks and most Phanerozoic grains with igneous rocks. These results are consistent with derivation from exposed crystalline sources within the Acatlán-Oaxacan block including the Grenvillian Oaxacan Complex, the East Mexico Arc, and the Early Cretaceous continental arc. The compositional disparities observed in individual samples reflect differences in source of individual turbiditic flows comprising the Chivillas Formation. We surmise that various rivers from the northern and southern Acatlán-Oaxacan block drained into the basin during the Early Cretaceous. Furthermore, detrital apatite fission-track analyses of Chivillas sandstones yielded mostly 42–40 Ma ages (Eocene) that post-date the shortening of the Mexican orogen in the southern Sierra Madre Oriental. Thermal models calculated based on track lengths indicate rapid exhumation of Chivillas rocks at 46–36 Ma, which is the time of the development of the Tehuacán Valley and reactivation of the Oaxaca Fault System as a normal fault.
Acknowledgments
This work was supported by PAPIIT-DGAPA-UNAM grant IN101520 to L. Solari and PAPIIT-DGAPA-UNAM grant IA105521 to U. Martens. The first author acknowledges the Consejo Nacional de Ciencia y Tecnología (CONACyT) for providing a master’s degree scholarship and the Sistema Nacional de Investigadores-CONACyT for a research assistant scholarship for the accomplishment of this work. We thank Juan Tomás Vásquez (Centro de Geociencias, Universidad Nacional Autónoma de México) for staining thin sections; Carlos Ortega-Obregón and Ofelia Pérez Arvizu (Centro de Geociencias, Universidad Nacional Autónoma de México) for providing technical assistance during sample preparation and isotopic dating. The Editorial handling of Dr Robert Stern and the careful reviews of Dr Aaron J. Martin and an anonymous reviewer are acknowledged. Their comments significantly improved the manuscript.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2022.2140209