Abstract

CID-VILLEGAS, Gonzalo et al. Late Cretaceous deformation at the border between the Mesa Central and the Sierra Madre Oriental, central Mexico. Bol. Soc. Geol. Mex [online]. 2022, vol.74, n.2, A230222.  Epub June 05, 2023. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2022v74n2a230222.

In central Mexico, two important Cretaceous tectonic events have been identified: the accretion of the Guerrero Terrain (Early Cretaceous) and the beginning of the Mexican Orogen (Late Cretaceous-Paleogene). Both events present a direction of tectonic transport to the northeast in the center of México, and they have been studied both in the Mesa Central and in the Sierra Madre Oriental. However, little study has characterized the contractile deformation in the border between both provinces. In order to contribute to a better understanding of the Late Cretaceous deformation in central Mexico, this research focuses on the border of both provinces, especially in the Juriquilla, San Miguel de Allende localities, and Sierra de los Cuarzos. The objectives of this research were a) Identify the contractile deformation of the Mesozoic rocks in the study area. b) Determine variations in the direction of tectonic transport of the study area concerning the Mesa Central and Sierra Madre Oriental. In this research, new structural data and U-Pb ages in detrital zircon grains are reported. The possibility of having two contractive deformation events is discussed. The D1 event is inferred contemporary to the accretion of the Guerrero Terrain and is observed in the oldest rocks of Sierra de los Cuarzos. On other hand, the maximum deposit ages obtained in San Miguel de Allende and Juriquilla, 110.2 ± 0.8 Ma and 110.5 ± 0.9 Ma (Early Albian), respectively, limit the age of the D2 deformation, being after ~ 110 Ma. Therefore, this resulting deformation contemporaneous with the formation of the Mexican Orogen. Event D2 is observed in all three areas. Through the structural analysis it was determined that D1 has a direction of transport to the southeast, while D2 has a direction of transport to the west-southwest or southwest. These transport directions differ from that of the Guerrero Terrain accretion and from the formation of the Mexican Orogen. This difference in the direction of transport could be the product of retrodeformation, and or heterogeneities in the basement.

Keywords : Cretaceous contractive deformation; structural analysis; tectonic transport; U-Pb geochronology; central Mexico.