U-Pb geochronology of intrusive rocks of northwestern Mesa Central province and Sector Tansversal of Sierra Madre Oriental, Mexico: Time and space distribution of inland Cretaceous-Paleogene magmatism during Mexican orogeny

摘要

At the northwest of Mesa Central province and the Sector Transversal of Sierra Madre Oriental, Mexico, intrusive magmatic rocks that range compositionally from quartz-monzodiorites to monzonites crop out and mainly intrude continental and marine sedimentary sequences ranging from Lower Triassic to Upper Cretaceous in age. Detrital zircon ages from a host sandstone of the most western studied intrusive rock suggest that they derived from a basement similar in age to the Guerrero Terrane. U-Pb age obtained in zircons from intrusive rocks ranges from Late Cretaceous to Oligocene. The analysis of distribution in space and time of these intrusive rocks shows that at the interior of the continent: 1) there are more intrusive rocks of Upper Cretaceous ages than previously thought, and 2) there is a little or null presence of magmatism during Paleocene. These remarkable aspects do not support a model of magmatic migration since similar to 110 Ma from the paleotrech of the western edge of North America, promoted by a change to a slab geometry subduction as has been previously proposed, and it appears that only after the re-establishment of magmatism during Eocene, age and geographic distribution fit within a model of magmatic migration. Therefore, alternative models should be proposed that better explain the distribution in space and time of these magmatic rocks based on subsequent geochemical and isotopic data.