TECTONO-SEDIMENTARY IMPLICATIONS OF CLASTIC INTERCALATIONS IN THE JURASSIC/CRETACEOUS BOUNDARY WITHIN THE MONTERREY TROUGH, NE MEXICO

Mesozoic sedimentary sequences in northeastern Mexico are dominated by carbonate successions. However, siliciclastic intercalations are reported in the Late Triassic–Middle Jurassic, and Jurassic/Cretaceous boundary. Particularly during the Jurassic/Cretaceous boundary sequences bordered the paleoelements of the Coahuila Block and Tamaulipas Arc, deposited in two major basins: The Monterrey Trough, with the La Casita Formation in the South; and the Sabinas Basin in the North with the Patula Arkose.

This work documents the sedimentological, petrographical, cathodoluminescence, geochemical, and geochronological characteristics, by verifying the results with multivariate statistical methods of compositional data. These methods result in a provenance analysis to understand and improve the depositional models and tectonic history of the NE Mexico.

The La Casita Formation shows ten facies associations interpreted as a deltaic shoreline influenced by wave, tides and fluvial systems with a 15°NW to 10°SE trend. Petrographical, geochemical, and cathodoluminescence analyses evidence rhyolitic, dacitic, andesitic, granodioritic, tuffaceous, and in minor proportion metamorphic source rocks compositions, deposited within an undissected volcanic rift and dissected rift environments. The zircon populations point out the Precambrian basement, Pan-African, Nazas, Permian-Triassic, and the Las Delicias Arcs as the sources of detritus.

The Patula Arkose shows sequences link to fluvial–alluvial process deposited in the central part of Sabinas Basin, with andesitic, granitic, rhyolitic, and metamorphic source rocks compositions, deposited within a dissected rift setting. The zircon family groups indicate the Permian–Triassic and Las Delicias arcs, Coahuila–Texas Craton, Pan–African, and Precambrian rock as the detrital input.

Our results contrast to the classical model of the NE Mexico during Jurassic/Cretaceous boundary which favors a tectonostratigraphic development linked from rift into a passive margin. The results show that the main tectonic control was an extensional process related to left-lateral faults, which develop pull-apart and strike-slip basins, closely related to the emplacement or accretion of the cordilleran arcs and the opening of the Gulf of Mexico.