Shortening and exhumation of Sierra de Catorce in northeastern Mexico, in light of 40Ar/39Ar illite dating and (U-Th)/He zircon thermochronology

Abstract

Abstract The Sierra de Catorce along the eastern margin of the Mesa Central in central northern Mexico exposes Triassic to Neogene rocks in two deeply incised canyons in the northern portion of the range, permitting a 3D view of structures and mineral fabrics associated with the Mexican Orogen. Triassic siliciclastic units, recording a penetrative deformation, are unconformably covered by less-deformed Jurassic volcaniclastic and fluvial deposits and Upper Jurassic shale and limestone. The shales acted as a regional decollement horizon, facilitating Late Cretaceous and Early Cenozoic thin-skinned shortening, related to the Sierra Madre Oriental fold and thrust belt, and accommodating translation of Cretaceous carbonate in the hanging wall. The post-tectonic Cenozoic cover consists of alluvial deposits and remnants of basaltic flows and cinder cones. The Sierra de Catorce allows for an opportunity to study the structural, temporal, and thermal evolution of internal portions of the Sierra Madre Oriental fold and thrust belt, employing geometric and kinematic structural analysis, optical and Scanning Electronic Microscopy fabric characterization, X-Ray diffraction of clays, 40Ar-39Ar illite dating, and zircon (U–Th)/He dating. Structural cross-cutting relationships point to at least three distinct Late Cretaceous-Paleogene shortening episodes, with the first being associated with initial thrust activity to the area and a second one characterized by intense shortening deformation, while a third and final episode of shortening deformation is only observed on a kilometric scale. 40Ar-39Ar illite ages from bed-parallel sheared layers and decollement zone suggest that after shortening within the Triassic units, bed-parallel shear was localized within Cretaceous carbonate ~91\xa0Ma. Intense shearing occurred along a major decollement horizon within Upper Jurassic calcareous shale at ~69\xa0Ma, resulting in the folding of Cretaceous strata in the hanging wall. Finally, illite 40Ar-39Ar ages recorded late folding of Upper Cretaceous turbidites at ~52\xa0Ma, accompanied by a rapid exhumation, as evidenced by ~50\xa0Ma zircon-He ages. This multiphase history of contractional deformation records the growth and propagation of the internal portion of the orogenic wedge of the Mexican Fold-Thrust belt (MFTB).