Guide to Key Outcrops for Reconstruction of the Geologic-Tectonic History of Sierra de Catorce: Northeastern Mexico

Abstract

In the Sierra de Catorce, there is an uplifted block in the southernmost Basin and Range province in northern San Luis Potosí, where most of the oldest stratigraphic units of the region are well exposed. The succession includes Upper Triassic siliciclastics consisting of an alternation of fine-grained sandstone and shale layers, interpreted as lateral equivalents to deep marine turbidites, named the Zacatecas Formation, known from several localities to the west in the region. At Real de Catorce, the previously described deposits underlie coarse chaotic deposits which are products of flow events that change upwards in a marine marginal succession that includes the Triassic-Jurassic boundary. Upwards, the succession includes volcanic and volcaniclastic strata related to the Lower to Middle Jurassic Nazas Formation, underlying conglomerate-breccia and red sandstones of the La Joya Formation that represents an erosional or break-up unconformity related to the initial spreading in the Gulf of Mexico Basin. La Joya Formation changes up-section into limestones of the Zuloaga Formation, which resulted from the Middle-Late Jurassic marine transgression. Outcrops in the General Canyon, along the route Carretas-Real de Catorce include typical strata that allow interpretation of the tectonic-paleogeographic evolution of the Late Triassic-Early Jurassic Pacific margin of Mexico, which evolved into extensional to transtensional basins related to the Gulf of Mexico Basin and probably in part, a result of back-arc extension related to the Nazas volcanic arc. Upper Jurassic strata in the region represent the bottom of the marine sedimentary succession deposited in the Central Mexico Basin, a trough shaped subsiding paleogeographic element in Central Mexico during Late Jurassic-Cretaceous time. Finally, we describe some outcrops that illustrate structures produced by contractile deformation (Late Cretaceous-Paleogene) and post-deformational magmatism (Eocene) that occurred in the area.