Geologic evolution of the Sierra Madre Oriental between Linares, Concepción del Oro, Saltillo, and Monterrey, Mexico

The Sierra Madre Oriental between Saltillo, Monterrey, and Linares shows a bend in structures that strike from approximately N 35° E to about N 35° W. Most of the rocks involved in the Curvature of Monterrey are Mesozoic in age and range from Late Triassic to Late Cretaceous. Large amplitude folds and thrust faults contribute to the structural complexity of this region. The structural trends present in northeast Mexico are the result of the Late Paleocene-Early Eocene Laramide Orogeny, and their different styles of folding are intimately related to the fundamental landforms of Early Mesozoic paleogeography. Relatively mild deformation is shown in the Mesozoic sedimentary cover that overlies the stable paleocontinental basement highs of the Coahuila, La Mula and Monclova Islands, Tamaulipas Archipelago, and El Burro-Peyotes Peninsula. The tight folding observed in the Sierra Madre Oriental is the result of regional northeastward décollement blocked by the basement highs. Two prominent west-northwest-trending lineaments transect the region: herein named the "Boquillas-Sabinas" and "Sierra Mojada-China" Lineaments. Prominent paleogeographic highs lie on the outside of the area bounded by these lineaments, with the area between occupied by major basins and small "islands". Recurrent motion along these lineaments seems likely and movement along them in Early Mesozoic time blocked out the paleogeographic elements discussed in this dissertation. It is proposed in this study that the structural features of northeast Mexico are the result of a sinistral relative movement of southern United States (westward) with respect to northern Mexico (eastward) during the Laramide Orogeny, contemporaneously with a regional décollement event produced by the tilting toward the northeast of the so-called "Unnamed Occidental Continent" . Thus from the detailed study of the mapped structures and stratigraphic sequences at the Curvature of Monterrey, and from detailed interpretations of satellite photographs, the model presented here for the mechanism of deformation of northeast Mexico explains not only the bend in structures at the Curvature of Monterrey, but also most of the structural trends in northeast Mexico, including the en e[]chelon folds in the Sabinas Gulf