The Sierra Madre Oriental Orocline: Paleomagnetism of the Nazas Province in NE Mexico

Curved mountain belts are spectacular natural features that contain crucial 3D information about the tectonic evolution of orogenic systems in the absence of other kinematic markers. The Mesozoic units exposed in the Mexican Fold and Thrust Belt in northeastern Mexico show a striking curvature, whose kinematic history has not been studied. The existing tectonic models of the region simply assumed the shape of the tectonic units as an inherent feature to the orogen. We investigated the kinematic history of this curvature through paleomagnetism and rock magnetism analyses, coupled with an exhaustive review of available published literature. The studied data sets indicate a protracted history of (re)magnetizations that occurred during the Late Jurassic-Paleocene times at least during the Late Jurassic, Cretaceous and early Eocene. More significantly, they show significant counterclockwise rotations in the northern flank of the curvature and moderate clockwise vertical axis rotations along its southern flank. This data set suggests that the Sierra Madre Oriental was a linear belt that experienced oroclinal bending or buckling during the Cretaceous to early Eocene period (120-50 Ma). The geological history of the American Cordillera is complex due to its extensive geological history. We have investigated a section of this Pacific-Panthalassa region: the remarkable curved sector of the Mexican Fold and Thrust Belt in northeastern Mexico. This winding area, known as the Sierra Madre Oriental, potentially holds important clues about the evolution of the North American crust. To contribute to a better understanding of this area and to complement the scarce geophysical and geological studies, we used the magnetic properties of rocks and reviewed existing published research to investigate. We've uncovered a complex history of rock magnetizations with at least two main events dating back to the Late Jurassic and Cretaceous periods. Our findings also reveal that these mountain ranges were rotated from their original position on vertical axes, suggesting they were originally linear and were bent or buckled during the period from approximately 120 to 50 million years ago. With Paleomagnetism we explore the nature of the striking curvature of the Northeastern section of the Mexican Fold-and-Thrust Belt Our study shows evidence of Orocline bending or Buckling during the major horizontal crustal shortening event of the Mesozoic in Mexico