STRUCTURAL STYLES AND STRAIN ORIENTATIONS IN THE BISHOP CAP HILLS OF SOUTH-CENTRAL NEW MEXICO

The Bishop Cap Hills are located in south-central New Mexico and have experienced deformation from Laramide time through the present (Seager, 1981). This deformation can be interpreted by analyzing structures observed in the field. These structures reflect the tectonic history with respect to both regional and local deformation episodes. Well-preserved normal and reverse faulting surfaces exhibit slickenlines indicative of the varying deformational episodes. Essential structural data is easily accessible in the field, and existing maps and cross sections provide an excellent opportunity for a quantitative structural analysis. The focus of this project will be to gather structural data in the field to determine the orientations of faults, folds, bedding planes, and fractures throughout the study area. These field measurements, along with the direction of movement along faults, can be used to calculate the orientations of the stresses that caused faulting. The fault kinematics will be compared to the geometry of folded rock layers in the study area, providing an independent check on the stress field determined from the fault data. Fractures and vein orientations will similarly be assessed and compared to the stress results calculated from the fault data. Microstructures observed in thin sections will be analyzed to provide a more precise understanding of the kinematic processes. This project will result in a model of the paleo-stress directions for different deformational episodes, providing an opportunity to better understand the tectonics of this part of the American southwest.