Late Cretaceous–early Tertiary Laramide deformation of the northern Colorado Plateau, Utah and Colorado

Abstract

The structure of the northern Colorado Plateau is dominated by a series of highly asymmetrical, presumably fault-cored anticlines: the Kaibab, Circle Cliffs, Miners Mountain, San Rafael Swell, Monument, and Uncompahgre uplifts. In map view, they are irregularly distributed with widely varying sizes and orientations. In Permian through Jurassic rocks, interpretations of outcrop-scale structures, including jointed Eshelby inclusions, stylolites, en échelon vein arrays, deformation bands and meso-scale faults, show principal stress directions that are consistently oriented within each uplift, but vary considerably between uplifts. In general, the results indicate that there are two groups of uplifts, one of which shows evidence of NE–SW-directed compressive stress, and another which shows evidence of NW–SE-contraction. Because deformation in the sedimentary cover is forced by differential movement of basement fault blocks, cover stress patterns may be interpreted as basement strain patterns. These results are similar to the kinematic interpretations of Kelley and Clinton (1960) and highlight the importance of oblique slip. Finally, examination of structural contours allows the interpretation of basement strain magnitudes and indicates that the major faults are not interconnected.